Dissertations / Theses on the topic 'HYDROGRAPH SEPARATION'

付記する学位プログラム名: グローバル生存学大学院連携プログラム
Kyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第20341号
工博第4278号
新制||工||1662(附属図書館)
京都大学大学院工学研究科社会基盤工学専攻
(主査)教授 寶 馨, 教授 立川 康人, 准教授 佐山 敬洋
学位規則第4条第1項該当

Glacier melt affects the geochemical composition of rivers; however, quantifying the glacier contribution to subarctic watershed-scale runoff has attracted limited attention. To estimate glacier contribution, we conducted a 6-year geochemical hydrograph separation study in a geologically heterogeneous glacierized watershed in Interior Alaska. Water samples were collected daily from Jarvis Creek during late April through September. Source waters were collected synoptically each year from rain, snow, baseflow (winter discharge), and the glacier terminus discharge. All samples were analyzed for stable water isotopes and dissolved ion concentrations. Stream surface water samples have large seasonal and inter-annual geochemical variation, however, source waters show distinct chemical signatures allowing the application of a geochemical hydrograph separation model to quantify relative source contribution to lowland streamflow. Considerable inter-annual differences within source water signatures emphasize the importance in informing the model with source waters sampled for each season. We estimated a seasonal average of 35% (20 to 44%) glacier terminus discharge contribution with a daily range of 2 (May) to 80% (September). If glacier contribution was to cease completely, stream discharge would be reduced by 48% and 22% in low and high rainfall summers, respectively. Combined with the documented shrinkage of glaciers, our findings emphasizes the need for further research on glacial wastage effect on subarctic watersheds.

The storm runoff of small springs and seeps in the West Kootenays was subjected to hydrograph separation using oxygen-18 and conductance methodologies. The results showed that the vast majority of storm discharge was groundwater. Under peak flow conditions, the ratio of prestorm water to storm water was 0.93 for Morley Spring, 0.88 for Anderson Creek, 0.87 for Elliott Creek, 0.84 for Chou Creek and 0.85 for Tank Creek. Further comparison between prestorm discharge and storm water indicated that the groundwater probably originated as spring snow melt. These implications are discussed with regard to the various logging development plans currently being proposed for the study sites.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

Thesis advisor: Rudolph Hon
Thesis advisor: Yvette Kuiper
Chloride-based deicers (NaCl, CaCl₂, MgCl₂), also referred to as road salt, are the most common substances used in maintaining safe roadway surfaces during the winter months. Upon application, road salt reacts with the accumulated snow or ice to form brine equilibrium solutions along the liquidus line in the salt-water system. Dissolved salts dissociate, leading to increased concentrations of the respective ions in nearby soils, surface water, and groundwater. Of the ions present in road salt, chloride has the advantage of tracking all chloride deicers at the same time and since chloride ions are conservative tracers in soils it stays unaffected by ionic exchange interferences. This study explores the mechanisms of chloride return flows by investigating chloride dissolved loads, chloride concentrations in stream waters, seasonal patterns, and changes over the course of four years in two separate watersheds in Massachusetts with differing degrees of urbanization. The chloride tracking technique used in this study is based on calibrated chloride concentrations obtained from specific conductance signals recorded every 15 minutes by automatic recording systems at two locations, one in rural central Massachusetts and the other in urban eastern Massachusetts. These systems are maintained by the USGS, which also provide the simultaneously recorded stream flow datasets. The dissolved chloride load carried by each river is calculated for each single 15-minute interval by multiplying water volume with the corresponding chloride concentration, resulting in a total of over 34,000 data points per annum per site. Hydrograph separation techniques were used to separate dissolved load transported by each river into two separate flow components, event flow resulting from precipitation events, and baseflow resulting from groundwater discharge. Well defined hydrograph baseflow supported periods yield consistent chloride concentrations independent of the season at either urban or rural study sites. Comparison of direct runoff dissolved chloride loads with the total annual dissolved loads suggests that only a small fraction of the deicers actually removed during the overland runoff events and that a minimum of 60% of the total load discharged each year in both urban and rural systems is transported by groundwater. From groundwater recharge by brines rural watersheds are currently retaining as much as 95% of the total chloride applied to roadways each year while urban and suburban watersheds may only retain 75% of the total chloride applied to roadways each year. The increased retention of chloride in rural areas is likely due to the decreased amount of chloride transported during winter seasons as event flow compared to urban watersheds
Thesis (MS) — Boston College, 2009
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Geology and Geophysics

Title from PDF of title page.
Document formatted into pages; contains 75 pages.
Thesis (M.S.C.E.)--University of South Florida, 2003.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
ABSTRACT: Analytical baseflow separation techniques such as those used in the automated hydrograph separation program HYSEP rely on a single input parameter that defines the period of time after which surface runoff ceases and all streamflow is considered baseflow. In HYSEP, this input parameter is solely a function of drainage basin contributing area. This method cannot be applied universally since in most regions the time of surface runoff cessation is a function of a number of different hydrologic and hydrogeologic basin characteristics, not just contributing drainage area. This study demonstrates that streamflow conductivity can be used as a natural tracer that integrates the different hydrologic and hydrogeologic basin characteristics that influence baseflow response. Used as an indicator of baseflow as a component of total flow, streamflow conductivity allows for an empirical approach to hydrograph separation using a simple mass balance algorithm.
ABSTRACT: Although conductivity values for surface-water runoff and ground-water baseflow must be identified to apply this mass balance algorithm, field studies show that assumptions based on streamflow at low flow and high flow conditions are valid for estimating these end member conductivities. The only data required to apply the mass balance algorithm are streamflow conductivity and discharge measurements. Using minimal data requirements, empirical hydrograph separation techniques can be applied that yield reasonable estimates of baseflow. This procedure was performed on data from 10 USGS gaging stations for which reliable, real-time conductivity data are available. Comparison of empirical hydrograph separations using streamflow conductivity data with analytical hydrograph separations demonstrates that uncalibrated, graphical estimation of baseflow can lead to substantial errors in baseflow estimates.
ABSTRACT: Results from empirical separations can be used to calibrate the runoff cessation input parameter used in analytical separation for each gaging station. In general, collection of stream conductivity data at gaging stations is relatively recent, while discharge measurements may extend many decades into the past. Results demonstrate that conductivity data available for a relatively short period of record can be used to calibrate the runoff cessation input parameter used for analytical separation. The calibrated analytical method can then be applied over a much longer period record since discharge data are the only requirement.
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Geochemical mixing methods utilizing ²²²Rn and chloride and statistical hydrograph separation techniques were carried out in an attempt to understand baseflow dynamics in a section of the Kern River in the Sierra Nevada of Southern California. ²²²Rn has become a valuable tool for evaluating groundwater inflow to a river, particularly when groundwater and surface water have similar major ion geochemistry. When using geochemical methods it is important to minimize uncertainty through comparison with separate tracers and techniques, though this is complicated in this setting. Snow melt discharge and regulation of natural river flow cause hydrograph-based techniques to suffer from inaccuracies. Geochemical mixing using major ions and stable isotopes are complicated by the chemical similarity between surface water and groundwater. ²²²Rn is a powerful tool to elucidate this relationship in this setting if major uncertainties, like rate of radon degassing and parafluvial and hyporheic radon production can be constrained.

Magister Scientiae - MSc (Environ & Water Science)
Studies have shown that the primary origin of salinity in river flows of the Sandspruit in the Berg Catchment located in the Western Cape Province of South Africa was mainly a result of atmospheric deposition of salts. The salts are transported to rivers through surface runoff and subsurface flow (i.e. through flow and groundwater flow). The purpose of this study was to determine the contributions of subsurface and surface flows to the total flows in the Sandspruit, Berg Catchment. Three rain events were studied. Water samples for two rain events were analysed for environmental tracers ?18O, Silica or Silicon dioxide (SiO2), Calcium (Ca2+) and Magnesium (Mg2+). Tracers used for two component hydrograph separation were ?18O and SiO2. The tracers, Ca2+ and Mg2+, revealed inconsistent contributions of both subsurface flow and surface flow. Two component hydrograph separations indicated is that groundwater is the dominant contributor to flow, while surface runoff mainly contributes during the onset of the storm event. Groundwater response to precipitation input indicated that boreholes near the river have a quicker response than boreholes further away from the river. Boreholes nearer to the river also indicate higher water levels in response to precipitation, in comparison to boreholes further from the river.

Previous hydrometric studies demonstrated the prevalence of overland flow as a hydrological pathway in the tropical rain forest catchment of South Creek, northeast Queensland. The purpose of this study was to consider this information in a mixing analysis with the aim of identifying sources of, and of estimating their contribution to, storm flow during two events in February 1993. K and acid-neutralizing capacity (ANC) were used as tracers because they provided the best separation of the potential sources, saturation overland flow, soil water from depths of 0.3, 0.6, and 1.2 m, and hillslope groundwater in a two-dimensional mixing plot. It was necessary to distinguish between saturation overland flow, generated at the soil surface and following unchanneled pathways, and overland flow in incised pathways. This latter type of overland flow was a mixture of saturation overland flow (event water) with high concentrations of K and a low ANC, soil water (preevent water) with low concentrations of K and a low ANC, and groundwater (preevent water) with low concentrations of K and a high ANC. The same sources explained the streamwater chemistry during the two events with strongly differing rainfall and antecedent moisture conditions. The contribution of saturation overland flow dominated the storm flow during the first, high-intensity, 178-mm event, while the contribution of soil water reached 50% during peak flow of the second, low-intensity, 44-mm event 5 days later. This latter result is remarkably similar to soil water contributions to storm flow in mountainous forested catchments of the southeastern United States. In terms of event and preevent water the storm flow hydrograph of the high-intensity event is dominated by event water and that of the low-intensity event by preevent water. This study highlights the problems of applying mixing analyses to overland flow-dominated catchments and soil environments with a poorly developed vertical chemical zonation and emphasizes the need for independent hydrometric information for a complete characterization of watershed hydrology and chemistry.

In agricultural catchments, hydrological processes play an important role in the export of nutrients. Water that enters a catchment during a rain event (event water) can have different flow paths and residence times. These affect the transport and biogeochemical transformation of nutrients until the water discharges at the outlet where catchments are usually monitored.This work focused on the contributions of event water and pre-event water (water that was already stored in the catchment before a rainfall event) to the stream. The work is necessary for further studies to develop an understanding of the relation of nutrients export and water flow paths. The method was based on isotopic hydrograph separation and performed on existing data. The stable isotope signature of oxygen in water (δ18O) was used as a tracer. A new study is planned using δ18O to distinguish different flow paths and residence times of water, and therefore a sequential rainfall collector was tested and improved for this purpose.The results of the hydrograph separation show that up to 54% of an increased discharge from a rainwater event is event water, but also that data in a higher temporal resolution is needed to quantify contributions of event water to the runoff for all the events. Additional and more advanced experiments of the rainfall collector would be an advantage, but it can also be used in the field as it is today. Based on the analysis and the revised sequential rainfall collector, a sampling strategy for future work is described.
I ett jordbruksavrinningsområde spelar hydrologiska processer en viktig roll vid export av näringsämnen. Vatten som adderas till ett avrinningsområde från ett regnevent (eventvatten) kan ha olika flödesvägar och olika uppehållstider. Dessa påverkar transporten och omvandlingen av biogeokemiska näringsämnen olika tills det att vattnet lämnar avrinningsområdet via ett utlopp.Arbetet har fokuserat på vilket bidrag eventvatten och vatten som redan lagrats i avrinningsområdet före regnhändelsen (pre-eventvatten) har till avrinningen till en flod. Arbetet är viktigt för att utveckla en förståelse för vattenflödesvägar som är nödvändiga för ytterligare undersökning av export av näringsämnen. Metoden baserades på en isotopisk hydrograf-separation och utfördes på existerande data. Spåraren som användes var den stabila isotopen av syre i vatten (δ18O). Eftersom en ny studie planeras med användning av δ18O för att skilja olika flödesvägar och uppehållstider för vatten, har en sekventiell regnuppfångare också testats och förbättras.Resultaten av den hydrografa separationen visar att upp till 54% av en ökad avrinning i floden som resultat av ett regnevent är eventvatten, men även att det finns behov av data med högre tidsmässig upplösning behövs för att kunna kvantifiera bidrag från eventvatten till avrinningen för alla event. Fler och mer avancerade tester av regnfångaren skulle vara en fördel, men den kan även i dagsläget användas i fält. Baserat på resultat från experiment av regnuppfångaren föreslås kort en provtagningsstrategi för framtida arbeten.

Understanding of the complex runoff generation mechanisms is important for water management and to predict the effects of land use and climate change on streamflow. In particular, the mechanisms through which precipitation becomes streamflow and the spatio-temporal variability of the runoff components is still unclear. The integrated use of isotopic and geochemical tracers, combined with hydrometric data, has proven to be a useful method to investigate hydrological processes in small catchments. In this study, we used stable isotopes of water, major ions and electrical conductivity as tracers together with hydrometric data to i) compare the response of the water table and soil moisture to the streamflow response during rainfall-runoff events, ii) analyze the spatial and temporal variability in tracer signature (stable isotopes of water, EC and major ions) of different end members contributing to stream runoff, iii) assess how the main event characteristics (total rainfall amount, intensity and antecedent wetness conditions) affect the event water contribution to stream runoff, and iv) investigate how the use of different tracers affects the results of the two-component hydrograph separation. The hydrometric and tracer data was analyzed for 15 rainfall-runoff events between September 2015 and October 2016 during different wetness conditions in a small catchment in the Italian pre-Alps. Continuous measurements for streamflow, precipitation, air temperature, shallow groundwater levels at six locations in different parts of the catchment (riparian, bottom of the hillslope, mid hillslope and upper hillslope), soil moisture at four locations along a riparian-hillslope transect were available for the study period. Samples for isotopic and geochemical analysis were taken from precipitation, stream, shallow groundwater, soil water at 5 locations (riparian at 10 cm and 20 cm depth; mid hillslope at 10 cm and 30 cm depth; upper hillslope at 30 cm depth). Electrical conductivity was measured directly in the field using a portable meter. Isotopic composition and ion concentrations were determined in the laboratory of Legnaro (Dip. TESAF, University of Padova) by laser absorption spectroscopy and ion-chromatography, respectively. Mixing plot analysis shows that precipitation, near-surface riparian soil water and shallow groundwater are the main contributors to runoff. Two-component hydrograph separation showed that new water contributions increase with increasing rainfall amount and intensity and decrease with increasing antecedent wetness conditions. During events with high rainfall intensity with dry antecedent conditions, the new water fraction was high, especially in the initial phase of the event and near the streamflow peak, suggesting that streamflow is mainly generated by direct channel precipitation and saturated overland flow in the riparian zone. With increasing wetness conditions, pre-event water dominated runoff, suggesting the development of subsurface stormflow and an increasing contribution from groundwater pools located in different parts of the catchment. In the middle and at the end of large events in wet periods, the new water fraction in streamflow increased due to the expansion of the saturated area near the stream and flow through shallow soil layers. Differences in the event water fractions computed using isotopes, EC or major ions, suggest an ionic enrichment of rainfall due to the accumulation of ions in the ephemeral portion of the stream and the soil surface.
Negli ultimi decenni e’ aumentato sempre di piu’ l’interesse nel meglio comprendere i complessi processi idrologici. In particolare, i meccanismi attraverso cui la precipitazione controlla i processi di generazione di deflusso superficiale e la variabilita’ spaziale e temporale delle componenti di deflusso sono attualmente ancora poco chiari. L’uso integrato dei traccianti isotopici e geochimici, abbinato ai dati idrometrici, si sta dimostrando uno strumento efficace e sempre piu’ utilizzato per studiare i sistemi idrologici e i meccanismi di generazione di deflusso superficiale e sottosuperficiale. In questo studio, gli isotopi stabili dell’acqua, la conducibilita’ elettrica e gli ioni sono stati utilizzati come traccianti insieme ai dati idrometrici al fine di i) analizzare la risposta della falda e dell’umidita’ del suolo rispetto alla risposta del torrente durante gli eventi di afflusso-deflusso ii) analizzare la variabilita’ spaziale e temporale dei traccianti (isotopi stabili dell’acqua, EC e ioni) nelle diverse componenti di deflusso superficiale iii) valutare il controllo esercitato dalle principali caratteristiche dell’evento sui processi di generazione di deflusso superficiale e ii) verificare come l’uso di diversi traccianti influenza i risultati ottenuti dalla separazione dell’idrogramma a due componenti. Per questo studio, sono stati analizzati i dati idrometrici e dei traccianti ricavati da 15 eventi di pioggia campionati durante diverse condizioni di umidita’ del suolo nel periodo che va da settembre 2015 ad ottobre 2016 in un piccolo bacino nelle prealpi italiane. Durante questo periodo sono stati misurati in continuo il livello del torrente, la precipitazione, la temperatura dell’aria, il livello della falda in 6 punti posti in diverse parti del bacino (zona riparia, zona di basso versante, versante) e l’umidita’ del suolo in 4 punti disposti lungo un transetto dal torrente al versante. Inoltre sono stati raccolti a scala di evento campioni di acqua per l’analisi isotopica e geochimica dalla pioggia, dal torrente, dalla falda e dal suolo in 5 punti a diverse profondita’ (nella zona riparia a 10 cm e 20 cm di profondita’; nella zona a meta’ versante a 10 cm e 30 cm di profondita’; nella parte alta del versante a 30 cm di profondita’). La conducibilita’ elettrica e’ stata misurata direttamente in campo utilizzando un conduttimetro. Le concentrazioni isotopiche e ioniche sono state misurate nel laboratorio di Legnaro (Dip. TESAF, Universita’ degli Studi di Padova) rispettivamente tramite spettroscopia laser e cromatografia ionica. L’analisi EMMA rivela che la precipitazione, l’acqua di suolo nella zona riparia e la falda superficiale sono le principali componenti che contribuiscono all’evento di piena. La tecnica di separazione dell’idrogramma a due componenti rivela che il contributo di acqua nuova al torrente aumenta con l’aumentare della pioggia totale e dell’intensita’ di pioggia mentre diminuisce durante condizioni di umidita’ antecedente l’evento umide. Durante gli eventi che avvengono in condizioni di umidita’ secche e che sono caratterizzati da elevate intensita’ di pioggia, l’acqua nuova contribuisce al torrente in maggior misura, soprattutto nelle fasi iniziali dell’evento e in prossimita’ del picco di portata, indicando che l’acqua nuova proviene principalmente dalla pioggia incanalata direttamente nel torrente e dal deflusso superficiale che si forma nella zona riparia. Con l’aumento delle condizioni di umidita’, l’acqua vecchia (di pre-evento) inizia a contribuire maggiormente al torrente, indicando uno sviluppo della connessione sottosuperficiale durante l’evento ed un maggior contributo di acqua di falda proveniente da diverse parti nel bacino. Nella fase intermedia e finale di eventi avvenuti durante periodi umidi e caratterizzati da elevate quantita’ di pioggia, aumenta la componente di acqua nuova nel torrente, aumento dovuto all’espansione della zona satura vicino al torrente. Le differenze riscontrate nel calcolo della componente di acqua nuova usando i traccianti isotopici e geochimici suggeriscono che la pioggia viene arricchita in ioni prima di essere incanalata nel torrente a causa dell’accumulo di ioni nella zona effimera del torrente e negli strati superficiali del suolo.

Orientador: Didier Gastmans
Resumo: A necessidade do estudo os diferentes processos do ciclo hidrológico de forma integrada tem se tornado cada vez mais urgente, uma vez que o uso do termo “crise hídrica” se torna cada vez mais frequente. Nesse sentido, a determinação de taxas de recarga e quantificação dos fluxos subterrâneos, aliados ao uso de isótopos estáveis (2H e 18O), que são excelentes traçadores da movimentação da água no ciclo hidrológico, impulsionaram esse estudo, buscando gerar informações científicas fundamentais para uma melhor gestão dos recursos hídricos. Situada numa porção de afloramento do Sistema Aquífero Guarani (SAG), a área de estudo está inserida em uma pequena bacia hidrográfica na porção oeste do estado de São Paulo, onde as águas subterrâneas e superficiais são responsáveis pelo abastecimento de inúmeras cidades da região. O estudo teve como principal objetivo compreender a dinâmica entre os diversos compartimentos do ciclo hidrológico, buscando mudanças nos padrões de precipitação e de recarga subterrânea, por métodos de fácil aplicação, como balanço hídrico e flutuações dos níveis d’água (WTF), bem como a aplicação de traçadores isotópicos (δ2H e δ18O) em diferentes sazonalidades. Ao considerar a sazonalidade dos dados isotópicos na chuva, águas superficiais e subterrâneas, pode-se observar que os valores de δ18O são mais empobrecidos durante a estação chuvosa e mais enriquecidos durante a estação seca. A diferença entre os sinais isotópicos permitiu compreender a movimentação da á... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The need to study the different processes of the hydrological cycle in an integrated way has become increasingly urgent since the use of the term "water crisis" becomes more and more frequent. In this sense, the determination of rates of recharge and quantification of the underground flows, together with the use of stable isotopes (2H and 18O), which are excellent tracers of water movement in the hydrological cycle, stimulated this study, seeking to generate scientific information fundamental to better management of water resources. Located in a portion of the outcrop of the Guarani Aquifer System (SAG), the study area is in a small hydrographic basin in the western portion of the state of São Paulo, where groundwater and surface waters are responsible for the supply of numerous cities located there. The main objective of this study is to understand the dynamics between the various compartments of the hydrological cycle, searching for changes in precipitation and underground recharge patterns, using easy-to-apply methods such as water balance and water level fluctuations (WTF), as well as the application of isotopic tracers (δ2H and δ18O) in different seasonal conditions. When considering the seasonality of the isotopic data in rainfall, surface water, and groundwater, it can be observed that δ18O values are more depleted during the rainy season and more enriched during the dry season. The difference between the isotopic signals allowed to understand the movement of the water... (Complete abstract click electronic access below)
Doutor

Aquesta tesi té com a objectiu analitzar el paper de la coberta forestal en la redistribució dels fluxos d’aigua, amb la finalitat de millorar el coneixement sobre el funcionament hidrològic de les conques Mediterrànies de capçalera. L’estudi s’ha realitzat a les conques d’investigació de Vallcebre, representatives dels ambients mediterranis de muntanya. Els processos hidrològics s’han estudiat a diferents escales espai-temporals a partir de mesures continues de pluja, trascol, escolament cortical, escorrentia, variables meteorològiques i mostreig dels isòtops estables de l’aigua. Els resultats obtinguts a escala de parcel·la, en un bosc de Pi roig (Pinus sylvestris L.) i un de roure martinenc (Quercus pubescens Willd.) han demostrat que l’escolament cortical, malgrat representar un percentatge petit de la pluja incident, representa una concentració important d’aigua i partícules directament a la base dels arbres. L’escolament cortical és el resultat d’una combinació complexa de factors biòtics i abiòtics, augmenta a major volum de pluja, però la duració de la pluja, la intensitat o la demanda evaporativa determinen la seva dinàmica temporal. D’altra banda, la mida dels arbres determina la diferent resposta d’individus de la mateixa espècie. En canvi, entre espècies, les diferències estan determinades per la capacitat d’emmagatzemar aigua a l’escorça o les diferents taxes d’evaporació. L’anàlisi de les partícules transportades pel trascol i l’escolament cortical, indica que la interacció entre la matèria particulada i les superfícies vegetals afecta a la mida i a la retenció de partícules. En general, la presència de fulles als roures incrementa la mida de les partícules, i les acícules dels pins augmenten la retenció de partícules. Finalment, cal destacar la pols del Sàhara com una font important de partícules a la zona d’estudi. Hem observat diferències isotòpiques entre l’aigua de pluja, el trascol i l’escolament cortical. Els processos de fraccionament isotòpic són més evidents per als episodis de baixa magnitud, en els que les capçades no s’arriben a saturar del tot. Aquests processos són deguts a una mescla de factors, per exemple l’evaporació pot ser el factor determinant a l’inici de la pluja, tot i que en condicions d’alta humitat ambiental, l’intercanvi isotòpic (entre aigua i vapor d’aigua) pot adquirir rellevància. En episodis on el senyal isotòpic varia al llarg de la pluja, la retenció de part de la pluja a les fulles i troncs pot produir tan enriquiment com empobriment. A escala de conca, hem observat que el senyal isotòpic de la pluja, a més de canviar per l’efecte de la coberta, canvia al variar el gradient d’elevació. Amb aquesta informació, hem analitzat l’efecte de la variabilitat espai-temporal del senyal isotòpic d’entrada a la conca de Can Vila sobre els resultats de la separació d’hidrogrames. Els resultats mostren que tot i que els hidrogrames estan dominats per aigua pre-existent a la conca, per algunes crescudes, la contribució d’aigua pre-existent pot variar significativament en funció de la localització del senyal isotòpic d’entrada utilitzat. La comparació dels resultats obtinguts en la separació d’hidrogrames utilitzant diferents senyals isotòpics d’entrada amb els resultats obtinguts utilitzant un senyal mitjà, ha permès definir una estratègia de mostreig “intel·ligent” que millora les separacions d’hidrogrames basades en isòtops estables a escala de petita conca. En conjunt, els resultats d’aquesta tesi destaquen el rol de l’escolament cortical com a flux preferencial d’aigua i nutrients, que pot afavorir els processos biogeoquímics a la base dels arbres. A més, els resultats recalquen que la variabilitat del senyal isotòpic de la pluja, degut als processos d’intercepció i gradients d’elevació, s’ha de tenir en compte per millorar la comprensió dels processos hidrològics en conques Mediterrànies de capçalera.
The present dissertation aims to analyse the role of forest cover on the redistribution of water fluxes and improve the current knowledge on hydrological functioning of Mediterranean headwater catchments. This study has been carried out in the Vallcebre research catchments, an area representative of these Mediterranean mountain environments. Continuous measurements of rainfall, throughfall, stemflow, runoff, meteorological data and stable isotopes of water have been used to investigate hydrological processes at different spatio-temporal scales. At the plot scale, the findings obtained from a Scots pine (Pinus sylvestris L.) and downy oak (Quercus pubescens Willd.) forest plots have shown that stemflow, despite being only a small portion of the incident precipitation, is a substantial source of water and particulate matter at the base of trees. Stemflow is the result of a complex combination of biotic and abiotic factors, it increases with the event size but the duration of rainfall, intensity or the evaporative demand highly influence its temporal dynamics. In addition, we have found the size of trees to be the main factor producing differences among individuals of each species. However, between species, main stemflow differences have been attributed to different bark storage capacities and different evaporation rates. Besides, through the analysis of the particles contained in throughfall and stemflow, we have observed that the interaction between particulate matter and vegetative surfaces affects the size and the retention of particles. In general, the presence of leaves in oaks increases the size of particles, and needles of pines enhance its retention. We have also found that Saharan dust events are a substantial source of particulate matter in the study area. Isotopic differences among rainfall, throughfall and stemflow have been observed. Fractionation processes are more evident for events of low rainfall amount, when canopies are not completely saturated. They can be caused by a mixture of factors, for example, evaporation is more likely to have a higher impact at the beginning of rainfall, however, under low evaporation conditions, isotopic exchange (between water and vapour) may acquire more relevance. In addition, for rainfall events with temporal variations of the isotopic composition, the retention of part of the final portion of rainfall on leaves and stems can also produce isotopic differences in both directions, enrichment or depletion. At the catchment scale we have found that, in addition to the isotopic changes produced by canopy interception processes, the isotopic composition of rainfall also varies along an elevation gradient. Throughout the Can Vila catchment and for several runoff events, the effect of the spatio-temporal variability of the input isotopic signal on hydrograph separation results has been tested. Results have shown that although the Isotopic Hydrograph Separations are dominated by pre-event water, for some floods, the pre-event water contribution can differ significantly depending on the single location of the input isotopic signal used. Comparing hydrograph separation results obtained using different single input signals, with results obtained using a catchment scale input isotopic signal, we could determine the most representative sampling location and define a “smart” sampling strategy for improving Isotopic Hydrograph Separations at the small catchment scale. Overall, findings gathered in the present dissertation highlight the role of stemflow as a preferential flow path of water and nutrients that can enhance biogeochemical processes at the base of trees during rainfall events. Results also emphasize that the isotopic variability of rainfall, due to canopy interception processes and elevation gradients, has to be taken into account for a better understanding of the hydrological processes in Mediterranean headwater catchments.

La presente tesi riporta i risultati di una ricerca bibliografica e sperimentale di campo relativamente al problema delle infiltrazioni di acque parassite (infiltrazioni) e di perdite di acque reflue (exfiltrazioni) in reti di fognatura urbana. Tale lavoro di tesi è stato sviluppato nell’ambito di un progetto Europeo denominato APUSS (Assessing Infiltration and Exfiltration on the Performance of Urban Sewer Systems) il cui obiettivo è stato quello di creare nuovi metodi e nuovi modelli per quantificare e prevedere le infiltrazioni ed exfiltrazioni. Tale progetto ha visto coinvolti gruppi di ricerca quali: INSA di Lione (FR), EAWAG di Zurigo (CH), Technological University di Dresda (DE), Faculty of Civil Engineering dell’Università di Praga (CZ), DHI Hydroinform di Praga (CZ), Hydroprojekt di Praga (CZ), Middlesex University di Londra (UK), LNEC di Lisbona (PT), Emschergenossenschaft di Essen (DE) e IRSA-CNR di Roma (IT). Il progetto è stato supportato dalla Commissione Europea nell’ambito del 5° Programma Quadro con lo scopo di contribuire all’implementazione di azioni per “La gestione sostenibile e la qualità dell’acqua” entro il contratto n° EVK1-CT-2000-00072 per lo sviluppo sostenibile, per l’ambiente e per l’energia. In particolare, il presente lavoro di tesi si è svolto in collaborazione con l’IRSA-CNR ed ha riguardato l’applicazione dei nuovi metodi di quantificazione dell’exfiltrazioni ed infiltrazioni sviluppati dal gruppo di ricerca dell’EAWAG. L’aspetto innovativo di questi metodi, rispetto a quelli tradizionalmente usati, risiede nella loro semplicità di applicazione ed economicità, pertanto, nella possibilità di monitorare lo stato strutturale, strettamente connesso alla quantità di exfiltrazioni ed infiltrazioni, di estese reti di fognature urbane. La presente tesi consiste in tre capitoli, il primo descrive la problematica e le tradizionali tecnologie di indagine delle fognature; il secondo tratta gli aspetti teorici alla base dei quattro metodi applicati: • metodo QUEST per la quantificazione delle exfiltrazioni; • metodo QUEST-C per la quantificazione delle exfiltrazioni; • metodo del pollutogramma per la quantificazione delle infiltrazioni; • metodo degli isotopi per la quantificazione delle infiltrazioni. QUEST e QUEST-C consistono in un bilancio di massa di traccianti chimici su tratti fognari dosati in modo discreto e continuo, rispettivamente. Il metodo del pollutogramma e quello degli isotopi si basano sul metodo della separazione degli idrogrammi applicati a reti fognarie usando come traccanti inquinai tipici delle acque reflue e l’isotopo 18O , rispettivamente. Il terzo capitolo descrive la metodologia di pianificazione delle campagne sperimentali e riporta e discute i risultati ottenuti dalla applicazioni, in due aree urbane a Roma, di questi quattro metodi. Infine, la precisione e l’accuratezza di tali metodi è stata stimata mediante simulazioni Monte Carlo.
This thesis deals with the problem of infiltration of parasitical water (infiltration) and leakage of wastewater (exfiltration) in urban sewer networks. That research has been developed within the framework of the European research project APUSS (Assessing Infiltration and Exfiltration on the Performance of Urban Sewer Systems) which partners were INSA de LYON (FR), EAWAG of Zurich (CH), Technological University of Dresden (DE), Faculty of Civil Engineering at University of Prague (CZ), DHI Hydroinform company in Prague (CZ), Hydroprojekt company in Prague (CZ), Middlesex University of London (UK), LNEC in Lisbon (PT), Emschergenossenschaft in Essen (DE) and IRSA-CNR in Rome (IT). That European project was supported by the European Commission under the 5th Framework Programme and it aimed at contributing to the implementation of the Key Action “Sustainable Management and Quality of Water” within the Energy, Environment and Sustainable Development Contract n° EVK1-CT-2000-00072. In particular, that work has been carried out in collaboration with IRSA-CNR and consisted of applying new methods for quantifying infiltration and exfiltration in urban sewer networks (i.e., pipes and house connections) which were developed by a research group of EAWAG. An innovative aspect is that these methods allow monitoring large urban sewer systems due to their speediness and cheapness of these methods. The thesis is subdivided into three chapters, the first one describes the problem and the traditional diagnostic techniques; the second one explains the four applied methods: 1. QUEST method for quantifying exfiltration; 2. QUEST-C method for quantifying exfiltration; 3. pollutograph method for quantifying infiltration; 4. isotopic method for quantifying infiltration. and deals with the theoretical aspects which the methods are based on. QUEST and QUEST-C consisted on a mass balance of chemical tracer injected into sewer pipes to be investigated in a slug and continuous way, respectively. The pollutograph and the isotopic methods based on the hydrograph separation method applied over urban sewer systems using typical wastewater pollutants and 18O water isotope, respectively. The third chapter describes the experimental planning and discusses the results of application of these methods in two urban areas in Rome and reports the results of an uncertainty analysis using Monte Carlo simulations.

Ce travail de thèse porte sur l’étude des mécanismes et des bilans de transfert des pesticides vers les cours d’eau sur deux bassins versants agricoles emboités, de tailles différentes en Gascogne (Sud Ouest de la France) : la Save à Larra (1110 km2).et le Montoussé (3,28 km2) à Auradé. Dans cette région, les pratiques d’une agriculture intensive conduisent à des risques importants pour les ressources en eau, notamment pendant les périodes de crue. C’est pour cela que nous avons porté une attention particulière dans cette étude à ces événements au cours desquels une grande quantité de contaminants sont transportés par les cours d’eau. Quatorze molécules de pesticides (herbicides et fongicides) largement utilisées sur ces bassins versants ont été étudiées grâce à un échantillonnage intensif, notamment en périodes de crue, durant deux années hydrologiques (2007/2008 et 2008/2009). La majorité des molécules étudiées présentent des concentrations qui dépassent les limites autorisées par l’Union Européenne pour l’eau potable (0.1 μg.L-1 pour chaque molécule et 0.5 μg.L-1 pour l’ensemble des molécules), notamment en périodes de crue. L’analyse des hystérésis mises en évidence sur les relations entre les concentrations (pesticides, MES, COD, POC) et les débits du cours d’eau permet de mieux comprendre les mécanismes de transfert des pesticides et de leurs paramètres de contrôle. Ces hystérésis montrent pour un même débit des concentrations différentes en montée et en descente de crue ; elles peuvent être dextres (sens des aiguilles d’une montre) ou senestres (sens inverse) suivant l’origine des molécules et l’écoulement responsable de leur transfert des sols vers les eaux. C’est pourquoi nous avons procédé dans cette étude à une séparation des différentes composantes (ruissellement superficiel, écoulement hypodermique, écoulement de nappe) de l’écoulement fluvial pour mieux comprendre la dynamique de transferts des pesticides et de leurs paramètres de contrôle. On peut ainsi mettre en évidence des relations positives entre MES, COD, COP ou certaines molécules de pesticides et les débits des écoulements de surface (ruissellement superficiel ou écoulement hypodermique suivant les caractéristiques physico-chimiques des molécules). Les calculs de flux des différents pesticides exportés par les cours d’eau montrent que 60 à 90% (suivant les molécules) des transports annuels se font durant les épisodes de crue. Les flux spécifiques (masse exportée par unité de surface) calculés sont plus importants sur le bassin versant de la Save que sur celui du Montoussé et les relations flux spécifiques-débits mettent en évidence des concentrations plus élévées sur la Save où l’utilisation des pesticides est globalement plus importante que sur le Montoussé où les pratiques sont raisonnées. L’analyse des pesticides dans l’eau filtrée et non filtrée nous a permis d’estimer la distribution de chaque molécule entre les phases particulaires et dissoutes (Kd). De plus, les valeurs de flux calculés pour chaque crue nous ont permis d’estimer un Kd moyen pour chaque molécule. Ces valeurs de Kd présentent une très bonne relation avec les valeurs de Kow (coefficient de partage octanol-eau) extraites de la littérature. De même, les pourcentages calculés de chaque pesticide exporté sous forme particulaire sont aussi très bien corrélés au Kow de chaque molécule
The mechanisms of pesticides transport to stream flow were studied in two agricultural nested catchments of different size in Gascogne region (South West of France): the Save river basin at Larra (1110 km2) and the Montoussé experimental watershed at Auradé (3.28 km2). The intensive agricultural practices used in this region lead to an important risk for water resources by pesticides, especially during storm events. This is why we have paid special attention on storm events when a large quantity of contaminant was transported during hydrological periods. Fourteen molecules of pesticides (herbicides and fungicides) were investigated during the study period. Both of these groups are widely used for agricultural purposed in these catchments. The results achieved over the two years monitoring (2007-2009) enable us to emphasize the principal processes, implied in pesticide transfer on these agricultural catchments. The majority of compounds are detected during storm runoff events. And, the average concentrations of some pesticides are exceeded at the authorization limit of the European Union for pesticide concentrations in drinking water (0.1 µg.L-1 for individual pesticides and 0.5 µg.L-1 for total pesticides). To better understand the mechanisms of pesticide transport hysteresis, patterns on the concentration-discharge relationship (result of different concentration of pesticides in rising and falling limb of storm) were studied. However, clockwise or anticlockwise hysteresis patterns could be observed for some molecules of pesticide and their controlling factors such as dissolved organic carbon (DOC), particulate organic carbon (POC) and total suspended matters (TSM) according to their transfer dynamic in the catchment. We proceeded with hydrograph separation of the main stormflow components (surface runoff, subsurface flow and groundwater) so that the main pesticide routing could be traced for its soil-river transfers. We also came to the conclusion that there is a positive relationship between riverine TSM, DOC and pesticide, concentrations and the discharges of surface or subsurface runoffs according to pesticide properties. Pesticide flux calculation shows between 60 to 90% of the molecule transport takes place during storm periods. Specific flux calculation also demonstrated the higher flux value in Save catchment than in Aurade with higher pesticide concentration for a given specific discharge. The latter result may be due to the more consumption of pesticide in Save catchment. The analyses of pesticides both in filtered and unfiltered water enabled us to estimate the distribution of pesticides into particulate and dissolved phases. Moreover, the pesticide flux values allow calculating average partition coefficients kd between dissolved and particulate fractions which present good relationship with Kow values (octanol-water) extracted from literature. The percentage of each pesticide transported as particulate forms is also well correlated to Kow

Les progrès technologiques récents permettent de mesurer à haute-fréquence les concentrations en ions dissous des eaux de rivières, sur de longues périodes. Ces nouvelles données, bien adaptées aux variations temporelles des débits, permettent aujourd'hui de préciser les liens entre les processus hydrologiques du bassin versant et la chimie du cours d'eau. Cependant, elles nécessitent le développement de méthodes adaptées. Cette thèse tente de répondre aux nouvelles questions qui se posent aujourd’hui: quels modèles et méthodes pouvons-nous utiliser pour exploiter les données haute-fréquences et comment transforment-elles notre connaissance de la qualité chimique des rivières ? Au cours de cette thèse, nous avons adapté différentes méthodes et méthodologies conçues à l'origine pour les données basse / moyenne fréquence et les avons appliquées au jeu de données haute-fréquence du River Lab de l'Observatoire Oracle-Orgeval (France). Pendant de nombreuses années, la taille des jeux de données concentrations-débits ayant été limitée, il était difficile d'analyser de manière détaillée la forme précise de la relation C-Q. Dans de nombreux cas, l’équation de puissance précédée d’une transformation logarithmique, semblait adequate. Aujourd’hui, toute la gamme des relations C-Q à haute-fréquance peut maintenant être incluse dans l'analyse. De cette dernière, comme alternative à la relation de puissance, nous proposons d’utiliser une transformation affine de puissance bilatérale. La séparation d’hydrogramme est peut-être l’un des plus anciens problèmes non résolus de l’hydrologie. Dans la thèse, nous avons utilisé conjointement les méthodes de séparation d’hydrogramme de type filtre numérique (RDF) et une équation de mélange à deux composantes basée sur le bilan de masse (MB). Le but etait d'identifier le paramètre du modèle RDF menant aux paramètres de l’équation de mélange les plus réalistes. Nous montrons que cette approche de couplage RDF-MB fonctionne avec un étalonnage spécifique et sur l'hypothèse simple de deux sources d’écoulement. Pour combiner la relation simple de puissance et le modèle de mélange, nous avons appliqué la transformation affine de puissance bilatérale aux deux composantes de l’équation de mélange, à l’aide d’une procédure d'identification multicritère. Le nouveau modèle combiné améliore considérablement, par rapport aux modèles de puissance et de mélange, la simulation des concentrations dans le cours d'eau. Enfin, nous avons développé une méthodologie pour identifier et quantifier les sources sur la seule base d’une analyse chimique. La nouvelle méthode développée au cours de la thèse, sans aucune hypothèse préalable sur la composition des sources potentielles, nous permet d'analyser la variabilité temporelle des sources chimiques et leur relation avec les différents régimes d'écoulement
Recent technological advances allow measuring high-frequency chemical concentrations in rivers over long periods. These new data sets, well adapted to the temporal variations of discharge, allows us today to specify the links between hydrological processes in catchments and the water stream chemistry. However, they require the development of adapted methods for data treatment. This thesis tries to answer to the following questions: which models and methods can we use to exploit high-frequency measurements and the way they are transforming our knowledge of the chemical water-quality? During the course of this thesis, we adapted different methods and methodologies originally designed for low / medium frequency data and applied then to high-frequency dataset of the River Lab of the Oracle-Orgeval observatory (France). For many years, since the size of the C-Q datasets was limited, it was difficult to analyse in much detail the precise shape of the C-Q relationship. In many cases, the power-law relationship appeared adequate, which explains its popularity, although many additions to the basic relation have been proposed to improve it. With the advent of high-frequency measuring devices, all the range of the relationship can now be included in the analysis. As a progressive alternative to the power law relationship and a log-log transformation, we propose to use a two-sided affine power scaling relationship. Hydrograph separation is perhaps one of the oldest unsolved problems of hydrology. In the thesis we aim to use jointly the Recursive Digital Filter (RDF) and Mass Balance (MB) methods in order to identify the RDF model parameter leading to the most realistic MB parameters. We show that a simple methodology proposed for the hydrograph separation (RDF-MB coupling approach) works, with a specific calibration and with the simple hypothesis of two sources of path flow. To combine the power-law relationship and the two-component mixing model, we applied the two-side affine power scaling relationship to the so-called base flow and quick flow (Cb and Cq) components, with a multicriterion identification procedure. The new combined model significantly improves, compared to power and mixing models, the simulation of stream river concentrations. Last, we develop a methodology for identifying and quantifying sources from a purely chemical point of view. The new method developed here, without any preliminary assumption on the composition of the potential sources, allows us analyzing the temporal variability of the end-member sources and their relationship to the different flow regimes

The aim of this paper is to describe and compare various methods of runoff separation. Therefore it is necessary to explain basic hydrological terms that are important for understanding the water regime of landscape. Long-term monitoring of the water regime of the whole catchment area can provide successful detection of hydrological extremes such as droughts or devastating floods. The paper is divided in two parts. The theoretical part includes the literature rerview explaining basic hydrological terms and individual components of water cycle in nature, summary of methods usually used for runoff separation, and the description of the applied methods. The practical part specifies the locality of Jenínský stream, located in the Český Krumlov district. This part further reflects separation of runoff based on the daily runoffs. Methods GROUND, MPGM and Chapman digital filter have been chosen to compare primary runoff and direct runoff. We have also considered the method of separation of minimal monthly runoff according to Kille for seven-year period in relation to the methods mentioned above. Finally, we have chosen several discharge waves for the method of recession curve analysis. The paper compares direct and primary runoff separated by individual methods in the catchment area of our interest.

Rain-on-snow events represent one of the basic mechanisms causing floods. Rain falling on the snow cover causes enhanced melting and the resulting runoff often exceeds the runoff caused by rain. During the winter seasons 2018 and 2019, water samples from the stream, snowpack and precipitation were repeatedly taken in the the Ptačí Brook catchment in the Šumava mountains, and the concentrations of 2 H and 18 O were measured in the laboratory. Based on the observed isotope ratios 18 O/16 O and 2 H/1 H in combination with other variables measured in the catchment, the two ROS events from 2019 were reconstructed. The ratio of heavy isotopes increased in the snowpack due to ROS events. Using the end member mixing equation, a hydrograph separation was performed for both investigated events. For the first event, it was not possible to clearly separate groundwater from rainfall, and thus the range of snow in the total runoff was determined by its separation from rainfall and subsequent separation from groundwater. The second event examined was separated directly into three components: rainfall, groundwater and snow. According to the analyses, the total runoff during ROS events in both cases was mostly formed by event water (a combination of rainfall and melt water). The melting water from the snow cover...

Near-level Prairie landscapes have received limited attention in hydrological research. For this thesis, hydrometric measurements and four tracing experiments were completed at three “riparian-to-stream” sites in the Catfish Creek Watershed (southeastern Manitoba) to enhance Prairie hydrology understanding. First, hydrologic state variables were examined to infer vertical and lateral water movement. Second, tracer data were analyzed to evaluate the relative importance of surface versus subsurface water movement. Results show that hydrologic state variables can be useful for inferring riparian-to-stream water movement. Tracer data also revealed that subsurface water movement can contribute significantly to streamflow during snowmelt- and rainfall-triggered events in the study watershed. This thesis demonstrated that subsurface flow is a significant runoff generation mechanism in Prairie landscapes, thus challenging surface water-focused conceptualizations and management strategies that are traditionally used. The findings summarized in this thesis will be critical to improve the performance of hydrological models when applied to the Prairies.
February 2017

This thesis is focused on the methods of separation of baseflow and comparing of these metods. It is analyzing concentrations of total phosphorus in the total runoff and influence of baseflow to concentrations of phosphorus in total runoff. The studied area is subcatchment P52 in the catchment Kopaninský flow. Subcatchments P52 is small (64,93 hectares), drained agro-forestry catchment in Českomoravská vrchovina (Czech-Moravian highlands), with a large proportion of forest area (64% forest and 31% of arable land). Studied the period is hydrological period 2009 - 2011. To obtain the necessary results are used daily flow, daily concentrations, daily precipitation of rain gauge station Velký Rybník and monthly precipitation from rain gauge stations of the ČHMŮ (Czech Hydrometeorological Institute) in Humpolec. For the separation of the baseflow and comparison of methods were selected five methods: - method of digital filter according to Chapman (1999), - method UKIH designed by Institute of hydrology (1980), - method RDF proposed by LINE AND Hollick (1979), - method FUKIH proposed by AKOSY AT. AL. (2009) and - method of Kille (1970). All methods are simple to perform and not challenging to input data. When comparing methods, the main problem is that, the results obtained by different methods are very different. Another point of this work is to evaluate the concentrations of total phosphorus in the tatal runoff. Here is analyzed series of daily concentrations of total phosphorus and monthly and annual average concentrations. Low and high concentrations are compared with the values ??of precipitation and clinks are searched between these values. The main problem is that, the concentration of phosphorus are not dependent only on precipitation. The last point is solution of influnence of baseflow to the amount of total phosphorus in the runoff. Here is used the procedure which described BYSTŘICKÝ in its work (2012). There are determined values concentrations typical of baseflow, for direct runoff and total runoff. Groups of values ??are mutually tested and compared. The results show that, the baseflow is negligible contributor of phosphorus to the total runoff, but to achieve more accurate results would be needed to analyse a longer time period (eg 10 years) and compare the results with several different river basins.