Articles de revues : « Hess Collection »

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Vuollekoski, H., M. Vogt, V. A. Sinclair, J. Duplissy, H. Järvinen, E. M. Kyrö, R. Makkonen et al. « Estimates of global dew collection potential on artificial surfaces ». Hydrology and Earth System Sciences 19, n^o 1 (29 janvier 2015) : 601–13. http://dx.doi.org/10.5194/hess-19-601-2015.

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Abstract. The global potential for collecting usable water from dew on an artificial collector sheet was investigated by utilizing 34 years of meteorological reanalysis data as input to a dew formation model. Continental dew formation was found to be frequent and common, but daily yields were mostly below 0.1 mm. Nevertheless, some water-stressed areas such as parts of the coastal regions of northern Africa and the Arabian Peninsula show potential for large-scale dew harvesting, as the yearly yield may reach up to 100 L m−2 for a commonly used polyethylene foil. Statistically significant trends were found in the data, indicating overall changes in dew yields of between ±10% over the investigated time period.

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O'Keeffe, Jimmy, Wouter Buytaert, Ana Mijic, Nicholas Brozović et Rajiv Sinha. « The use of semi-structured interviews for the characterisation of farmer irrigation practices ». Hydrology and Earth System Sciences 20, n^o 5 (12 mai 2016) : 1911–24. http://dx.doi.org/10.5194/hess-20-1911-2016.

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Abstract. For the development of sustainable and realistic water security, generating information on the behaviours, characteristics, and drivers of users, as well as on the resource itself, is essential. In this paper we present a methodology for collecting qualitative and quantitative data on water use practices through semi-structured interviews. This approach facilitates the collection of detailed information on actors' decisions in a convenient and cost-effective manner. Semi-structured interviews are organised around a topic guide, which helps lead the conversation in a standardised way while allowing sufficient opportunity for relevant issues to emerge. In addition, they can be used to obtain certain types of quantitative data. While not as accurate as direct measurements, they can provide useful information on local practices and users' insights. We present an application of the methodology on farmer water use in two districts in the state of Uttar Pradesh in northern India. By means of 100 farmer interviews, information was collected on various aspects of irrigation practices, including irrigation water volumes, irrigation cost, water source, and their spatial variability. Statistical analyses of the information, along with data visualisation, are also presented, indicating a significant variation in irrigation practices both within and between districts. Our application shows that semi-structured interviews are an effective and efficient method of collecting both qualitative and quantitative information for the assessment of drivers, behaviours, and their outcomes in a data-scarce region. The collection of this type of data could significantly improve insights on water resources, leading to more realistic management options and increased water security in the future.

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Peters, A., et W. Durner. « Large zero-tension plate lysimeters for soil water and solute collection in undisturbed soils ». Hydrology and Earth System Sciences 13, n^o 9 (18 septembre 2009) : 1671–83. http://dx.doi.org/10.5194/hess-13-1671-2009.

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Abstract. Water collection from undisturbed unsaturated soils to estimate in situ water and solute fluxes in the field is a challenge, in particular if soils are heterogeneous. Large sampling devices are required if preferential flow paths are present. We present a modular plate system that allows installation of large zero-tension lysimeter plates under undisturbed soils in the field. To investigate the influence of the lysimeter on the water flow field in the soil, a numerical 2-D simulation study was conducted for homogeneous soils with uni- and bimodal pore-size distributions and stochastic Miller-Miller heterogeneity. The collection efficiency was found to be highly dependent on the hydraulic functions, infiltration rate, and lysimeter size, and was furthermore affected by the degree of heterogeneity. In homogeneous soils with high saturated conductivities the devices perform poorly and even large lysimeters (width 250 cm) can be bypassed by the soil water. Heterogeneities of soil hydraulic properties result into a network of flow channels that enhance the sampling efficiency of the lysimeter plates. Solute breakthrough into zero-tension lysimeter occurs slightly retarded as compared to the free soil, but concentrations in the collected water are similar to the mean flux concentration in the undisturbed soil. To validate the results from the numerical study, a dual tracer study with seven lysimeters of 1.25×1.25 m area was conducted in the field. Three lysimeters were installed underneath a 1.2 m filling of contaminated silty sand, the others deeper in the undisturbed soil. The lysimeters directly underneath the filled soil material collected water with a collection efficiency of 45%. The deeper lysimeters did not collect any water. The arrival of the tracers showed that almost all collected water came from preferential flow paths.

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Putman, Annie L., et Gabriel J. Bowen. « Technical Note : A global database of the stable isotopic ratios of meteoric and terrestrial waters ». Hydrology and Earth System Sciences 23, n^o 10 (28 octobre 2019) : 4389–96. http://dx.doi.org/10.5194/hess-23-4389-2019.

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Abstract. The hydrogen and oxygen stable isotope ratios of water have been used to identify sources, transport pathways, and phase-change processes within the water cycle, supporting hydrologic, forensic, ecologic, and hydroclimatic investigations. Here, we introduce a unique, open-access, global database of stable water isotope ratios (δ18O, δ17O, and δ2H) from various water types. This database facilitates data preservation, supports standardized metadata collection, and decreases the time investment for meta-analytic research and reference dataset discovery. As of July 2019, the database includes 231 586 samples from 52 210 sites, associated with 218 projects, spanning 1949 through 2019. Key information stored includes the hydrogen and oxygen isotope ratios, water type, collection date and time, site location, and project information. To promote rapid data discovery and collaboration, the database exposes metadata such as data owner contact information of embargoed data, but only permits downloads of public data. The database is supported by two companion apps, one for processing and upload of analytical data from laboratories and the other an iOS application that supports the digital collection of sample metadata.

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Hall, Dorothy K., George A. Riggs, Nicolo E. DiGirolamo et Miguel O. Román. « Evaluation of MODIS and VIIRS cloud-gap-filled snow-cover products for production of an Earth science data record ». Hydrology and Earth System Sciences 23, n^o 12 (20 décembre 2019) : 5227–41. http://dx.doi.org/10.5194/hess-23-5227-2019.

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Abstract. MODerate resolution Imaging Spectroradiometer (MODIS) cryosphere products have been available since 2000 – following the 1999 launch of the Terra MODIS and the 2002 launch of the Aqua MODIS – and include global snow-cover extent (SCE) (swath, daily, and 8 d composites) at 500 m and ∼5 km spatial resolutions. These products are used extensively in hydrological modeling and climate studies. Reprocessing of the complete snow-cover data record, from Collection 5 (C5) to Collection 6 (C6) and Collection 6.1 (C6.1), has provided improvements in the MODIS product suite. Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Collection 1 (C1) snow-cover products at a 375 m spatial resolution have been available since 2011 and are currently being reprocessed for Collection 2 (C2). Both the MODIS C6.1 and the VIIRS C2 products will be available for download from the National Snow and Ice Data Center beginning in early 2020 with the complete time series available in 2020. To address the need for a cloud-reduced or cloud-free daily SCE product for both MODIS and VIIRS, a daily cloud-gap-filled (CGF) snow-cover algorithm was developed for MODIS C6.1 and VIIRS C2 processing. MOD10A1F (Terra) and MYD10A1F (Aqua) are daily, 500 m resolution CGF SCE map products from MODIS. VNP10A1F is the daily, 375 m resolution CGF SCE map product from VIIRS. These CGF products include quality-assurance data such as cloud-persistence statistics showing the age of the observation in each pixel. The objective of this paper is to introduce the new MODIS and VIIRS standard CGF daily SCE products and to provide a preliminary evaluation of uncertainties in the gap-filling methodology so that the products can be used as the basis for a moderate-resolution Earth science data record (ESDR) of SCE. Time series of the MODIS and VIIRS CGF products have been developed and evaluated at selected study sites in the US and southern Canada. Observed differences, although small, are largely attributed to cloud masking and differences in the time of day of image acquisition. A nearly 3-month time-series comparison of Terra MODIS and S-NPP VIIRS CGF snow-cover maps for a large study area covering all or parts of 11 states in the western US and part of southwestern Canada reveals excellent correspondence between the Terra MODIS and S-NPP VIIRS products, with a mean difference of 11 070 km2, which is ∼0.45 % of the study area. According to our preliminary validation of the Terra and Aqua MODIS CGF SCE products in the western US study area, we found higher accuracy of the Terra product compared with the Aqua product. The MODIS CGF SCE data record beginning in 2000 has been extended into the VIIRS era, which should last at least through the early 2030s.

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Mangel, Adam R., Stephen M. J. Moysey et John Bradford. « Reflection tomography of time-lapse GPR data for studying dynamic unsaturated flow phenomena ». Hydrology and Earth System Sciences 24, n^o 1 (14 janvier 2020) : 159–67. http://dx.doi.org/10.5194/hess-24-159-2020.

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Abstract. Ground-penetrating radar (GPR) reflection tomography algorithms allow non-invasive monitoring of water content changes resulting from flow in the vadose zone. The approach requires multi-offset GPR data that are traditionally slow to collect. We automate GPR data collection to reduce the survey time significantly, thereby making this approach to hydrologic monitoring feasible. The method was evaluated using numerical simulations and laboratory experiments that suggest reflection tomography can provide water content estimates to within 5 % vol vol−1–10 % vol vol−1 for the synthetic studies, whereas the empirical estimates were typically within 5 %–15 % of measurements from in situ probes. Both studies show larger observed errors in water content near the periphery of the wetting front, beyond which additional reflectors were not present to provide data coverage. Overall, coupling automated GPR data collection with reflection tomography provides a new method for informing models of subsurface hydrologic processes and a new method for determining transient 2-D soil moisture distributions.

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Assumpção, Thaine H., Ioana Popescu, Andreja Jonoski et Dimitri P. Solomatine. « Citizen observations contributing to flood modelling : opportunities and challenges ». Hydrology and Earth System Sciences 22, n^o 2 (28 février 2018) : 1473–89. http://dx.doi.org/10.5194/hess-22-1473-2018.

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Abstract. Citizen contributions to science have been successfully implemented in many fields, and water resources is one of them. Through citizens, it is possible to collect data and obtain a more integrated decision-making process. Specifically, data scarcity has always been an issue in flood modelling, which has been addressed in the last decades by remote sensing and is already being discussed in the citizen science context. With this in mind, this article aims to review the literature on the topic and analyse the opportunities and challenges that lie ahead. The literature on monitoring, mapping and modelling, was evaluated according to the flood-related variable citizens contributed to. Pros and cons of the collection/analysis methods were summarised. Then, pertinent publications were mapped into the flood modelling cycle, considering how citizen data properties (spatial and temporal coverage, uncertainty and volume) are related to its integration into modelling. It was clear that the number of studies in the area is rising. There are positive experiences reported in collection and analysis methods, for instance with velocity and land cover, and also when modelling is concerned, for example by using social media mining. However, matching the data properties necessary for each part of the modelling cycle with citizen-generated data is still challenging. Nevertheless, the concept that citizen contributions can be used for simulation and forecasting is proved and further work lies in continuing to develop and improve not only methods for collection and analysis, but certainly for integration into models as well. Finally, in view of recent automated sensors and satellite technologies, it is through studies as the ones analysed in this article that the value of citizen contributions, complementing such technologies, is demonstrated.

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Vrebos, D., T. Vansteenkiste, J. Staes, P. Willems et P. Meire. « Water displacement by sewer infrastructure in the Grote Nete catchment, Belgium, and its hydrological regime effects ». Hydrology and Earth System Sciences 18, n^o 3 (26 mars 2014) : 1119–36. http://dx.doi.org/10.5194/hess-18-1119-2014.

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Abstract. Urbanization and especially increases in impervious areas, in combination with the installation of wastewater treatment infrastructure, can impact the runoff from a catchment and river flows in a significant way. These effects were studied for the Grote Nete catchment in Belgium based on a combination of empirical and model-based approaches. Effective impervious area, combined with the extent of the wastewater collection regions, was considered as an indicator for urbanization pressure. It was found that wastewater collection regions ranging outside the boundaries of the natural catchment boundaries caused changes in upstream catchment area between −16 and +3%, and upstream impervious areas between −99 and +64%. These changes lead to important intercatchment water transfers. Simulations with a physically based and spatially distributed hydrological catchment model revealed not only significant impacts of effective impervious area on seasonal runoff volumes but also low and peak river flows. Our results show the importance, as well as the difficulty, of explicitly accounting for these artificial pressures and processes in the hydrological modeling of urbanized catchments.

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Bulcock, H. H., et G. P. W. Jewitt. « Field data collection and analysis of canopy and litter interception in commercial forest plantations in the KwaZulu-Natal Midlands, South Africa ». Hydrology and Earth System Sciences 16, n^o 10 (19 octobre 2012) : 3717–28. http://dx.doi.org/10.5194/hess-16-3717-2012.

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Abstract. It is well accepted that the total evaporation in forested areas is greater than in grasslands, largely due to the differences in the amount of rainfall that is intercepted by the forest canopy and litter and due to higher transpiration rates. However, interception is the least studied of these components of the hydrological cycle. The study aims to measure and quantify the canopy and litter interception by Eucalyptus grandis, Pinus patula and Acacia mearnsii, at the Two Streams research catchment in the KwaZulu-Natal Midlands of South Africa for the three-year period April 2008 to March 2011. The results from this study showed that canopy and litter interception contributed a significant amount of the water evaporated in a forest water balance. The canopy interception by E. grandis, A. mearnsii and P. patula was 14.9%, 27.7% and 21.4% of gross precipitation, respectively, while litter interception was 8.5%, 6.6% and 12.1% of gross precipitation, respectively.

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Michelsen, Nils, Gerrit Laube, Jan Friesen, Stephan M. Weise, Ali Bakhit Ali Bait Said et Thomas Müller. « Technical note : A microcontroller-based automatic rain sampler for stable isotope studies ». Hydrology and Earth System Sciences 23, n^o 6 (19 juin 2019) : 2637–45. http://dx.doi.org/10.5194/hess-23-2637-2019.

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Abstract. Automatic samplers represent a convenient way to gather rain samples for isotope (δ18O and δ2H) and water quality analyses. Yet, most commercial collectors are expensive and do not reduce post-sampling evaporation and the associated isotope fractionation sufficiently. Thus, we have developed a microcontroller-based automatic rain sampler for timer-actuated collection of integral rain samples. Sampling periods are freely selectable (minutes to weeks), and the device is low-cost, simple, robust, and customizable. Moreover, a combination of design features reliably minimizes evaporation from the collection bottles. Evaporative losses were assessed by placing the pre-filled sampler in a laboratory oven with which a diurnal temperature regime (21–31 ∘C) was simulated for 26 weeks. At the end of the test, all bottles had lost less than 1 % of the original water amount, and all isotope shifts were within the analytical precision. These results show that even multi-week field deployments of the device would result in rather small evaporative mass losses and isotope shifts. Hence, we deem our sampler a useful addition to devices that are currently commercially available and/or described in the scientific literature. To enable reproduction, all relevant details on hard- and software are openly accessible.

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Booker, D. J., et M. C. Acreman. « Generalisation of physical habitat-discharge relationships ». Hydrology and Earth System Sciences 11, n^o 1 (17 janvier 2007) : 141–57. http://dx.doi.org/10.5194/hess-11-141-2007.

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Abstract. Physical habitat is increasingly used worldwide as a measure of river ecosystem health when assessing changes to river flows, such as those caused by abstraction. The major drawback with this approach is that defining precisely the relationships between physical habitat and flow for a given river reach requires considerable data collection and analysis. Consequently, widely used models such as the Physical Habitat Simulation (PHABSIM) system are expensive to apply. There is, thus, a demand for rapid methods for defining habitat-discharge relationships from simple field measurements. This paper reports the analysis of data from 63 sites in the UK where PHABSIM has been applied. The results demonstrate that there are strong relationships between single measurements of channel form and river hydraulics and the habitat available for target species. The results can form the basis of a method to estimate sensitivity of physical habitat to flow change by visiting a site at only one flow. Furthermore, the uncertainty in estimates reduces as more information is collected. This allows the user to select the level of investment in data collection appropriate for the desired confidence in the estimates. The method is demonstrated using habitat indicators for different life stages of Atlantic salmon, brown trout, roach and dace.

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Foroozand, Hossein, et Steven V. Weijs. « Objective functions for information-theoretical monitoring network design : what is “optimal” ? » Hydrology and Earth System Sciences 25, n^o 2 (19 février 2021) : 831–50. http://dx.doi.org/10.5194/hess-25-831-2021.

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Abstract. This paper concerns the problem of optimal monitoring network layout using information-theoretical methods. Numerous different objectives based on information measures have been proposed in recent literature, often focusing simultaneously on maximum information and minimum dependence between the chosen locations for data collection stations. We discuss these objective functions and conclude that a single-objective optimization of joint entropy suffices to maximize the collection of information for a given number of stations. We argue that the widespread notion of minimizing redundancy, or dependence between monitored signals, as a secondary objective is not desirable and has no intrinsic justification. The negative effect of redundancy on total collected information is already accounted for in joint entropy, which measures total information net of any redundancies. In fact, for two networks of equal joint entropy, the one with a higher amount of redundant information should be preferred for reasons of robustness against failure. In attaining the maximum joint entropy objective, we investigate exhaustive optimization, a more computationally tractable greedy approach that adds one station at a time, and we introduce the “greedy drop” approach, where the full set of stations is reduced one at a time. We show that no greedy approach can exist that is guaranteed to reach the global optimum.

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Huttenlauch, Anna Blume. « Street Scenes and other Scenes from Berlin - Legal Issues in the Restitution of Art after the Third Reich ». German Law Journal 7, n^o 10 (1 octobre 2006) : 819–31. http://dx.doi.org/10.1017/s2071832200005137.

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The news that Ernst Ludwig Kirchner's painting “Berliner Strassenszene“ (Berlin Street Scene) will be up for sale in New York on November 8, 2006 has stirred up the international art scene for the past two months. The sale was announced shortly after the Berlin state senate had returned the painting to the heirs of its original owners, Jewish art collectors Alfred and Tekla Hess. For the past 26 years the piece had been hanging in the Brücke Museum in Berlin and formed a cornerstone of the museum's expressionist collection. Bought, from public funds, in 1980, for a little over $ 1 Million US, the painting is expected to sell this fall for $ 18 Million to $ 25 Million US.

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Almagro, André, Paulo Tarso S. Oliveira, Antônio Alves Meira Neto, Tirthankar Roy et Peter Troch. « CABra : a novel large-sample dataset for Brazilian catchments ». Hydrology and Earth System Sciences 25, n^o 6 (9 juin 2021) : 3105–35. http://dx.doi.org/10.5194/hess-25-3105-2021.

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Abstract. In this paper, we present the Catchments Attributes for Brazil (CABra), which is a large-sample dataset for Brazilian catchments that includes long-term data (30 years) for 735 catchments in eight main catchment attribute classes (climate, streamflow, groundwater, geology, soil, topography, land cover, and hydrologic disturbance). We have collected and synthesized data from multiple sources (ground stations, remote sensing, and gridded datasets). To prepare the dataset, we delineated all the catchments using the Multi-Error-Removed Improved-Terrain Digital Elevation Model (MERIT DEM) and the coordinates of the streamflow stations provided by the Brazilian Water Agency, where only the stations with 30 years (1980–2010) of data and less than 10 % of missing records were included. Catchment areas range from 9 to 4 800 000 km2, and the mean daily streamflow varies from 0.02 to 9 mm d−1. Several signatures and indices were calculated based on the climate and streamflow data. Additionally, our dataset includes boundary shapefiles, geographic coordinates, and drainage area for each catchment, aside from more than 100 attributes within the attribute classes. The collection and processing methods are discussed, along with the limitations for each of our multiple data sources. CABra intends to improve the hydrology-related data collection in Brazil and pave the way for a better understanding of different hydrologic drivers related to climate, landscape, and hydrology, which is particularly important in Brazil, having continental-scale river basins and widely heterogeneous landscape characteristics. In addition to benefitting catchment hydrology investigations, CABra will expand the exploration of novel hydrologic hypotheses and thereby advance our understanding of Brazilian catchments' behavior. The dataset is freely available at https://doi.org/10.5281/zenodo.4070146 and https://thecabradataset.shinyapps.io/CABra/ (last access: 7 June 2021).

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García, Daniel. « Ilustraciones del presente número : obras de Daniel García ». PSICOANÁLISIS EN LA UNIVERSIDAD, n^o 3 (13 mai 2020) : 175. http://dx.doi.org/10.35305/rpu.v0i3.51.

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Daniel García es artista plastico y ha participado de numerosas muestras individuales y colectivas desde 19181. Su obra integra colecciones publicas y privadas, entre las que se cuentan la del museo Nacional de Bellas Artes (MNBA), el Museo Castagnino+macro de Rosario, el Museo Caraffa de Córdoba, el Museo de Arte Contemporáneo de Salta, el Museo de Arte Contemporánero de Bahia Blanca, el Museo de Arte Latinoamericano de Buenos Aires (MALBA), el fondo Nacional de las Artes y la Hess Collection (Napa Valley, Estados Unidos y colomé, Salta). Durante 25 años ha ilustrado cubiertas de libros para Beatriz Viterbo Editora. ha publicado los libros Casi Boyitas, Yo soy Gilda (junto a Gilda Di Crosta), Un gato que camina solo, (Ivan Rosado, 2014) y Bandido (Ivan Rosado, 2015)

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Rau, Gabriel C., Vincent E. A. Post, Margaret Shanafield, Torsten Krekeler, Eddie W. Banks et Philipp Blum. « Error in hydraulic head and gradient time-series measurements : a quantitative appraisal ». Hydrology and Earth System Sciences 23, n^o 9 (4 septembre 2019) : 3603–29. http://dx.doi.org/10.5194/hess-23-3603-2019.

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Abstract. Hydraulic head and gradient measurements underpin practically all investigations in hydrogeology. There is sufficient information in the literature to suggest that head measurement errors can impede the reliable detection of flow directions and significantly increase the uncertainty of groundwater flow rate calculations. Yet educational textbooks contain limited content regarding measurement techniques, and studies rarely report on measurement errors. The objective of our study is to review currently accepted standard operating procedures in hydrological research and to determine the smallest head gradients that can be resolved. To this aim, we first systematically investigate the systematic and random measurement errors involved in collecting time-series information on hydraulic head at a given location: (1) geospatial position, (2) point of head, (3) depth to water, and (4) water level time series. Then, by propagating the random errors, we find that with current standard practice, horizontal head gradients <10-4 are resolvable at distances ⪆170 m. Further, it takes extraordinary effort to measure hydraulic head gradients <10-3 over distances <10 m. In reality, accuracy will be worse than our theoretical estimates because of the many possible systematic errors. Regional flow on a scale of kilometres or more can be inferred with current best-practice methods, but processes such as vertical flow within an aquifer cannot be determined until more accurate and precise measurement methods are developed. Finally, we offer a concise set of recommendations for water level, hydraulic head and gradient time-series measurements. We anticipate that our work contributes to progressing the quality of head time-series data in the hydrogeological sciences and provides a starting point for the development of universal measurement protocols for water level data collection.

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Ribeiro Neto, A., C. A. Scott, E. A. Lima, S. M. G. L. Montenegro et J. A. Cirilo. « Infrastructure sufficiency in meeting water demand under climate-induced socio-hydrological transition in the urbanizing Capibaribe River basin – Brazil ». Hydrology and Earth System Sciences 18, n^o 9 (8 septembre 2014) : 3449–59. http://dx.doi.org/10.5194/hess-18-3449-2014.

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Abstract. Water availability for a range of human uses will increasingly be affected by climate change, especially in the arid and semiarid tropics. The main objective of this study is to evaluate the infrastructure sufficiency in meeting water demand under climate-induced socio-hydrological transition in the Capibaribe River basin (CRB). The basin has experienced spatial and sectoral (agriculture-to-urban) reconfiguration of water demands. Human settlements that were once dispersed, relying on intermittent sources of surface water, are now larger and more spatially concentrated, which increases water-scarcity effects. Based on the application of linked hydrologic and water-resources models using precipitation and temperature projections of the IPCC SRES (Special Report: Emissions Scenarios) A1B scenario, a reduction in rainfall of 26.0% translated to streamflow reduction of 60.0%. We used simulations from four members of the HadCM3 (UK Met Office Hadley Centre) perturbed physics ensemble, in which a single model structure is used and perturbations are introduced to the physical parameterization schemes in the model (Chou et al., 2012). We considered that the change of the water availability in the basin in the future scenarios must drive the water management and the development of adaptation strategies that will manage the water demand. Several adaptive responses are considered, including water-loss reductions, wastewater collection and reuse, and rainwater collection cisterns, which together have potential to reduce future water demand by 23.0%. This study demonstrates the vulnerabilities of the infrastructure system during socio-hydrological transition in response to hydroclimatic and demand variabilities in the CRB and also indicates the differential spatial impacts and vulnerability of multiple uses of water to changes over time. The simulations showed that the measures proposed and the water from interbasin transfer project of the São Francisco River had a positive impact over the water supply in the basin, mainly for human use. Industry and irrigation will suffer impact unless other measures are implemented for demand control.

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Chalouhi, Nohra, Mario Zanaty, Alex Whiting, Stavropoula Tjoumakaris, David Hasan, Norman Ajiboye, Shannon Hann, Robert H. Rosenwasser et Pascal Jabbour. « Treatment of Ruptured Intracranial Aneurysms With the Pipeline Embolization Device ». Neurosurgery 76, n^o 2 (29 décembre 2014) : 165–72. http://dx.doi.org/10.1227/neu.0000000000000586.

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ABSTRACT BACKGROUND: The pipeline embolization device (PED) has been used for treatment of unruptured aneurysms. Little is known about the use of the PED in ruptured aneurysms. OBJECTIVE: To assess the safety and efficacy of the PED in ruptured intracranial aneurysms. METHODS: This is a case series with prospective data collection on 20 patients with freshly ruptured aneurysms who were treated with PED (with or without adjunctive coiling) at 2 cerebrovascular centers. Patients were loaded with aspirin and clopidogrel or received an infusion of tirofiban intraoperatively. RESULTS: Hunt and Hess grades were I in 7 patients (35%), II in 9 (45%), and III in 4 (20%). The mean duration from hemorrhage to PED placement was 7 ± 7.0 days. A single device was used in all but 1 patient (95%). The procedure was staged in 20%. There was only 1 complication (5%); this was a fatal intraoperative aneurysm dome rupture that occurred during adjunctive coil deployment. Adjunctive coiling was used in 30%. No patient required an invasive procedure after PED placement. Follow-up angiography (mean, 5.3 ± 4.2 months; range, 2-12 months) showed 100% occlusion in 12 (80%) and incomplete occlusion in 3 patients (20%). At latest follow-up, 19 patients achieved a favorable outcome (modified rankin scale 0–2). CONCLUSION: In our preliminary experience, treatment of ruptured aneurysms with the PED was associated with low complication rates, high occlusion rates, and favorable outcomes. These findings suggest that PED may be a safe and effective option for patients with favorable Hunt and Hess grades and aneurysms difficult to treat with conventional methods.

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Musa, Z. N., I. Popescu et A. Mynett. « A review of applications of satellite SAR, optical, altimetry and DEM data for surface water modelling, mapping and parameter estimation ». Hydrology and Earth System Sciences 19, n^o 9 (1 septembre 2015) : 3755–69. http://dx.doi.org/10.5194/hess-19-3755-2015.

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Abstract. Hydrological data collection requires deployment of physical infrastructure like rain gauges, water level gauges, as well as use of expensive equipment like echo sounders. Many countries around the world have recorded a decrease in deployment of physical infrastructure for hydrological measurements; developing countries especially have less of this infrastructure and, where it exists, it is poorly maintained. Satellite remote sensing can bridge this gap, and has been applied by hydrologists over the years, with the earliest applications in water body and flood mapping. With the availability of more optical satellites with relatively low temporal resolutions globally, satellite data are commonly used for mapping of water bodies, testing of inundation models, precipitation monitoring, and mapping of flood extent. Use of satellite data to estimate hydrological parameters continues to increase due to use of better sensors, improvement in knowledge of and utilization of satellite data, and expansion of research topics. A review of applications of satellite remote sensing in surface water modelling, mapping and parameter estimation is presented, and its limitations for surface water applications are also discussed.

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Dorigo, W. A., W. Wagner, R. Hohensinn, S. Hahn, C. Paulik, A. Xaver, A. Gruber et al. « The International Soil Moisture Network : a data hosting facility for global in situ soil moisture measurements ». Hydrology and Earth System Sciences 15, n^o 5 (30 mai 2011) : 1675–98. http://dx.doi.org/10.5194/hess-15-1675-2011.

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Abstract. In situ measurements of soil moisture are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. In addition, long-term time series of in situ soil moisture measurements themselves can reveal trends in the water cycle related to climate or land cover change. Nevertheless, on a worldwide basis the number of meteorological networks and stations measuring soil moisture, in particular on a continuous basis, is still limited and the data they provide lack standardization of technique and protocol. To overcome many of these limitations, the International Soil Moisture Network (ISMN; http://www.ipf.tuwien.ac.at/insitu) was initiated to serve as a centralized data hosting facility where globally available in situ soil moisture measurements from operational networks and validation campaigns are collected, harmonized, and made available to users. Data collecting networks share their soil moisture datasets with the ISMN on a voluntary and no-cost basis. Incoming soil moisture data are automatically transformed into common volumetric soil moisture units and checked for outliers and implausible values. Apart from soil water measurements from different depths, important metadata and meteorological variables (e.g., precipitation and soil temperature) are stored in the database. These will assist the user in correctly interpreting the soil moisture data. The database is queried through a graphical user interface while output of data selected for download is provided according to common standards for data and metadata. Currently (status May 2011), the ISMN contains data of 19 networks and more than 500 stations located in North America, Europe, Asia, and Australia. The time period spanned by the entire database runs from 1952 until the present, although most datasets have originated during the last decade. The database is rapidly expanding, which means that both the number of stations and the time period covered by the existing stations are still growing. Hence, it will become an increasingly important resource for validating and improving satellite-derived soil moisture products and studying climate related trends. As the ISMN is animated by the scientific community itself, we invite potential networks to enrich the collection by sharing their in situ soil moisture data.

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von Freyberg, Jana, Julia L. A. Knapp, Andrea Rücker, Bjørn Studer et James W. Kirchner. « Technical note : Evaluation of a low-cost evaporation protection method for portable water samplers ». Hydrology and Earth System Sciences 24, n^o 12 (8 décembre 2020) : 5821–34. http://dx.doi.org/10.5194/hess-24-5821-2020.

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Abstract. Automated field sampling of streamwater or precipitation for subsequent analysis of stable water isotopes (2H and 18O) is often conducted with off-the-shelf automated samplers. However, when water samples are stored in the field for days and weeks in open bottles inside autosamplers, their isotopic signatures can be altered by evaporative fractionation and vapor mixing. We therefore designed an evaporation protection method which modifies autosampler bottles using a syringe housing and silicone tube, and we tested whether this method reduces evaporative fractionation and vapor mixing in water samples stored for up to 24 d in 6712 full-size portable samplers (Teledyne ISCO, Lincoln, USA). Laboratory and field tests under different temperature and humidity conditions showed that water samples in bottles with evaporation protection were far less altered by evaporative fractionation and vapor mixing than samples in conventional open bottles. Our design is a cost-efficient approach to upgrade the 1 L sample bottles of the ISCO autosamplers, allowing secure water sample collection in warm and dry environments. Our design can be readily adapted (e.g., by using a different syringe size) to fit the bottles used by many other field autosamplers.

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Darling, W. G., et J. C. Talbot. « The O and H stable isotope composition of freshwaters in the British Isles. 1. Rainfall ». Hydrology and Earth System Sciences 7, n^o 2 (30 avril 2003) : 163–81. http://dx.doi.org/10.5194/hess-7-163-2003.

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Abstract. An understanding of the hydrological cycle in stable isotopic terms requires the characterisation of rainfall. This paper reviews existing and new data for the British Isles. Rainfall at the Wallingford (Oxfordshire) collection station was collected daily from November 1979 to October 1980. Large variations in isotopic content were noted, sometimes from day to day. Winter rainfall was similar to summer in amount, and only slightly depleted isotopically. Amount and temperature correlations with δ18O were generally low, only the autumn and winter temperature relationships being significant. A 20-year monthly dataset from 1982 to 2001 for Wallingford gives the following regression: δ2H = 7.0δ18O + 1.2, a slope somewhat below the world meteoric line but consistent with the those from other long-term stations in NW Europe. The data showed uncorrelated maxima and minima for each year, but rather more consistent amount-weighted averages. Although there is only a small difference in gradient between summer and winter rainfall values, when plotted against the month of the year there are clear changes in the values of both isotopes, and the δ2H-δ18O relationship as demonstrated by the d-excess parameter. The isotope-amount correlation is low but significant, with summer months appearing to be well-correlated when considered in terms of month of the year. On this same seasonal basis temperature has a strong correlation throughout the year, giving a positive δ18O-temperature relationship of 0.25 ‰ per °C change. The Wallingford monthly record is compared with data from Keyworth (Nottinghamshire) and the Valentia station of the GNIP (IAEA-WMO Global Network for Isotopes in Precipitation) in SW Ireland. While not large, differences between the stations are broadly attributable to the balance between maritime and continental influences. Over the period September 1981 to August 1982 the maximum number of monthly collection stations was operating across the British Isles. While a comparison of the sites serves mostly to illustrate the variability of British weather in space and time, there is clear isotopic evidence for the predominance of frontal rainfall in winter and convective rainfall in summer. The effect of altitude on isotopic content was measured within a high-relief stream catchment in Scotland. The best correlations occurred during winter, when an average relationship of approximately –0.30 ‰ δ18O per 100 m increase in altitude was observed. It is well established that rainfall isotopic composition changes in response to alterations in climate. However these changes are difficult to detect isotopically in the short term, even when the changes are indexed, e.g. in the form of the NAO (North Atlantic Oscillation). The brief duration of rainfall isotope records is a further hindrance; for the British Isles proxies such as tree-ring cellulose may have some value in extending the record back. Keywords: stable isotopes, rainfall,British Isles

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Doriean, Nicholas J. C., William W. Bennett, John R. Spencer, Alexandra Garzon-Garcia, Joanne M. Burton, Peter R. Teasdale, David T. Welsh et Andrew P. Brooks. « Intensive landscape-scale remediation improves water quality of an alluvial gully located in a Great Barrier Reef catchment ». Hydrology and Earth System Sciences 25, n^o 2 (23 février 2021) : 867–83. http://dx.doi.org/10.5194/hess-25-867-2021.

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Abstract. Gully erosion can be a major disruptor to global fluvial sediment budgets. Gully erosion in the catchments of the Great Barrier Reef is attributed to ∼40 % of fine suspended sediment pollution to the freshwater and marine ecosystems downstream. Mitigating this source of erosion will have a lasting positive impact on the water quality of connected rivers and the receiving marine environment. Here we conduct a preliminary evaluation of the ability of intensive landscape-scale gully remediation to reduce suspended sediment and associated nutrient export from a catchment draining to the Great Barrier Reef. The gully remediation method was a first attempt, in the region, at investing a high level of financial (total cost of remediation AUD ∼90 000) and logistical effort (e.g. intensive earthworks, including the establishment of an on-site quarry) to develop long-lasting erosion mitigation measures (i.e. regraded, compacted, and battered gully walls, rock armouring of banks and channel, and installation of rock check dams). A novel suspended sediment monitoring network, comprised of a suite of new and established automated monitoring methods capable of operating in remote environments, was used to evaluate the water quality of a remediated gully, a control gully, and their respective catchments. The recently developed pumped active suspended sediment (PASS) sampler optimised to sample ephemeral water flows was deployed in gully outlets and catchment runoff flow paths. This study demonstrates how the combination of low- and high-cost water quality monitoring techniques can be deployed in a configuration that ensures sample collection redundancy and complementary data collection between methods. Monitoring was conducted during two consecutive wet seasons and, thus, can only provide preliminary information. Monitoring over longer timescales (i.e. 5–10 years) will need to be carried out in order to validate the findings discussed herein. Samples collected from the remediated gully had significantly lower suspended sediment concentrations compared to the control gully, providing preliminary evidence that the remediation works were successful in stabilising erosion within the gully. Dissolved and particulate nutrient concentrations were also significantly lower in the remediated gully samples, consistent with the decreased suspended sediment concentrations. The novel combination of suspended sediment measurements from both the gully channels and overland flows in the surrounding gully catchments suggests that sediment and nutrients at the remediated site are likely sourced from erosion processes occurring within the catchment of the gully (at relatively low concentrations). In contrast, the primary source of suspended sediment and associated nutrients at the control gully was erosion from within the gully itself. This study demonstrates the potential of landscape-scale remediation as an effective mitigation action for reducing suspended sediment and nutrient export from alluvial gullies. It also provides a useful case study for the monitoring effort required to appropriately assess the effectiveness of this type of erosion control.

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Minkman, Ellen, Maarten van der Sanden et Martine Rutten. « Practitioners' viewpoints on citizen science in water management : a case study in Dutch regional water resource management ». Hydrology and Earth System Sciences 21, n^o 1 (9 janvier 2017) : 153–67. http://dx.doi.org/10.5194/hess-21-153-2017.

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Abstract. In recent years, governmental institutes have started to use citizen science as a form of public participation. The Dutch water authorities are among them. They face pressure on the water governance system and a water awareness gap among the general public, and consider citizen science a possible solution. The reasons for practitioners to engage in citizen science, and in particular those of government practitioners, have seldom been studied. This article aims to pinpoint the various viewpoints of practitioners at Dutch regional water authorities on citizen science. A Q-methodological approach was used because it allows for exploration of viewpoints and statistical analysis using a small sample size. Practitioners (33) at eight different water authorities ranked 46 statements from agree to disagree. Three viewpoints were identified with a total explained variance of 67 %. Viewpoint A considers citizen science a potential solution that can serve several purposes, thereby encouraging citizen participation in data collection and analysis. Viewpoint B considers citizen science a method for additional, illustrative data. Viewpoint C views citizen science primarily as a means of education. These viewpoints show water practitioners in the Netherlands are willing to embrace citizen science at water authorities, although there is no support for higher levels of citizen engagement.

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McCulloch, J. S. G. « All our yesterdays : a hydrological retrospective ». Hydrology and Earth System Sciences 11, n^o 1 (17 janvier 2007) : 3–11. http://dx.doi.org/10.5194/hess-11-3-2007.

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Abstract. This paper traces the development and eventual recognition of hydrology as a scientific subject in its own right in the UK and, later, in the European Geophysical Society (EGS), now the European Geosciences Union (EGU). In the early 1960s, to facilitate decisions of executive government departments in meeting the rapidly increasing demand for industrial and domestic water supplies, a small Hydrological Research Unit (HRU) was established by the UK Department of Scientific and Industrial Research(DSIR) to investigate the comparative water use of forested and grassed upland catchments. These small beginnings in the HRU developed in a few years into the highly multi-disciplinary Institute of Hydrology (IH) as a source of independent advice for policy makers, with a capability to undertake longer term research, monitoring and data collection than was feasible in individual government departments or in the universities. Within IH, the range of specialities included not only engineering, physics, geography, geology, meteorology and instrumentation but also pollution, plant physiology, ecology, chemistry and economics. Said quickly in retrospect, the trajectory of the growth of IH seems smooth but, in reality, it masked many struggles between competing disciplines and departments before hydrology was recognised as a subject in its own right – the science of water.

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Wang, X. P., Z. N. Wang, R. Berndtsson, Y. F. Zhang et Y. X. Pan. « Desert shrub stemflow and its significance in soil moisture replenishment ». Hydrology and Earth System Sciences 15, n^o 2 (11 février 2011) : 561–67. http://dx.doi.org/10.5194/hess-15-561-2011.

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Abstract. Stemflow of xerophytic shrubs represents a significant component of water replenishment to the soil-root system influencing water utilization of plant roots at the stand scale, especially in water scarce desert ecosystems. In this study, stemflow of Caragana korshinskii was quantified by an aluminum foil collar collection method on re-vegetated sand dunes of the Shapotou restored desert ecosystem in northwestern China. Time domain reflectometry probes were inserted horizontally at 20 different soil profile depths under the C. korshinskii shrub to monitor soil moisture variation at hourly intervals. Results indicated that 2.2 mm precipitation was necessary for the generation of stemflow for C. korshinskii. Stemflow averaged 8% of the gross precipitation and the average funnelling ratio was as high as 90. The soil moisture in the uppermost soil profile was strongly correlated with individual rainfall and the stemflow strengthened this relationship. Therefore, it is favourable for the infiltrated water redistribution in the deeper soil profile of the root zone. Consequently, stemflow contributes significantly to a positive soil moisture balance in the root zone and the replenishment of soil moisture at deeper soil layers. This plays an important role in plant survival and the general ecology of arid desert environments.

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Loosvelt, L., H. Vernieuwe, V. R. N. Pauwels, B. De Baets et N. E. C. Verhoest. « Local sensitivity analysis for compositional data with application to soil texture in hydrologic modelling ». Hydrology and Earth System Sciences 17, n^o 2 (1 février 2013) : 461–78. http://dx.doi.org/10.5194/hess-17-461-2013.

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Abstract. Compositional data, such as soil texture, are hard to deal with in the geosciences as standard statistical methods are often inappropriate to analyse this type of data. Especially in sensitivity analysis, the closed character of the data is often ignored. To that end, we developed a method to assess the local sensitivity of a model output with resect to a compositional model input. We adapted the finite difference technique such that the different parts of the input are perturbed simultaneously while the closed character of the data is preserved. This method was applied to a hydrologic model and the sensitivity of the simulated soil moisture content to local changes in soil texture was assessed. Based on a high number of model runs, in which the soil texture was varied across the entire texture triangle, we identified zones of high sensitivity in the texture triangle. In such zones, the model output uncertainty induced by the discrepancy between the scale of measurement and the scale of model application, is advised to be reduced through additional data collection. Furthermore, the sensitivity analysis provided more insight into the hydrologic model behaviour as it revealed how the model sensitivity is related to the shape of the soil moistureretention curve.

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Ferrier, R. C. « The DYNAMO Project : An Introduction ». Hydrology and Earth System Sciences 2, n^o 4 (31 décembre 1998) : 375–83. http://dx.doi.org/10.5194/hess-2-375-1998.

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Abstract. European concerns about the consequences of anthropogenic impacts on environmental quality have led to the establishment of various dynamic modelling approaches through which the consequences of impacts over time can be assessed. Similarly, throughout Europe, there has been extensive collection of regional data on "environmental capital" resulting in the production of wide area mapping of environmental quality (soils, land use etc). The aim of the DYNAMO was to integrate data and models, specifically; (1) to enhance the existing process based models to evaluate the impacts of multiple drivers of environmental change; (2) to evaluate these models at intensively studied (and manipulated) catchments and stands; (3) to scale up in time from observations collected over several years to predict the long term impacts over decades, and (4) to scale up in space from the individual site level to regional, National and European scale. The project aims to develop and enhance regional modelling approaches so that European scale impacts of acidic deposition, land use (forestry practices) and global change can be determined without compromising process level understanding of ecosystem function. The DYNAMO project contributes to the EU TERI (Terrestrial Ecosystems Research Initiative) framework of the Environment and Climate Programme of the European Commission.

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Suárez, F., J. E. Aravena, M. B. Hausner, A. E. Childress et S. W. Tyler. « Assessment of a vertical high-resolution distributed-temperature-sensing system in a shallow thermohaline environment ». Hydrology and Earth System Sciences 15, n^o 3 (30 mars 2011) : 1081–93. http://dx.doi.org/10.5194/hess-15-1081-2011.

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Abstract. In shallow thermohaline-driven lakes it is important to measure temperature on fine spatial and temporal scales to detect stratification or different hydrodynamic regimes. Raman spectra distributed temperature sensing (DTS) is an approach available to provide high spatial and temporal temperature resolution. A vertical high-resolution DTS system was constructed to overcome the problems of typical methods used in the past, i.e., without disturbing the water column, and with resistance to corrosive environments. This paper describes a method to quantitatively assess accuracy, precision and other limitations of DTS systems to fully utilize the capacity of this technology, with a focus on vertical high-resolution to measure temperatures in shallow thermohaline environments. It also presents a new method to manually calibrate temperatures along the optical fiber achieving significant improved resolution. The vertical high-resolution DTS system is used to monitor the thermal behavior of a salt-gradient solar pond, which is an engineered shallow thermohaline system that allows collection and storage of solar energy for a long period of time. The vertical high-resolution DTS system monitors the temperature profile each 1.1 cm vertically and in time averages as small as 10 s. Temperature resolution as low as 0.035 °C is obtained when the data are collected at 5-min intervals.

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Barraqué, B., R. M. Formiga Johnsson et A. L. Nogueira de Paiva Britto. « The development of water services and their interaction with water resources in European and Brazilian cities ». Hydrology and Earth System Sciences 12, n^o 4 (26 août 2008) : 1153–64. http://dx.doi.org/10.5194/hess-12-1153-2008.

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Abstract. The extension and complexity of large cities creates "urban water" and a related issue: public water services, including public water supply, sewage collection and treatment, and storm water control, had previously become a policy sector separate from water resource allocation issues thanks to water transport and treatment technologies. Large metropolitan areas today cannot take nature for granted anymore, and they need to protect water resources, if only to reduce the long term cost of transporting and treating water. In this paper, we compare the historical development of water services in European and Brazilian metropolitan areas, placing the technological developments in their geographic, socio-economic and political contexts. Our frame is to follow the successive contributions of civil engineering, sanitary engineering, and environmental engineering: the "quantity of water" and civil engineering paradigm allowed to mobilise water in and out of the city, and up the hills or the floors; in the "water quality" and chemical/sanitary engineering paradigm, water treatment gave more freedom to cities to take water from rivers closer to them, but also to reduce sewer discharge impacts; lastly, the environmental engineering paradigm proposes to overcome the supply side perspective, by introducing demand side management, water conservation, water allocation flexibilisation, and an integrated approach to water services, water resources management, and land use policies.

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Wilson, T. G., C. Cortis, N. Montaldo et J. D. Albertson. « Development and testing of a large, transportable rainfall simulator for plot-scale runoff and parameter estimation ». Hydrology and Earth System Sciences 18, n^o 10 (22 octobre 2014) : 4169–83. http://dx.doi.org/10.5194/hess-18-4169-2014.

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Abstract. There is increased interest in the interplay between vegetation conditions and overland flow generation. The literature is unclear on this relationship, and there is little quantitative guidance for modeling efforts. Therefore, experimental efforts are needed, and these call for a lightweight transportable plot-scale (>10 m2) rainfall simulator that can be deployed quickly and quickly redeployed over various vegetation cover conditions. Accordingly, a variable-intensity rainfall simulator and collection system was designed and tested in the laboratory and in the field. The system was tested with three configurations of common pressure washing nozzles producing rainfall intensities of 62, 43, and 32 mm h-1 with uniformity coefficients of 76, 65, and 62%, respectively, over a plot of 15.12 m2. Field tests were carried out on a grassy field with silt–loam soil in Orroli, Sardinia, in July and August 2010, and rainfall, soil moisture, and runoff data were collected. The two-term Philip infiltration model was used to find optimal values for the saturated hydraulic conductivity of the soil surface and bulk soil, soil water retention curve slope, and air entry suction head. Optimized hydraulic conductivity values were similar to both the measured final infiltration rate and literature values for saturated hydraulic conductivity. This inexpensive (less than USD 1000) rainfall simulator can therefore be used to identify field parameters needed for hydrologic modeling.

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Anas, Mohamad, Prisca Kiki Wulandari, Destriana Saraswati et Diah Febri Utami. « The Role of Religious Leaders Amid Conflict of Public Resistance to Industrial Activities in Gresik ». KARSA : Journal of Social and Islamic Culture 28, n^o 2 (13 janvier 2021) : 306–36. http://dx.doi.org/10.19105/karsa.v28i2.4069.

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The research constitutes an analysis on the conflict between community in Ujungpangkah, Gresik, East Java and a gas company, PT Aramada Hess (now PGN Saka Energy Indonesia). The research aims at finding a conflict resolution model that is distinctive, appropriate, and successful. To support the qualitative research, data collection methods use purposive sampling, participatory observation techniques, in-depth interviews and document reviews. The collected data are analysed with the theory of mapping C.R. SIPPABIO. The theory under which the researcher applying to understand the role of Ujungpangkah religious leaders in resolving conflicts between the community and PGN Saka Energy Indonesia. As a result, it is found that: 1) public leaders are derived from various groups (fishermen, fishpond entrepreneurs and Islamic boarding school leaders) who positively resolve the conflict; 2) the intervention method is used as conflict resolution with a negotiation model; 3) Ujungpangkah religious leaders become social cohesion in this open conflict.

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Mazzoleni, Maurizio, Martin Verlaan, Leonardo Alfonso, Martina Monego, Daniele Norbiato, Miche Ferri et Dimitri P. Solomatine. « Can assimilation of crowdsourced data in hydrological modelling improve flood prediction ? » Hydrology and Earth System Sciences 21, n^o 2 (14 février 2017) : 839–61. http://dx.doi.org/10.5194/hess-21-839-2017.

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Abstract. Monitoring stations have been used for decades to properly measure hydrological variables and better predict floods. To this end, methods to incorporate these observations into mathematical water models have also been developed. Besides, in recent years, the continued technological advances, in combination with the growing inclusion of citizens in participatory processes related to water resources management, have encouraged the increase of citizen science projects around the globe. In turn, this has stimulated the spread of low-cost sensors to allow citizens to participate in the collection of hydrological data in a more distributed way than the classic static physical sensors do. However, two main disadvantages of such crowdsourced data are the irregular availability and variable accuracy from sensor to sensor, which makes them challenging to use in hydrological modelling. This study aims to demonstrate that streamflow data, derived from crowdsourced water level observations, can improve flood prediction if integrated in hydrological models. Two different hydrological models, applied to four case studies, are considered. Realistic (albeit synthetic) time series are used to represent crowdsourced data in all case studies. In this study, it is found that the data accuracies have much more influence on the model results than the irregular frequencies of data availability at which the streamflow data are assimilated. This study demonstrates that data collected by citizens, characterized by being asynchronous and inaccurate, can still complement traditional networks formed by few accurate, static sensors and improve the accuracy of flood forecasts.

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Viero, Daniele P. « Comment on “Can assimilation of crowdsourced data in hydrological modelling improve flood prediction?” by Mazzoleni et al. (2017) ». Hydrology and Earth System Sciences 22, n^o 1 (10 janvier 2018) : 171–77. http://dx.doi.org/10.5194/hess-22-171-2018.

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Abstract. Citizen science and crowdsourcing are gaining increasing attention among hydrologists. In a recent contribution, Mazzoleni et al. (2017) investigated the integration of crowdsourced data (CSD) into hydrological models to improve the accuracy of real-time flood forecasts. The authors used synthetic CSD (i.e. not actually measured), because real CSD were not available at the time of the study. In their work, which is a proof-of-concept study, Mazzoleni et al. (2017) showed that assimilation of CSD improves the overall model performance; the impact of irregular frequency of available CSD, and that of data uncertainty, were also deeply assessed. However, the use of synthetic CSD in conjunction with (semi-)distributed hydrological models deserves further discussion. As a result of equifinality, poor model identifiability, and deficiencies in model structure, internal states of (semi-)distributed models can hardly mimic the actual states of complex systems away from calibration points. Accordingly, the use of synthetic CSD that are drawn from model internal states under best-fit conditions can lead to overestimation of the effectiveness of CSD assimilation in improving flood prediction. Operational flood forecasting, which results in decisions of high societal value, requires robust knowledge of the model behaviour and an in-depth assessment of both model structure and forcing data. Additional guidelines are given that are useful for the a priori evaluation of CSD for real-time flood forecasting and, hopefully, for planning apt design strategies for both model calibration and collection of CSD.

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Imbach, P., L. Molina, B. Locatelli, O. Roupsard, P. Ciais, L. Corrales et G. Mahé. « Climatology-based regional modelling of potential vegetation and average annual long-term runoff for Mesoamerica ». Hydrology and Earth System Sciences 14, n^o 10 (11 octobre 2010) : 1801–17. http://dx.doi.org/10.5194/hess-14-1801-2010.

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Abstract. Mean annual cycles of runoff, evapotranspiration, leaf area index (LAI) and potential vegetation were modelled for Mesoamerica using the SVAT model MAPSS with different climatology datasets. We calibrated and validated the model after building a comprehensive database of regional runoff, climate, soils and LAI. The performance of several gridded precipitation climatology datasets (CRU, FCLIM, WorldClim, TRMM, WindPPT and TCMF) was evaluated and FCLIM produced the most realistic runoff. Annual runoff was successfully predicted (R2=0.84) for a set of 138 catchments, with a low runoff bias (12%) that might originate from an underestimation of the precipitation over cloud forests. The residuals were larger in small catchments but remained homogeneous across elevation, precipitation, and land-use gradients. Assuming a uniform distribution of parameters around literature values, and using a Monte Carlo-type approach, we estimated an average model uncertainty of 42% of the annual runoff. The MAPSS model was most sensitive to the parameterization of stomatal conductance. Monthly runoff seasonality was mimicked "fairly" in 78% of the catchments. Predicted LAI was consistent with MODIS collection 5 and GLOBCARBON remotely sensed global products. The simulated evapotranspiration:runoff ratio increased exponentially for low precipitation areas, highlighting the importance of accurately modelling evapotranspiration below 1500 mm of annual rainfall with the help of SVAT models such as MAPSS. We propose the first high-resolution (1 km2 pixel) maps combining average long-term runoff, evapotranspiration, leaf area index and potential vegetation types for Mesoamerica.

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Peischl, S., J. P. Walker, C. Rüdiger, N. Ye, Y. H. Kerr, E. Kim, R. Bandara et M. Allahmoradi. « The AACES field experiments : SMOS calibration and validation across the Murrumbidgee River catchment ». Hydrology and Earth System Sciences 16, n^o 6 (22 juin 2012) : 1697–708. http://dx.doi.org/10.5194/hess-16-1697-2012.

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Abstract. Following the launch of the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission on 2 November 2009, SMOS soil moisture products need to be rigorously validated at the satellite's approximately 45 km scale and disaggregation techniques for producing maps with finer resolutions tested. The Australian Airborne Cal/val Experiments for SMOS (AACES) provide the basis for one of the most comprehensive assessments of SMOS data world-wide by covering a range of topographic, climatic and land surface variability within an approximately 500 × 100 km2 study area, located in South-East Australia. The AACES calibration and validation activities consisted of two extensive field experiments which were undertaken across the Murrumbidgee River catchment during the Australian summer and winter season of 2010, respectively. The datasets include airborne L-band brightness temperature, thermal infrared and multi-spectral observations at 1 km resolution, as well as extensive ground measurements of near-surface soil moisture and ancillary data, such as soil temperature, soil texture, surface roughness, vegetation water content, dew amount, leaf area index and spectral characteristics of the vegetation. This paper explains the design and data collection strategy of the airborne and ground component of the two AACES campaigns and presents a preliminary analysis of the field measurements including the application and performance of the SMOS core retrieval model on the diverse land surface conditions captured by the experiments. The data described in this paper are publicly available from the website: http://www.moisturemap.monash.edu.au/aaces.

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Gleeson, T., D. M. Allen et G. Ferguson. « Teaching hydrogeology : a review of current practice ». Hydrology and Earth System Sciences 16, n^o 7 (18 juillet 2012) : 2159–68. http://dx.doi.org/10.5194/hess-16-2159-2012.

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Abstract. Hydrogeology is now taught in a broad spectrum of departments and institutions to students with diverse backgrounds. Successful instruction in hydrogeology thus requires a variety of pedagogical approaches depending on desired learning outcomes and the background of students. We review the pedagogical literature in hydrogeology to highlight recent advances and analyze a 2005 survey among 68 hydrogeology instructors. The literature and survey results suggest there are only ~ 15 topics that are considered crucial by most hydrogeologists and > 100 other topics that are considered crucial by some hydrogeologists. The crucial topics focus on properties of aquifers and fundamentals of groundwater flow, and should likely be part of all undergraduate hydrogeology courses. Other topics can supplement and support these crucial topics, depending on desired learning outcomes. Classroom settings continue to provide a venue for emphasizing fundamental knowledge. However, recent pedagogical advances are biased towards field and laboratory instruction with a goal of bolstering experiential learning. Field methods build on the fundamentals taught in the classroom and emphasize the collection of data, data uncertainty, and the development of vocational skills. Laboratory and computer-based exercises similarly build on theory, and offer an opportunity for data analysis and integration. The literature suggests curricula at all levels should ideally balance field, laboratory, and classroom pedagogy into an iterative and integrative whole. An integrated, iterative and balanced approach leads to greater student motivation and advancement of theoretical and vocational knowledge.

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Faneca Sànchez, M., J. L. Gunnink, E. S. van Baaren, G. H. P. Oude Essink, B. Siemon, E. Auken, W. Elderhorst et P. G. B. de Louw. « Modelling climate change effects on a Dutch coastal groundwater system using airborne electromagnetic measurements ». Hydrology and Earth System Sciences 16, n^o 12 (3 décembre 2012) : 4499–516. http://dx.doi.org/10.5194/hess-16-4499-2012.

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Abstract. The forecast of climate change effects on the groundwater system in coastal areas is of key importance for policy makers. The Dutch water system has been deeply studied because of its complex system of low-lying areas, dunes, land won to the sea and dikes, but nowadays large efforts are still being done to find out the best techniques to describe complex fresh-brackish-saline groundwater dynamic systems. In this paper, we describe a methodology consisting of high-resolution airborne electromagnetic (EM) measurements used in a 3-D variable-density transient groundwater model for a coastal area in the Netherlands. We used the airborne EM measurements in combination with borehole-logging data, electrical conductivity cone penetration tests and groundwater samples to create a 3-D fresh-brackish-saline groundwater distribution of the study area. The EM measurements proved to be an improvement compared to older techniques and provided quality input for the model. With the help of the built 3-D variable-density groundwater model, we removed the remaining inaccuracies of the 3-D chloride field and predicted the effects of three climate scenarios on the groundwater and surface water system. Results showed significant changes in the groundwater system, and gave direction for future water policy. Future research should provide more insight in the improvement of data collection for fresh-brackish-saline groundwater systems as it is of high importance to further improve the quality of the model.

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Hutchins, M. G., S. G. Anthony, R. A. Hodgkinson et P. J. A. Withers. « Modularised process-based modelling of phosphorus loss at farm and catchment scale ». Hydrology and Earth System Sciences 6, n^o 6 (31 décembre 2002) : 1017–30. http://dx.doi.org/10.5194/hess-6-1017-2002.

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Abstract. In recent years, a co-ordinated programme of data collection has resulted in the collation of sub-hourly time-series of hydrological, sediment and phosphorus loss data, together with soil analysis, cropping and management information for two small (< 200 ha) headwater agricultural catchments in the UK Midlands (Rosemaund, Herefordshire and Cliftonthorpe, Leicestershire). These data sets have allowed the dynamics of phosphorus loss to be characterised and the importance of both storm runoff and drainflow to be identified, together with incidental losses following manure and fertiliser additions in contributing to total annual loss. A modularised process-based model has been developed to represent current understanding of the dynamics of phosphorus loss. Modules describing runoff and sediment generation and associated phosphorus adsorption/desorption dynamics are described and tested. In the model, the effect of a growing crop on sediment detachment processes is represented and the stability of topsoil is considered so that, overall, the model is responsive to farm management factors. Importantly, using data sets available from national-scale survey programmes to estimate model parameters, a transferable approach is presented, requiring only sub-hourly rainfall data and field-specific landcover information for application of the model to new sites. Results from application of the model to the hydrological year 1998–99 are presented. Assessment of performance, which suggests that the timing of simulated responses is acceptable, has focused attention on quantifying landscape and in-stream retention and remobilisation processes. Keywords: phosphorus, erosion, process-based modelling, agriculture

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Agarwal, Ankit, Norbert Marwan, Rathinasamy Maheswaran, Ugur Ozturk, Jürgen Kurths et Bruno Merz. « Optimal design of hydrometric station networks based on complex network analysis ». Hydrology and Earth System Sciences 24, n^o 5 (8 mai 2020) : 2235–51. http://dx.doi.org/10.5194/hess-24-2235-2020.

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Abstract. Hydrometric networks play a vital role in providing information for decision-making in water resource management. They should be set up optimally to provide as much information as possible that is as accurate as possible and, at the same time, be cost-effective. Although the design of hydrometric networks is a well-identified problem in hydrometeorology and has received considerable attention, there is still scope for further advancement. In this study, we use complex network analysis, defined as a collection of nodes interconnected by links, to propose a new measure that identifies critical nodes of station networks. The approach can support the design and redesign of hydrometric station networks. The science of complex networks is a relatively young field and has gained significant momentum over the last few years in different areas such as brain networks, social networks, technological networks, or climate networks. The identification of influential nodes in complex networks is an important field of research. We propose a new node-ranking measure – the weighted degree–betweenness (WDB) measure – to evaluate the importance of nodes in a network. It is compared to previously proposed measures used on synthetic sample networks and then applied to a real-world rain gauge network comprising 1229 stations across Germany to demonstrate its applicability. The proposed measure is evaluated using the decline rate of the network efficiency and the kriging error. The results suggest that WDB effectively quantifies the importance of rain gauges, although the benefits of the method need to be investigated in more detail.

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Sinclair, S., et G. G. S. Pegram. « A comparison of ASCAT and modelled soil moisture over South Africa, using TOPKAPI in land surface mode ». Hydrology and Earth System Sciences 14, n^o 4 (6 avril 2010) : 613–26. http://dx.doi.org/10.5194/hess-14-613-2010.

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Abstract. In this paper we compare two independent soil moisture estimates over South Africa. The first estimate is a Soil Saturation Index (SSI) provided by automated real-time computations of the TOPKAPI hydrological model, adapted to run as a collection of independent 1 km cells with centres on a grid with a spatial resolution of 0.125°, at 3 h intervals. The second set of estimates is the remotely sensed ASCAT Surface Soil Moisture product, temporally filtered to yield a Soil Wetness Index (SWI). For the TOPKAPI cells, the rainfall forcing used is the TRMM 3B42RT product, while the evapotranspiration forcing is based on a modification of the FAO56 reference crop evapotranspiration (ET0). ET0 is computed using forecast fields of meteorological variables from the Unified Model (UM) runs done by the South African Weather Service (SAWS); the UM forecast fields were used, because reanalysis is not done by SAWS. To validate these ET0 estimates we compare them with those computed using observed meteorological data at a network of weather stations; they were found to be unbiased with acceptable scatter. Using the rainfall and evapotranspiration forcing data, the percentage saturation of the TOPKAPI soil store is computed as a Soil Saturation Index (SSI), for each of 6984 unconnected uncalibrated TOPKAPI cells at 3 h time-steps. These SSI estimates are then compared with the SWI estimates obtained from ASCAT. The comparisons indicate a good correspondence in the dynamic behaviour of SWI and SSI for a significant proportion of South Africa.

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McClain, M. E., L. Chícharo, N. Fohrer, M. Gaviño Novillo, W. Windhorst et M. Zalewski. « Training hydrologists to be ecohydrologists and play a leading role in environmental problem solving ». Hydrology and Earth System Sciences 16, n^o 6 (22 juin 2012) : 1685–96. http://dx.doi.org/10.5194/hess-16-1685-2012.

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Abstract. Ecohydrology is a relatively new and rapidly growing subject area in the hydrology curriculum. It is a trans-disciplinary science derived from the larger earth systems science movement and examining mutual interactions of the hydrological cycle and ecosystems. It is also an applied science focused on problem solving and providing sound guidance to catchment-scale integrated land and water resources management. The principle spheres of ecohydrology include (i) climate-soil-vegetation-groundwater interactions at the land surface with special implications for land use, food production and climate change; (ii) riparian runoff, flooding, and flow regime dynamics in river corridors with special implications for water supply, water quality, and inland fisheries; and (iii) fluvial and groundwater inputs to lakes/reservoirs, estuaries, and coastal zones with special implications for water quality and fisheries. We propose an educational vision focused on the development of professional and personal competencies to impart a depth of scientific knowledge in the theory and practice of ecohydrology and a breadth of cross-cutting knowledge and skills to enable ecohydrologists to effectively collaborate with associated scientists and communicate results to resource managers, policy-makers, and other stakeholders. In-depth knowledge in hydrology, ecology, and biogeochemistry is emphasized, as well as technical skills in data collection, modeling, and statistical analysis. Cross-cutting knowledge is framed in the context of integrated water resources management. Personal competencies to be fostered in educational programs include creative thinking, cooperation, communication, and leadership. We consider a life-long learning context but highlight the importance of master's level training in the professional formation of ecohydrologists.

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Wang, S., B. J. Fu, G. Y. Gao, X. L. Yao et J. Zhou. « Soil moisture and evapotranspiration of different land cover types in the Loess Plateau, China ». Hydrology and Earth System Sciences 16, n^o 8 (22 août 2012) : 2883–92. http://dx.doi.org/10.5194/hess-16-2883-2012.

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Abstract. We studied the impacts of re-vegetation on soil moisture dynamics and evapotranspiration (ET) of five land cover types in the Loess Plateau in northern China. Soil moisture and temperature variations under grass (Andropogon), subshrub (Artemisia scoparia), shrub (Spiraea pubescens), plantation forest (Robinia pseudoacacia), and crop (Zea mays) vegetation were continuously monitored during the growing season of 2011. There were more than 10 soil moisture pulses during the period of data collection. Surface soil moisture of all of the land cover types showed an increasing trend in the rainy season. Soil moisture under the corn crop was consistently higher than the other surfaces. Grass and subshrubs showed an intermediate moisture level. Grass had slightly higher readings than those of subshrub most of the time. Shrubs and plantation forests were characterized by lower soil moisture readings, with the shrub levels consistently being slightly higher than those of the forests. Despite the greater post-rainfall loss of moisture under subshrub and grass vegetation than forests and shrubs, subshrub and grass sites exhibit a higher soil moisture content due to their greater soil retention capacity in the dry period. The daily ET trends of the forests and shrub sites were similar and were more stable than those of the other types. Soils under subshrubs acquired and retained soil moisture resources more efficiently than the other cover types, with a competitive advantage in the long term, representing an adaptive vegetation type in the study watershed. The interactions between vegetation and soil moisture dynamics contribute to structure and function of the ecosystems studied.

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Wade, A. J., E. J. Palmer-Felgate, S. J. Halliday, R. A. Skeffington, M. Loewenthal, H. P. Jarvie, M. J. Bowes et al. « Hydrochemical processes in lowland rivers : insights from in situ, high-resolution monitoring ». Hydrology and Earth System Sciences 16, n^o 11 (22 novembre 2012) : 4323–42. http://dx.doi.org/10.5194/hess-16-4323-2012.

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Abstract. This paper introduces new insights into the hydrochemical functioning of lowland river systems using field-based spectrophotometric and electrode technologies. The streamwater concentrations of nitrogen species and phosphorus fractions were measured at hourly intervals on a continuous basis at two contrasting sites on tributaries of the River Thames – one draining a rural catchment, the River Enborne, and one draining a more urban system, The Cut. The measurements complement those from an existing network of multi-parameter water quality sondes maintained across the Thames catchment and weekly monitoring based on grab samples. The results of the sub-daily monitoring show that streamwater phosphorus concentrations display highly complex dynamics under storm conditions dependent on the antecedent catchment wetness, and that diurnal phosphorus and nitrogen cycles occur under low flow conditions. The diurnal patterns highlight the dominance of sewage inputs in controlling the streamwater phosphorus and nitrogen concentrations at low flows, even at a distance of 7 km from the nearest sewage treatment works in the rural River Enborne. The time of sample collection is important when judging water quality against ecological thresholds or standards. An exhaustion of the supply of phosphorus from diffuse and multiple septic tank sources during storm events was evident and load estimation was not improved by sub-daily monitoring beyond that achieved by daily sampling because of the eventual reduction in the phosphorus mass entering the stream during events. The results highlight the utility of sub-daily water quality measurements and the discussion considers the practicalities and challenges of in situ, sub-daily monitoring.

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Bailey, R. T., M. Ahmadi, T. K. Gates et M. Arabi. « Spatially distributed influence of agro-environmental factors governing nitrate fate and transport in an irrigated stream–aquifer system ». Hydrology and Earth System Sciences 19, n^o 12 (18 décembre 2015) : 4859–76. http://dx.doi.org/10.5194/hess-19-4859-2015.

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Abstract. Elevated levels of nitrate (NO3) in groundwater systems pose a serious risk to human populations and natural ecosystems. As part of an effort to remediate NO3 contamination in irrigated stream–aquifer systems, this study elucidates agricultural and environmental parameters and processes that govern NO3 fate and transport at the regional (500 km2), local (50 km2), and field scales (< 1 km2). Specifically, the revised Morris sensitivity analysis method was applied to a finite-difference nitrogen cycling and reactive transport model of a regional-scale study site in the lower Arkansas River valley in southeastern Colorado. The method was used to rank the influence of anthropogenic activities and natural chemical processes on NO3 groundwater concentration, NO3 mass leaching, and NO3 mass loading to the Arkansas River from the aquifer. Sensitivity indices were computed for the entire study area in aggregate as well as each canal command area, crop type, and individual grid cells. Results suggest that fertilizer loading, crop uptake, and heterotrophic denitrification govern NO3 fate and transport for the majority of the study area, although their order of influence on NO3 groundwater concentration and mass leaching varies according to crop type and command area. Canal NO3 concentration and rates of autotrophic denitrification, nitrification, and humus decomposition also dominate or partially dominate in other locations. Each factor, with the exception of O2 reduction rate, is the dominating influence on NO3 groundwater concentration at one or more locations within the study area. Results can be used to determine critical processes and key management actions for future data collection and remediation strategies, with efforts able to be focused on localized areas.

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Bandaragoda, C., et B. T. Neilson. « Increasing parameter certainty and data utility through multi-objective calibration of a spatially distributed temperature and solute model ». Hydrology and Earth System Sciences 15, n^o 5 (20 mai 2011) : 1547–61. http://dx.doi.org/10.5194/hess-15-1547-2011.

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Abstract. To support the goal of distributed hydrologic and instream model predictions based on physical processes, we explore multi-dimensional parameterization determined by a broad set of observations. We present a systematic approach to using various data types at spatially distributed locations to decrease parameter bounds sampled within calibration algorithms that ultimately provide information regarding the extent of individual processes represented within the model structure. Through the use of a simulation matrix, parameter sets are first locally optimized by fitting the respective data at one or two locations and then the best results are selected to resolve which parameter sets perform best at all locations, or globally. This approach is illustrated using the Two-Zone Temperature and Solute (TZTS) model for a case study in the Virgin River, Utah, USA, where temperature and solute tracer data were collected at multiple locations and zones within the river that represent the fate and transport of both heat and solute through the study reach. The result was a narrowed parameter space and increased parameter certainty which, based on our results, would not have been as successful if only single objective algorithms were used. We also found that the global optimum is best defined by multiple spatially distributed local optima, which supports the hypothesis that there is a discrete and narrowly bounded parameter range that represents the processes controlling the dominant hydrologic responses. Further, we illustrate that the optimization process itself can be used to determine which observed responses and locations are most useful for estimating the parameters that result in a global fit to guide future data collection efforts.

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Reszler, Christian, Jürgen Komma, Hermann Stadler, Elmar Strobl et Günter Blöschl. « A propensity index for surface runoff on a karst plateau ». Hydrology and Earth System Sciences 22, n^o 12 (30 novembre 2018) : 6147–61. http://dx.doi.org/10.5194/hess-22-6147-2018.

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Abstract. Karst aquifers are an important water resource, but are particularly vulnerable to pollution due to the typically short residence times. As the rainwater runs off on the surface it may collect contamination from faeces and other sources, before infiltrating the surface. It is therefore important to understand the spatial distribution of the frequency of surface runoff in karst areas. This paper proposes a new field-mapping method for the ability of the landscape to produce and convey surface runoff. The mapping method is based on (i) prior spatial information (e.g. geological map, terrain model), (ii) a visual assessment from a distance at the landscape scale (e.g. traces of surface runoff) and (iii) local data collection in the field (e.g. soil moisture, grain size distribution). The focus on variables that can be assessed from a distance in the landscape makes the method suitable for mapping larger areas than traditional field mapping. The mapping method is developed and tested for the 60 km2 Hochschwab area in Austria. The field mapping is used to specify a surface runoff propensity index which is tested against the spatial distribution of observed sink holes in the area. The mapping indicates that, in the study region, runoff occurs much more frequently in the poorly karstified dolomitic areas than in the limestone areas that are highly karstified. On dolomites, low permeable soils or debris prevail, often resulting in a permanent surface drainage network. On karstified limestone, sometimes overlaid by debris, surface runoff only occurs through infiltration excess at high rainfall intensities. Overall the analyses suggest that the mapping method is suitable for efficiently and reliably identifying spatial patterns of the ability of the landscape to produce and convey surface runoff in karst areas.

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Akhtar, M. K., G. A. Corzo, S. J. van Andel et A. Jonoski. « River flow forecasting with artificial neural networks using satellite observed precipitation pre-processed with flow length and travel time information : case study of the Ganges river basin ». Hydrology and Earth System Sciences 13, n^o 9 (10 septembre 2009) : 1607–18. http://dx.doi.org/10.5194/hess-13-1607-2009.

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Abstract. This paper explores the use of flow length and travel time as a pre-processing step for incorporating spatial precipitation information into Artificial Neural Network (ANN) models used for river flow forecasting. Spatially distributed precipitation is commonly required when modelling large basins, and it is usually incorporated in distributed physically-based hydrological modelling approaches. However, these modelling approaches are recognised to be quite complex and expensive, especially due to the data collection of multiple inputs and parameters, which vary in space and time. On the other hand, ANN models for flow forecasting are frequently developed only with precipitation and discharge as inputs, usually without taking into consideration the spatial variability of precipitation. Full inclusion of spatially distributed inputs into ANN models still leads to a complex computational process that may not give acceptable results. Therefore, here we present an analysis of the flow length and travel time as a basis for pre-processing remotely sensed (satellite) rainfall data. This pre-processed rainfall is used together with local stream flow measurements of previous days as input to ANN models. The case study for this modelling approach is the Ganges river basin. A comparative analysis of multiple ANN models with different hydrological pre-processing is presented. The ANN showed its ability to forecast discharges 3-days ahead with an acceptable accuracy. Within this forecast horizon, the influence of the pre-processed rainfall is marginal, because of dominant influence of strongly auto-correlated discharge inputs. For forecast horizons of 7 to 10 days, the influence of the pre-processed rainfall is noticeable, although the overall model performance deteriorates. The incorporation of remote sensing data of spatially distributed precipitation information as pre-processing step showed to be a promising alternative for the setting-up of ANN models for river flow forecasting.

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Verstraeten, W. W., B. Muys, J. Feyen, F. Veroustraete, M. Minnaert, L. Meiresonne et A. De Schrijver. « Comparative analysis of the actual evapotranspiration of Flemish forest and cropland, using the soil water balance model WAVE ». Hydrology and Earth System Sciences 9, n^o 3 (21 septembre 2005) : 225–41. http://dx.doi.org/10.5194/hess-9-225-2005.

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Abstract. This paper focuses on the quantification of the green – vegetation related – water flux of forest stands in the temperate lowland of Flanders. The underlying reason of the research was to develop a methodology for assessing the impact of forests on the hydrologic cycle in comparison to agriculture. The tested approach for calculating the water use by forests was based on the application of the soil water balance model WAVE. The study involved the collection of data from 14 forest stands, the calibration and validation of the WAVE model, and the comparison of the water use (WU) components – transpiration, soil and interception evaporation – between forest and cropland. For model calibration purposes simulated and measured time series of soil water content at different soil depths, period March 2000–August 2001, were compared. A multiple-site validation was conducted as well. Actual tree transpiration calculated with sap flow measurements in three forest stands gave similar results for two of the three stands of pine (Pinus sylvestris L.), but WAVE overestimated the actual measured transpiration for a stand of poplar (Populus sp.). A useful approach to compare the WU components of forest versus cropland is scenario analysis based on the validated WAVE model. The statistical Profile Analysis method was implemented to explore and analyse the simulated WU time series. With an average annual rainfall of 819 mm, the results reveal that forests in Flanders consume more water than agricultural crops. A 30 years average of 491 mm for 10 forests stands versus 398 mm for 10 cropped agricultural fields was derived. The WU components, on yearly basis, also differ between the two land use types (transpiration: 315 mm for forest and 261 mm for agricultural land use; soil evaporation: 47 mm and 131 mm, for forest and cropland, respectively). Forest canopy interception evaporation was estimated at 126 mm, while it was negligible for cropland.

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Dragonetti, Giovanna, Alessandro Comegna, Ali Ajeel, Gian Piero Deidda, Nicola Lamaddalena, Giuseppe Rodriguez, Giulio Vignoli et Antonio Coppola. « Calibrating electromagnetic induction conductivities with time-domain reflectometry measurements ». Hydrology and Earth System Sciences 22, n^o 2 (28 février 2018) : 1509–23. http://dx.doi.org/10.5194/hess-22-1509-2018.

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Abstract. This paper deals with the issue of monitoring the spatial distribution of bulk electrical conductivity, σb, in the soil root zone by using electromagnetic induction (EMI) sensors under different water and salinity conditions. To deduce the actual distribution of depth-specific σb from EMI apparent electrical conductivity (ECa) measurements, we inverted the data by using a regularized 1-D inversion procedure designed to manage nonlinear multiple EMI-depth responses. The inversion technique is based on the coupling of the damped Gauss–Newton method with truncated generalized singular value decomposition (TGSVD). The ill-posedness of the EMI data inversion is addressed by using a sharp stabilizer term in the objective function. This specific stabilizer promotes the reconstruction of blocky targets, thereby contributing to enhance the spatial resolution of the EMI results in the presence of sharp boundaries (otherwise smeared out after the application of more standard Occam-like regularization strategies searching for smooth solutions). Time-domain reflectometry (TDR) data are used as ground-truth data for calibration of the inversion results. An experimental field was divided into four transects 30 m long and 2.8 m wide, cultivated with green bean, and irrigated with water at two different salinity levels and using two different irrigation volumes. Clearly, this induces different salinity and water contents within the soil profiles. For each transect, 26 regularly spaced monitoring soundings (1 m apart) were selected for the collection of (i) Geonics EM-38 and (ii) Tektronix reflectometer data. Despite the original discrepancies in the EMI and TDR data, we found a significant correlation of the means and standard deviations of the two data series; in particular, after a low-pass spatial filtering of the TDR data. Based on these findings, this paper introduces a novel methodology to calibrate EMI-based electrical conductivities via TDR direct measurements. This calibration strategy consists of a linear mapping of the original inversion results into a new conductivity spatial distribution with the coefficients of the transformation uniquely based on the statistics of the two original measurement datasets (EMI and TDR conductivities).

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