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Annual time series of modeled discharge to the ocean and to endorheic basins under natural (gray line) and disturbed (black line) conditions 1901-2002. Land refers to internally draining (Central Asian Drainage basin, Caspian Sea, Aral Sea, and major endorheic lakes in Africa). Additional model results using different precipitation data sets indicate the uncertainties in the discharge to the oceans as a result of uncertainties in precipitation data sets GPCP 1dd (red), VASClimO (blue) GPCC mon(green) under natural conditions.
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![Fig. 4. Significant trends [mm a −2 ] in modeled annual values of...](profile/Balazs-Fekete-5/publication/41908023/figure/fig4/AS:670014726213668@1536755367981/Significant-trends-mm-a-2-in-modeled-annual-values-of-evapotranspiration-for-a_Q320.jpg)
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This paper presents a new reconstruction of the 20th century global hydrography using fully coupled water balance and transport model in a flexible modeling framework. The modeling framework allows a high level of configurability both in terms of input forcings and model structure. Spatial and temporal trends in hydrological cycle components are as...
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... section will first discuss the total predicted terrestrial discharge over the last century and then the predicted dis- charge for individual oceans and from continents reflecting the impact of variations in the climate drivers alone and from changes induced by the expansion of irrigated lands and the operation of reservoirs (Fig. ...
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... in precipitation input translate to changes in the long-term mean terrestrial discharge between −11% (using GPCCmon data) and +2% using GPCP1dd data (Table 2 and Fig. ...
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... the trend in discharge under natural conditions is −1.2 km 3 a −1 (significant) and under disturbed conditions −1.4 km 3 a −1 (insignificant). It is important to note, that our modeled discharge under disturbed conditions can be higher than the estimated dis- charge under natural conditions in very dry years, for exam- ple in 1984 and 2000 (Fig. 7) . This can largely be explained with the irrigation in grid cells along the Nile river and in the Nile delta that do not fall in the same grid cell as the river and therefore cannot be supplied by river discharge. As the local runoff in these regions is close to zero, water is primarily supplied from fossil groundwater sources and the ...
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... range in predicted discharge entering the Arctic ocean therefore varies considerably; compared to CRU based prediction, GPCP1dd discharge is 72% higher whereas VASClimO data results in discharge that is 12% lower than the long-term CRU based discharge ( Fig. 7 and Table 2). For endorheic basins, the GPCP1dd predictions are 30% lower, whereas GPCPmon predictions are 17% lower than those based on CRU. For other ocean basins, the differences are less pronounced and are less than ...
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This study was carried out to support and enhance a series of global studies assessing contemporary and future changes in nutrient export from watersheds (Global Nutrient Export from Watersheds (NEWS)). Because hydrography is one of the most important drivers in nutrient transport, it was essential to establish how climatic changes and direct human...
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... Reservoirs constructed for irrigation, flood control, water supply, hydropower generation, etc., have had a pronounced effect on river flow regimes and terrestrial hydrology (Ekka et al., 2022;Haddeland et al., 2014;Kåresdotter et al., 2022;Poff et al., 1997). Consequently, the development of reservoir operation models that can be integrated with rainfall-runoff process simulation in hydrologic models has received significant attention (Chen et al., 2022;Coerver et al., 2018;Dang et al., 2020;Döll et al., 2003;Hanasaki et al., 2006;Haddeland et al., 2006;Meigh et al., 1999;Solander et al., 2016;Van Beek et al., 2011;Wisser et al., 2010;Yang et al., 2019;Yassin et al., 2019;G. Zhao et al., 2016). ...
... Lack of details on reservoir operation has led to some outstanding modeling issues, such as ignoring the existence of reservoirs (Abbaspour et al., 2015;De Paiva et al., 2013), assuming no human control on reservoir storage (e.g., a scheme implemented in the National Water Model which utilizes level pool routing) (Döll et al., 2003;Gochis et al., 2020;Meigh et al., 1999), and setting up simplified reservoir operation rules for routing flows through a reservoir (Hanasaki et al., 2006;Wisser et al., 2010). The simplified approaches for modeling reservoirs range from defining an empirical linear relationship between reservoir inflow and reservoir release (as in Wisser et al., 2010) to specifying total releases for the entire year based on storage at the beginning of the year (Hanasaki et al., 2006). ...
... Lack of details on reservoir operation has led to some outstanding modeling issues, such as ignoring the existence of reservoirs (Abbaspour et al., 2015;De Paiva et al., 2013), assuming no human control on reservoir storage (e.g., a scheme implemented in the National Water Model which utilizes level pool routing) (Döll et al., 2003;Gochis et al., 2020;Meigh et al., 1999), and setting up simplified reservoir operation rules for routing flows through a reservoir (Hanasaki et al., 2006;Wisser et al., 2010). The simplified approaches for modeling reservoirs range from defining an empirical linear relationship between reservoir inflow and reservoir release (as in Wisser et al., 2010) to specifying total releases for the entire year based on storage at the beginning of the year (Hanasaki et al., 2006). Simplified approaches have found widespread applications in global modeling studies. ...
We assess the overall watershed system representation via fully coupling a generic reservoir operation model with a conceptual rainfall‐runoff model. The performance of the coupled model is evaluated comprehensively by examining watershed outflow simulations, model parameter values, and a key internal flux of the watershed model (here reservoir inflow). Five published generic reservoir operation models are coupled with a watershed rainfall‐runoff model, and results are compared across the coupled models and one additional model called ResIgnore that ignores reservoir operation. Traditional loosely coupled watershed hydrologic models (where calibrated inflow is routed through reservoir operation models) are used as baselines to examine the differences in simulation performance and parameterization obtained from the fully coupled models. We find that fully coupling the Generic Data‐Driven Reservoir Operation Model (GDROM) and the Dynamically Zoned Target Release (DZTR) reservoir operation models with the rainfall‐runoff model obtains robust simulations of watershed outflow with realistic parameterization, suggesting that they can be reliably integrated into large‐scale hydrological models for simulating streamflow in heavily dammed watersheds. Our results also show that compared to ResIgnore, the fully coupled watershed models more accurately simulate the entire distribution of watershed outflow, obtain more realistic values of model parameters, and simulate reservoir inflow with higher accuracy. Finally, we note that the prediction intervals of watershed outflow obtained from the GDROM‐ and DZTR‐based fully coupled models consistently envelop observed watershed outflow across the study watersheds, indicating that GDROM and DZTR can be suitable reservoir components of large‐scale hydrology models.
... To model reservoir operations at the largest scale, global reservoir databases and uncalibrated operating rules are available (Hanasaki et al., 2006;Wisser et al., 2010;Lehner et al., 2011b). By simulating how much water is released from a reservoir at each timestep, uncalibrated reservoir operating rules integrated into global hydrological models have been shown to yield significant improvements in streamflow simulations (Abeshu et al., 2023;Hanasaki et al., 2006). ...
... supply. Instead, in many uncalibrated models, this type of reservoir is often collated into one 'non-irrigation' category (Hanasaki et al., 2006;Wisser et al., 2010). In this case reservoir rules usually aim to (where possible) release mean flow at all times of the year or reduce intra-annual variability. ...
Reservoirs are key components of many water supply systems, providing functional capability to manage, and often mitigate, hydrological variability across space and time. The presence and operation of a reservoir controls the downstream flow regime, such that in many locations understanding reservoir operations is crucial to understanding the hydrological functioning of a catchment. Although substantial progress has been made in modelling reservoir operations, several key challenges remain, particularly for large-scale applications including hundreds of reservoirs. In these cases, generic and uncalibrated reservoir operating rules are often applied. However, these rules were developed from global reservoir databases that consist mostly of large irrigation reservoirs and thus are not transferable to smaller reservoirs or those fulfilling other purposes, such as water supply. An alternative option is to use a calibrated, data-driven approach but such techniques require reservoir inflows, outflows and storage data which are rarely available across hundreds of reservoirs. To overcome these problems, here we design a set of simple reservoir operating rules (with only two calibrated parameters) focused on simulating small water supply reservoirs across large scales with various types of open access data (general catchment attributes such as surface area or reservoir capacity, and flows at downstream gauges). Using Great Britain as a case study, we integrate our rules into a national-scale hydrological model and compare hydrological simulations from two modelling scenarios, with and without the new reservoir component. Our simple reservoir operating rules significantly increase model performance in reservoir-impacted catchments, particularly when the rules are calibrated individually at each downstream gauge. We also test the feasibility of using transfer functions (which transform reservoir and catchment attributes into operating rule parameters) to identify a nationally-consistent parameterisation. This works well in ~50 % of the catchments, while nuances in individual reservoir operations limit performance in others. We suggest that our approach should provide a lower benchmark for simulations in catchments containing water supply reservoirs, and that more complex methods should only be considered where they outperform our simple approach.
... B Atila Matias atilaoceano@gmail.com Extended author information available on the last page of the article the world, which represents about 17% of the total discharge to the oceans and over a third of the total discharge to the Atlantic Ocean (Dai and Trenberth 2002;Wisser et al. 2010). The Amazon River plume (ARP) features an extensive area with low salinity water (< 35.0) (Fig. 1a) and high concentration of nutrients and suspended material that propagates over thousands of kilometers in the tropical Atlantic Ocean (Hellweger and Gordon 2002;Coles et al. 2013;Korosov et al. 2015). ...
Motivated by the extreme hydrological events that caused an abnormal reduction and increase in discharge from the Amazon River in 2010 and 2012, respectively, this work investigates the seasonal variability of the sea surface salinity (SSS) in the western tropical Atlantic Ocean over these years. SMOS satellite data and a 1/12\(^{\circ }\) horizontal resolution of the coordinate ocean model (HYCOM) are used to investigate the SSS seasonal variation and assess the balance of mixed layer salinity (MLS) and the mechanisms that rule the SSS seasonal cycle. Two simulations with the same configuration, but with and without tides effects, are employed to investigate the impact of tides on the MLS balance in the region. The results show that the SSS of the Amazon River plume (ARP) was about 1.0 larger and covered a smaller area during the summer and early year boreal autumn of 2012 compared to 2010 in the area located to northwest of the North Brazil Current (NBC) retroflection region, even with the expressive increase in the supply of fresh water from the Amazon River in 2012 compared to 2010. This variability in SSS occurs shortly after the maximum discharge of the Amazon River and is associated with the highest input of freshwater precipitation from the Intertropical Convergence Zone (ITCZ) during the 2010 boreal spring and summer. The impact of tidal swings on the MLS balance in the western region of the tropical Atlantic Ocean occurs mainly in the area near the mouth of the Amazon and Pará Rivers, especially in the northwest portion of the mouth of the Amazon River until approximately Cabo Cassiporé. The forced tidal model shows an increase in MLS over the entire seasonal cycle of about 1.2, as well as a decrease in the contribution of zonal advection to the MLS balance, which reduces the zonal component from the west and increases the meridional component towards the north.
... We derived the pristine and altered monthly river flow datasets from the water balance model (WBM) river discharge outputs 53 at a 6 min grid-cell resolution using the TerraClimate high-resolution dataset of monthly climate forcings 54 for the period 2000-2020 using Python version 3.9.7. River basin delineation and flow routing configurations are defined by the WBM 6 min topological river network used to establish local discharge and river flow 53 . The pristine and altered WBM runs use the same climate forcings for the 2000-2020 time period, but the altered runs use human alterations to the water cycle, including water extraction for irrigation and large reservoirs as an indicator of flow alteration. ...
... This mask is applied to eliminate noise in the modelled data associated with very low irrigation and discharge values in headwater grid cells. The river network and river basin extents, including the continent definitions, are given by the WBM 53,57 , with the naming convention taken from the Global Runoff Data Centre Major River Basins of the World 58 . We used QGIS version 3.38.8 ...
... Annual rainfall data came from the GPCC precipitation data (mm) available at https://psl.noaa.gov/data/gridded/data.gpcc.html. The data for the surface water hydrology were derived from existing published datasets 53,57 . ...
Safe and just Earth system boundaries (ESBs) for surface water and groundwater (blue water) have been defined for sustainable water management in the Anthropocene. Here we assessed whether minimum human needs could be met with surface water from within individual river basins alone and, where this is not possible, quantified how much groundwater would be required. Approximately 2.6 billion people live in river basins where groundwater is needed because they are already outside the surface water ESB or have insufficient surface water to meet human needs and the ESB. Approximately 1.4 billion people live in river basins where demand-side transformations would be required as they either exceed the surface water ESB or face a decline in groundwater recharge and cannot meet minimum needs within the ESB. A further 1.5 billion people live in river basins outside the ESB, with insufficient surface water to meet minimum needs, requiring both supply- and demand-side transformations. These results highlight the challenges and opportunities of meeting even basic human access needs to water and protecting aquatic ecosystems.
... Irrigated agriculture plays a crucial role in global food production and security, accounting for ∼20% of total cropland but producing approximately 40% of the world's food (Siebert and Döll, 2010). The past century has witnessed a rapid expansion of irrigation, with the global area equipped for irrigation increasing from ∼53 million hectares (Mha) in 1901 (Wisser et al., 2010) to ∼310 Mha circa 2005(Siebert et al., 2013. With the growing population and increasing demand for food, global irrigated areas could further increase to as high as 1,800 Mha by 2050 (Puy et al., 2020). ...
Flooded rice paddies are important for modifying land surface energy and water budgets, especially in Asian countries. This study incorporated shallow paddy water into the Noah with Multi‐Parameterization (Noah‐MP) model to enhance its performance in capturing the distinct features of small Bowen ratios over flooded rice fields. The paddy surface water was parameterized as one integrated layer along with the top soil layer, and meteorological measurements from two crop sites in Japan, that is, SAITO (early rice) and SAGA (late rice), were employed for model evaluation at the field scale. The simulation results show that the model performance was significantly improved by combining the incorporation of paddy water and the calibration of rice crop parameters, particularly at SAGA. Compared with the reference run using the original version of Noah‐MP for SAGA, the underestimation in latent heat and the overestimation in sensible heat during daytime were decreased by ∼74 W m⁻² (∼67%) and ∼92 W m⁻² (∼55%), respectively. Approximately 60%–70% of this improvement was contributed by using calibrated rice crop parameters, while the rest of 30%–40% was from further incorporating paddy water. The decreased ground surface resistance owing to the presence of paddy water was crucial for capturing the features of small Bowen ratios. The observed water depth might help mitigate the underestimation of latent heat nonlinearly. This work may benefit the study of land‐atmosphere interactions and local and regional weather and climate in Asia with the widely used coupled Weather Research and Forecasting/Noah‐MP model.
... Accessibility to groundwater resources is vital in populated and dry parts of the world [16][17][18]. Surface water is declining sharply as the temperature rises [19][20][21], and it increases the competition for surface water resources [22][23][24]. Groundwater drought occurs in periods while the volume of rainfall in that period is less than the long-term average [25]. ...
As one of the most catastrophic atmospheric events, drought affects various aspects of the environment. Groundwater resources are one of the sectors that are influenced by long-term droughts and have received insufficient attention compared to other aspects of the environment. Rainfall data collected by 23 metrological stations for 20 years (2005, 2010, 2015, 2020) was used to investigate the drought event and its situation in Qazvin Plain, the central plateau of Iran. Drought characteristics are evaluated using the 24-month standardized precipitation index (SPI). The results of SPI indicated that insufficient precipitation, excessive use of groundwater for irrigation, and utilization of uncontrolled wells caused a significant reduction in groundwater aquifers from 2015 to 2020. To assess the performance of the SPI, a five-year moving average of available precipitation data was calculated, and the result confirmed the outcomes of the SPI. Appropriate geostatistical interpolation methods are used to generate maps of drought zoning. Based on the results of this investigation in the northeastern part of the study area, June and November had the highest and lowest rates of drought, respectively. The linear regression between the annual average of precipitation and the changes in groundwater aquifer level exposed a significant correlation of R2 = 0.4253. Furthermore, linear regression between 24-month SPI and groundwater aquifer level indicated a correlation of R2 = 0.614. Considering the results of this study, the reduction of groundwater aquifer levels in Qazvin Plain from 2015 to 2015 exposed a significant negative difference compared to previous years (2005 to 2010).
... Reservoirs can have a significant impact on river discharge and affect the spatiotemporal distribution of surface water resources (Biemans et al., 2011). Model and satellite data show that seasonal water storage variability in reservoirs accounts for more than half of changes in surface water storage (Cooley et al., 2021;Wisser et al., 2010). Some of existing hydrological models consider the effect of reservoirs on river discharge (Han et al., 2020). ...
... Conceptual models are often used to simulate reservoir operation, which may deviate from the reality (Döll et al., 2003;Hanasaki et al., 2006;Wisser et al., 2010). Accurate monitoring of reservoir water level and storage therefore helps understand the role of reservoirs in water flow regulation and water resource management in a basin (Han et al., 2020). ...
The Lancang-Mekong River (LMR) is an important transboundary river in Southeast Asia shared by China, Myanmar, Laos,Thailand, Cambodia, and Vietnam from upstream to downstream. Construction and operation of dams in the LMR basin has profoundly affected its natural streamflow regime. It is therefore important to monitor changes in reservoir water storage and to quantify the impact of reservoir operation on the redistribution of
surface water resources over this basin. Given the difficulty in obtaining in-situ measurements of reservoirs on the LMR, we integrated multisource remote sensing, including satellite altimetry and optical and synthetic aperture radar (SAR) images, to generate weekly water levels and water storages of nine largest reservoirs on the main stem of the LMR from 2017 to 2021. Specifically, partial surface water extent (SWE) of reservoirs was extracted from Sentinel-1 SAR images and digital elevation models (DEMs), using Random Forest algorithms trained by partial SWE derived from Sentinel-2 optical images, showing an overall accuracy higher than 95%. Based on the partial SWE and water level estimates from ICESat-2 and Global Ecosystem Dynamics Investigation (GEDI, International Space Station-based) data, the relationships between water levels and partial SWE were derived to convert partial SWE into water level time series. Furthermore, water storage time series of the nine reservoirs were obtained from water level time series and hypsometric functions derived from SRTM DEMs that were corrected by ICESat-2 data to remove systematic errors. For the Xiaowan Reservoir on the Lancang River, there is close agreement between remote sensing-derived water levels and in-situ water levels in terms of a normalized RMSE lower than 5%. Results indicate that multisource remote sensing has large potential for high-temporal-resolution monitoring of reservoir water levels and water storage. This could more precisely evaluate impacts of cascade reservoirs on the streamflow of the LMR and facilitate drought and flood mitigation for riverine countries.
... Кроме непосредственных наблюдений за водным стоком, которые являются основой рационального и экологически ориентированного водопользования, перспективны методы оценки стока с помощью математического моделирования и дистанционного зондирования Земли. Примером моделирования формирования стока местного водосбора Обской и Тазовской губ может служить работа [37], в которой для задания граничных условий гидродинамической модели Обской губы сток 196 рек, непосредственно впадающих в губу, рассчитан с использованием гидрологической воднобалансовой модели WBM (Water Balance Model), разработанной в Университете Нью-Гэмпшира [38]. Однако данные моделирования все же должны подтверждаться данными натурных наблюдений. ...
Fresh water supply is a basic need of the gas and oil industry of the Yamal-Gydan region. Small rivers flowing into the Ob’ and Taz Bay could be used for solving this problem. The purpose of the study is to summarise the available research data on the runoff of small rivers and to calculate the catchment areas using GIS technologies. The study covers more than 200 small rivers in the catchment area of the Ob’ and Taz Bay. It is established that there have been no stationary observations of the water runoff on them. Expedition observations of water discharges of small rivers are summarized. More than 40 small rivers are involved in water consumption. The runoff data from water users in the State Water Registry are questionable and need to be critically analyzed. Published annual runoff maps of the Yamal-Gydan region are presented in a unified form. Consolidation of the annual runoff maps showed an overall latitudinal distribution of the runoff isolines. The reliability of river runoff estimates from maps is largely determined by the accuracy of the catchment area calculations. GIS calculation of the river catchment areas has been done using two methods. Automated digitization by DEM has given incorrect results, which need to be verified. Manual digitization of catchments is labour-intensive, but gives reliable results for the lowland relief of the Yamal-Gydan region. For the first time, small rivers’ catchment areas obtained by GIS have been calculated. Difficulties arise in using the names of small rivers, which are different from one source to another. It is necessary to organize government monitoring on small rivers including obligatory measurements of water discharge, first of all on the Sabetta-Yakha, Se-Yakha and Messo-Yakha rivers, which provide fresh water to economic facilities. The modeling of runoff formation and the use of satellite image data are promising directions of runoff assessment.
... Analyses were performed using data on global climate zones based on the Köppen Climate Classification (Chen and Chen, 2013), elevation using the Copernicus DEM GLO-30 (European Space Agency and Airbus, 2021), mountain regions using the Global Mountain K3 (Karagulle et al., 2017), regional precipitation, evapotranspiration, and population data from the Water Balance Model (WBM), and a global gridded hydrological model with a spatial resolution of 0.5 ○ (Grogan, 2016;Grogan et al., 2022;Vörösmarty et al., 1989;Wisser et al., 2010). The dataset on climate variables provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis 5th Generation (ERA5) (Bell et al., 2020;Hersbach et al., 2018) was utilized in WBM. ...
... The dataset on climate variables provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis 5th Generation (ERA5) (Bell et al., 2020;Hersbach et al., 2018) was utilized in WBM. Further model details and documentation can be found in the original sources (Grogan, 2016;Grogan et al., 2022;Kåresdotter et al., 2022;Wisser et al., 2010). Yearly mean precipitation, evapotranspiration, and population density were used as proxies for water availability and use and were calculated from daily values per grid cell and extracted per region (Africa, Asia, Rest of the World). ...
Despite strong interest and conflict research spanning multiple disciplines, connections between water flows and conflicts remain unclear, due to incomplete datasets on water-related conflict-cooperation events and poor understanding of socioeconomic and biophysical causes of such conflicts. The dataset on water-related conflict-cooperation events compiled in this study extends to 2019, updating previous datasets that covered only up to 2008, yielding important new insights on cooperation-conflict trends. Global and regional trends were analyzed using the new events dataset, together with changes in hydroclimatic variables and population density. The analysis revealed that water-related cooperation was far more common than conflicts across all regions, in both drier and wetter climates, indicating that abundance and lack of water can both promote cooperation. However, conflict events were more common in drier climates where water is scarcer. This cooperation-conflict balance shifted in the 2000s, with conflict events increasing, to outnumber cooperation events in 2017. The main shift occurred in Africa and Asia, where increased conflicts in Africa coincided with a prolonged period of below-average precipitation and severe drought, while the shift in Asia coincided with increased evapotranspiration caused by human activities and increased population density. Differences between regions were confirmed by event descriptions, with events in Africa relating to water access and farmer-herder conflicts, and events in Asia relating to irrigation and dam construction. These differences highlight the need for regional-scale analysis of water-related conflict-cooperation trends and pathways. With climate change and human activities expected to increase, the increasing trend in conflict events could persist, with water resources becoming a more frequent cause of future conflict. Identifying these complex cooperation-conflict changes is vital in determining future actions required to reduce conflict events and promote cooperation on water.
... To assess the impact of planned and existing reservoirs on energy systems and their alterations to hydrologic regimes, hydrologic models have been developed with varying degrees of complexity of reservoir representations (Grill et al., 2014;Giuliani et al., 2016;Arheimer et al., 2017;Lu et al., 2018: Hoang et al., 2019Wan et al., 2021). These include the incorporation of reservoir operation at regional scales (Zhao et al., 2016;Wang et al., 2019;Fleischmann et al. 2021;Wei et al., 2021; Turner et al., 2020), national scales (Ehsani et al., 2017), and global scales (Wisser et al., 2010;Wada et al., 2016;Hanasaki et al., 2018;Veldkamp et al., 2018). Currently, this is often achieved by coupling reservoir operation schemes that can generally be divided into conceptual ones and data-driven ones. ...
... Despite the progress in representing reservoirs in hydrologic simulations, uncertainties still exist in modeled reservoir releases and storages, especially for reservoirs with no in-situ operation data (inflow, release, storage, etc.) (hereinafter 'ungauged reservoirs') (Dang et al., 2020;Yassin et al., 2019). Although a variety of reservoir operation schemes have been developed to reproduce observed reservoir storages and releases, these schemes often introduce structures or parameters that need to be estimated from historic reservoir operation records or inferred from detailed operation rules for individual reservoirs (Wisser et al., 2010;Zajac et al., 2017;Hoang et al., 2019). However, these data are often unavailable to researchers especially when there is limited stakeholder engagement. ...
... The second one is selected from the WBM model (Wisser et al., 2010), hereinafter 'W10', and the release of reservoirs in the W10 scheme is, ...
Assessments of water and energy security over historical and future periods require hydrologic models that can accurately simulate reservoir operations. However, scare reservoir operation data limits the accuracy of current reservoir representations in simulating reservoir behaviors. Furthermore, the reliability of these representations under changing inflow regimes remains unclear, which makes their application for long future planning horizons questionable. To this end, we propose a synergistic framework to predict the release, storage, and hydropower production of ungauged reservoirs (i.e., reservoirs without in-situ inflow, release, storage data) by combining remotely sensed reservoir operating patterns and model-simulated reservoir inflow with conceptual reservoir operation schemes within a land surface-hydrologic model. A previously developed reservoir operation scheme is extended with a storage anomaly-based calibration approach to accommodate to the relatively short time series and large time intervals of remotely sensed data. By setting up controlled experiments in the Yalong River Basin in China, we show that remote sensing can improve the parameter estimation and simulations of ungauged reservoirs for all selected reservoir operation schemes, thereby improving the downstream flood and streamflow simulations. However, most of these schemes show degraded accuracies of reservoir operation simulations under a changing inflow regime, which could lead to unreliable assessments of future water resources and hydropower production. In comparison, our newly extended reservoir operation scheme can be more adaptable to flow regime variations. Our study provides a practical framework for reservoir impact assessments and predictions with the ongoing development of satellite altimetry projects such as SWOT.
