<p> "Jason's Creek" is a stream draining 2.2 km^2 of arctic limestone terrain. Its annual regime consists of a ten-month period in which it is frozen to its bed, a short spring flood which occurs shortly after tenperatures cross the freezing-point in late June, and a period of about two months during which discharge is relatively low and fluctuates diurnally in response to inputs of radiative and heat energy to the snowpack. In 1970, the spring flood occupied the first two weeks of July and effected the discharge of some nine-tenths of total annual runoff. Tne low flow period was punctuated by rainstorms which generated sharply-defined floods: basin response was rapid and efficient, for storm runoff is facilitated over the unvegetated ground and through the shallow active layer above the permafrost table. Covariance and spectral analyses suggest a basin lag time of five hours, both for low discharges of snowmelt water and flood discharge of rainwater. It appears, from the spectra of the time series, that radiation is a better index of snowmelt discharge than is temperature.</p> <p> Most of the annual removal of sediment from the basin takes place during the spring flood, when the stream is turbid and movement of channel bed material is vigorous, In the longer period after the flood the main component of stream load is the solute load. The concentration of dissolved material varies inversely while suspended sediment concentration varies directly with discharge. Solute concentrations are lower than those commonly found in limestone streams at lower latitudes, suggesting that in "Jason's Creek" the increased solubility of CO2 at low temperatures is more than counteracted by a decrease in the rate of solution of CaCO3. There are also indications that the concentration of CO2 in snowmelt water 2 may be smaller, in absolute terms, than in rainwater.</p> <p> The role of water is crucial in many processes acting on slopes and delivering detritus to stream channels; rills, for example, remove ions in solution and fine particles in suspension, notably from the base of talus slopes, and lubrication of the active layer after rainstorms generates bowl-slide and mudflow activity.</p> / Thesis / Master of Science (MSc)

Lake Mead, the largest reservoir in the United States along the Colorado River on the border between the states of Nevada and Arizona, is one of the nation's most important sources of freshwater. As reported by the U.S. drought monitor (USDM), the entire region has been experiencing recurring severe to extreme droughts since the early 2000s, which have further intensified during the past two years. The drought-driven water deficit caused Lake Mead's water volume to decrease to approximately one-third of its capacity, creating a water crisis and negatively affecting soil and groundwater storage across the region. Water deficits have further reduced the mass of water loading on the Earth's crust, causing it to elastically deform. I observe this process from the ground by recording the vertical land motion occurring at Global Navigation Satellite System (GNSS) stations, or from space via Interferometric Synthetic Aperture Radar (InSAR) technology. In this study, I analyze vertical deformation observations from GNSS sites and multi-temporal InSAR analysis of Sentinel-1A/B to investigate the contribution of water mass changes in lake, soil, and groundwater to the deformation signal. To achieve this, I remove the effects of glacial isostatic adjustment and non-tidal mass loads from GNSS/InSAR observations. Our findings indicate that recent drought periods led to a notable uplift near Lake Mead, averaging 7.3 mm/year from 2012 to 2015 and an even larger rate of 8.6 mm/year from 2020 to 2023. Further, I provide an estimate of the expected vertical crustal deformation in response to well-known changes in lake and soil moisture storage. For that, I quantify hydrological loads through two different loading models. These include the application of Green's functions for an elastic, layered, self-gravitating, spherical Earth, and the Love load numbers from the Preliminary Reference Earth Models (PREMs), as well as elastic linearly homogeneous half-space Earth models. I further test various load models against the GNSS observations. Our research further investigates the impact of local crustal properties and evaluates the output of several elastic loading models using crustal properties and different model types under non-drought and drought conditions. For future studies, I suggest a comprehensive analysis of the deformation field InSAR data. Also, rigorous monitoring of groundwater levels is essential to accurately predict changes in water masses based on deformation. In addition, for each data set, I suggest implementing an uncertainty analysis to assess the predictability of groundwater level changes based on vertical loading deformation observed by INSAR/GNSS data around the region. Obtaining such estimates will provide valuable insight into the dynamic interactions of the local aquifers with Lake Mead. / Master of Science / The drought has led to a decline of approximately 40 meters in Lake Mead since 1999. During the process of water mass loss from a lake, the crust lifts and extends from the center. However, the water mass loss seen on the lake is not sufficient to explain the movement seen at nearby GPS sites. Hence, the uplift loading of water loss in the form of other hydrological components surrounding Lake Mead needs to be estimated. Here, I analyze several models that best fit the geodetic displacements and try to fill in the gap in deformation observations.

Land use/cover has shown significant changes during the past three decades in Ethiopia especially in the highlands of the country. That resulted in changes in streamflows and other hydrological processes. The existing land and water resources system of the area is adversely affected due the rapid growth of population, deforestation, surface erosion and sediment transport. The main objective of this study is to evaluate the impact of land use/cover changes in the hydrology of Beles Basin, Ethiopia. The physically based hydrologic model, SWAT, was developed for the Beles basin, Ethiopia by combining geospatial and climatic data. ArcGIS has been used to process geospatial data which includes the Digital Elevation Model (DEM) which has a resolution of 90 m, land use/cover and soil maps. A simple Interpolation technique has been used to fill in the missing precipitation data. The GIS interface version of SWAT (ArcSWAT) has the capability to utilize ArcGIS to facilitate input data preparation and output data generation. Idrisi Andes in cooperation with ArcGIS 9.2 used to generate landuse/cover maps from Landsat data of three different years. Three SWAT models were set up using the three generated land use/cover maps and used to evaluate the land use/cover change and its impacts on the streamflow of study basin. The primary hydrological model was evaluated through sensitivity analysis, model calibration, and model validation for realistic prediction of the different hydrological components in the basin. Out of twenty six flow parameters sixteen parameters were found to be sensitive. But the most sensitive ten parameters were selected and used for model calibration. The model calibration was carried out using observed streamflow data from 01 January 2001 to 31 December 2002 and a validation period from 01 January 2003 to 31 December 2004. The coefficient of determinations (R2) was 0.74 and the Nash-Sutcliffe simulation efficiency (NSE) was 0.62which indicated that the model was able to predict streamflow with reasonable accuracy. However, the hydrograph of the cumulative hydrographs of the calibration and validation periods showed significant discrepancies between the observed and the simulated data of each period.  The average yearly flow volume of the observed streamflow on the cumulative hydrograph of the calibration period has exceeded the simulated streamflow. On the other hand on the cumulative hydrograph of the validation period the average yearly flow volume of the simulated streamflow was higher than the observed streamflow. The simulated result of the streamflow data from different land use/cover maps revealed that the change in the land use/cover classes of the basin throughout the study periods.

No description available.

The Occoquan Watershed is a 1515 square kilometer basin located in northern Virginia and contains two principal waterbodies: the Occoquan Reservoir and Lake Manassas. Both waterbodies are principal drinking water supplies for local residents and experience eutrophication and summer algae growth. They are continuously threatened by new development from the rapid expansion of the greater Washington D.C. region. The Occoquan model, consisting of six HSPF and two CE-QUAL-W2 submodels linked in a complex way, has been developed and applied to simulate hydrology and water quality activities in the two major reservoirs and the associated drainage areas. The studied water quality constituents include temperature, dissolved oxygen, ammonium nitrogen, oxidized nitrogen, orthophosphate phosphorus, and algae. The calibration of the linked model is for the years 1993-95, with a validation period of 1996-97. The results show that a successful calibration can be achieved using the linked approach, with moderate additional effort. The spatial and temporal distribution of hydrology processes, nutrient detachment and transport, stream temperature and dissolved oxygen were well reproduced by HSPF submodels. By using the outputs generated by HSPF submodels, the CE-QUAL-W2 submodels adequately captured the water budgets, hydrodynamics, temperature, temporal and spatial distribution of dissolved oxygen, ammonium nitrogen, oxidized nitrogen, orthophosphate phosphorus, and algae in Lake Manassas and Occoquan Reservoir. This demonstrates the validity of linking two types of state of the art water quality models: the watershed model HSPF and the reservoir model CE-QUAL-W2. One of the advantages of the linked model approach is to develop a direct cause and effect relationship between upstream activities and downstream water quality. Therefore, scenarios of various land use proposals, BMP implementation, and point source management can be incorporated into HSPF applications, so that the CE-QUAL-W2 submodels can use the boundary conditions corresponding with these scenarios to predict the water quality variations in the receiving waterbodies. In this research, two land use scenarios were developed. One represented the background condition assuming all the land covered by forest and the other represented the environmental stress posed by future commercial and residential expansion. The results confirm the increases of external nutrient loads due to urbanization and other human activities, which eventually lead to nutrient enrichment and enhanced algae growth in the receiving waterbodies. The increases of external nutrient loads depend on land use patterns and are not evenly spread across the watershed. The future development in the non urban areas will greatly increase the external nutrient production and BMPs should be implemented to reduce the potential environmental degradation. For the existing urban areas, the model results suggest a potential threshold of nutrient production despite future land development. The model results also demonstrate the catchment function of Lake Manassas in reducing nutrient transport downstream. / Ph. D.

El conocimiento de los procesos hidrológicos es esencial para la gestión de los recursos hídricos tanto desde el punto de vista cuantitativo (crecidas o sequías) como desde el punto de vista cualitativo (contaminación). El funcionamiento hidrológico de las cuencas mediterráneas es aún bastante desconocido a pesar de los diferentes estudios realizados desde hace una veintena de años. Los progresos realizados en la identificación y modelización de los procesos hidrológicos corresponden casi en la totalidad a investigaciones realizadas en clima templado-húmedo (Bonell y Balek, 1993; Buttle, 1994). Esta falta de información, fuerza según Bonell (1993) a la "transferencia de resultados", a pesar de la necesidad evidente de desarrollar aproximaciones diferentes, principalmente en el ámbito de la modelización (Pilgrim et al. 1988). Por lo que se refiere a la modelación hidrológica, los estudios disponibles (Durand et al., 1992; Parkin et al., 1996; Piñol et al., 1997 entre otros) muestran serias dificultades para reproducir las primeras crecidas de otoño, después del periodo estival seco. Para estas cuencas parece difícil modelizar correctamente uno o más años hidrológicos completos con un solo juego de parámetros (Piñol et al., 1997, Bernal et al., 2004). El clima mediterráneo está caracterizado por una dinámica estacional muy marcada del régimen de precipitaciones y de la evapotranspiración, que favorece la alternancia durante el año de periodos secos y húmedos. Esto modifica fuertemente el estado hidrológico de la cuenca, de lo que deriva un comportamiento hidrológico complejo y no-lineal (Piñol et al. 1999). La necesidad de comprender el funcionamiento hidrológico de un sistema responde a dos cuestiones importantes: por un lado es el procedimiento más indicado para proporcionar elementos útiles a la gestión integrada de los recursos hídricos y por otro lado es fundamental para la modelación del comportamiento de nutrientes por ejemplo como el nitrato. / Medici ., C. (2010). Progressive development of a hydrologic and inorganic nitrogen conceptual model to improve the understanding of small Mediterranean catchments behaviour [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8428

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22760号 / 工博第4759号 / 新制||工||1744(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 清水 芳久, 教授 田中 宏明, 教授 米田 稔 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The water-energy nexus holds paramount relevance in the context of the transition to a carbon free energy system, being water the only renewable energy source with reliable storage capacity. Modelling hydropower production in a large domain over a long time window represents an open challenge due to a variety of reasons: firstly, high-resolution, large-scale hydrological modelling in a context of uncertainty needs calibration, thus representing a computationally intensive task due to the large domain and time window over which calibration is needed; secondly, as stated by many works in literature, hydropower production modelling and in particular reservoir modelling is a very information-demanding procedure, and excessive simplifications adopted to face the lack of information might lead to consistent bias in the predictions. This thesis can be subdivided into three main parts: firstly, the model that was used to perform every analysis, HYPERstreamHS, will be presented. The model is a continuous, large-scale hydrological model embedding a dual-layer MPI framework (i.e. Message Passing Interface, a common standard in parallel computing) that ensures optimal scalability of the model, greatly reducing the computation time needed. Explicit simulation of water diversions due to hydropower production is also included in the model, and adopts only publicly available information, making the model widely applicable. Secondly, a first validation of the model will be presented, and the adopted approach will be compared with some other approaches commonly found in literature, showing that the inclusion of a high level of detail is crucial to ensure a reliable performance of the model; this first application was performed on the Adige catchment, where extensive information on human systems was available, and allowed to effectively assess which information were indispensable and which, in turn, could be simplified to some extent while preserving model performance. Finally, the model setup has been applied on a relevant portion of the Western Italian Alps; in this case, two different meteorological input forcing data sets were adopted, in order to assess the differences in their performance in terms of hydropower production modelling. This latter study indeed represents a preliminary analysis and will provide stepping stone to extend the modelling framework to the Italian Alpine Region.

In recent years, the Soil-Plant-Atmosphere (SPA) continuum has faced unprecedented challenges due to anthropogenic modifications and climate change. Understanding the complex dynamics of this system in response to such changes is crucial for addressing contemporary environmental concerns. Albert Einstein's famous quote, "The measure of intelligence is the ability to change", resonates deeply throughout this doctoral thesis. This thesis aims to address the complex issue of SPA interactions by developing a comprehensive set of models capable of representing the intricate dynamics of this system. At the core of this research lies the integration of sophisticated descriptions of hydrological and plant biochemical processes into a novel ecohydrological model, GEOSPACE-1D (Soil Plant Atmosphere Continuum Estimator model in GEOframe). Through a combination of theoretical exploration, engineering methodologies, and empirical experiments, this thesis aims to advance our understanding of SPA interactions. The development of adaptable models, represents a significant contribution to the field. The thesis emphasizes the practical implications of employing models to analyze experimental data, thereby enhancing our comprehension of various phenomena. In conclusion, this thesis provides valuable insights into SPA interactions and lays the groundwork for future research and applications. By embracing the challenge of understanding and modeling the SPA continuum, this work contributes to the ongoing efforts to address environmental challenges and promote sustainable practices.

Climate change is expected to lead to more intense and severe rainfall events in the future, significantly increasing the risk of urban flooding. This change, characterized by spatial and temporal shifts in precipitation patterns, presents a challenge to the capacity of existing urban drainage systems, which may lead to higher runoff volumes than they were initially designed to handle. Relying solely on enlarging stormwater infrastructure to tackle this issue could be expensive and may transfer the flooding risk downstream, rather than effectively resolving it. Furthermore, climate change may also lead to prolonged dry spells, potentially resulting in soil compaction and diminished soil infiltration rates. Given these considerations, it is essential to ensure urban drainage systems are both adaptable and space-efficient, with an enhanced capacity to manage the heightened rainfall caused by climate change.   As awareness of the hydrological and environmental impacts of urbanization on catchments grows, there has been a paradigm shift toward adopting green infrastructure solutions. These approaches diverge from traditional 'end-of-pipe' strategies, emphasizing more holistic and sustainable methods. The overall aim of this thesis is to investigate the implications of climatic conditions and geographic location on the retention and detention capacity of three types of infiltration-based facilities: a biofilter cell, a green roof, and a grass swale. A rainfall-runoff model of a biofilter cell and a green roof, combined with swale irrigation experiments, was used to evaluate the capacity of these facilities to reduce runoff volumes and attenuate peak flows. The analysis was conducted in four urban areas representing oceanic (Cfc), humid continental (Dfb), and subarctic (Dfc) climatic zones. The assessment also includes the effect of temporal and spatial variation of saturated hydraulic conductivities (ksat). Swale irrigation experiments were conducted to evaluate the effect of outflow controls on swale retention and detention capacities, under high soil moisture conditions.   Results for biofilter cells and green roofs showed that retention capacities were influenced by the combined effect of antecedent wetness, the extent of winter periods, and the frequency and intensity of rainfall events. Conversely, green roofs were found to have a higher sensitivity to initial soil conditions and antecedent dry weather periods, which was observed through a spread distribution of runoff volume reductions. Grass swales exhibited a large spatial distribution of hydraulic conductivity (ksat) values, with lower values at the swale bottom and higher values at the slope on the right side. Results from a full-scale infiltration test showed that overall, grass swale infiltration capacities are representative of the measured ksat values at the swale bottom. Finally, the presence of outflow controls was observed to enhance the retention and detention capacities of grass swales, even under high levels of soil moisture content. This increase in swale hydrological functionality was influenced by swale outflow controls, leading to greater utilization of the grass swale surface area. Differences between swales with outflow controls and those without were noted due to the effect of the additional storage capacity provided by an outlet control weir. Conversely, it was shown that swales without outflow controls experienced limited retention under high soil moisture content, restricted by the finite capacity of surface depression storage.