Search

Investigating the reliability of ancient hydraulic structures constructed without modern probabilistic criteria allows an understanding of why and how the structure fails. In this paper, we present an extended method, firstly introduced by Torres-Alves and Morales-Nápoles (2020), to perform the reliability analysis of the Nezahualcoyotl's dike that was designed (most likely) without probabilistic criteria. The dike was built around 1450 by the Aztec empire dividing Lake Texcoco from north to south (present-day Mexico City). We estimate the probability of failure due to overflow. By using a discrete time-state Markov chain and bi-variate copulas to generate large synthetic observations of the environmental variables precipitation and evaporation. In addition to the previous methodology, two sources of uncertainty were taken into account (i) the characterization of the environmental conditions during the dry season to estimate initial water levels on the lake and (ii) the influence of surface runoff and subsurface seepage losses on the water levels. The extended method allows for better characterization of the lacustrine system. Therefore an improved extent of the hydrology of the system and a more reliable estimation of the probability of failure of Nezahualcoyotl's dike are presented., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Hydraulic Structures and Flood Risk

Recently, new numerical methods have been applied to weather data for the estimation of water budget, especially when the lack of measured data is considerable. Geostatistics is one of the most powerful approaches when it comes to studying spatially relevant natural phenomena, as it considers the spatial correlation among measurements over a specific study area and provides the associate uncertainty. In this study, we tested the feasibility of using a geostatistical method to provide a reliable estimation of the water budget of the Foro river basin (Central Italy) by comparing the obtained results with those of a traditional yet robust method. The results obtained with the geostatistical approach proved to be in line with the ones from the traditional method. Additionally, it was possible to quantify the uncertainty associated with the discharge values, making the estimates more reliable than the ones obtained with the traditional approach. However, the yearly distribution of river discharge obtained using both methods appeared to be dissimilar to the measured ones. The surface water uses, as well as the regulatory effect of the carbonate and alluvial aquifer regime, may affect the river discharge variability over the year and then can account for similar discrepancies between the inflow and outflow water volumes., Sanitary Engineering

Des préoccupations environnementales liées à l’exploitation des hydrocarbures non conventionnels sont apparues au cours de la dernière décennie. La région de Fox Creek, située dans le centre ouest de l'Alberta, a été l'une des régions les plus actives pour la production d’hydrocarbures au Canada au cours des 50 dernières années, et a donc été choisie comme sujet d’étude. La CGC a débuté un projet dans cette région en 2019, dont l'objectif principal est d'étudier les impacts potentiels des activités pétrolières et gazières sur les aquifères peu profonds. Ce projet multidisciplinaire et multi-institutionnel comprend différents volets. Cette maîtrise de recherche visait spécifiquement à caractériser l'aquifère rocheux fracturé d’un bassin versant d’une superficie de 425 km2 de la région de Fox Creek et à améliorer la compréhension des connexions hydrauliques potentielles entre les unités géologiques profondes et les aquifères superficiels. Dans ce contexte, des modèles numériques avec les logiciels FLONET et CATHY ont été développés pour simuler les écoulements locaux et semi-régionaux sur une section transversale. Pour ce faire, nous avons utilisé des données hydrogéologiques issues des bases de données provinciales, des rapports et des articles, et des données météorologiques. Les modèles 2D ont été calés en utilisant la piézométrie régionale, en essayant de trouver la bonne combinaison de paramètres de conductivité hydraulique et de taux de recharge. Des scénarios ont été développés pour déterminer quelles seraient les conditions nécessaires pour avoir une remontée des fluides à partir de la formation la plus profonde vers la surface. Les résultats de cette maîtrise, en plus des deux modèles numériques, comprennent une revue de littérature exhaustive sur les propriétés des formations rocheuses présentes dans la région et un bilan hydrique pour la région d’étude, qui inclut la définition d’un intervalle pour la recharge de l'aquifère. Les travaux réalisés dans le cad

The concept of a water balance is a foundational topic in hydrology classrooms. While understanding and applying this concept is crucial to the introduction of more advanced topics, students often struggle to develop a thorough understanding of the relationships between components, assumptions, and limitations of a water balance. To aid students in developing a working understanding of a water balance, we developed a web application that runs a one dimensional Thornthwaite-type water balance at any of thousands of NOAA climate stations across the continental United States using the local soil-water storage capacity at the station location. Within the app, students can manipulate the soil-water storage capacity, latitude, temperature, and precipitation to better understand how it works and explore scenarios of land use, extreme weather, and climate change. The application is free and will run on any device that can open an internet browser window (laptops, chromebooks, smartphones, etc). Here we present the details of the model, functionality of the application, and link to several ready-made classroom activities. Finally, results from student surveys in two hydrology classrooms show that students may learn water balance concepts more effectively than traditional methods such as spreadsheet computations.

Des préoccupations environnementales liées à l’exploitation des hydrocarbures non conventionnels sont apparues au cours de la dernière décennie. La région de Fox Creek, située dans le centre ouest de l'Alberta, a été l'une des régions les plus actives pour la production d’hydrocarbures au Canada au cours des 50 dernières années, et a donc été choisie comme sujet d’étude. La CGC a débuté un projet dans cette région en 2019, dont l'objectif principal est d'étudier les impacts potentiels des activités pétrolières et gazières sur les aquifères peu profonds. Ce projet multidisciplinaire et multi-institutionnel comprend différents volets. Cette maîtrise de recherche visait spécifiquement à caractériser l'aquifère rocheux fracturé d’un bassin versant d’une superficie de 425 km2 de la région de Fox Creek et à améliorer la compréhension des connexions hydrauliques potentielles entre les unités géologiques profondes et les aquifères superficiels. Dans ce contexte, des modèles numériques avec les logiciels FLONET et CATHY ont été développés pour simuler les écoulements locaux et semi-régionaux sur une section transversale. Pour ce faire, nous avons utilisé des données hydrogéologiques issues des bases de données provinciales, des rapports et des articles, et des données météorologiques. Les modèles 2D ont été calés en utilisant la piézométrie régionale, en essayant de trouver la bonne combinaison de paramètres de conductivité hydraulique et de taux de recharge. Des scénarios ont été développés pour déterminer quelles seraient les conditions nécessaires pour avoir une remontée des fluides à partir de la formation la plus profonde vers la surface. Les résultats de cette maîtrise, en plus des deux modèles numériques, comprennent une revue de littérature exhaustive sur les propriétés des formations rocheuses présentes dans la région et un bilan hydrique pour la région d’étude, qui inclut la définition d’un intervalle pour la recharge de l'aquifère. Les travaux réalisés dans le cad

Observation-based climate model evaluation and future projections help policymakers in developing action plans for efficient management of water resources and mitigation of the impacts of hazardous extremes. Apart from this socioeconomic importance, the scientific value cannot be overstated, especially in light of the upcoming Fifth U.S. National Climate Assessment (NCA) report. In this study, we evaluate the realism of hydroclimate variability in the historical simulations of a suite of coupled general circulation models (CGCMs) participating in the fifth and sixth phases of the Coupled Model Intercomparison Project (CMIP5 and CMIP6). Our results demonstrate systematic biases in the simulated seasonal precipitation-most prominently, wet bias over the mountainous western United States in winter, and dry bias over the U.S. central plains in summer. A distinctive feature of this work is our focus on the examination of the atmospheric water budget, in particular the relative importance of remote and local contributions-convergence of moisture fluxes and local land surface processes (evapotranspiration) respectively-in helping produce precipitation. This diagnosis reveals that the leading contribution of the remote influence in winter is overestimated by the CMIP6 multimodel mean (MMM), whereas the local influence, which is more influential in summer, is underestimated. Our results aid in understanding the drivers of seasonal precipitation over the United States, where precipitation will likely increase by the end of the century but with significant model disagreement for the summer and fall. In support of ongoing NCA efforts, our study aims to contribute a comprehensive, regional-level analysis of the moisture budget and emphasizes the importance of realistically simulating its major components in CGCMs.

The concept of a water balance is a foundational topic in hydrology classrooms. While understanding and applying this concept is crucial to the introduction of more advanced topics, students often struggle to develop a thorough understanding of the relationships between components, assumptions, and limitations of a water balance. To aid students in developing a working understanding of a water balance, we developed a web application that runs a one dimensional Thornthwaite-type water balance at any of thousands of NOAA climate stations across the continental United States using the local soil-water storage capacity at the station location. Within the app, students can manipulate the soil-water storage capacity, latitude, temperature, and precipitation to better understand how it works and explore scenarios of land use, extreme weather, and climate change. The application is free and will run on any device that can open an internet browser window (laptops, chromebooks, smartphones, etc). Here we present the details of the model, functionality of the application, and link to several ready-made classroom activities. Finally, results from student surveys in two hydrology classrooms show that students may learn water balance concepts more effectively than traditional methods such as spreadsheet computations.

The concept of a water balance is a foundational topic in hydrology classrooms. While understanding and applying this concept is crucial to the introduction of more advanced topics, students often struggle to develop a thorough understanding of the relationships between components, assumptions, and limitations of a water balance. To aid students in developing a working understanding of a water balance, we developed a web application that runs a one dimensional Thornthwaite-type water balance at any of thousands of NOAA climate stations across the continental United States using the local soil-water storage capacity at the station location. Within the app, students can manipulate the soil-water storage capacity, latitude, temperature, and precipitation to better understand how it works and explore scenarios of land use, extreme weather, and climate change. The application is free and will run on any device that can open an internet browser window (laptops, chromebooks, smartphones, etc). Here we present the details of the model, functionality of the application, and link to several ready-made classroom activities. Finally, results from student surveys in two hydrology classrooms show that students may learn water balance concepts more effectively than traditional methods such as spreadsheet computations.

Proper knowledge of potential groundwater recharge (PGR) and its spatiotemporal distribution are essential for sustainable groundwater management, especially within the context of climate change. Here, a robust GIS-based water budget framework was developed to estimate PGR at a regional scale and map its spatial distribution. This framework is demonstrated over the Saguenay-Lac-Saint-Jean region (13 200 km2) of Quebec (Canada). The PGR mapping process was based on a model incorporating water budget components. The vertical inflows (VI) include water amounts from rainfall and snowmelt, whereby the latter was assessed using HYDROTEL model. VI were combined with the maximum and minimum temperatures to estimate actual evapotranspiration (AET), while the surface runoff (RuS) was assessed using the curve number method. Field observations of annual variation in temperatures and the water budget components, over a period of 100 years (1910–2009), were used to provide a comprehensive overview of the effects of climate change on PGR. The last 10 years of the observation period (i.e., 2000–2009) indicate that 6% of the study area has PGR rates of 35%–50%. PGR rates of 20%–35% occur in 58% of the study area, while 36% have PGR of 5%–20%. The trend analysis of temperature time series reveals an average of 1.1 ± 0.6°C increase over 100 years. Also, an increase in the water budget components is observed. Despite the increasing trends of RuS and AET, PGR still showed an increasing trend with an average increase of 0.7 ± 0.4 mm/year over the past 100 years. This observation indicates that the increase in VI was enough to compensate for the increases in AET and RuS. This finding of an increasing PGR in the study area provides useful information for future studies focusing on predicting long-term PGR evolution and for the development of efficient long-term groundwater management strategies.

Accurate knowledge of the rain amount is a crucial driver in several hydrometeorological applications. This is especially true in complex orography territories, which are typically impervious, thus, leaving most mountain areas ungauged. Due to their spatial and temporal coverage, weather radars can potentially overcome such an issue. However, weather radar, if not accurately processed, can suffer from several limitations (e.g., beam blocking, altitude of the observation, path attenuation, and indirectness of the measurement) that can hamper the reliability of the rain estimates performed. In this study, a comparison between rain gauge and weather radar retrievals is performed in the target area of the Abruzzo region in Italy, which is characterized by a heterogeneous orography ranging from the seaside to Apennine ridge. Consequently, the Abruzzo region has an inhomogeneous distribution of the rain gauges, with station density decreasing with the altitude reaching approximately 1500 m a.s.l. Notwithstanding, pluviometric inflow spatial distribution shows a subregional dependency as a function of four climatic and altimetric factors: coastal, hilly, mountain, and inner plain areas (i.e., Marsica). Such areas are used in this analysis to characterize the radar retrieval vs. rain gauge amounts in each of those zones. Compared to previous studies on the topic, the analysis presented the importance of an accurate selection of the climatic and altimetric subregional areas where the radar vs. rain gauge comparison is undertaken. This aspect is not only of great importance to correct biases in radar retrieval in a more selective way, but it also paves the way for more accurate hydrometeorological applications (e.g., hydrological model initialization and quantification of aquifer recharge), which, in general, require the accurate knowledge of rain amounts upstream of a basin. To fill the gap caused by the uneven rain gauge distribution, ordinary Kriging (OK) was applied on a, Sanitary Engineering

Taditionally, watershed-scale hydrology is simulated by distributed hydrological models with offline meteorological forcing data, or by regional regional climate models that link atmospheric and land hydrology interactions. Global climate model (GCMs) are rarely used to study watershed-scale hydrology due to the relatively coarse grid resolution, computationally expensive downscaling, and simplified physical processes. Recently, however, watershed-scale hydrology analysis has become possible in GCMs due to the development of variable-resolution GCMs that dynamically couple the hydrological processes between atmospheric and land systems at fine resolutions in selected regions and coarse resolution elsewhere. In this study, we used the variable-resolution Community Earth System Model (VR-CESM) with refined-resolution (14 km) in the western U.S. and eastern China to evaluate smaller watershed-scale hydrology. We compared the historical VR-CESM outputs with gauge measurements and other hydrological models (e.g., National Water Model in the U.S.) and calibrated the subsurface runoff capacities in four mountainous watersheds. An RCP8.5 projection from 2007 to 2050 is used to estimate the impact of changing precipitation and snow climatology on watershed hydrology. We also analyzed the long-term runoff variability and the possibility of extreme runoff events as simulated by the VR-CESM. Although calibration is not possible in larger-scale watersheds, VR-CESM simulates the long-term annual variability of watersheds and provides insights on climate change impacts on hydrology. We conclude that refined-resolution VR-CESM can be used for watershed-scale hydrology analysis to understand water resources and water balance, in addition to traditional watershed-scale hydrological models. It enables hydrological analysis at multiple watersheds in one simulation and can help understand the two-way dynamics between land surface hydrology and atmospheric processes, and is especially pr

The Caspian Sea (CS) delivers considerable ecosystem services to millions of people. It experienced water level variations of 3 m during the 20th century alone. Robust scenarios of future CS level are vital to inform environmental risk management and water-use planning. In this study we investigated the water budget variation in the CS drainage basin and its potential impact on CS level during the 21st century using projected climate from selected climate change scenarios of shared socioeconomic pathways (SSPs) and representative concentration pathways (RCPs), and explored the impact of human extractions. We show that the size of the CS prescribed in climate models determines the modelled water budgets for both historical and future projections. Most future projections show drying over the 21st century. The moisture deficits are more pronounced for extreme radiative forcing scenarios (RCP8.5/SSP585) and for models where a larger CS is prescribed. By 2100, up to 8 (10) m decrease in CS level is found using RCP4.5 (RCP8.5) models, and up to 20 (30) m for SSP245 (SSP585) scenario models. Water extraction rates are as important as climate in controlling future CS level, with potentially up to 7 m further decline, leading to desiccation of the shallow northern CS. This will have wide-ranging implications for the livelihoods of the surrounding communities; increasing vulnerability to freshwater scarcity, transforming ecosystems, as well as impacting the climate system. Caution should be exercised when using individual models to inform policy as projected CS level is so variable between models. We identify that many climate models either ignore, or do not properly prescribe, CS area. No future climate projections include any changes in CS surface area, even when the catchment is projected to be considerably drier. Coupling between atmosphere and lakes within climate models would be a significant advance to capture crucial two-way feedbacks.

The boreal forest will be strongly affected by climate change and in turn, these vast ecosystems may significantly impact global climatology and hydrology due to their exchanges of carbon and water with the atmosphere. It is now crucial to understand the intricate relationships between precipitation and evapotranspiration in these environments, particularly in less-studied locations characterized by a cold and humid climate. This study presents state-of-the-art measurements of energy and water budgets components over three years (2016–2018) at the Montmorency Forest, Québec, Canada: a balsam fir boreal forest that receives ∼1600 mm of precipitation annually (continental subarctic climate; Köppen classification subtype Dfc). Precipitation, evapotranspiration and potential evapotranspiration at the site are compared with observations from thirteen experimental sites around the world. These intercomparison sites (89 study-years) encompass various types of climate and vegetation (black spruces, jack pines, etc.) encountered in boreal forests worldwide. The Montmorency Forest stands out by receiving the largest amount of precipitation. Across all sites, water availability seems to be the principal evapotranspiration constraint, as precipitation tends to be more influential than potential evapotranspiration and other factors. This leads to the Montmorency Forest generating the largest amount of evapotranspiration, on average ∼550 mm y−1. This value appears to be an ecosystem maximum for evapotranspiration, which may be explained either by a physiological limit or a limited energy availability due to the presence of cloud cover. The Montmorency Forest water budget evacuates the precipitation excess mostly by watershed discharges, at an average rate of ∼1050 mm y−1, with peaks during the spring freshet. This behaviour, typical of mountainous headwater basins, necessarily influence downstream hydrological regimes to a large extent. This study provides a much needed insight i

Stormwater bioretention cells (BRCs) are a variety of green stormwater infrastructure with the potential to restore pre-urban water balance, provided they can be tailored to infiltrate and evapotranspire (i.e., harvest) urban runoff in proportions consistent with pre-urban hydrologic conditions. This paper evaluates their capacity to do so, focusing on evapotranspirative harvest, which is relatively understudied, and the capacity of CSR (Competitve, Stress-tolerant, and Ruderal) functional type to serve as an overarching framework characterizing the water use strategy of BRC plants. The goal is to determine if harvest (and therefore the ratio of urban runoff infiltrated to harvested; the I:H ratio) might be fine-tuned to meet pre-urban values in BRCs through informed manipulation of plant community composition. This study focuses on 3 critical plant water use traits, the turgor loss point, the point of incipient water stress, and maximum stomatal conductance. A global plant traits meta-analysis identified degree of plant competitiveness and stress tolerance as significant determinants of all three water use traits, with stem type (woody vs herbaceous) also being significant, but only for turgor loss point. Based on these results, six water use scenarios appropriate for plants with different CSR type/stem type combinations were developed. BRC plants spanning the range of CSR types necessary to actionize these scenarios were determined to be available in eight major climate zones of the coterminous US, suggesting that regulating plant water use in BRCs using CSR is likely feasible. Hydraulic simulations (Hydrus 1D) were conducted for each scenario in all eight climate zones and revealed significant differences in evapotranspirative harvest and I:H ratios in simulated BRCs. Competitive woody plants had the highest evapotranspiration and lowest I:H ratios; 1.5-1.8 times more evapotranspiration and a 1.6-2 times lower I:H ratio than stress tolerant herbaceous plants, on

Using open-access data sets on water and soil from Swedish authorities and compiling them in a QGIS-programme made it possible to present and visualise the water budget of the Lagan River Catchment. Based on the estimations of the water volume in groundwater reservoirs and lakes the total maximum available volume in the Lagan River Catchment area was determined to be 9.36 km3. Of this 75.9% (7.10 km3) is found within groundwater reservoirs and 24.1% (2.26 km3) is present in lakes. This study indicates that GIS-based parameters are useful for specifying what a water budget in a catchment area looks like.The use of GIS-based parameters also allows for the development of interactive maps which can be used to visualize different conditions in the catchment area. In addition, many people who work with water management have a good habit of using GIS tools. Utilizing open data sources means that the number of additional measurements can be kept low. Furthermore, the use of open sources contributes to increased transparency in the development process

Using an Argo dataset and the ECCOv4 reanalysis, a volume budget was performed to address the main mechanisms driving the volume change of the interior water masses in the Southern Hemisphere oceans between 2006 and 2015. The subduction rates and the isopycnal and diapycnal water-mass transformation were estimated in a density-spiciness (sigma-tau) framework. Spiciness, defined as thermohaline variations along isopycnals, was added to the potential density coordinates to discriminate between water masses spreading on isopycnal layers. The main positive volume trends were found to be associated with the Subantarctic Mode Waters (SAMW) in the South Pacific and South Indian Ocean basins, revealing a lightening of the upper waters in the Southern Hemisphere. The SAMW exhibits a two-layer density structure in which subduction and diapycnal transformation from the lower to the upper layers accounted for most of the upper-layer volume gain and lower-layer volume loss, respectively. The Antarctic Intermediate Waters, defined here between the 27.2 and 27.5 kg m(-3) isopycnals, showed the strongest negative volume trends. This volume loss can be explained by their negative isopyncal transformation southward of the Antarctic Circumpolar Current into the fresher and colder Antarctic Winter Waters (AAWW) and northward into spicier tropical/subtropical Intermediate Waters. The AAWW is destroyed by obduction back into the mixed layer so that its net volume change remains nearly zero. The proposed mechanisms to explain the transformation within the Intermediate Waters are discussed in the context of Southern Ocean dynamics. The sigma-tau decomposition provided new insight on the spatial and temporal water-mass variability and driving mechanisms over the last decade.

In terrains with limited soil cover and groundwater storage, groundwater resource management is governed by the spatial nature of storage, recharge and distributed local extraction. Local soils act as important groundwater reservoirs for residents who have no other feasible water supply. A novel heuristic methodology is presented which accounts for the spatial distribution of storage and extraction, using existing topographical and geological databases in addition to well data to construct an applied conceptual groundwater model with assumed stratigraphy. The method uses a geographic information systems (GIS) environment and allows for modelling climate and land-use scenarios. Several scenarios were examined, demonstrating that average reservoir volumes meet demand but at the local levels depletion of reservoirs occurs. Groundwater abstraction in excess of 50% of the approximate freshwater storage was observed in the model, particularly near the coast. Soil-filled valleys may act as local hydraulic barriers by maintaining a higher pressure head as they are less susceptible to large-level fluctuations than the hard rock and may aid in preventing contamination from saline water provided no direct hydraulic connection is present. The method demonstrates the importance of a spatial approach in managing groundwater resources and could be used as a tool in increasing water security., QC 20210112

Using an Argo dataset and the ECCOv4 reanalysis, a volume budget was performed to address the main mechanisms driving the volume change of the interior water masses in the Southern Hemisphere oceans between 2006 and 2015. The subduction rates and the isopycnal and diapycnal water-mass transformation were estimated in a density-spiciness (sigma-tau) framework. Spiciness, defined as thermohaline variations along isopycnals, was added to the potential density coordinates to discriminate between water masses spreading on isopycnal layers. The main positive volume trends were found to be associated with the Subantarctic Mode Waters (SAMW) in the South Pacific and South Indian Ocean basins, revealing a lightening of the upper waters in the Southern Hemisphere. The SAMW exhibits a two-layer density structure in which subduction and diapycnal transformation from the lower to the upper layers accounted for most of the upper-layer volume gain and lower-layer volume loss, respectively. The Antarctic Intermediate Waters, defined here between the 27.2 and 27.5 kg m(-3) isopycnals, showed the strongest negative volume trends. This volume loss can be explained by their negative isopyncal transformation southward of the Antarctic Circumpolar Current into the fresher and colder Antarctic Winter Waters (AAWW) and northward into spicier tropical/subtropical Intermediate Waters. The AAWW is destroyed by obduction back into the mixed layer so that its net volume change remains nearly zero. The proposed mechanisms to explain the transformation within the Intermediate Waters are discussed in the context of Southern Ocean dynamics. The sigma-tau decomposition provided new insight on the spatial and temporal water-mass variability and driving mechanisms over the last decade.

The precise determination of the reference evapotranspiration ensures computing real values of the crop water requirements. The objective of the study was to evaluate nine methods to determine the reference evapotranspiration for the environmental conditions of the Tumbaco Valley located in the province of Pichincha (Ecuador). Monthly climatological data from La Tola station was used to estimate ETo. The methods used to determine ETO were FAO56, Class A pan, modified Thornthwaite, Hargreaves, Jensen - Haise, Makkink, Priestley - Taylor, Turc and FAO Radiation. The following inferential parameters were used in the analysis, considering FAO56 as base: the absolute mean error, the coefficient of determination, the concordance coefficient and the confident coefficient. The results for monthly average climatological data showed that: i) the FAO Radiation method presented good statistical indexes; ii) the methods Jensen and Haise, Makkink and Priestley - Taylor presented poor indexes; iii) the methods Class A pan, modified Thornthwaite, Hargreaves and Turc presented the lowest inferential values. In conclusion, the method that should be used to estimate monthly ETo for the agro ecological environment of the Tumbaco Valley with good accuracy is FAO56., La estimación precisa de la evapotranspiración de referencia permite obtener valores más reales sobre las necesidades hídricas de los cultivos. El objetivo del estudio consistió en evaluar nueve métodos a fin de estimar la evapotranspiración de referencia para las condiciones ambientales del Valle de Tumbaco, ubicado en la provincia de Pichincha (Ecuador). Se utilizó información climatológica mensual de la estación La Tola para determinar ETo. Los métodos analizados fueron: FAO56, Tanque evaporímetro, Thornthwaite modificado, Hargreaves, Jensen-Haise, Makkink, Priestley-Taylor, Turc y FAO Radiación. Se calcularon los siguientes parámetros inferenciales para el análisis de los resultados, tomando como base FAO56: error medio absoluto, coeficiente de determinación, coeficiente de concordancia y coeficiente de confiabilidad. Los resultados principales fueron: i) el método FAO Radiación presentó una precisión buena; ii) los métodos Jensen and Haise, Makkink y Priestley and Taylor, presentaron índices tolerables; iii) los métodos del tanque evaporímetro, Thornthwaite modificado, Hargreaves y Turc proporcionaron índices inferenciales muy pobres. En conclusión, el método que debe utilizarse para determinar ETo mensual para el entorno agroecológico del Valle de Tumbaco es FAO56.

Using an Argo dataset and the ECCOv4 reanalysis, a volume budget was performed to address the main mechanisms driving the volume change of the interior water masses in the Southern Hemisphere oceans between 2006 and 2015. The subduction rates and the isopycnal and diapycnal water-mass transformation were estimated in a density-spiciness (sigma-tau) framework. Spiciness, defined as thermohaline variations along isopycnals, was added to the potential density coordinates to discriminate between water masses spreading on isopycnal layers. The main positive volume trends were found to be associated with the Subantarctic Mode Waters (SAMW) in the South Pacific and South Indian Ocean basins, revealing a lightening of the upper waters in the Southern Hemisphere. The SAMW exhibits a two-layer density structure in which subduction and diapycnal transformation from the lower to the upper layers accounted for most of the upper-layer volume gain and lower-layer volume loss, respectively. The Antarctic Intermediate Waters, defined here between the 27.2 and 27.5 kg m(-3) isopycnals, showed the strongest negative volume trends. This volume loss can be explained by their negative isopyncal transformation southward of the Antarctic Circumpolar Current into the fresher and colder Antarctic Winter Waters (AAWW) and northward into spicier tropical/subtropical Intermediate Waters. The AAWW is destroyed by obduction back into the mixed layer so that its net volume change remains nearly zero. The proposed mechanisms to explain the transformation within the Intermediate Waters are discussed in the context of Southern Ocean dynamics. The sigma-tau decomposition provided new insight on the spatial and temporal water-mass variability and driving mechanisms over the last decade.

FortWhyte Alive; a protected urban green space located in southwestern Winnipeg has in recent years been experiencing water quality deterioration (eutrophication) in its five (4 interconnected, 1 isolated) endorheic lakes. With the pathways of nutrients to these lakes not fully understood, a water budget (2018 – 2019) investigation was conducted using innovative approaches to identify the contribution of all possible water sources particularly groundwater inflow to the lakes. The interconnected lakes (Devonian, Lake 3, Lake 2, and Muir) formed part of a single sub-basin while Lake Cargill formed part of another sub-basin. Surface inflows to all the lakes were estimated from HOBO water loggers while potential evaporation from the lakes was estimated from stable water isotopes analyses of 100 lake water samples ranging from 0 - 7 m. Surface inflows via Devonian contributed about 31% of the total surface inflow received by the interconnected lakes while contributions via Lake 3 and Muir were 43% and 26% respectively. Surface inflow depth in the interconnected lakes was about 53% of the system’s total inflow while groundwater inflow depth was about 8% of the system’s total inflow. The surface inflow depth in Lake Cargill was about 35% of its total lake inflow with no groundwater inflow. Lakewater loss was about 2.3% of the total outflow. The E: I ratios for the interconnected lakes and Lake Cargill were 0.75 and 1.03 respectively. The high evaporation rates in the lakes and large water residence times (> 3years) contributed to lake eutrophication.

FortWhyte Alive; a protected urban green space located in southwestern Winnipeg has in recent years been experiencing water quality deterioration (eutrophication) in its five (4 interconnected, 1 isolated) endorheic lakes. With the pathways of nutrients to these lakes not fully understood, a water budget (2018 – 2019) investigation was conducted using innovative approaches to identify the contribution of all possible water sources particularly groundwater inflow to the lakes. The interconnected lakes (Devonian, Lake 3, Lake 2, and Muir) formed part of a single sub-basin while Lake Cargill formed part of another sub-basin. Surface inflows to all the lakes were estimated from HOBO water loggers while potential evaporation from the lakes was estimated from stable water isotopes analyses of 100 lake water samples ranging from 0 - 7 m. Surface inflows via Devonian contributed about 31% of the total surface inflow received by the interconnected lakes while contributions via Lake 3 and Muir were 43% and 26% respectively. Surface inflow depth in the interconnected lakes was about 53% of the system’s total inflow while groundwater inflow depth was about 8% of the system’s total inflow. The surface inflow depth in Lake Cargill was about 35% of its total lake inflow with no groundwater inflow. Lakewater loss was about 2.3% of the total outflow. The E: I ratios for the interconnected lakes and Lake Cargill were 0.75 and 1.03 respectively. The high evaporation rates in the lakes and large water residence times (> 3years) contributed to lake eutrophication.

Using an Argo dataset and the ECCOv4 reanalysis, a volume budget was performed to address the main mechanisms driving the volume change of the interior water masses in the Southern Hemisphere oceans between 2006 and 2015. The subduction rates and the isopycnal and diapycnal water-mass transformation were estimated in a density-spiciness (sigma-tau) framework. Spiciness, defined as thermohaline variations along isopycnals, was added to the potential density coordinates to discriminate between water masses spreading on isopycnal layers. The main positive volume trends were found to be associated with the Subantarctic Mode Waters (SAMW) in the South Pacific and South Indian Ocean basins, revealing a lightening of the upper waters in the Southern Hemisphere. The SAMW exhibits a two-layer density structure in which subduction and diapycnal transformation from the lower to the upper layers accounted for most of the upper-layer volume gain and lower-layer volume loss, respectively. The Antarctic Intermediate Waters, defined here between the 27.2 and 27.5 kg m(-3) isopycnals, showed the strongest negative volume trends. This volume loss can be explained by their negative isopyncal transformation southward of the Antarctic Circumpolar Current into the fresher and colder Antarctic Winter Waters (AAWW) and northward into spicier tropical/subtropical Intermediate Waters. The AAWW is destroyed by obduction back into the mixed layer so that its net volume change remains nearly zero. The proposed mechanisms to explain the transformation within the Intermediate Waters are discussed in the context of Southern Ocean dynamics. The sigma-tau decomposition provided new insight on the spatial and temporal water-mass variability and driving mechanisms over the last decade.

The precise determination of the reference evapotranspiration ensures computing real values of the crop water requirements. The objective of the study was to evaluate nine methods to determine the reference evapotranspiration for the environmental conditions of the Tumbaco Valley located in the province of Pichincha (Ecuador). Monthly climatological data from La Tola station was used to estimate ETo. The methods used to determine ETO were FAO56, Class A pan, modified Thornthwaite, Hargreaves, Jensen - Haise, Makkink, Priestley - Taylor, Turc and FAO Radiation. The following inferential parameters were used in the analysis, considering FAO56 as base: the absolute mean error, the coefficient of determination, the concordance coefficient and the confident coefficient. The results for monthly average climatological data showed that: i) the FAO Radiation method presented good statistical indexes; ii) the methods Jensen and Haise, Makkink and Priestley - Taylor presented poor indexes; iii) the methods Class A pan, modified Thornthwaite, Hargreaves and Turc presented the lowest inferential values. In conclusion, the method that should be used to estimate monthly ETo for the agro ecological environment of the Tumbaco Valley with good accuracy is FAO56., La estimación precisa de la evapotranspiración de referencia permite obtener valores más reales sobre las necesidades hídricas de los cultivos. El objetivo del estudio consistió en evaluar nueve métodos a fin de estimar la evapotranspiración de referencia para las condiciones ambientales del Valle de Tumbaco, ubicado en la provincia de Pichincha (Ecuador). Se utilizó información climatológica mensual de la estación La Tola para determinar ETo. Los métodos analizados fueron: FAO56, Tanque evaporímetro, Thornthwaite modificado, Hargreaves, Jensen-Haise, Makkink, Priestley-Taylor, Turc y FAO Radiación. Se calcularon los siguientes parámetros inferenciales para el análisis de los resultados, tomando como base FAO56: error medio absoluto, coeficiente de determinación, coeficiente de concordancia y coeficiente de confiabilidad. Los resultados principales fueron: i) el método FAO Radiación presentó una precisión buena; ii) los métodos Jensen and Haise, Makkink y Priestley and Taylor, presentaron índices tolerables; iii) los métodos del tanque evaporímetro, Thornthwaite modificado, Hargreaves y Turc proporcionaron índices inferenciales muy pobres. En conclusión, el método que debe utilizarse para determinar ETo mensual para el entorno agroecológico del Valle de Tumbaco es FAO56.

FortWhyte Alive; a protected urban green space located in southwestern Winnipeg has in recent years been experiencing water quality deterioration (eutrophication) in its five (4 interconnected, 1 isolated) endorheic lakes. With the pathways of nutrients to these lakes not fully understood, a water budget (2018 – 2019) investigation was conducted using innovative approaches to identify the contribution of all possible water sources particularly groundwater inflow to the lakes. The interconnected lakes (Devonian, Lake 3, Lake 2, and Muir) formed part of a single sub-basin while Lake Cargill formed part of another sub-basin. Surface inflows to all the lakes were estimated from HOBO water loggers while potential evaporation from the lakes was estimated from stable water isotopes analyses of 100 lake water samples ranging from 0 - 7 m. Surface inflows via Devonian contributed about 31% of the total surface inflow received by the interconnected lakes while contributions via Lake 3 and Muir were 43% and 26% respectively. Surface inflow depth in the interconnected lakes was about 53% of the system’s total inflow while groundwater inflow depth was about 8% of the system’s total inflow. The surface inflow depth in Lake Cargill was about 35% of its total lake inflow with no groundwater inflow. Lakewater loss was about 2.3% of the total outflow. The E: I ratios for the interconnected lakes and Lake Cargill were 0.75 and 1.03 respectively. The high evaporation rates in the lakes and large water residence times (> 3years) contributed to lake eutrophication.

FortWhyte Alive; a protected urban green space located in southwestern Winnipeg has in recent years been experiencing water quality deterioration (eutrophication) in its five (4 interconnected, 1 isolated) endorheic lakes. With the pathways of nutrients to these lakes not fully understood, a water budget (2018 – 2019) investigation was conducted using innovative approaches to identify the contribution of all possible water sources particularly groundwater inflow to the lakes. The interconnected lakes (Devonian, Lake 3, Lake 2, and Muir) formed part of a single sub-basin while Lake Cargill formed part of another sub-basin. Surface inflows to all the lakes were estimated from HOBO water loggers while potential evaporation from the lakes was estimated from stable water isotopes analyses of 100 lake water samples ranging from 0 - 7 m. Surface inflows via Devonian contributed about 31% of the total surface inflow received by the interconnected lakes while contributions via Lake 3 and Muir were 43% and 26% respectively. Surface inflow depth in the interconnected lakes was about 53% of the system’s total inflow while groundwater inflow depth was about 8% of the system’s total inflow. The surface inflow depth in Lake Cargill was about 35% of its total lake inflow with no groundwater inflow. Lakewater loss was about 2.3% of the total outflow. The E: I ratios for the interconnected lakes and Lake Cargill were 0.75 and 1.03 respectively. The high evaporation rates in the lakes and large water residence times (> 3years) contributed to lake eutrophication.

Precipitation on the Tibetan Plateau (TP) showed different spatial changes during 1979-2016, with an increasing trend over the northern Tibetan Plateau (NTP) and a slightly negative trend over the southern Tibetan Plateau (STP). The changes in precipitation moisture sources over the NTP and STP are investigated using the improved Water Accounting Model with an atmospheric reanalysis as well as observational precipitation and evaporation data. The results show the region in the northwest (region NW), ranging from the TP to Europe dominated by the westerlies, provides 38.9% of precipitation moisture for the NTP, and the region in the southeast (region SE), ranging from the TP to the Indian Ocean and Indochina dominated by the Asian monsoons, provides 51.4% of precipitation moisture for the STP. For the precipitation increase over the NTP, the SE and TP are the main contributors, contributing around 35.8% and 51.7% of the increase, respectively. The contributions from the SE and TP to the STP are, however, minor and insignificant. Meanwhile, the NW shows a negative trend of -4.2 ± 2.9mmyr-1 decade-1 (significant at the 0.01 level), which contributes to the negative precipitation trend over the STP. Results during the wet season indicate that moisture sources from the areas dominated by the Asian monsoons have contributed more precipitated moisture for the NTP, but not for the STP. Further analysis reveals that precipitated moisture originating from the Indian subcontinent has increased for the NTP while it has decreased for the STP during 1979-2016.

Precipitation on the Tibetan Plateau (TP) showed different spatial changes during 1979-2016, with an increasing trend over the northern Tibetan Plateau (NTP) and a slightly negative trend over the southern Tibetan Plateau (STP). The changes in precipitation moisture sources over the NTP and STP are investigated using the improved Water Accounting Model with an atmospheric reanalysis as well as observational precipitation and evaporation data. The results show the region in the northwest (region NW), ranging from the TP to Europe dominated by the westerlies, provides 38.9% of precipitation moisture for the NTP, and the region in the southeast (region SE), ranging from the TP to the Indian Ocean and Indochina dominated by the Asian monsoons, provides 51.4% of precipitation moisture for the STP. For the precipitation increase over the NTP, the SE and TP are the main contributors, contributing around 35.8% and 51.7% of the increase, respectively. The contributions from the SE and TP to the STP are, however, minor and insignificant. Meanwhile, the NW shows a negative trend of -4.2 ± 2.9mmyr -1 decade -1 (significant at the 0.01 level), which contributes to the negative precipitation trend over the STP. Results during the wet season indicate that moisture sources from the areas dominated by the Asian monsoons have contributed more precipitated moisture for the NTP, but not for the STP. Further analysis reveals that precipitated moisture originating from the Indian subcontinent has increased for the NTP while it has decreased for the STP during 1979-2016., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Water Resources

Land surface models (LSMs) have traditionally been designed to focus on providing lower-boundary conditions to the atmosphere with less focus on hydrological processes. State-of-the-art application of LSMs includes a land data assimilation system (LDAS), which incorporates available land surface observations to provide an improved realism of surface conditions. While improved representations of the surface variables (such as soil moisture and snow depth) make LDAS an essential component of any numerical weather prediction (NWP) system, the related increments remove or add water, potentially having a negative impact on the simulated hydrological cycle by opening the water budget. This paper focuses on evaluating how well global NWP configurations are able to support hydrological applications, in addition to the traditional weather forecasting. River discharge simulations from two climatological reanalyses are compared: one "online" set, which includes land-atmosphere coupling and LDAS with an open water budget, and an "offline" set with a closed water budget and no LDAS. It was found that while the online version of the model largely improves temperature and snow depth conditions, it causes poorer representation of peak river flow, particularly in snowmelt-dominated areas in the high latitudes. Without addressing such issues there will never be confidence in using LSMs for hydrological forecasting applications across the globe. This type of analysis should be used to diagnose where improvements need to be made; considering the whole Earth system in the data assimilation and coupling developments is critical for moving toward the goal of holistic Earth system approaches.

With increasing power production from renewable energy sources, sub-daily variations in energy demand need to be balanced. Today, hydropower is commonly used as balancing power. In this study, we quantified the impact of capacity constraints, in terms of reservoir volume and hydropower capacity, on the potential to comply with instant energy demand. To evaluate the impact, we developed two new metrics, power market impact and system efficiency ratio, which are based on two threshold flow regimes derived from natural flow as lower threshold release and regulated flow (based on hourly energy prices) as upper threshold release. The operation support model comprises 96 different regulation scenarios based on varying combinations of hydropower and reservoir capacities. For each scenario, an hourly water balance was simulated, to obtain the highest complying with upper threshold release based on actual energy demand. We tested the framework on the Kemijoki river with defined thresholds based on the natural flow regime (tributary river Ounasjoki) and the hourly energy price in Finland in 2017, and estimated the impact of regulation on hourly flow regime at the Taivalkoski hydropower station. The annual flow regime impact in 2013, 2014 and 2015 was estimated to be 74%, 84% and 61%, respectively, while the monthly impact varied from 27% to 100%. Our framework for evaluating interactions between the power market and sub-daily regulation practices is a useful novel tool for sustainable river management and can be easily applied to different rivers and regions and evaluated for different timescales., QC 20191206

Land surface models (LSMs) have traditionally been designed to focus on providing lower-boundary conditions to the atmosphere with less focus on hydrological processes. State-of-the-art application of LSMs includes a land data assimilation system (LDAS), which incorporates available land surface observations to provide an improved realism of surface conditions. While improved representations of the surface variables (such as soil moisture and snow depth) make LDAS an essential component of any numerical weather prediction (NWP) system, the related increments remove or add water, potentially having a negative impact on the simulated hydrological cycle by opening the water budget. This paper focuses on evaluating how well global NWP configurations are able to support hydrological applications, in addition to the traditional weather forecasting. River discharge simulations from two climatological reanalyses are compared: one "online" set, which includes land-atmosphere coupling and LDAS with an open water budget, and an "offline" set with a closed water budget and no LDAS. It was found that while the online version of the model largely improves temperature and snow depth conditions, it causes poorer representation of peak river flow, particularly in snowmelt-dominated areas in the high latitudes. Without addressing such issues there will never be confidence in using LSMs for hydrological forecasting applications across the globe. This type of analysis should be used to diagnose where improvements need to be made; considering the whole Earth system in the data assimilation and coupling developments is critical for moving toward the goal of holistic Earth system approaches.

Land surface models (LSMs) have traditionally been designed to focus on providing lower-boundary conditions to the atmosphere with less focus on hydrological processes. State-of-the-art application of LSMs includes a land data assimilation system (LDAS), which incorporates available land surface observations to provide an improved realism of surface conditions. While improved representations of the surface variables (such as soil moisture and snow depth) make LDAS an essential component of any numerical weather prediction (NWP) system, the related increments remove or add water, potentially having a negative impact on the simulated hydrological cycle by opening the water budget. This paper focuses on evaluating how well global NWP configurations are able to support hydrological applications, in addition to the traditional weather forecasting. River discharge simulations from two climatological reanalyses are compared: one "online" set, which includes land-atmosphere coupling and LDAS with an open water budget, and an "offline" set with a closed water budget and no LDAS. It was found that while the online version of the model largely improves temperature and snow depth conditions, it causes poorer representation of peak river flow, particularly in snowmelt-dominated areas in the high latitudes. Without addressing such issues there will never be confidence in using LSMs for hydrological forecasting applications across the globe. This type of analysis should be used to diagnose where improvements need to be made; considering the whole Earth system in the data assimilation and coupling developments is critical for moving toward the goal of holistic Earth system approaches.

Widespread groundwater overdraft in alluvial aquifer systems like the Central Valley (CV) in California, USA, has increased interest in managed aquifer recharge (MAR). Like most clastic sedimentary basins, recharge to the productive semi-confined CV aquifer system remains a challenge due to the presence of nearly ubiquitous, multiple confining units (silt and clay) that limit recharge pathways. Previous studies suggest the presence of interconnected networks of coarse-texture sand and gravel deposits that bypass regional confining units over a small fraction of the CV near the American and Cosumnes rivers. Here, variably saturated infiltration and recharge processes were simulated across a domain that includes high-resolution representation of the heterogeneous alluvial geologic architecture in this area. Results show that recharge potential is highly dependent on subsurface geologic architecture, with a nearly 2 order-of-magnitude range of recharge across the domain. Where interconnected coarse-texture recharge pathways occur, results show that these features can (1) accommodate rapid, high-volume MAR and (2) propagate widespread and rapid pressure responses over multi-kilometer distances in the semi-confined aquifer system. For all MAR simulations, results show that the majority of MAR is accommodated by filling unsaturated-zone (UZ) pore volume. Results also show that coarse-texture UZ facies (where present) accommodate the majority of MAR volume during early time, but fine-texture facies ultimately accommodate the majority of the total MAR volume, even for coarse-dominated sites. These findings highlight the large variability of MAR potential across the landscape and demonstrate the importance of fine-texture facies for accommodating MAR in alluvial aquifer systems.

Water budgets integrate and summarize the water inputs and outputs that are essential for effective water resources management. Using water data collected from different sources, we constructed three water budgets (a 12-year annual average, a wet year, and a critically dry year) for the Sacramento–San Joaquin Delta (Delta), the Sacramento River (SR) watershed, and the San Joaquin River (SJR) watershed. Although multiple water budgets for the Delta exist, the water budgets presented here are the first to provide all three of the following: (1) water budgets for the entire Delta watershed, divided into management-relevant components, (2) comparisons between wet and dry years and between different regions of the watershed, and (3) discussion of major gaps and uncertainties in the available water data to guide and inform future data collection and water management. Results show that, from 1998 to 2009, the Delta received 24.2 million acre feet (maf) of water each year on average, which primarily exited the Delta as river outflow (71%), water exports (22%), and evapotranspiration (ET; 6%). The SR watershed received 56.9 maf of water (95% as precipitation). The major outputs from the SR watershed were ET (63%) and flows to the Delta (34%). In the SJR watershed, total water input was 28.7 maf composed of precipitation (74%), water imported from the Delta (18%), and storage depletion (7%). The major outputs from the SJR watershed were ET (65%), water exports (19%), and flows to the Delta (14%). Most values varied greatly from year to year. Although streamflows, water exports, and valley precipitation are relatively well measured and estimated, uncertainties are higher for groundwater storage change as well as for ET and precipitation in montane regions. Improvement in data collection and synthesis in these components is necessary to build a more detailed and accurate water budget.

The boreal forest will be strongly affected by climate change and in turn, these vast ecosystems may significantly impact global climatology and hydrology due to their exchanges of carbon and water with the atmosphere. It is now crucial to understand the intricate relationships between precipitation and evapotranspiration in these environments, particularly in less-studied locations characterized by a cold and humid climate. This study presents state-of-the-art measurements of energy and water budgets components over three years (2016–2018) at the Montmorency Forest, Québec, Canada: a balsam fir boreal forest that receives ∼1600 mm of precipitation annually (continental subarctic climate; Köppen classification subtype Dfc). Precipitation, evapotranspiration and potential evapotranspiration at the site are compared with observations from thirteen experimental sites around the world. These intercomparison sites (89 study-years) encompass various types of climate and vegetation (black spruces, jack pines, etc.) encountered in boreal forests worldwide. The Montmorency Forest stands out by receiving the largest amount of precipitation. Across all sites, water availability seems to be the principal evapotranspiration constraint, as precipitation tends to be more influential than potential evapotranspiration and other factors. This leads to the Montmorency Forest generating the largest amount of evapotranspiration, on average ∼550 mm y−1. This value appears to be an ecosystem maximum for evapotranspiration, which may be explained either by a physiological limit or a limited energy availability due to the presence of cloud cover. The Montmorency Forest water budget evacuates the precipitation excess mostly by watershed discharges, at an average rate of ∼1050 mm y−1, with peaks during the spring freshet. This behaviour, typical of mountainous headwater basins, necessarily influence downstream hydrological regimes to a large extent. This study provides a much needed insight i

Precipitation on the Tibetan Plateau (TP) showed different spatial changes during 1979-2016, with an increasing trend over the northern Tibetan Plateau (NTP) and a slightly negative trend over the southern Tibetan Plateau (STP). The changes in precipitation moisture sources over the NTP and STP are investigated using the improved Water Accounting Model with an atmospheric reanalysis as well as observational precipitation and evaporation data. The results show the region in the northwest (region NW), ranging from the TP to Europe dominated by the westerlies, provides 38.9% of precipitation moisture for the NTP, and the region in the southeast (region SE), ranging from the TP to the Indian Ocean and Indochina dominated by the Asian monsoons, provides 51.4% of precipitation moisture for the STP. For the precipitation increase over the NTP, the SE and TP are the main contributors, contributing around 35.8% and 51.7% of the increase, respectively. The contributions from the SE and TP to the STP are, however, minor and insignificant. Meanwhile, the NW shows a negative trend of -4.2 ± 2.9mmyr -1 decade -1 (significant at the 0.01 level), which contributes to the negative precipitation trend over the STP. Results during the wet season indicate that moisture sources from the areas dominated by the Asian monsoons have contributed more precipitated moisture for the NTP, but not for the STP. Further analysis reveals that precipitated moisture originating from the Indian subcontinent has increased for the NTP while it has decreased for the STP during 1979-2016., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Water Resources

Accurate estimates of the components of the surface terrestrial water and energy budgets are crucial to understand the interactions between land and atmosphere. These interactions play a critical role in modulating drought, heatwaves and other extreme events. In-situ measurements provide the most reliable direct estimates of these terms, however in many parts of the globe they are scarce or not available at all, and therefore cannot meet the spatial scale we need. The advancement of satellite technology and remote sensing retrieval algorithms has made it possible to estimate many fluxes from space, and led to the development of a suite of satellite-driven estimates of water and energy fluxes at the global gridded scale. These include entirely satellite-based estimates, reanalysis products, or model outputs driven by remotely-sensed surface properties. These global estimates have near complete spatial coverage, something lacking in in-situ observations. The aim of this thesis is to improve the current global gridded estimates of the water and energy fluxes by exploiting the accuracy of in-situ measurements and the coverage of existing, predominantly satellite-based gridded estimates, as well as physical relationships between them. A novel weighting technique is applied to derive hybrid estimates from a range of available satellite driven estimates of individual budget variables. It is an optimal merging method that accounts not only for performance differences between the participating products, but also the dependence of their errors, which has been ignored by the majority of similar attempts. This technique also provides rigorous estimates of uncertainty associated with the hybrid estimates that reflects their discrepancy with direct observations. We apply the merging technique to derive hybrid best estimates for net radiation, sensible, latent and ground heat flux and runoff. In a further post processing step, all the hybrid best estimates are further adjusted by

Water budgets integrate and summarize the water inputs and outputs that are essential for effective water resources management. Using water data collected from different sources, we constructed three water budgets (a 12-year annual average, a wet year, and a critically dry year) for the Sacramento–San Joaquin Delta (Delta), the Sacramento River (SR) watershed, and the San Joaquin River (SJR) watershed. Although multiple water budgets for the Delta exist, the water budgets presented here are the first to provide all three of the following: (1) water budgets for the entire Delta watershed, divided into management-relevant components, (2) comparisons between wet and dry years and between different regions of the watershed, and (3) discussion of major gaps and uncertainties in the available water data to guide and inform future data collection and water management. Results show that, from 1998 to 2009, the Delta received 24.2 million acre feet (maf) of water each year on average, which primarily exited the Delta as river outflow (71%), water exports (22%), and evapotranspiration (ET; 6%). The SR watershed received 56.9 maf of water (95% as precipitation). The major outputs from the SR watershed were ET (63%) and flows to the Delta (34%). In the SJR watershed, total water input was 28.7 maf composed of precipitation (74%), water imported from the Delta (18%), and storage depletion (7%). The major outputs from the SJR watershed were ET (65%), water exports (19%), and flows to the Delta (14%). Most values varied greatly from year to year. Although streamflows, water exports, and valley precipitation are relatively well measured and estimated, uncertainties are higher for groundwater storage change as well as for ET and precipitation in montane regions. Improvement in data collection and synthesis in these components is necessary to build a more detailed and accurate water budget.

Widespread groundwater overdraft in alluvial aquifer systems like the Central Valley (CV) in California, USA, has increased interest in managed aquifer recharge (MAR). Like most clastic sedimentary basins, recharge to the productive semi-confined CV aquifer system remains a challenge due to the presence of nearly ubiquitous, multiple confining units (silt and clay) that limit recharge pathways. Previous studies suggest the presence of interconnected networks of coarse-texture sand and gravel deposits that bypass regional confining units over a small fraction of the CV near the American and Cosumnes rivers. Here, variably saturated infiltration and recharge processes were simulated across a domain that includes high-resolution representation of the heterogeneous alluvial geologic architecture in this area. Results show that recharge potential is highly dependent on subsurface geologic architecture, with a nearly 2 order-of-magnitude range of recharge across the domain. Where interconnected coarse-texture recharge pathways occur, results show that these features can (1) accommodate rapid, high-volume MAR and (2) propagate widespread and rapid pressure responses over multi-kilometer distances in the semi-confined aquifer system. For all MAR simulations, results show that the majority of MAR is accommodated by filling unsaturated-zone (UZ) pore volume. Results also show that coarse-texture UZ facies (where present) accommodate the majority of MAR volume during early time, but fine-texture facies ultimately accommodate the majority of the total MAR volume, even for coarse-dominated sites. These findings highlight the large variability of MAR potential across the landscape and demonstrate the importance of fine-texture facies for accommodating MAR in alluvial aquifer systems.

Land surface models (LSMs) have traditionally been designed to focus on providing lower-boundary conditions to the atmosphere with less focus on hydrological processes. State-of-the-art application of LSMs includes a land data assimilation system (LDAS), which incorporates available land surface observations to provide an improved realism of surface conditions. While improved representations of the surface variables (such as soil moisture and snow depth) make LDAS an essential component of any numerical weather prediction (NWP) system, the related increments remove or add water, potentially having a negative impact on the simulated hydrological cycle by opening the water budget. This paper focuses on evaluating how well global NWP configurations are able to support hydrological applications, in addition to the traditional weather forecasting. River discharge simulations from two climatological reanalyses are compared: one "online" set, which includes land-atmosphere coupling and LDAS with an open water budget, and an "offline" set with a closed water budget and no LDAS. It was found that while the online version of the model largely improves temperature and snow depth conditions, it causes poorer representation of peak river flow, particularly in snowmelt-dominated areas in the high latitudes. Without addressing such issues there will never be confidence in using LSMs for hydrological forecasting applications across the globe. This type of analysis should be used to diagnose where improvements need to be made; considering the whole Earth system in the data assimilation and coupling developments is critical for moving toward the goal of holistic Earth system approaches.

Precipitation on the Tibetan Plateau (TP) showed different spatial changes during 1979-2016, with an increasing trend over the northern Tibetan Plateau (NTP) and a slightly negative trend over the southern Tibetan Plateau (STP). The changes in precipitation moisture sources over the NTP and STP are investigated using the improved Water Accounting Model with an atmospheric reanalysis as well as observational precipitation and evaporation data. The results show the region in the northwest (region NW), ranging from the TP to Europe dominated by the westerlies, provides 38.9% of precipitation moisture for the NTP, and the region in the southeast (region SE), ranging from the TP to the Indian Ocean and Indochina dominated by the Asian monsoons, provides 51.4% of precipitation moisture for the STP. For the precipitation increase over the NTP, the SE and TP are the main contributors, contributing around 35.8% and 51.7% of the increase, respectively. The contributions from the SE and TP to the STP are, however, minor and insignificant. Meanwhile, the NW shows a negative trend of -4.2 ± 2.9mmyr -1 decade -1 (significant at the 0.01 level), which contributes to the negative precipitation trend over the STP. Results during the wet season indicate that moisture sources from the areas dominated by the Asian monsoons have contributed more precipitated moisture for the NTP, but not for the STP. Further analysis reveals that precipitated moisture originating from the Indian subcontinent has increased for the NTP while it has decreased for the STP during 1979-2016., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Water Resources

Land surface models (LSMs) have traditionally been designed to focus on providing lower-boundary conditions to the atmosphere with less focus on hydrological processes. State-of-the-art application of LSMs includes a land data assimilation system (LDAS), which incorporates available land surface observations to provide an improved realism of surface conditions. While improved representations of the surface variables (such as soil moisture and snow depth) make LDAS an essential component of any numerical weather prediction (NWP) system, the related increments remove or add water, potentially having a negative impact on the simulated hydrological cycle by opening the water budget. This paper focuses on evaluating how well global NWP configurations are able to support hydrological applications, in addition to the traditional weather forecasting. River discharge simulations from two climatological reanalyses are compared: one "online" set, which includes land-atmosphere coupling and LDAS with an open water budget, and an "offline" set with a closed water budget and no LDAS. It was found that while the online version of the model largely improves temperature and snow depth conditions, it causes poorer representation of peak river flow, particularly in snowmelt-dominated areas in the high latitudes. Without addressing such issues there will never be confidence in using LSMs for hydrological forecasting applications across the globe. This type of analysis should be used to diagnose where improvements need to be made; considering the whole Earth system in the data assimilation and coupling developments is critical for moving toward the goal of holistic Earth system approaches.

The study examines possible water savings by replacing alfalfa with winter wheat in the Fergana Valley, located upstream of the Syrdarya River in Central Asia. Agricultural reforms since the 1990s have promoted this change in cropping patterns in the Central Asian states to enhance food security and social benefits. The water use of alfalfa, winter wheat/fallow, and winter wheat/green gram (double cropping) systems is compared for high-deficit, low-deficit, and full irrigation scenarios using hydrological modeling with the HYDRUS-1D software package. Modeling results indicate that replacing alfalfa with winter wheat in the Fergana Valley released significant water resources, mainly by reducing productive crop transpiration when abandoning alfalfa in favor of alternative cropping systems. However, the winter wheat/fallow cropping system caused high evaporation losses from fallow land after harvesting of winter wheat. Double cropping (i.e., the cultivation of green gram as a short duration summer crop after winter wheat harvesting) reduced evaporation losses, enhanced crop output and hence food security, while generating water savings that make more water available for other productive uses. Beyond water savings, this paper also discusses the economic and social gains that double cropping produces for the public within a broader developmental context.

In recent years there has been an increase in the average temperature in different regions, which is associated with an increase in evapotranspiration, causing greater deficit and water stress in areas with arid climates. The climate of the Province of Neuquén presents a marked gradient of precipitations west-east, in areas near the mountain range of the Andes stand out cold winters with rains and snowfalls, and summers drier and more temperate; to the east, precipitation decreases, presenting a semi-desert environment identified with the Patagonian steppe. The knowledge of theevolution of the different components of the water balance in arid zones is offundamental importance for the estimation of the coverage of the hydric requirements of the vegetation, and of the different productive activities that are developed in the area; as well as for the control of the state of the wetlands (mallines). In this work, the spatial variations of the moisture balance components are presented in detail from information from the network of surface meteorological stations in the province of Neuquén, En los últimos años se ha producido un aumento de la temperatura media en distintas regiones, lo que se asocia con un aumento en la evapotranspiración, provocando mayor déficit y estrés hídrico en zonas con climas áridos. El clima de la provincia del Neuquén presenta un marcado gradiente de precipitaciones oeste-este, en áreas cercanas a la cordillera de los Andes se destacan inviernos fríos con lluvias y nevadas, y veranos más secos y templados; hacia el este disminuye la precipitación presentando un ambiente semidesértico identificado con la estepa patagónica. El conocimiento de la evolución de las distintas componentes del balance hídrico en zonas áridas es de fundamental importancia para la estimación de la cobertura vegetal y sus requerimientos hídricos, considerando las diversas actividades productivas que se desarrollan en la región. En el presente trabajo se presentan en detalle las variaciones espaciales de las componentes del balance de humedad, a partir de información de superficie de la red estaciones meteorológicas de la provincia del Neuquén.

In recent years there has been an increase in the average temperature in different regions, which is associated with an increase in evapotranspiration, causing greater deficit and water stress in areas with arid climates. The climate of the Province of Neuquén presents a marked gradient of precipitations west-east, in areas near the mountain range of the Andes stand out cold winters with rains and snowfalls, and summers drier and more temperate; to the east, precipitation decreases, presenting a semi-desert environment identified with the Patagonian steppe. The knowledge of theevolution of the different components of the water balance in arid zones is offundamental importance for the estimation of the coverage of the hydric requirements of the vegetation, and of the different productive activities that are developed in the area; as well as for the control of the state of the wetlands (mallines). In this work, the spatial variations of the moisture balance components are presented in detail from information from the network of surface meteorological stations in the province of Neuquén, En los últimos años se ha producido un aumento de la temperatura media en distintas regiones, lo que se asocia con un aumento en la evapotranspiración, provocando mayor déficit y estrés hídrico en zonas con climas áridos. El clima de la provincia del Neuquén presenta un marcado gradiente de precipitaciones oeste-este, en áreas cercanas a la cordillera de los Andes se destacan inviernos fríos con lluvias y nevadas, y veranos más secos y templados; hacia el este disminuye la precipitación presentando un ambiente semidesértico identificado con la estepa patagónica. El conocimiento de la evolución de las distintas componentes del balance hídrico en zonas áridas es de fundamental importancia para la estimación de la cobertura vegetal y sus requerimientos hídricos, considerando las diversas actividades productivas que se desarrollan en la región. En el presente trabajo se presentan en detalle las variaciones espaciales de las componentes del balance de humedad, a partir de información de superficie de la red estaciones meteorológicas de la provincia del Neuquén.

The study examines possible water savings by replacing alfalfa with winter wheat in the Fergana Valley, located upstream of the Syrdarya River in Central Asia. Agricultural reforms since the 1990s have promoted this change in cropping patterns in the Central Asian states to enhance food security and social benefits. The water use of alfalfa, winter wheat/fallow, and winter wheat/green gram (double cropping) systems is compared for high-deficit, low-deficit, and full irrigation scenarios using hydrological modeling with the HYDRUS-1D software package. Modeling results indicate that replacing alfalfa with winter wheat in the Fergana Valley released significant water resources, mainly by reducing productive crop transpiration when abandoning alfalfa in favor of alternative cropping systems. However, the winter wheat/fallow cropping system caused high evaporation losses from fallow land after harvesting of winter wheat. Double cropping (i.e., the cultivation of green gram as a short duration summer crop after winter wheat harvesting) reduced evaporation losses, enhanced crop output and hence food security, while generating water savings that make more water available for other productive uses. Beyond water savings, this paper also discusses the economic and social gains that double cropping produces for the public within a broader developmental context.

In recent years there has been an increase in the average temperature in different regions, which is associated with an increase in evapotranspiration, causing greater deficit and water stress in areas with arid climates. The climate of the Province of Neuquén presents a marked gradient of precipitations west-east, in areas near the mountain range of the Andes stand out cold winters with rains and snowfalls, and summers drier and more temperate; to the east, precipitation decreases, presenting a semi-desert environment identified with the Patagonian steppe. The knowledge of theevolution of the different components of the water balance in arid zones is offundamental importance for the estimation of the coverage of the hydric requirements of the vegetation, and of the different productive activities that are developed in the area; as well as for the control of the state of the wetlands (mallines). In this work, the spatial variations of the moisture balance components are presented in detail from information from the network of surface meteorological stations in the province of Neuquén, En los últimos años se ha producido un aumento de la temperatura media en distintas regiones, lo que se asocia con un aumento en la evapotranspiración, provocando mayor déficit y estrés hídrico en zonas con climas áridos. El clima de la provincia del Neuquén presenta un marcado gradiente de precipitaciones oeste-este, en áreas cercanas a la cordillera de los Andes se destacan inviernos fríos con lluvias y nevadas, y veranos más secos y templados; hacia el este disminuye la precipitación presentando un ambiente semidesértico identificado con la estepa patagónica. El conocimiento de la evolución de las distintas componentes del balance hídrico en zonas áridas es de fundamental importancia para la estimación de la cobertura vegetal y sus requerimientos hídricos, considerando las diversas actividades productivas que se desarrollan en la región. En el presente trabajo se presentan en detalle las variaciones espaciales de las componentes del balance de humedad, a partir de información de superficie de la red estaciones meteorológicas de la provincia del Neuquén.

In recent years there has been an increase in the average temperature in different regions, which is associated with an increase in evapotranspiration, causing greater deficit and water stress in areas with arid climates. The climate of the Province of Neuquén presents a marked gradient of precipitations west-east, in areas near the mountain range of the Andes stand out cold winters with rains and snowfalls, and summers drier and more temperate; to the east, precipitation decreases, presenting a semi-desert environment identified with the Patagonian steppe. The knowledge of theevolution of the different components of the water balance in arid zones is offundamental importance for the estimation of the coverage of the hydric requirements of the vegetation, and of the different productive activities that are developed in the area; as well as for the control of the state of the wetlands (mallines). In this work, the spatial variations of the moisture balance components are presented in detail from information from the network of surface meteorological stations in the province of Neuquén, En los últimos años se ha producido un aumento de la temperatura media en distintas regiones, lo que se asocia con un aumento en la evapotranspiración, provocando mayor déficit y estrés hídrico en zonas con climas áridos. El clima de la provincia del Neuquén presenta un marcado gradiente de precipitaciones oeste-este, en áreas cercanas a la cordillera de los Andes se destacan inviernos fríos con lluvias y nevadas, y veranos más secos y templados; hacia el este disminuye la precipitación presentando un ambiente semidesértico identificado con la estepa patagónica. El conocimiento de la evolución de las distintas componentes del balance hídrico en zonas áridas es de fundamental importancia para la estimación de la cobertura vegetal y sus requerimientos hídricos, considerando las diversas actividades productivas que se desarrollan en la región. En el presente trabajo se presentan en detalle las variaciones espaciales de las componentes del balance de humedad, a partir de información de superficie de la red estaciones meteorológicas de la provincia del Neuquén.

The frequent scarcity of water in the coastal aquifers of the Mediterranean areas makes essential the adequate management of groundwater with a good knowledge of the inputs and the outputs of the aquifers. The establishment of the water budget of aquifers is often hindered by uncertainties in the connection with other aquifers and the sea, or the permeability of layers that can disconnect hydraulically parts of the system. In the study of these regions, a common challenge is the lack of information at deep locations or disperse data in time and space that do not allow to provide reliable answers. Under these circumstances, the construction of simplified numerical models simulating groundwater flow can be used to verify or deny different hypothesis. In this study, the characteristics of Torrevieja aquifer (South East of Spain) have been analyzed proposing alternative conceptual models to explain the annual deficit of 4.4 Mm3 between inputs and outputs. The effect of a semipermeable top layer and the differentiation of the aquifer in two parts with distinct recharge sources was tested and compared with the hydrochemical information of groundwater samples to provide new perspectives about the characteristics of this aquifer. This study also shows how to use common hydrogeological tools and information of databases to address the uncertainties in the study of coastal aquifers.