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The island of Cyprus located in the center of the Eastern Mediterranean Basin, on the sea route from the old world to the west has huge water-based problems. This study, it was aimed to reveal the water deficit and trends on water deficit in the Turkish Republic of Northern Cyprus (KKTC). In this context, the traces of water deficit were investigated using water budgets. Water budgets were created and the amount and duration of water deficit were calculated. Statistically significant trends were investigated in the stations. In this context, the possible trends on the water deficit and the water surplus series were investigated separately. The results of the study showed that water deficit occurs in the KKTC throughout most of the year. The amount and duration of water deficit differ between the northern and inner parts of KKTC. Trend analyzes revealed that there are statistically significant trends in both water deficit and water surplus throughout the KKTC. In addition, a statistically significant decrease trend was detected in the number of months that have water deficit on an annual scale., Doğu Akdeniz Havzası’nın merkezinde, eski dünyadan batıya açılan deniz yolu üzerinde yer alan Kıbrıs adası bölge coğrafyasında su kökenli problemlerin en çok yaşandığı yerler arasındadır. Bu çalışmada Kuzey Kıbrıs Türk Cumhuriyeti (KKTC)’ndeki su noksanlığının ortaya çıkartılması ve su noksanlığına ait eğilimlerin araştırılması amaçlanmıştır. Çalışma dönemi boyunca hidrolojik bütçeler oluşturularak su noksanı miktar ve süresi hesaplanmıştır. Su noksanlığı ve su fazlalığı tespit edilen aylarda istatistiksel açıdan anlamlı bir artış veya azalış olup olmadığı sorusuna yanıt aranmış ve bu kapsamda eğilim analizleri gerçekleştirilmiştir. Çalışma bulguları KKTC genelinde yılın büyük bir kısmında su noksanlığı gerçekleştiğini göstermiştir. Kuzey ve iç kesimler arasında su noksanı miktar ve süresi farklılık sergilemektedir. Eğilim analizleri KKTC genelinde gerek su fazlalığında gerekse su noksanlığında istatistiksel açıdan anlamlı yönelimler gerçekleştiğini ortaya çıkartmıştır. Su fazlalığı kaydedilen aylarda tespit edilen anlamlı eğilimler su fazlasının azaldığını gösterirken, su noksanlığı kaydedilen aylarda tespit edilen anlamlı eğilimler su noksanının arttığını göstermiştir. Otuz bir yıllık kesintisiz dönem boyunca yıllık ölçekte su fazlası olan ay sayısında istatistiksel açıdan anlamlı azalma eğilimi tespit edilmiştir.

This study develops a set of models to investigate the water budget of Lake Urmia in Iran, a permanent hypersaline lake that has suffered a declining water level since the late 1990s. The models ar...

Whether there is enough water in California to meet the needs of residents, businesses, agriculture, and the natural environment, now and in the future, is important to Californians. One of the tools used to assess water availability in California is the water budget, which quantifies how much water enters and leaves the state, and how it is used or stored each year. While this information is useful for tracking quantity, it does not provide any information regarding the quality of the water. The objective of this thesis is to determine whether a method can be established for defining the quality of the water in a water budget in California. To do so requires determining whether a method can be established for creating a scale of water quality using the applicable water quality definitions for the types of water in a water budget in California. That requires determining how water quality is defined. This thesis introduces a six-step method for creating a scale of water quality categories that includes water found in both the natural and built environments in California. The method involves: selecting a geographical context; collecting water quality data applicable to the selected location; compiling water quality parameter data; organising water quality parameters in a matrix; ordering the rows of water quality parameter data values to form categories of water quality; and documenting data sources and notes. This thesis also introduces a seven-step method for creating a water budget, in the form of a modified mass flow diagram, that depicts the quality of each quantity of water. The method involves: delineating the system boundary for the water balance: selecting the water budget time period to be used for analysis; collecting water quantity data applicable to the selected system boundary and time period; drawing a modified mass flow diagram; selecting and assigning a colour code to the selected water quality scale; applying the colour code representing water quality to the modified mass flow diagram; and ordering diagram slices by level of water quality. The findings indicate that a water budget that includes water quality allows for areas of more efficient use, alternatives to over-extraction, and opportunities for reuse to be identified. Viewing the quantities and qualities depicted together on the same graphic allows like quantities and qualities to be matched, revealing opportunities for meeting demand using different water sources. Adding water quality to water budgets may not only show areas where there is room for improvement, but also depict areas where there are resources and opportunities that might not have been visually obvious from a table of numbers., Hughes Hall, Cambridge University

International audience; In semi-arid regions as in India, where agriculture relies on groundwater abstraction, increase of water resources availability through managed aquifer recharge (MAR) or rainwater harvesting (RWH) is often perceived as a major solution. Studies on these structures efficiency exists but despite the interest, limited information is available on the temporal variation of their replenishment. In a monsoon driven climate, the inter-annual variations are crucial to assess the potential of water storage and multi-year management especially for these structures. Here, we aim at developing a methodology to reconstruct water storage of RWH tanks to further improve our understanding on long term efficiency and multi-years drought management. To tackle this issue, long-term monitoring of a RWH tank located in Telangana in southern India is achieved by a combination of field monitoring over 2 years (tanks surface and water levels) and a daily water balance compared to LANDSAT measurements of the tank area. The procedure allows reconstructing the tank filling dynamic over a 14-years period at a daily time step and show the extreme variability of the tank filling level. During this period, the yearly maximum tank volume ranges from 8 650 to ~ 200 000 m 3. On the 14-years period, the tank reach its maximum capacity only once and, for 1/3 of the time, yearly maximum replenishment is below 15 % of its capacity. The surface water availability remains limited in time since the tank dries-up annually, except for 2 years. However, water percolation to the aquifer is slightly enhanced for some years. During this monitoring period, very few extreme raining events (6) contribute for more than 50 % of the collected volume. This observation highlights (1) the dependency of the structure to extreme storm events, (2) the limited capacity for a multiyear's management and (3) the farmers vulnerability to successive droughts.

Like civilization and technology, our understanding of the global water cycle has been continuously evolving, and we have adapted our quantification methods to better exploit new technological resources. The accurate quantification of global water fluxes and storages is crucial in studying the global water cycle. These fluxes and storages physically interact with each other, are related through the water budget, and are constrained by it. First attempts to quantify them date back to the early 1900s, and during the past few decades, they have received an increasing research interest, which is reflected in the vast amount of data sources available nowadays. However, these data have not been comprehensive enough due to the high spatiotemporal variability of the global water cycle. Herein, we provide a comprehensive review of the chronological evolution of global water cycle quantification, the distinct data sources and methods used, and a critical assessment of their contribution to improving the spatiotemporal monitoring of the global water cycle. The chronology of global water cycle components shows that the uncertainty of flux estimates over oceans remains higher than that over land. Comparing the standard deviation and the interquartile range of the estimates from the 2000s onward with those from all the estimates (1905-2019), we can affirm that statistical variability has diminished in recent years. Moreover, the variability of ocean precipitation and evaporation estimates from the 2000 onward was reduced by more than $$70\%$$ compared with earlier studies. These findings advocate that the consistency of global water cycle quantification has been improved.

Effects of water mass imbalance and hydrometeor transport on the enthalpy flux and water phase on diabatic heating rate in computing the regional energy and water budget of the atmosphere over ocean are investigated. Equations of energy and water budget of the atmospheric column that explicitly consider the velocity of liquid and ice cloud particles, and rain and snow are formulated by separating water variables from dry air. Differences of energy budget equations formulated in this study from those used in earlier studies are that 1) diabatic heating rate depends on water phase, 2) diabatic heating due to net condensation of nonprecipitating hydrometeors is included, and 3) hydrometeors can be advected with a different velocity from the dry-air velocity. Convergence of water vapor associated with phase change and horizontal transport of hydrometeors is to increase diabatic heating in the atmospheric column where hydrometeors are formed and exported and to reduce energy where hydrometeors are imported and evaporated. The process can improve the regional energy and water mass balance when energy data products are integrated. Effects of enthalpy transport associated with water mass transport through the surface are cooling to the atmosphere and warming to the ocean when the enthalpy is averaged over the global ocean. There is no net effect to the atmosphere and ocean columns combined. While precipitation phase changes the regional diabatic heating rate up to 15 W m−2, the dependence of the global mean value on the temperature threshold of melting snow to form rain is less than 1 W m−2.

A field experiment was conducted during the rainy season of 2014, in the steeply sloping agricultural land of northern Laos to determine the factors that cause the generation of surface runoff wate...

The formerly perennial Katuma River in western Tanzania starts in a protected forest, it then flows through irrigated rice farms before reaching Lake Katavi, a floodplain wetland whose outflow regulates the river flow through the Katavi National Park (KNP) down to its outlet at Lake Rukwa, which has no outlet. In recent years, due to overexploitation of water for irrigation, the Katuma River dried out for up to four months per year and this greatly degraded the KNP ecosystem, the siltation of river lead to flooding of the adjacent areas during heavy rains, and the water level of Lake Rukwa has decreased by 4 m since 1992 while its fishery yield and water quality also deteriorated. In 2016, a total of 46 illegal weirs were removed from the Katuma River upstream of KNP. Following that, the river zero-flow periods were reduced by two months and Lake Rukwa water level rose by 1 m. We suggest that the construction of a low V-notch weir at the outlet of the Lake Katavi wetlands would further reduce the Katuma River zero-flow periods by an additional month, thus returning the river nearly to its former perennial status. The enforcement of regulations governing the construction of irrigation weirs is essential. These ecohydrology solutions do not eliminate the threats, but they amplify the opportunities for sustainable development at the basin scale. This example of active governance of water resources at the basin scale can be applied throughout Tanzania and in semi-arid East Africa in general.

Planted forests are increasing in area worldwide in recent decades and play an important role in carbon sequestration programs. However, the effects of plantations on water resources are largely unknown. Here, we investigate the effects of Eucalyptus sp. plantations on water budget fluxes in the southern Brazilian grasslands biome. We evaluated green (canopy interception and evapotranspiration) and blue (discharge) water flows in three watersheds: two watersheds predominantly covered with eucalyptus, either in the first years after planting or at the end of the rotation, and one watershed with livestock-grazing grassland. We used field measurements of rainfall, streamflow, and throughfall and estimated canopy interception and evapotranspiration by water balance. Water flows in the monitored watersheds with eucalyptus plantations were influenced by forest developmental stage. Annual canopy interception and transpiration were always higher in the watersheds with eucalyptus than in the one with grassland, except for the transpiration in the first year after plantation in the watershed with young eucalyptus. An increase in evapotranspiration (green water flow) and the consequent decrease in streamflow (blue water flow) should be considered in local water resource management. Studies of catchment hydrology and forest management for improved water use efficiency and streamflow regulation are needed, particularly in understudied regions.

Global and regional water cycle includes precipitation, water vapor divergence, and change of column water vapor in the atmosphere, and land surface evapotranspiration, terrestrial water storage change, and river discharge, which is linked to ocean salinity near the river mouth. The water cycle is a crucial component of the Earth system, and numerous studies have addressed its individual components (e.g., precipitation). Here we assess, for the first time, if remote sensing and reanalysis datasets can accurately and self-consistently portray the Amazon water cycle. This is further assisted with satellite ocean salinity measurements near the mouth of the Amazon River. The widely used practice of taking the mean of an ensemble of datasets to represent water cycle components (e.g., precipitation) can produce large biases in water cycle closure. Closure is achieved with only a small subset of data combinations (e.g., ERA5 precipitation and evapotranspiration plus GRACE satellite terrestrial water storage), which rules out the lower precipitation and higher evapotranspiration estimates, providing valuable constraints on assessments of precipitation, evapotranspiration, and their ratio. The common approach of using the Óbidos stream gauge (located hundreds of kilometers from the river mouth) multiplied by a constant (1.25) to represent the entire Amazon discharge is found to misrepresent the seasonal cycle, and this can affect the apparent influence of Amazon discharge on tropical Atlantic salinity.

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. Published version

The water in the air is composed of water vapor and hydrometeors, which are inseparable in the global atmosphere. Precipitation basically comes from hydrometeors instead of directly from water vapor, but hydrometeors are rarely focused on in previous studies. When assessing the maximum potential precipitation, it is necessary to quantify the total amount of hydrometeors present in the air within an area for a certain period of time. Those hydrometeors that have not participated in precipitation formation in the surface, suspending in the atmosphere to be exploited, are defined as the cloud water resource (CWR). Based on the water budget equations, we defined 16 terms (including 12 independent ones) respectively related to the hydrometeors, water vapor, and total water substance in the atmosphere, and 12 characteristic variables related to precipitation and CWR such as precipitation efficiency (PE) and renewal time (RT). Correspondingly, the CWR contributors are grouped into state terms, advection terms, and source/sink terms. Two methods are developed to quantify the CWR (details of which are presented in the companion paper) with satellite observations, atmospheric reanalysis data, precipitation products, and cloud resolving models. The CWR and related variables over North China in April and August 2017 are thus derived. The results show that CWR has the same order of magnitude as surface precipitation (Ps). The hydrometers converted from water vapor (Cvh) during the condensation process is the primary source of precipitation. It is highly correlated with Ps and contributes the most to the CWR over a large region. The state variables and advection terms of hydrometeors are two orders of magnitude lower than the corresponding terms of water vapor. The atmospheric hydrometeors can lead to higher PE than water vapor (several tens of percent versus a few percent), with a shorter RT (only a few hours versus several days). For daily CWR, the state terms are important, but for monthly and longer-time mean CWR, the source/sink terms (i.e., cloud microphysical processes) contribute the largest; meanwhile, the advection terms contribute less for larger study areas.

Forest fires are becoming more frequent and larger in the subarctic Canadian Shield, so understanding the effect of fire on catchment scale water budgets is becoming increasingly important. The objective of this study was to determine the water budget impact of a forest fire that partially burned a ~450 km2 subarctic Canadian Shield basin. Water budget components were measured in a pair of catchments; one burnt and another unburnt. Burnt and unburnt areas had comparable net radiation, but ground thaw was deeper in burned areas. Snowpacks were deeper in burns. Differences in streamflow between the catchments were within measurement uncertainty. Enhanced winter streamflow from the burned watershed was evident by icing growth at the streamflow gauge location, which was not observed in the unburned catchment. A new framework to assess hydrological resilience to forest fire across the region revealed that watersheds with higher bedrock and open water fractions are more resilient to hydrological change after fire in the subarctic shield, and resilience decreases with increasingly wet conditions.

The importance of characterizing the ecohydrological interactions in natural, damaged/drained, and restored bogs is underscored by the importance of peatlands to global climate change and the growing need for peatland restoration. An understudied aspect of peatland ecohydrology is how shallow lateral flow impacts local hydrological conditions and water balance, which are critical for peatland restoration success. A novel method is presented using microcosms installed in the field to understand the dynamics of shallow lateral flow. Analysis of the difference in water table fluctuation inside and outside the microcosm experimental areas allowed the water balance to be constrained and the calculation of lateral flow and evapotranspiration. As an initial demonstration of this method, a series of four microcosm experiments were set up in locations with differing ecological quality and land management histories, on a raised bog complex in the midlands of Ireland. The timing and magnitude of the lateral flow differed considerably between locations with differing ecological conditions, indicating that shallow lateral flow is an important determining factor in the ecohydrological trajectory of a recovering bog system. For locations where Sphagnum spp. moss layer was present, a slow continuous net lateral input of water from the upstream catchment area supported the water table during drought periods, which was not observed in locations lacking Sphagnum. Consistent with other studies, evapotranspiration was greater in locations with a Spaghnum moss layer than in locations with a surface of peat soil., A series of microcosm experiments were used to conduct microscale hydrological measurements. These measurements contribute to the understanding of the complex ecohydrological interaction between storage, transmissivity, and shallow lateral flow as Sphagnum moss develops on a previously degraded bog.

Understanding how natural processes arise from complex interactions between particular processes at small spatiotemporal scales and in turn how these processes form patterns at large spatiotemporal scales is one of the current principal questions in environmental science. The problem is very complicated, as in many cases, key processes are often studied by researchers in separate disciplines such as ecology, soil science or hydrology. One of the major obstacles is that the processes at a landscape scale are difficult to manipulate and, in many cases, even measure. In particular, the belowground processes are in many cases overlooked or at least understudied. Here we briefly describe a methodological solution used to cope with this problem and describe artificial catchments designed for experimental manipulation at the level of a landscape, called FALCON. This array has two treatments: one mimics a site reclaimed using an alder plantation and the other was left to unassisted primary succession. For each treatment, there were two replicates in four similar catchments. Individual catchments are hydrologically isolated from the environment and equipped with instruments, so that all the main processes and all significant flows of substances and energy in the ecosystem can be monitored, including the cycling of water, nutrients and gas between the ecosystem and the atmosphere. In addition, in each catchment there are sets of lysimeters, which allow the study of small-scale processes and how these can be extrapolated to the catchment scale. In addition, two lysimetric fields exist alongside the catchments for monitoring the effects of the experimental manipulation.

We used climate models to assess the effects of 2 distinct anthropogenic forcings on the water budget in the Amazon basin: (1) increasing global greenhouse gases under the RCP8.5 scenario, and (2) land cover change caused by deforestation. The Eta regional climate model, driven by the Brazilian Earth System Model version 2.5 (BESM 2.5), was used to simulate the climate response under the RCP8.5 scenario and due to deforestation throughout the 21st century. Changes in energy and water budgets led to an increase in temperature that reached 5°C throughout the basin. In the RCP8.5 scenario, moisture convergence, precipitation and evapotranspiration all decreased. In this scenario, the positive feedback mechanism was predominant, as the reductions in evapotranspiration and moisture convergence acted in the same direction to reduce precipitation. In the future deforestation scenarios, reductions in precipitation were even stronger. In this case, the negative feedback mechanism predominated, in which the relative reduction in evapotranspiration was greater than the reduction in precipitation, leading to an increase in moisture convergence over the region. Changes in temperature and the water cycle were intensified in the future deforestation scenarios. These results show that the 2 anthropogenic factors can change the water budget and cause an imbalance in the climate-biome system in the Amazon basin, highlighting the need for public conservation policies to halt the increase in environmental degradation in the Amazon basin and to reduce greenhouse gases emissions due the burning of fossil fuels.

In this study, the evolution of precipitation efficiency (PE) and water budget of mesoscale convective systems (MCSs), which produced heavy rainfall over the South China Sea and southern Taiwan on 25 - 28 August 2015, are investigated using satellite observations and model simulations. The MCS is embedded within the southwesterly monsoon flow from Indo China with abundant moisture. The evolution of PE and water budget is first examined in a quasi-Lagrangian framework following the movement of targeted MCS, and is confirmed in an Eulerian framework over the broad-scale area enclosing the MCS. The sensitivity of water budget and moisture fluxes to low-level moisture amount and horizontal wind speed is investigated. Water budget in the quasi-Lagrangian framework shows that if the low-level large-scale moisture is increased (decreased) by 10%, the total condensation and deposition will be increased (decreased) by 10% (30 - 40%); moisture flux convergence will be significantly enhanced within the MCS to generate more precipitation, and evaporation will be more pronounced over the region of weak convection. Similar results are found in an Eulerian framework. For the strong convective cells (radar reflectivity of greater than 35 dBZ) within the MCS, the calculated large-scale PE is 20 - 25% and the microphysical PE is 35 - 40%. The surface precipitation is highly sensitive to the large-scale moisture change, and less sensitive to wind-speed change. In particular, 10% decrease of low-level (below 700 hPa) relative humidity results in 10 - 20% decrease of moisture flux and 10 - 40% reduction of surface precipitation.

Artificial groundwater recharge is a process of induced replenishment of the groundwater via the assist of human activities. It is far the planned, human activity of increasing the quantity of groundwater available via works designed to grow the natural replacement or percolation of surface water into the groundwater aquifers, resulting in a corresponding increase in the amount of groundwater available for the concept. In an area like Musunuru Mandal in Andhra Pradesh, there is a need for recharge of groundwater identified by Jal Shakti Abhiyan. This study explains the demand and consumption of water and estimates the water budget in Musunuru village. In this study, the major source of water for agriculture is rainfall or borewells (tube wells). To identify the water demand in the village and suggesting the best practice approach to reduce the risk of Musunuru with an experimental study on groundwater recharge techniques. Among all the recharge techniques this study chooses the low budget soak pit method with materials like a reused plastic drum and locally available construction materials in Musunuru. By using this proposed low budget soak pit method 85% of groundwater recharge contributes.

Lake Velence is a shallow soda lake whose water level and water quality show a severely deteriorating tendency in recent years. Until recently, the groundwater component in the lake’s water budget has not been taken into consideration. To integrate the lake into the groundwater flow system at the regional scale, methods of “basin hydraulics” were applied. In addition, 17 water samples were collected for δ2H and δ18O, and for ΣU, 226Ra and 222Rn activity measurements to use these parameters as environmental tracers of groundwater contribution. Groundwater mapping revealed that groundwater recharges in Velence Hills and the local elevations south of the lake, whereas discharge occurs by the lake’s shoreline and along surface watercourses. The results indicated that Lake Velence is the discharge point of local groundwater flow systems known to be more sensitive to climate changes and anthropogenic activities (e.g., contamination, overexploitation). Groundwater and lake water have similar uranium activity concentrations serving as another sign of groundwater inflow into the lake. Therefore, it is necessary to consider both the groundwater component in the lake’s water management and its vulnerability regarding local and short-term changes in the catchment area.

Understanding the climatic complexity and its consequences on glacier health are of critical importance for the health of the Himalayan glacier and its contribution to the water budget. In this study, satellite datasets are used to estimate the glacier area loss, snow cover variability, and reanalysis data for climatic trends for four glacierised basins (Chandra, Bhaga, Miyar, and Parvati) of the Western Himalaya. In total, 257 glaciers covering a glacierised area of 1306 km2, having a mean altitude of 5200 m asl, and an average slope of 18°, were analyzed using Corona (1971) and Sentinel (2018) satellite data. These glaciers have experienced a significant glacier area loss rate (0.2 km2a−1) and an increase in the number of glaciers on account of fragmentation. Snow cover estimate during 2000–2019 using MODIS data showed no significant change or a slight decrease in snow cover area during the last two decades. However, the ERA-Interim reanalysis data revealed a systematic decrease in precipitation, an increase in temperature and an increase in liquid precipitation over the region during 1979–2018. The increased liquid precipitation possibly contributed to the faster melting of the snow and ice and consequently affected the glaciers’ health. The observed glacier fragmentation and glacier mass loss over the five decades and enhanced rainfall activity revealed a significant influence of climatic changes over the glacierised region in Western Himalaya.

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 practical for projecting climate change impacts. However, it is challenging to apply VR-CESM for hydrologic analysis in regulated watersheds as human factors (e.g., pumping, irrigation, water diversion) have not been fully addressed in VR-CESM.

The global water cycle is one of the most important Earth cycles. In this work, we evaluate the global water budget evapotranspiration minus precipitation (E-P) from the latest state-of-the-art climate Earth system modelling, the Energy Exas-cale Earth System Model (E3SM), and six global climate models (GCMs) within the Coupled Model Intercomparison Project Phase 6 (CMIP6) historical runs for the period 1980–2010. ERA5 is applied as a reference dataset in this evaluation. The eigenvalue structure is a novel approach that is utilized to assess the similarity between the long-term annual average global spatial distribution of the water cycle components and their corresponding budgets from the E3SM and six GCMs, w.r.t. the reference dataset ERA5. This evaluation is critical for future climate prediction using the E3SM.

The accurate estimation of evapotranspiration (ET) is essential for understanding the land surface–atmosphere interaction; however, current ET products have large uncertainties, and irrigation effects on ET are not well represented. In this study, the monthly ET was reconstructed (ETrecon) from GLDAS land surface models (LSMs) over the Yellow River basin of China, which was achieved by using observation-based precipitation, naturalized streamflow, and downscaled consumed irrigation water from the census annual data via an irrigation scheme. The results showed that the monthly ETrecon series were generally improved relative to the original LSM-based ET, with improvements in the correlation coefficient, Nash–Sutcliffe efficiency, mean absolute error, and root-mean-square error by 0.6%–1.8%, 1.2%–14.6%, 1.3%–21.0%, and 2.1%–20.4%, respectively. The ETrecon results were also superior to the collected ET synthesis products in terms of statistics, with generally higher peak values occurring in ETrecon. Regarding the annual time scale, the ETrecon values were close to the water balance ET values, which have been widely used as benchmark data. The interannual variability in ETrecon was good overall and was associated with the LSM precipitation variability and partitioning of precipitation into ET and runoff. The reconstruction method can provide an alternative ET estimate for other river basins. This study will also be valuable for studies and applications in climate change evaluation, drought assessment, and water resources management.

Middle America is affected by tropical cyclones (TCs) from the Eastern Pacific and the North Atlantic Oceans. We characterize the regional climatology (1998-2016) of the TC contributions to the atmospheric branch of the hydrological cycle, from May to December. TC contributions to rainfall are quantified using Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) product 3B42 and TC tracks derived from three sources: the International Best Track Archive for Climate Stewardship (IBTrACS), and an objective feature tracking method applied to the Japanese 55-year and ERA-Interim reanalyses. From July to October, TCs contribute 10-30% of rainfall over the west and east coast of Mexico and central Mexico, with the largest monthly contribution during September over the Baja California Peninsula (up to 90%). TCs are associated with 40-60% of daily extreme rainfall (above the 95th percentile) over the coasts of Mexico. IBTrACS and reanalyses agree on TC contributions over the Atlantic Ocean but disagree over the Eastern Pacific Ocean and continent; differences over the continent are mainly attributed to discrepancies in TC tracks in proximity to the coast and TC lifetime. Reanalysis estimates of TC moisture transports show that TCs are an important moisture source for the regional water budget. TC vertically integrated moisture flux (VIMF) convergence can turn regions of weak VIMF divergence by the mean circulation into regions of weak VIMF convergence. We discuss deficiencies in the observed and reanalysis TC tracks, which limit our ability to quantify robustly the contribution of TCs to the regional hydrological cycle.

Drought is one of the most recurrent natural disasters with cataclysmic effects on water budget, crop production, economic progression and public health. These consequences are magnified by the cli...

The authors propose a modified complementary method to estimate regional evapotranspiration (ET) under different climatic and physical conditions using only meteorological data. The purpose of this...

ÖsszefoglalásA folyamatalapú hidrológiai számításoknak és az azokra épülő vízminőségi, ökológiai elemzéseknek jelentős a bemenő adatigénye, ami a jövőben várhatóan tovább növekszik. A méréstechnológia rohamos fejlődésével a hidrológiai modellek bemenő adatai közül mára a szűk keresztmetszetet lokális és vízgyűjtő léptéken is a felszín alatti viszonyok, és elsősorban a talajok szivárgáshidraulikai tulajdonságainak számszerűsítése jelenti. A helyzetet felismerve a közelmúltban különböző módszertannal több talajtani, talajhidrológiai adatbázist is kidolgoztak. Kutatásunkban azt vizsgáljuk, hogy a 100 m felbontású hazai talajadatok és európai becslő algoritmusok alapján számított talajhidrológiai paraméterek (i) megbízható bemeneti adatforrást biztosítanak-e, és (ii) a korábban rendelkezésre álló adatállományokhoz képest javítják-e a hidrológiai számítások jóságát talajszelvény szintű vízforgalmi modellben.Az Erdészeti Tudományos Intézet (NAIK ERTI) két mintaterületén (Fiad és Szalafő) mért meteorológiai és talajnedvesség-idősorok segítségével 5-5 darab talajszelvényszintű vízforgalmi modellváltozatot állítottunk fel Hydrus-1D környezetben. Ezek kizárólag a talajtani paraméterezésükben (réteghatárok helye, telített vízvezető képesség és retenciós görbe együtthatók) tértek el: a talajrétegek jellemzésére felhasználtuk (i) a kalibráció-validáció eredményeit (“legjobbnak vélt” verzió), (ii) a helyszíni mintavételből származó laboratóriumi méréseket, (iii) a mért talajtulajdonságok alapján, az európai becslő függvényekkel (EU-PTF) számított talajhidrológiai tulajdonságokat, (iv) a hazai DOSoReMI adatbázis alapján, az EUPTF- ekkel számított talajhidrológiai tulajdonságokat, illetve (v) az EUSoilHydroGrids térképeket. A modellváltozatokat a mért és számított talajnedvesség-idősorok összevetése (NSME, RMSE, R2) alapján értékeltük. Emellett összehasonlítottuk a számított vízmérlegeket is.Az öt-öt modellváltozat esetében lényegesen eltért a mért-számított talajnedvességi idősorok illeszkedése. Fiadon egyedül a kalibráció adott elfogadható eredményt (NSME = 0.49), a másik négy változat kifejezetten gyengének bizonyult (három esetben NSME < 0). Szalafőn minden változat pozitív NSME-re vezetett, a kalibráció kiválónak tekinthető (NSME = 0.75). A várakozással ellentétben a mért talajhidrológiai paraméterekre épülő modellváltozatok adták a legrosszabb illeszkedést, míg a hatékonysági rangsorban a kalibrált modellek után az EU-SoilHydroGrids változatok következtek. A szimulációkból levezetett vízmérlegek Fiadon csak kevéssé, míg Szalafőn nagymértékben függtek a talajparaméterezéstől. A vizsgálat fontos tapasztalata, hogy a talajszelvény feltárás gyakorlata – érthető módon – elsősorban nem a hidrológiai modellezés szempontjaihoz igazodik, így az adatbizonytalanság forrása lehet. A vizsgálat eredményei alapján folytatjuk a Balaton vízgyűjtő talajhidrológiai paramétereinek 3D térképezését.

Pan evaporation plays a critical role in estimating water budget and modeling crop water requirements. However, it has been measured at a very limited number of meteorological stations. Estimation of pan evaporation from measured meteorological variables offers an important alternative and drawn increasing attention in the recent years. This paper investigated the performance of support vector machine (SVM) in the estimation of monthly pan evaporation using commonly measured meteorological variables in Three Gorges Reservoir Area in China. Evaluation suggested that SVM models showed remarkable performances and significantly outperformed the empirical model. The SVM model with polynomial as kernel function outperformed that with radial basis function. In the case of unavailable measurements of pan evaporation and meteorological variables to construct the SVM model, pan evaporation can be well-estimated by SVM model developed using data at other sites. The results indicated that the SVM method would be a promising alternative over the traditional approaches for estimating pan evaporation from measured meteorological variables.

Accurate estimation of pan evaporation (Epan) is very important in water resources management, irrigation scheduling and water budget of lakes. This study investigates the accuracy of two heuristic...

Water budget, hydrogeology, Soča/Isonzo River, climate change, Flowpath 2017, National meeting on hydrogeology 2017

The calculation of runoff and infiltration parameters is a fundamental task for water budget estimation and water resources management. The “Kenessey method” allows these values to be calculated and its use is widespread among water scientists and practitioners. Due to language barriers and inefficient translation in past decades, the method has undergone some misinterpretations and is now far from its original usefulness and purpose. The use of the modified method can give unreal results for specific climatic zones. The purpose of this paper is to point out these methodological variations and to return to the original approach, improving it with modern technology.

Precipitation changes in a warming climate have been examined with a focus on either mean precipitation or precipitation extremes, but changes in the full probability distribution of precipitation have not been well studied. This paper develops a methodology for the quantile-conditional column moisture budget of the atmosphere for the full probability distribution of precipitation. Analysis is performed on idealized aquaplanet model simulations under 3-K uniform SST warming across different horizontal resolutions. Because the covariance of specific humidity and horizontal mass convergence is much reduced when conditioned onto a given precipitation percentile range, their conditional averages yield a clear separation between the moisture (thermodynamic) and circulation (dynamic) effects of vertical moisture transport on precipitation. The thermodynamic response to idealized climate warming can be understood as a generalized “wet get wetter” mechanism, in which the heaviest precipitation of the probability distribution is enhanced most from increased gross moisture stratification, at a rate controlled by the change in lower-tropospheric moisture rather than column moisture. The dynamic effect, in contrast, can be interpreted by shifts in large-scale atmospheric circulations such as the Hadley cell circulation or midlatitude storm tracks. Furthermore, horizontal moisture advection, albeit of secondary role, is important for regional precipitation change. Although similar mechanisms are at play for changes in both mean precipitation and precipitation extremes, the thermodynamic contributions of moisture transport to increases in high percentiles of precipitation tend to be more widespread across a wide range of latitudes than increases in the mean, especially in the subtropics.

The present study investigates the impact of climate change on the availability of groundwater resources in Italy and in Campania region (Southern Italy). A 20-year average from 1996 to 2015 of annual water budget components (namely total precipitation, actual evapotranspiration, surface runoff and aquifer recharge) has been evaluated over a 1-km resolution grid and have been projected considering four climate change scenarios (from the Fifth Assessment Report of the United Nations Intergovernmental Panel on Climate Change) and three different future 20-year time periods (2020–2039, 2040–2059 and 2080–2099). The groundwater balance has been carried out on a yearly basis using the “Nationwide GIS-based regular gridded hydrological water budget” procedure, which has been developed by the Italian National Institute for Environmental Protection and Research (ISPRA). The different scenarios of groundwater resources have been compared and matched to the 20-year average of latest historical values related to the period 1996–2015, leading to interesting considerations about the future depletion of groundwater resources. Nationwide results have been compared with those of Campania region, in order to underline the significant differences of climate change impact on groundwater resources at local scale, especially in a typical Mediterranean climate where groundwater resources represent the main source of water for human needs.

Quantification of the water budget of an arid inland river ecosystem is essential but still a challenge for the sustainable development of water resources. In situ observed data were used to analyze the monthly and annual water budgets and the soil hydrological cycle for six typical ecosystems in the Heihe River Basin (HRB). The two-source model was used to partition evapotranspiration (ET) into transpiration (T) and evaporation, after which the validated model was applied to quantitatively analyze the biological water use fraction [T/Ecosystem Water Supply (WS)] for different ecosystems. There were differences in the water budgets of the different ecosystems due to differences in climate, vegetation, soil, and external inputs. Precipitation in the HRB decreased from upstream to downstream, whereas there was a gradual increase in ET. External sources of water (e.g., natural runoff from upstream, irrigation in the middle reaches, and groundwater recharge in the lower reaches) to soil layers played an important role in regulating the water budgets of HRB ecosystems. Cropland obtained the maximum biological water use fraction (0.50), followed by Populus euphratica (0.49), alpine meadow (0.49), alpine swamp meadow (0.44), Tamarix ramosissima (0.42), and Kalidium foliatum (0.4). The soil water residence time (at a depth of 40 cm) varied from 14 d to 97 d (average of 60 d). The order of plant species in terms of soil water residence time was: K. foliatum (88 d) > T. ramosissima (72 d) > alpine meadow (68 d) > alpine swamp meadow (63 d) > cropland (53 d) > P. euphratica forest (20 d). Differences in the biological water use fraction and soil water residence time could be attributed to the characteristics of the water budget for each ecosystem. This study quantified the water budget, biological water use, and soil hydrological cycle across typical ecosystems in HRB, and can act as a reference for ecosystem management of the arid inland river basin.

Despite the accuracy of GRACE terrestrial water storage estimates and the variety of global hydrological datasets providing precipitations, evapotranspiration, and runoff data, it remains challenging to find datasets satisfying the water budget equation at the global scale.We select commonly used and widely-assessed datasets. We use several precipitations (CPC, CRU, GPCC, GPCP, GPM, MSWEP, TRMM, ERA5 Land, MERRA2), evapotranspiration (land surface models CLSM, Noah, VIC from GLDAS 2.0, 2.1, and 2.2; GLEAM, MOD16, SSEBop, ERA5 Land, MERRA2), and runoff (land surface models CLSM, Noah, VIC from GLDAS 2.0, 2.1, and 2.2; GRUN, ERA5 Land, MERRA2) datasets to assess the water storage change over more than 150 hydrological basins. Both mascons and spherical harmonics coefficients are used as the reference terrestrial water storage from different centres processing GRACE data. The analysis covers a wide range of climate zones over the globe and is conducted over 2003-2014.The water budget closure is evaluated with Root Mean Square Deviation (RMSD), Nash-Sutcliffe Efficiency (NSE), and seasonal decomposition. Each dataset is assessed individually across all basins and dataset combinations are also ranked according to their performances. We obtain a total of 1080 combinations, among which several are suitable to close the water budget. Although none of the combinations performs consistently well over all basins, GPCP precipitations provide generally good results, together with GPCC and GPM. A better water budget closure is generally obtained when using evapotranspiration from Catchment Land Surface Models (GLDAS CLSM), while reanalyses ERA5 Land and MERRA2 are especially suitable in cold regions. Concerning runoff, the machine learning GRUN dataset performs remarkably well across climate zones, followed by ERA5 Land and MERRA2 in cold regions. We also highlight highly unrealistic values in evapotranspiration computed with version 2.2 of GLDAS (using data assimilation from GRACE) in most of the cold basins. Our results are robust as changing the GRACE product from one centre to the other does not affect our conclusions.

In Mediterranean climates, prolonged droughts lead to a significant shift in the precipitation -runoff relationship, usually in the direction of proportionally less precipitation allocated to runoff compared to wet periods. This shift may impact discharge predictions, as many hydrological and land surface models assume that hydrological processes are stationary even under a significant change of the climate (i.e., multi-year droughts) and are generally calibrated with more weight on discharge peaks than low flows. Here, we investigate whether multi-year droughts result in a change in the precipitation-runoff relationship over continental European climates (which has never been fully explored before). 30-year records of annual rainfall and runoff from a dataset (>200) of small- and medium-scale (150 to 10000 km2) European catchments were used to test the existence of statistical shifts in the precipitation–runoff relationship. This was achieved by fitting a multivariate regression across annual cumulative full-natural flow, basin-wide annual precipitation, and a categorical variable denoting multi-year drought and non-drought years.Results demonstrate that multi-year droughts cause a shift in the precipitation–runoff relationship regardless of predominant climate , with the magnitude of this shift ranging between 20 and 80%. We explore mechanisms of these shifts and potential explanatory factors, including catchment properties and characteristics.Understanding changes in the precipitation-runoff relationship is paramount to make models and water resource management more robust to droughts, especially in a warming and more variable climate.

Assessing the water balance including subsurface runoff in high Alpine catchments is still a major challenge due to environmental and meteorological complexity, and mostly data-lacking hydrology. The aim of this study is the determination of the water balance components and water budget with focus on approximation of interflow, subsurface runoff and groundwater interactions, depending on sediment and bedrock properties.In this process we investigate a small, high data providing Alpine catchment in the Wipp Valley (Tyrol, AT) to evaluate the best modelling approach in order to apply it on catchments along the Austrian Brenner axis. Thus, a direct model comparison of the main study catchment, with its (moderate data providing) neighbouring valley is carried out. The main study catchment (Padaster Valley) covers 11.2 km2 and is located east of Steinach am Brenner in the Wipp Valley. Due to its partially usage as a deposital site, respectively a landfill for the tunnel excavation material of the Brenner Base Tunnel, this valley represents a highly interesting site in a hydrological aspect. Thus, the Padaster Valley is highly monitored and hence predestined for hydrological investigations. Hydrological data such as discharge is measured high frequently on four gauges, meteorological data on two gauges. An additional study catchment (Navis Valley) covers 63 km2 and is located northerly next the Padaster Valley. Seven gauges provide meteorological data, however, continuous discharge data is just measured at the valley mouth. Further meteorological data for both areas will be contributed by the ZAMG (Zentralanstalt für Meteorologie und Geodynamik), whose INCA model provide a high spatial resolution dataset of 1km. However, in order to gain a better overall understanding of subsurface runoff and hydrogeological processes, geological data will be considered and incorporated/integrated in the modelling process. This includes geological maps, - cross sections and geophysical analysis, which help to estimate the bedrock topography, and consequently the volume as well as deeper seated hydrogeological properties of the sediment cover. In this context, continuous data from 7 groundwater observation wells provide information regarding groundwater levels and hydraulic head. To increase the model accuracy regarding subsurface flow processes, subsurface-depending runoff types after Pirkl & Sausgruber (2015) are applied. Furthermore, several maps such as land use, surface runoff coefficient and soil map including grain size distribution of the layers have been compiled by in-situ fieldwork for this study. In order to model the water budget, subsurface runoff and overall hydrological slope properties, the distributed hydrological Model WaSIM (Richards version; Schulla, 1997) is applied. The model is based on a modular system which uses physically-based algorithms.The present study is been carried out by the Austrian Research Centre for Forests (BFW) in collaboration with the Brenner Base Tunnel (BBT-SE).