To see the other types of publications on this topic, follow the link: Strahler stream order.
Journal articles on the topic 'Strahler stream order'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 28 journal articles for your research on the topic 'Strahler stream order.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Wang, Yichu, Jinren Ni, Yao Yue, et al. "Solving the mystery of vanishing rivers in China." National Science Review 6, no. 6 (2019): 1239–46. http://dx.doi.org/10.1093/nsr/nwz022.
Full textAbstract:
Abstract A major controversy was sparked worldwide by a recent national water census claiming that the number of Chinese rivers with watersheds ≥100 km2 was less than half the previous estimate of 50 000 rivers, which also stimulates debates on the potential causes and consequences. Here, we estimated the number of rivers in terms of stream-segmentation characteristics described by Horton, Strahler and Shreve stream-order rules, as well as their mixed mode for named rivers recorded in the Encyclopedia of Rivers and Lakes in China. As a result, the number of ‘vanishing rivers’ has been found to be highly relevant to statistical specifications in addition to the erroneous inclusion of pseudo-rivers primarily generated in arid or frost-thaw areas. The modified Horton stream-order scheme reasonably depicts the configuration of complete natural streams from headwater to destination, while the Strahler largely projects the fragmentation of the named river networks associated with human aggregation to the hierarchical river systems.
2
Hughes, Robert M., Philip R. Kaufmann, and Marc H. Weber. "National and regional comparisons between Strahler order and stream size." Journal of the North American Benthological Society 30, no. 1 (2011): 103–21. http://dx.doi.org/10.1899/09-174.1.
Full text
3
Lanfear, Kenneth J. "A FAST ALGORITHM FOR AUTOMATICALLY COMPUTING STRAHLER STREAM ORDER 1." JAWRA Journal of the American Water Resources Association 26, no. 6 (1990): 977–81. http://dx.doi.org/10.1111/j.1752-1688.1990.tb01432.x.
Full text
4
Guth, P. L. "Geomorphometry of drainage basins: a global view from the Shuttle Radar Topography Mission." Hydrology and Earth System Sciences Discussions 8, no. 1 (2011): 1929–49. http://dx.doi.org/10.5194/hessd-8-1929-2011.
Full textAbstract:
Abstract. A suite of 42 geomorphometric parameters for each of 26 272 drainage basins larger than 100 km2 from the Hydrosheds Shuttle Radar Topography digital elevation model shows the global distribution of Strahler order for streams and drainage basins; the largest basins are order 9. Many common parameters depend both on the size of the basin, and the scale of the digital elevation model used for the computations. These drainage basins display the typical longitudinal stream profiles, but the major basins tend to be more convex than the smaller basins.
5
Guth, P. L. "Drainage basin morphometry: a global snapshot from the shuttle radar topography mission." Hydrology and Earth System Sciences 15, no. 7 (2011): 2091–99. http://dx.doi.org/10.5194/hess-15-2091-2011.
Full textAbstract:
Abstract. A suite of 42 morphometric parameters for each of 26 272 drainage basins larger than 100 km2 from the Hydrosheds Shuttle Radar Topography digital elevation model shows the global distribution of Strahler order for streams and drainage basins. At the scale of 15 arc s spacing (232 to 464 m) the largest basins are order 9. Many common parameters depend both on the size of the basin, and the scale of the digital elevation model used for the computations. These drainage basins display the typical longitudinal stream profiles, but the major basins tend to be generally more concave than the smaller basins.
6
Prepas, Ellie E., Gordon Putz, Daniel W. Smith, Janice M. Burke, and J. Douglas MacDonald. "The FORWARD Project: Objectives, framework and initial integration into a Detailed Forest Management Plan in Alberta." Forestry Chronicle 84, no. 3 (2008): 330–37. http://dx.doi.org/10.5558/tfc84330-3.
Full textAbstract:
The Forest Watershed and Riparian Disturbance (FORWARD) project input into the Millar Western Forest Products Ltd. Detailed Forest Management Plan consists of three main components: 1) watershed and stream layer maps and associated datasets; 2) soil and wetland layer maps and associated datasets; and 3) a lookup table that permits planners to determine runoff coefficients (the variable selected for hydrological modelling) for functional first order watersheds, based upon various site factors and time since disturbance. The watershed and stream layer component includes a hydrological network, a Digital Elevation Model, and Strahler classified streams and watersheds for functional first and third order watersheds in the entire Millar Western Forest Management Agreement area. Relatively coarse mineral soils (which drain quickly) and wetlands (which retain water) were the key features that needed to be identified for the FORWARD modelling effort; therefore, the soil and wetland layers represent a combined soil texture and wetland coverage. The runoff coefficient lookup table integrates predictions of hydrologic impacts of harvest into planning. Key words: forest management, watershed, hydrology, stream, soils, wetlands, modelling
7
Turner, Peter A., Timothy J. Griffis, Xuhui Lee, John M. Baker, Rodney T. Venterea, and Jeffrey D. Wood. "Indirect nitrous oxide emissions from streams within the US Corn Belt scale with stream order." Proceedings of the National Academy of Sciences 112, no. 32 (2015): 9839–43. http://dx.doi.org/10.1073/pnas.1503598112.
Full textAbstract:
N2O is an important greenhouse gas and the primary stratospheric ozone depleting substance. Its deleterious effects on the environment have prompted appeals to regulate emissions from agriculture, which represents the primary anthropogenic source in the global N2O budget. Successful implementation of mitigation strategies requires robust bottom-up inventories that are based on emission factors (EFs), simulation models, or a combination of the two. Top-down emission estimates, based on tall-tower and aircraft observations, indicate that bottom-up inventories severely underestimate regional and continental scale N2O emissions, implying that EFs may be biased low. Here, we measured N2O emissions from streams within the US Corn Belt using a chamber-based approach and analyzed the data as a function of Strahler stream order (S). N2O fluxes from headwater streams often exceeded 29 nmol N2O-N m−2⋅s−1 and decreased exponentially as a function of S. This relation was used to scale up riverine emissions and to assess the differences between bottom-up and top-down emission inventories at the local to regional scale. We found that the Intergovernmental Panel on Climate Change (IPCC) indirect EF for rivers (EF5r) is underestimated up to ninefold in southern Minnesota, which translates to a total tier 1 agricultural underestimation of N2O emissions by 40%. We show that accounting for zero-order streams as potential N2O hotspots can more than double the agricultural budget. Applying the same analysis to the US Corn Belt demonstrates that the IPCC EF5r underestimation explains the large differences observed between top-down and bottom-up emission estimates.
8
Gleyzer, Alexander, Michael Denisyuk, Alon Rimmer, and Yigal Salingar. "A FAST RECURSIVE GIS ALGORITHM FOR COMPUTING STRAHLER STREAM ORDER IN BRAIDED AND NONBRAIDED NETWORKS." Journal of the American Water Resources Association 40, no. 4 (2004): 937–46. http://dx.doi.org/10.1111/j.1752-1688.2004.tb01057.x.
Full text
9
Mallmann, P., A. Montibeller, F. Hino, et al. "DATA MINING APPLIED FOR DETERMINING STREAM FLOW PERMANENCE." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2020 (August 21, 2020): 131–35. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2020-131-2020.
Full textAbstract:
Abstract. Streamflow permanence is an aspect of great legal importance in Brazil, because streams, depending on their flow regime, are protected or not by law. Various methods, from field methods to computational methods, are used to determine the flow regime of streams, however some are too time spending and computational methods usually need gaging information as input. Furthermore, computational methods used to extract drainage networks do not identify the flow regimes of streams, and modelled drainage networks always need to be refined manually, as some authors indicate that up to 55% of modelled drainage length is ephemeral in some cases. This work proposes a semi-automatic computational method to determine the flow regime of first order streams, which uses 11 morphometric attributes of the mini drainage basins of these streams to develop a classification model using decision tree algorithms. WEKA package was used to perform the data mining process, which resulted on the development of a compact 8 node decision tree. Ten-fold stratified cross-validation was used to validate the model, which obtained an accuracy rate of 70%. The drainage network of the study area extracted with the classical approach was refined after the result of the classification was obtained. Quantitative analysis of channel length by Strahler order shows an overall reduction of 25% in channel length after refinement was undertaken, and for 1st order streams, as much as 31% were classified as ephemeral. Modelling the drainage areas of headwater streams represents a new approach to determining stream flow permanence, and inclusion of new attributes in the model may yield better results in future research.
10
Remmel, Tarmo K., Kenton W. Todd, and James Buttle. "A comparison of existing surficial hydrological data layers in a low-relief forested Ontario landscape with those derived from a LiDAR DEM." Forestry Chronicle 84, no. 6 (2008): 850–65. http://dx.doi.org/10.5558/tfc84850-6.
Full textAbstract:
The current provincial-extent digital elevation model (DEM) and corresponding hydrological maps for Ontario have been produced using traditional photogrammetry and aerial photograph interpretation. This process is labour-intensive and requires visual interpretation of stereo image pairs. The ground surface and small hydrological features may be inaccurately delineated in areas where vegetation is dense or the ground is otherwise shielded from aerial view. In an effort to improve and automate delineation of hydrological features, we examined the behaviour and final products of the D8 flowrouting algorithm in 2 software environments (TAS and TauDEM for ArcGIS) operating on a high spatial resolution DEM derived using canopy-penetrating light detection and ranging (LiDAR) technology in a pilot study in the Romeo Malette Forest (41.25°N, 81.50°W). Filtered LiDAR data points (5-m spacing) were interpolated using IDW, TIN, and splines, each resulting in a 2.5-m spatial resolution DEM. Results demonstrate improved realism in the characterization of surficial hydrology by LIDAR derived products as compared to applying identical algorithms on existing coarser provincial data. Benefits include the ability to represent streams of lower Strahler order to define crisp watershed boundaries, and the more accurate identification of local depressions that form potentially wet sites. This approach identifies wet sites that should be avoided during forest operations (e.g., skidder traffic) and can provide additional information for trail layout, road planning, and water crossings. By increasing the number of uses of LiDAR, the capital investment in these data becomes increasingly palatable for forest companies interested in obtaining detailed plans of their forest holdings. Key words: LiDAR, DEM, OBM, spatial resolution, interpolation, Strahler stream order, flow routing, topographic wetness
11
حمد بن أحمد التويجري, حمد بن أحمد التويجري. "Wadi Al-Mashqar in Al-Majmaah: Al-Morphometric Study using Digital." journal of King Abdulaziz University Arts And Humanities 28, no. 14 (2020): 274–80. http://dx.doi.org/10.4197/art.28-14.8.
Full textAbstract:
morphometric analysis plays a major role in assessment of rivers and dry basins. This study aims to determine the morphometric variables of the Wadi Al-Mashqar basin, which is one of the most important wadies in the Arriyadh region. The wadi outlet crosses through Al-Majma’ah city and confluences with the Al Kalbi wadi, which adds to the importance of the study, as over the last decades, Al-Majma’ah city has witnessed various flooding events. DEM was used as the main source data to extract morphometric characteristics. GIS was used as a tool to analyze the factors. Wadi Al-Mashqar ranks a five, according to Strahler stream order, with a total of 425 streams and total length of 627 km. The results indicate that the limited impact of torrential rain on the urban area in Al-Majma’ah city is due to the low drainage density, which averages 1.2 km/km2, as this leads to a slow impact of torrents.
12
Vasconcelos, Vitor Vieira, Omar Pereira Campos, and Paulo Pereira Martins Junior. "Perfil Geomorfológico de Maturidade da Bacia do Rio Paracatu (Geomorphological maturity profile of the Paracatu river basin )." Revista Brasileira de Geografia Física 9, no. 6 (2016): 2075. http://dx.doi.org/10.26848/rbgf.v9.6.p2075-2081.
Full textAbstract:
Apresenta-se uma avaliação da maturidade do perfil geomorfológico da Bacia do Rio Parcatu, afluente do Rio São Francisco. As relações entre comprimento e queda média dos seguimentos de rios para cada ordem pelo método de Strahler são analizados por leis empíricas para comparação com um perfil teórico de máximo equilíbrio. Os resultados demonstram que a Bacia do Rio Paracatu está próxima de seu estágio máximo de maturidade, embora ainda não o tenha alcançado completamente. A partir do estudo aplicado, são tecidas reflexões sobre as possibilidades de investigação de bacias hidrográficas com base em abordagens de entropia, meta-estabilidade, geovulnerabilidade e evolução geomorfológica. A B S T R A C T An assessment of the maturity of the geomorphological profile of the Paracatu River Basin, a tributary of the São Francisco River, is presented. The relationship between length and average stream fall for each order using the Strahler method is analysed using empirical laws for a comparison to a theoretical profile of maximum equilibrium. The results show that the Paracatu River Basin is close to its maximum stage of maturity, though it has not achieved it completely. Based on this study, reflections are made about the possibilities to study this watershed based on entropy approaches, metastability, geological vulnerability and geomorphological evolution. Keywords: Equilibrium profile, entropy, metastability, geovulnerability, geomorphological evolution, Paracatu.
13
C.J, Pavithra, Balakrishna H.B, and Aravinda P.T. "MORPHOMETRIC ANAYSIS OF THE MAJOR VALLEY SYSTEMS AROUND BENGALURU." International Journal of Advanced Research 9, no. 07 (2021): 991–1002. http://dx.doi.org/10.21474/ijar01/13202.
Full textAbstract:
The three major Valley systems of Bengaluru namely Vrishabhavathi Valley, Hebbal Valley and Kormangala-Challaghatta Valley houses many lakes and play a very important role in its hydrological processes. The morphometric analysis helps us to learn about the characteristics of the underlying rock type, pervious nature of soil, slope gradients, runoff behavior and water retention potential within the Valley systems. Morphometric analysis was carried out for Linear, areal and relief aspects. The Survey of India topographical maps and Digital Elevation Model data were used to prepare the base map and the drainage maps with the help of GIS software. The Strahler system of stream ranking was adopted. Among the three Valleys, Vrishabhavathi Valley is observed to be the largest Valley in terms of area and perimeter. Vrishabhavathi Valley basin has sixth order stream as the highest stream order where as the other two Valleys have fifth order stream as the highest order. The drainage pattern formed within the Valley systems was observed to be dendritic. The watershed shape factor showed that the Vrishabhavathi Valley is elongated in shape where as the K-C Valley and the Hebbal Valleys are less elongated in shape comparatively. The drainage density of the three Valleys revealed that they fall under coarse drainage density classification. The relief aspects of the three Valleys exhibit low reliefs indicating a flat surface. This helps in designing a sustainable management plan for the three major Valley systems in terms of their conservation and also ensure sustainable soil and water usage within the Valley systems.
14
Key, Marcus M., Patrick N. Wyse Jackson, and Louis J. Vitiello. "Stream channel network analysis applied to colony-wide feeding structures in a Permian bryozoan from Greenland." Paleobiology 37, no. 2 (2011): 287–302. http://dx.doi.org/10.1666/10008.1.
Full textAbstract:
Colony-wide feeding currents are a common feature of many bryozoan colonies. These feeding currents are centered on excurrent macular chimneys that expel previously filtered water away from the colony surface. In some bryozoans these macular chimneys consist of a branching channel network that converges at a point in the center of the chimney. The bifurcating channels of the maculae are analogous to a stream channel network in a closed basin with centripetal drainage. The classical methods of stream channel network analysis from geomorphology are here used to quantitatively analyze the number and length of macular channels in bryozoans. This approach is applied to a giant branch of the trepostome bryozoan Tabulipora from the Early Permian Kim Fjelde Formation in North Greenland. Its large size allowed 18 serial tangential peels to be made through the 8-mm-thick exozone. The peels intersected two stellate maculae as defined by contiguous exilapores. The lengths of 1460 channels radiating from the maculae were measured and their Horton-Strahler stream order and Shreve magnitude scored.We hypothesize that if fossil bryozoan maculae function as excurrent water chimneys, then they should conform to Horton's laws of stream networks and behave like closed basins with centripetal drainage. Results indicate that the stellate maculae in this bryozoan behaved liked stream channel networks exhibiting landscape maturation and stream capture. They conformed to the Law of Stream Number. They have a Bifurcation Ratio that falls within the range of natural stream channel networks. They showed a pattern opposite that expected by the Law of Stream Lengths in response to behavior characteristic of a centripetal drainage pattern in a closed basin. Thus, the stellate maculae in this bryozoan probably functioned as excurrent water chimneys with the radiating channels serving to efficiently collect the previously filtered water, conducting it to the central chimney for expulsion away from the colony surface.
15
Ducharne, A. "Importance of stream temperature to climate change impact on water quality." Hydrology and Earth System Sciences 12, no. 3 (2008): 797–810. http://dx.doi.org/10.5194/hess-12-797-2008.
Full textAbstract:
Abstract. The sensitivity of some aspects of water quality to climate change was assessed in the Seine River (France) with the biogeochemical model RIVERSTRAHLER, which describes the transformations and fluxes of C, N, P and Si between the main microbiological populations, the water column and the sediment, along the entire river network. Point and diffuse sources are prescribed, stream temperature undergoes a sinusoidal annual cycle constrained by observations, and runoff is calculated by a physically-based land surface model. The reference simulation, using meteorological forcing of 1986–1990 and point sources of 1991, compares very well with observations. The climate change simulated by a general circulation model under the SRES emission scenario A2 was used to simulate the related changes in runoff and stream temperature. To this end, a statistical analysis was undertaken of the relationships between the water and air temperatures in the Seine watershed over 1993–1999, using 88 points that correctly sampled the variability of the tributaries. Most of stream temperature variance was explained by the lagged moving average of air temperature, with parameters that depended on Strahler stream order. As an interesting simplification, stream temperature changes could be approximated by air temperature changes. This modelling framework was used to analyse of the relative influence of the water warming and discharge reduction induced by climate change on biogeochemical water quality in Paris and downstream. Discharge reduction increased phytoplankton growth and oxygen deficits. Water warming decreased dissolved oxygen, increased phytoplankton biomass during the growth period, and reduced it afterwards, when loss factors dominate. It was also shown that these impacts were enhanced when point source inputs of nutrient and organic carbon increased.
16
Ducharne, A. "Importance of stream temperature to climate change impact on water quality." Hydrology and Earth System Sciences Discussions 4, no. 4 (2007): 2425–60. http://dx.doi.org/10.5194/hessd-4-2425-2007.
Full textAbstract:
Abstract. The sensitivity of water quality to climate change was assessed in the Seine River (France) with the biogeochemical model RIVERSTRAHLER, which describes the transformations and fluxes of C, N, P and Si between the main microbiological populations, the water column and the sediment, along the entire river network. Point and diffuse sources are prescribed, stream temperature undergoes a sinusoidal annual cycle constrained by observations, and runoff is calculated by a physically-based land surface model. The reference simulation, using meteorological forcing of 1986–1990 and point sources of 1991, compares very well with observations. The climate change simulated by a general circulation model under the SRES emission scenario A2 was used to simulate the related changes in runoff and stream temperature. To this end, a statistical analysis was undertaken of the relationships between the water and air temperatures in the Seine watershed over 1993–1999, using 88 points that correctly sampled the variability of the tributaries. Most of stream temperature variance was explained by the lagged moving average of air temperature, with parameters that depended on Strahler stream order. As an interesting simplification, stream temperature changes could be approximated by air temperature changes. This modelling framework was used to analyse of the relative influence of the water warming and discharge reduction induced by climate change on water quality in Paris and downstream. Discharge reduction increased phytoplankton growth and oxygen deficits. Water warming decreased dissolved oxygen, increased phytoplankton biomass during the growth period, and reduced it afterwards, when loss factors dominate. It was also shown that these impacts were enhanced when point source inputs of nutrient and organic matter increased.
17
Santos, Vanessa Cristina Dos, Mhamad El Hage, Laurent Polidori, and José Cândido Stevaux. "EFFECT OF DIGITAL ELEVATION MODEL MESH SIZE ON GEOMORPHIC INDICES: A CASE STUDY OF THE IVAÍ RIVER WATERSHED - STATE OF PARANÁ, BRAZIL." Boletim de Ciências Geodésicas 23, no. 4 (2017): 684–99. http://dx.doi.org/10.1590/s1982-21702017000400045.
Full textAbstract:
Abstract: Geomorphometry is the science of quantitative description of land surface morphology by the mean of geomorphic indices extracted from Digital Elevation Models (DEMs). The analysis of these indices is the first and most common procedure performed in several geoscience-related subjects. This study aims to assess the impact of mesh size degradation on different local and regional geomorphic indices extracted for GDEM and TOPODATA DEMs. Thus, these DEMs, having a mesh size of 30 m, were subsampled to 60, 120 and 240 m and then geomorphic indices were calculated using the full resolution DEM and the subsampled ones. Depending on their behavior, these indices are then classified into stable and unstable. The results show that the most affected indices are slope and hydrographic indices such as Strahler order, stream sinuosity and fractal dimension and watershed perimeter, whereas elevation remains stable. It also shows that the effect depends on the presence of the canopy and geological structures in the studied area.
18
Skelton, James, Robert P. Creed, Lukas Landler, Kevin M. Geyer, and Bryan L. Brown. "Geographic patterns of crayfish symbiont diversity persist over half a century despite seasonal fluctuations." Freshwater Crayfish 22, no. 1 (2016): 9–18. http://dx.doi.org/10.5869/fc.2016.v22-1.9.
Full textAbstract:
Abstract We analyzed historical data from 1961-1965 for species occurrences of branchiobdellidans and their crayfish hosts throughout the Mountain Lake Region of southwestern Virginia, USA to quantify geographic variability in species composition and identify patterns in host and symbiont diversity. We collected contemporary census data of branchiobdellidan assemblages from the same region in 2011-2014 for intra-annual variation in symbiont abundance and species composition. We compared historical and contemporary records to assess the stability of geographic patterns in symbiont diversity over decadal timescales. Branchiobdellidan assemblages followed a hump-shaped relationship with Strahler stream order. Much of the geographic variation in symbiont species composition was explained by host species composition, despite low host fidelity in branchiobdellidans. There were strong seasonal cycles in branchiobdellidan abundance and species composition. A comparison of historical and contemporary records revealed little change in species distributions over 50 years. Thus, branchiobdellidan species composition changes predictably along habitat gradients, tracks variation in host composition, is repeatable across decadal timescales, and follow strong cyclic seasonal changes in total and relative abundances. These results suggest that complex but deterministic ecological processes drive symbiont population dynamics at multiple spatial and temporal scales.
19
Arnaud-Fassetta, Gilles, Gabriel Melun, Paul Passy, Guillaume Brousse, and Olivier Theureaux. "How to Quantify the Dynamics of Single (Straight or Sinuous) and Multiple (Anabranching) Channels from Imagery for River Restoration." Applied Sciences 11, no. 17 (2021): 8075. http://dx.doi.org/10.3390/app11178075.
Full textAbstract:
Since the 2000s, European rivers have undergone restoration works to give them back a little more ‘freedom space’ and consolidate the hydro-sedimentary continuum and biological continuity as required by the Water Framework Directive (WFD). In high-energy rivers, suppression of lateral constraints (embankment removal) leads to geomorphological readjustments in the modification of both the active-channel length and active-channel width. The article provides a new methodological development to overcome the shortcomings of traditional methods (based on diachronic cross-section analysis) unable to simultaneously take into account these geometric adjustments after active-channel restoration. It allows us to follow and precisely quantify the geomorphological changes of the active channel faced to the stakes (i.e., structures or urbanized, recreation or agricultural areas) in the floodplain. The methodology proposes three new indicators (distance from active channel to stakes or floodplain margins as indicator 1; distance from stakes to active channel as indicator 2; diachronic distance as indicator 3) and a metric analysis grid in the 2D Euclidean space. It is applied to the Clamoux River (order 4, Strahler; bankfull, specific stream power: 280 W/m2) in the Aude watershed (Mediterranean France). The paper shows the full potential of this methodological protocol to be able to meet managers’ expectations as closely as possible within the framework of the multi-annual active-channel monitoring.
20
Borges, Alberto V., François Darchambeau, Thibault Lambert, et al. "Variations in dissolved greenhouse gases (CO<sub>2</sub>, CH<sub>4</sub>, N<sub>2</sub>O) in the Congo River network overwhelmingly driven by fluvial-wetland connectivity." Biogeosciences 16, no. 19 (2019): 3801–34. http://dx.doi.org/10.5194/bg-16-3801-2019.
Full textAbstract:
Abstract. We carried out 10 field expeditions between 2010 and 2015 in the lowland part of the Congo River network in the eastern part of the basin (Democratic Republic of the Congo), to describe the spatial variations in fluvial dissolved carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) concentrations. We investigate the possible drivers of the spatial variations in dissolved CO2, CH4 and N2O concentrations by analyzing covariations with several other biogeochemical variables, aquatic metabolic processes (primary production and respiration), catchment characteristics (land cover) and wetland spatial distributions. We test the hypothesis that spatial patterns of CO2, CH4 and N2O are partly due to the connectivity with wetlands, in particular with a giant wetland of flooded forest in the core of the Congo basin, the “Cuvette Centrale Congolaise” (CCC). Two transects of 1650 km were carried out from the city of Kisangani to the city of Kinshasa, along the longest possible navigable section of the river and corresponding to 41 % of the total length of the main stem. Additionally, three time series of CH4 and N2O were obtained at fixed points in the main stem of the middle Congo (2013–2018, biweekly sampling), in the main stem of the lower Kasaï (2015–2017, monthly sampling) and in the main stem of the middle Oubangui (2010–2012, biweekly sampling). The variations in dissolved N2O concentrations were modest, with values oscillating around the concentration corresponding to saturation with the atmosphere, with N2O saturation level (%N2O, where atmospheric equilibrium corresponds to 100 %) ranging between 0 % and 561 % (average 142 %). The relatively narrow range of %N2O variations was consistent with low NH4+ (2.3±1.3 µmol L−1) and NO3- (5.6±5.1 µmol L−1) levels in these near pristine rivers and streams, with low agriculture pressure on the catchment (croplands correspond to 0.1 % of catchment land cover of sampled rivers), dominated by forests (∼70 % of land cover). The covariations in %N2O, NH4+, NO3- and dissolved oxygen saturation level (%O2) indicate N2O removal by soil or sedimentary denitrification in low O2, high NH4+ and low NO3- environments (typically small and organic matter rich streams) and N2O production by nitrification in high O2, low NH4+ and high NO3- (typical of larger rivers that are poor in organic matter). Surface waters were very strongly oversaturated in CO2 and CH4 with respect to atmospheric equilibrium, with values of the partial pressure of CO2 (pCO2) ranging between 1087 and 22 899 ppm (equilibrium ∼400 ppm) and dissolved CH4 concentrations ranging between 22 and 71 428 nmol L−1 (equilibrium ∼2 nmol L−1). Spatial variations were overwhelmingly more important than seasonal variations for pCO2, CH4 and %N2O as well as day–night variations for pCO2. The wide range of pCO2 and CH4 variations was consistent with the equally wide range of %O2 (0.3 %–122.8 %) and of dissolved organic carbon (DOC) (1.8–67.8 mg L−1), indicative of generation of these two greenhouse gases from intense processing of organic matter either in “terra firme” soils, wetlands or in-stream. However, the emission rate of CO2 to the atmosphere from riverine surface waters was on average about 10 times higher than the flux of CO2 produced by aquatic net heterotrophy (as evaluated from measurements of pelagic respiration and primary production). This indicates that the CO2 emissions from the river network were sustained by lateral inputs of CO2 (either from terra firme or from wetlands). The pCO2 and CH4 values decreased and %O2 increased with increasing Strahler order, showing that stream size explains part of the spatial variability of these quantities. In addition, several lines of evidence indicate that lateral inputs of carbon from wetlands (flooded forest and aquatic macrophytes) were of paramount importance in sustaining high CO2 and CH4 concentrations in the Congo river network, as well as driving spatial variations: the rivers draining the CCC were characterized by significantly higher pCO2 and CH4 and significantly lower %O2 and %N2O values than those not draining the CCC; pCO2 and %O2 values were correlated to the coverage of flooded forest on the catchment. The flux of greenhouse gases (GHGs) between rivers and the atmosphere averaged 2469 mmol m−2 d−1 for CO2 (range 86 and 7110 mmol m−2 d−1), 12 553 µmol m−2 d−1 for CH4 (range 65 and 597 260 µmol m−2 d−1) and 22 µmol m−2 d−1 for N2O (range −52 and 319 µmol m−2 d−1). The estimate of integrated CO2 emission from the Congo River network (251±46 TgC (1012 gC) yr−1), corresponding to nearly half the CO2 emissions from tropical oceans globally (565 TgC yr−1) and was nearly 2 times the CO2 emissions from the tropical Atlantic Ocean (137 TgC yr−1). Moreover, the integrated CO2 emission from the Congo River network is more than 3 times higher than the estimate of terrestrial net ecosystem exchange (NEE) on the whole catchment (77 TgC yr−1). This shows that it is unlikely that the CO2 emissions from the river network were sustained by the hydrological carbon export from terra firme soils (typically very small compared to terrestrial NEE) but most likely, to a large extent, they were sustained by wetlands (with a much higher hydrological connectivity with rivers and streams).
21
Habtu, Worku, and Jayappa K. S. "Use of ASTER DEM data for Morphometric Analysis of Megech Dirma-Watersheds, Blue Nile Basin, Ethiopia: Implications for Soil and Water Conservation." Remote Sensing of Land 5, no. 1 (2021): 27–40. http://dx.doi.org/10.21523/gcj1.2021050103.
Full textAbstract:
Quantitative morphometric analysis was carried out for Megech-Dirma, sub-basin of the Blue Nile, by estimating (1) linear, (2) aerial, and (3) relief aspects. An endeavor has been made to measure the Megech-Dirma watershed’s morphometric characteristics to implement conservation methods for soil and water properly. ASTER DEM has been used as input data for extracting morphometric parameters. Strahler’s classification scheme was used to classify the extracted drainage network in ArcGIS extension ArcMap 10.4. The watershed covers a total surface area of 1309.56 km2. The shape of the watersheds as calculated from elongation, circularity, and form factors reveals the elongated shape and the watersheds parade dendritic pattern. The sub-watersheds include third-order for Megech and sixth-order streams. Lower stream orders, in particular first-order streams, dominate the sub-watersheds. The length of overland flow has a higher value (1.06) for Megech indicates low relief, whereas the values of length of overland flow, which are relatively low (0.20) for Dirma, indicate high relief. The drainage density of the study watershed was morphometrically analyzed and obtained 0.47 km/km2 for the Megech sub-basin, which indicates the basin is highly permeable and result in better underground water storage capacity and 2.46 for the Dirma sub-basin indicating very coarse and coarse channel, respectively. The ruggedness number for Megech and Dirma sub-basins was 0.56 and 0.07, respectively, indicating moderate and long, rugged topography, which could be susceptible to flash flood and soil erosion. The dissection index values for Megech 0.40 and 0.36 for Dirma show river sub-basins are moderately dissected. The ruggedness number is 0.56 for Megech implies moderate soil erosion probability, whereas the high infiltration number (14.29) for Dirma river shows the high runoff potential in the sub-basin. The findings of this study include drainage morphometry data that can be used to better understand watershed characteristics and serve as a framework for better planning, management, and decision-making to ensure the long-term use of watershed resources of water and soil.
22
Wang, Ai, Lihua Tang, and Dawen Yang. "Spatial and temporal variability of nitrogen load from catchment and retention along a river network: a case study in the upper Xin'anjiang catchment of China." Hydrology Research 47, no. 4 (2015): 869–87. http://dx.doi.org/10.2166/nh.2015.055.
Full textAbstract:
Understanding the spatial and temporal variability of nitrogen load and characteristics of retention along a river network is important for land management and water resources protection. This study employs a geomorphology-based non-point source pollution model (GBNP) to simulate the hillslope hydrological processes and transport of sediment and pollutants in the upper Xin'anjiang (XAJ) catchment. Based on the simulation, the spatial and temporal distribution of total nitrogen (TN) load from hillslopes and retention characteristics along the river network are analyzed. The results indicate that annual TN load ranges from 0.54 ton/km2 to 1.88 ton/km2 and is relatively higher during spring and summer. Average TN load positively correlates with irrigated cropland area (r =0.820) and negatively correlates with forest (r = −0.43). Seasonal TN retention ratios in the river network range from 0% to 81%, and streams of order 1 in the Horton–Strahler system have the highest retention ratio and are followed by orders 2, 3, and 4, which are mainly determined by the river hydraulic properties. Results of scenarios analysis demonstrate that TN retention ratios in the river network increase with TN load from hillslopes, but reach a maximum value rapidly, which indicates the limitation of the self-purification capacity of rivers.
23
Ceola, Serena, Alberto Montanari, Juraj Parajka, Alberto Viglione, Günter Blöschl, and Francesco Laio. "Human signatures derived from nighttime lights along the Eastern Alpine river network in Austria and Italy." Proceedings of the International Association of Hydrological Sciences 373 (May 12, 2016): 131–36. http://dx.doi.org/10.5194/piahs-373-131-2016.
Full textAbstract:
Abstract. Understanding how human settlements and economic activities are distributed with reference to the geographical location of streams and rivers is of fundamental relevance for several issues, such as flood risk management, drought management related to increased water demands by human population, fluvial ecosystem services, water pollution and water exploitation. Besides the spatial distribution, the evolution in time of the human presence constitutes an additional key question. This work aims at understanding and analysing the spatial and temporal evolution of human settlements and associated economic activity, derived from nighttime lights, in the Eastern Alpine region. Nightlights, available at a fine spatial resolution and for a 22-year period, constitute an excellent data base, which allows one to explore in details human signatures. In this experiment, nightlights are associated to five distinct distance-from-river classes. Our results clearly point out an overall enhancement of human presence across the considered distance classes during the last 22 years, though presenting some differences among the study regions. In particular, the river network delineation, by considering different groups of river pixels based on the Strahler order, is found to play a central role in the identification of nightlight spatio-temporal trends.
24
Korte, David M., and Abdul Shakoor. "Landslide Susceptibility and Soil Loss Estimates for Drift Creek Watershed, Lincoln County, Oregon." Environmental and Engineering Geoscience 26, no. 2 (2020): 167–84. http://dx.doi.org/10.2113/eeg-2251.
Full textAbstract:
ABSTRACT Drift Creek watershed, Lincoln County, Oregon, is a source of drinking water as well as a reproductive habitat for endangered salmon and trout species. Landslides, exacerbated by logging, are suspected as a cause of water quality deterioration in the watershed. To investigate the impact of landslides on water quality, we mapped landslide distribution and susceptibility, determined engineering properties of landslide-prone soil and rock, and estimated soil loss resulting from landslide-derived sediment within 30 m of Strahler third-order-or-higher streams in the watershed. We mapped 570 landslides using LiDAR imaging, orthophotographs, and field observations. We used logistic regression to determine the most significant variables contributing to landslide occurrence and to create a watershed-scale landslide susceptibility map. Siletz River Volcanics and the sedimentary Tyee Formation make up 85 percent of the watershed, with the sedimentary Yamhill and Nestucca formations making up the majority of the rest. Sedimentary rocks dominate in the Upper Drift Creek watershed, and volcanic dominate in the lower portion. The largest landslide deposits and the highest susceptibility occur in the sedimentary rock formations. The Siletz River Volcanics has a larger abundance of landslides than the sedimentary rock formations, but they are smaller in size with lower susceptibility of occurrence. The soil loss model indicates that the average annual soil loss from landslide deposits in the Upper Drift Creek watershed is 65 tons/acre/yr compared to 29 tons/acre/yr in the Lower Drift Creek watershed. The model also indicates that soil loss from areas along roads in the watershed is high.
25
Zharkova, V., and O. Khabarova. "Additional acceleration of solar-wind particles in current sheets of the heliosphere." Annales Geophysicae 33, no. 4 (2015): 457–70. http://dx.doi.org/10.5194/angeo-33-457-2015.
Full textAbstract:
Abstract. Particles of fast solar wind in the vicinity of the heliospheric current sheet (HCS) or in a front of interplanetary coronal mass ejections (ICMEs) often reveal very peculiar energy or velocity profiles, density distributions with double or triple peaks, and well-defined streams of electrons occurring around or far away from these events. In order to interpret the parameters of energetic particles (both ions and electrons) measured by the WIND spacecraft during the HCS crossings, a comparison of the data was carried out with 3-D particle-in-cell (PIC) simulations for the relevant magnetic topology (Zharkova and Khabarova, 2012). The simulations showed that all the observed particle-energy distributions, densities, ion peak velocities, electron pitch angles and directivities can be fitted with the same model if the heliospheric current sheet is in a status of continuous magnetic reconnection. In this paper we present further observations of the solar-wind particles being accelerated to rather higher energies while passing through the HCS and the evidence that this acceleration happens well before the appearance of the corotating interacting region (CIR), which passes through the spacecraft position hours later. We show that the measured particle characteristics (ion velocity, electron pitch angles and the distance at which electrons are turned from the HCS) are in agreement with the simulations of additional particle acceleration in a reconnecting HCS with a strong guiding field as measured by WIND. A few examples are also presented showing additional acceleration of solar-wind particles during their passage through current sheets formed in a front of ICMEs. This additional acceleration at the ICME current sheets can explain the anticorrelation of ion and electron fluxes frequently observed around the ICME's leading front. Furthermore, it may provide a plausible explanation of the appearance of bidirectional "strahls" (field-aligned most energetic suprathermal electrons) at the leading edge of ICMEs as energetic electrons generated during a magnetic reconnection at the ICME-front current sheet.
26
Matsoukis, Constantinos, Laurent O. Amoudry, Lucy Bricheno, and Nicoletta Leonardi. "Investigation of Spatial and Temporal Salinity Distribution in a River Dominated Delta through Idealized Numerical Modelling." Estuaries and Coasts, January 29, 2021. http://dx.doi.org/10.1007/s12237-021-00898-2.
Full textAbstract:
AbstractThe world’s river deltas are increasingly vulnerable due to pressures from human activities and environmental change. In deltaic regions, the distribution of salinity controls the resourcing of fresh water for agriculture, aquaculture and human consumption; it also regulates the functioning of critical natural habitats. Despite numerous insightful studies, there are still significant uncertainties on the spatio-temporal patterns of salinity across deltaic systems. In particular, there is a need for a better understanding of the salinity distribution across deltas’ channels and for simple predictive relationships linking salinity to deltas’ characteristics and environmental conditions. We address this gap through idealized three-dimensional modelling of a typical river-dominated delta configuration and by investigating the relationship between salinity, river discharge and channels’ bifurcation order. Model results are then compared with real data from the Mississippi River Delta. Results demonstrate the existence of simple one-dimensional and analytical relationships describing the salinity field in a delta. Salinity and river discharge are exponentially and negatively correlated. The Strahler-Horton method for stream labelling of the delta channels was implemented. It was discovered that salinity increases with decreasing stream order. These useful relationships between salinity and deltas’ bulk features and geometry might be applied to real case scenarios to support the investigation of deltas vulnerability to environmental change and the management of deltaic ecosystems.
27
McDowell, R. W., Z. P. Simpson, A. G. Ausseil, Z. Etheridge, and R. Law. "The implications of lag times between nitrate leaching losses and riverine loads for water quality policy." Scientific Reports 11, no. 1 (2021). http://dx.doi.org/10.1038/s41598-021-95302-1.
Full textAbstract:
AbstractUnderstanding the lag time between land management and impacts on riverine nitrate–nitrogen (N) loads is critical to understand when action to mitigate nitrate–N leaching losses from the soil profile may start improving water quality. These lags occur due to leaching of nitrate–N through the subsurface (soil and groundwater). Actions to mitigate nitrate–N losses have been mandated in New Zealand policy to start showing improvements in water quality within five years. We estimated annual rates of nitrate–N leaching and annual nitrate–N loads for 77 river catchments from 1990 to 2018. Lag times between these losses and riverine loads were determined for 34 catchments but could not be determined in other catchments because they exhibited little change in nitrate–N leaching losses or loads. Lag times varied from 1 to 12 years according to factors like catchment size (Strahler stream order and altitude) and slope. For eight catchments where additional isotope and modelling data were available, the mean transit time for surface water at baseflow to pass through the catchment was on average 2.1 years less than, and never greater than, the mean lag time for nitrate–N, inferring our lag time estimates were robust. The median lag time for nitrate–N across the 34 catchments was 4.5 years, meaning that nearly half of these catchments wouldn’t exhibit decreases in nitrate–N because of practice change within the five years outlined in policy.
28
Ruiz-González, Clara, Juan Pablo Niño-García, Martin Berggren, and Paul A. Del Giorgio. "Contrasting dynamics and environmental controls of dispersed bacteria along a hydrologic gradient." Advances in Oceanography and Limnology 8, no. 2 (2017). http://dx.doi.org/10.4081/aiol.2017.7232.
Full textAbstract:
Freshwater bacterioplankton communities are influenced by the transport of bacteria from the surrounding terrestrial environments. It has been shown that, although most of these dispersed bacteria gradually disappear along the hydrologic continuum, some can thrive in aquatic systems and become dominant, leading to a gradual succession of communities. Here we aimed at exploring the environmental factors driving the structure of such contrasting bacterial populations as well as their functional properties. Using Illumina sequencing of the 16S rRNA gene, we characterized the taxonomic composition of bacterioplankton communities from 10 streams and rivers in Québec spanning the whole hydrologic continuum (river Strahler order 0 to 7), which were sampled in two occasions. With the aim to understand the fate and controls of the transported bacteria, among the taxa present at the origin of the hydrologic gradient (i.e., in the smallest headwater streams) we identified two types of dynamics: i) ‘Tourist’ taxa, which were those that decreased in abundance from the headwaters towards the largest rivers, and ii) ‘Seed’ taxa, those that increased their abundances along the hydrologic continuum. Communities changed gradually from the fast-flowing headwater streams dominated by ‘Tourist’ taxa (ca. 95% of the sequences) towards the largest rivers (Strahler order 4-7) where ‘Seed’ taxa comprised up to 80% of community sequences. Variation in taxonomic composition of the communities dominated by ‘Tourist’ taxa in streams seemed related to different degree of terrestrial inputs, whereas compositional changes in ‘Seed’ communities in the large rivers were linked to differences in autochthonous processes. Finally, the two types of communities differed significantly in their metabolic potential assessed through Biolog Ecoplates. All this suggests that hydrologic transport modulates the gradual replacement of two contrasting population types subjected to different environmental controls and with different metabolic potentials. Moreover, we show that the separate exploration of the two pools of taxa allows unveiling environmental drivers and processes operating on them that remain hidden if explored at the whole community level.