scholarly journals Simulating past changes in the balance between water demand and availability and assessing their main drivers at the river basin scale

2015 ◽  
Vol 19 (3) ◽  
pp. 1263-1285 ◽  
Author(s):  
J. Fabre ◽  
D. Ruelland ◽  
A. Dezetter ◽  
B. Grouillet

Abstract. In this study we present an integrative modeling framework aimed at assessing the balance between water demand and availability and its spatial and temporal variability over long time periods. The model was developed and tested over the period 1971–2009 in the Hérault (2500 km2, France) and the Ebro (85 000 km2, Spain) catchments. Natural streamflow was simulated using a conceptual hydrological model. The regulation of river flow was accounted for through a widely applicable demand-driven reservoir management model applied to the largest dam in the Hérault Basin and to 11 major dams in the Ebro Basin. Urban water demand was estimated from population and monthly unit water demand data. Water demand for irrigation was computed from irrigated area, crop and soil data, and climatic forcing. Water shortage was assessed at a 10-day time step by comparing water demand and availability through indicators calculated at strategic resource and demand nodes. The outcome of this study is twofold. First, we were able to correctly simulate variations in influenced streamflow, reservoir levels and water shortage between 1971 and 2009 in both basins, taking into account climatic and anthropogenic pressures and changes in water management strategies over time. Second, we provided information not available through simple data analysis on the influence of withdrawals and consumptive use on streamflow and on the drivers of imbalance between demand and availability. Observed past variations in discharge were explained by separating anthropogenic and climatic pressures in our simulations: 3% (20%) of the decrease in the Hérault (Ebro) discharge were linked to anthropogenic changes. Although key areas of the Hérault Basin were shown to be highly sensitive to hydro-climatic variability, the balance between water demand and availability in the Ebro Basin appears to be more critical, owing to high agricultural pressure on water resources. The modeling framework developed and tested in this study will be used to assess water balance under climatic and socioeconomic prospective scenarios and to investigate the effectiveness of adaptation policies aimed at maintaining the balance between water demand and availability.

2014 ◽  
Vol 11 (11) ◽  
pp. 12315-12364 ◽  
Author(s):  
J. Fabre ◽  
D. Ruelland ◽  
A. Dezetter ◽  
B. Grouillet

Abstract. The aim of this study was to assess the balance between water demand and availability and its spatial and temporal variability from 1971 to 2009 in the Herault (2500 km2, France) and the Ebro (85 000 km2, Spain) catchments. Natural streamflow was evaluated using a conceptual hydrological model. The regulation of river flow was accounted for through a widely applicable demand-driven reservoir management model applied to the largest dam in the Herault basin and to 11 major dams in the Ebro basin. Urban water demand was estimated from population and monthly unit water consumption data. Water demand for irrigation was computed from irrigated area, crop and soil data, and climatic forcing. Finally, a series of indicators comparing water supply and water demand at strategic resource and demand nodes were computed at a 10 day time step. Variations in water stress in each catchment over the past 40 years were successfully modeled, taking into account climatic and anthropogenic pressures and changes in water management strategies over time. Observed changes in discharge were explained by separating human and hydro-climatic pressures on water resources: respectively 20 and 3% of the decrease in the Ebro and the Herault discharges were linked to human-induced changes. Although key areas of the Herault basin were shown to be highly sensitive to hydro-climatic variability, the balance between water uses and availability in the Ebro basin appears to be more critical, owing to high agricultural pressure on water resources. The proposed modeling framework is currently being used to assess water stress under climatic and socio-economic prospective scenarios. Further research will investigate the effectiveness of adaptation policies aimed at maintaining the balance between water use and availability.


2019 ◽  
Author(s):  
Wim Joost van Hoek ◽  
Lauriane Vilmin ◽  
Arthur H. W. Beusen ◽  
José M. Mogollón ◽  
Xiaochen Liu ◽  
...  

Abstract. Here, we present the implementation of the freshwater carbon (C) cycle in the Dynamic In-stream Chemistry module (CARBON-DISC), which is part of the Integrated Model to Assess the Global Environment-Dynamic Global Nutrient Model (IMAGE-DGNM). A coupled hydrology-biogeochemistry approach with 0.5 by 0.5-degree resolution accounts for the spatial and temporal variability in dynamic conditions in the aquatic continuum using independent global databases. This process-based model resolves the concentrations, transformations and transfer fluxes of dissolved inorganic carbon (DIC), dissolved organic carbon (DOC) and terrestrial and autochthonous particulate organic carbon (POC) from headwaters to river mouth with a time step of 1 month for the period 1950–2000. This is a major step forward in basin scale modelling of the C processing in freshwater systems, since simulated results can be validated at every location and point in time, and the model can be applied for retrodiction and to analyse future scenarios. Validation of the model with long-term measurement data shows a fair agreement, considering that this is a global model. To analyse the performance of the full production-respiration DISC module, two other schemes are presented, including an abiotic system excluding any in-stream processing of DOC and allochthonous production, and an extended abiotic system including heterotrophic respiration, but excluding production. Furthermore, a sensitivity analysis shows that many parameters, such as temperature, solar radiation, organic sediment mineralization rate and C inputs, including particulate organic carbon from terrestrial vegetation and dissolved inorganic carbon from groundwater, strongly affect atmosphere-freshwater exchange of CO2.


2021 ◽  
Author(s):  
Mohammed Basheer ◽  
Victor Nechifor ◽  
Alvaro Calzadilla ◽  
Julien Harou

<p>This study introduces a co-evolutionary macro-economy and river system simulation framework that integrates a monthly river system simulation model with a Computable General Equilibrium (CGE) model. At each annual time step, the two models perform iterative bidirectional communication. The CGE model quantifies changes to annual water and electricity demands and non-hydro electricity generation capacity, and the river system model seeks to meet the water and electricity demands subject to the spatial and temporal availability of river flow, infrastructure capacities (i.e., reservoir storage, non-hydro, and hydro capacities), and infrastructure operating rules. The co-evolutionary modeling framework is based on open-source modeling tools. This multi-sector simulation framework is demonstrated on the Eastern Nile River System to examine the benefits of a flexible collaborative management approach for the Grand Ethiopian Renaissance Dam (GERD), whereby the GERD helps meet water demands in Egypt during multi-year droughts and increases water storage during periods of high flows. The performance of the flexible collaborative approach is compared to a recent GERD operation proposal negotiated by Ethiopia, Sudan, and Egypt in Washington D.C. but has not been accepted by Ethiopia. The two GERD operating approaches are examined across multiple 30-year river flow sequences to test the river system resilience to inter-annual flow variability.</p>


Author(s):  
J. Fabre ◽  
D. Ruelland ◽  
A. Dezetter ◽  
B. Grouillet

Abstract. This study assesses water stress by 2050 in river basins facing increasing human and climatic pressures, by comparing the impacts of various combinations of possible future socio-economic and climate trends. A modelling framework integrating human and hydro-climatic dynamics and accounting for interactions between resource and demand at a 10-day time step was developed and applied in two basins of different sizes and with contrasted water uses: the Herault (2500 km2, France) and the Ebro (85 000 km2, Spain) basins. Natural streamflow was evaluated using a conceptual hydrological model (GR4j). A demand-driven reservoir management model was designed to account for streamflow regulations from the main dams. Urban water demand was estimated from time series of population and monthly unit water consumption data. Agricultural water demand was computed from time series of irrigated area, crop and soil data, and climate forcing. Indicators comparing water supply to demand at strategic resource and demand nodes were computed. This framework was successfully calibrated and validated under non-stationary human and hydro-climatic conditions over the last 40 years before being applied under four combinations of climatic and water use scenarios to differentiate the impacts of climate- and human-induced changes on streamflow and water balance. Climate simulations from the CMIP5 exercise were used to generate 18 climate scenarios at the 2050 horizon. A baseline water use scenario for 2050 was designed based on demographic and local socio-economic trends. Results showed that projected water uses are not sustainable under climate change scenarios.


2021 ◽  
Author(s):  
Selina Meier ◽  
Randy Munoz ◽  
Christian Huggel

<p>Water scarcity is increasingly becoming a problem in many regions of the world. On the one hand, this can be attributed to changes in precipitation conditions due to climate change. On the other hand, this is also due to population growth and changes in consumer behaviour. In this study, an analysis is carried out for the highly glaciated Vilcanota River catchment (9808 km<sup>2</sup> – 1.2% glacier area) in the Cusco region (Peru). Possible climatic and socioeconomic scenarios up to 2050 were developed including the interests from different water sectors, i.e. agriculture, domestic and energy.</p><p>The analysis consists of the hydrological simulation at a monthly time step from September 2043 to August 2050 using a simple glacio-hydrological model. For historic conditions (1990 to 2006) a combination of gridded data (PISCO precipitation) and weather stations was used. Future scenario simulations were based on three different climate models for both RCP 2.6 and 8.5. Different glacier outlines were used to simulate changes in glacier surface through the time for both historic (from satellite data) and future (from existing literature) scenarios. Furthermore, future water demand simulations were based on the SSP1 and SSP3 scenarios.</p><p>Results from all scenarios suggest an average monthly runoff of about 130 m<sup>3</sup>/s for the Vilcanota catchment between 2043 and 2050. This represents a change of about +5% compared to the historical monthly runoff of about 123 m<sup>3</sup>/s. The reason for the increase in runoff is related to the precipitation data from the selected climate models. However, an average monthly deficit of up to 50 m<sup>3</sup>/s was estimated between April and November with a peak in September. The seasonal deficit is related to the seasonal change in precipitation, while the water demand seems to have a less important influence.</p><p>Due to the great uncertainty of the modelling and changes in the socioeconomic situation, the data should be continuously updated. In order to construct a locally sustainable water management system, the modelling needs to be further downscaled to the different subcatchments in the Vilcanota catchment. To address the projected water deficit, a new dam could partially compensate for the decreasing storage capacity of the melting glaciers. However, the construction of the dam could meet resistance from the local population if they cannot be promised and communicated multiple uses of the new dam. Sustainable water management requires the cooperation of all stakeholders and all stakeholders should be able to benefit from it so that they will support future projects.</p>


2021 ◽  
Author(s):  
Aristeidis Koutroulis ◽  
Manolis Grillakis ◽  
Camilla Mathison ◽  
Eleanor Burke

<p>The JULES land surface model has a wide ranging application in studying different processes of the earth system including hydrological modeling [1]. Our aim is to tune the existing configuration of the global river routing scheme at 0.5<sup>o</sup> spatial resolution [2] and improve river flow simulation performance at finer temporal scales. To do so, we develop a factorial experiment of varying effective river velocity and meander coefficient, components of the Total Runoff Integrating Pathways (TRIP) river routing scheme. We test and adjust best performing configurations at the basin scale based on observations from GRDC 230 stations that exhibiting a variety of hydroclimatic and physiographic conditions. The analysis was focused on watersheds of near-natural conditions [3] to avoid potential influences of human management on river flow. The HydroATLAS database [4] was employed to identify basin scale descriptive hydro-environmental indicators that could be associated with the components of the TRIP. These indicators summarize hydrologic and physiographic characteristics of the drainage area of each flow gauge. For each basin we select the best performing set of TRIP parameters per basin resulting to the optimal efficiency of river flow simulation based on the Nash–Sutcliffe and Kling–Gupta efficiency metrics. We find that better performance is driven predominantly by characteristics related to the stream gradient and terrain slope. These indicators can serve as descriptors for extrapolating the adjustment of TRIP parameters for global land configurations at 0.5<sup>o</sup> spatial resolution using regression models.</p><p> </p><p>[1] Papadimitriou et al 2017, Hydrol. Earth Syst. Sci., 21, 4379–4401</p><p>[2] Falloon et al 2007. Hadley Centre Tech. Note 72, 42 pp.</p><p>[3] Fang Zhao et al 2017 Environ. Res. Lett. 12 075003</p><p>[4] Linke et al 2019, Scientific Data 6: 283.</p>


Ocean Science ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 261-279 ◽  
Author(s):  
A. Christensen ◽  
M. Butenschön ◽  
Z. Gürkan ◽  
I. J. Allen

Abstract. First results of a coupled modelling and forecasting system for fisheries on habitat-bound stocks are being presented. The system consists currently of three mathematically, fundamentally different model subsystems coupled offline: POLCOMS providing the physical environment implemented in the domain of the north-west European shelf, the SPAM model which describes sandeel stocks in the North Sea, and the third component, the SLAM model, which connects POLCOMS and SPAM by computing the physical–biological interaction. Our major experience by the coupling model subsystems is that well-defined and generic model interfaces are very important for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows for analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and to quantify the impacts on the higher trophic level, in this case the sandeel population, demonstrated here on the basis of hindcast data. The coupled forecasting system is tested for some typical scientific questions appearing in spatial fish stock management and marine spatial planning, including determination of local and basin-scale maximum sustainable yield, stock connectivity and source/sink structure. Our presented simulations indicate that sandeel stocks are currently exploited close to the maximum sustainable yield, even though periodic overfishing seems to have occurred, but large uncertainty is associated with determining stock maximum sustainable yield due to stock inherent dynamics and climatic variability. Our statistical ensemble simulations indicates that the predictive horizon set by climate interannual variability is 2–6 yr, after which only an asymptotic probability distribution of stock properties, like biomass, are predictable.


Agromet ◽  
2011 ◽  
Vol 25 (1) ◽  
pp. 9
Author(s):  
Siti Nurdhawata ◽  
Bambang Dwi Dasanto

<em>Generally, reservoir can overcome problem of water availability in particular region. The reservoir collects excess water during rainy season to be used at the time of water shortage during dry season. In Pidie, the largest water sources are from Krueng Baro Geunik and Krueng Tiro. The reservoir is located at Krueng Rukoh with Krueng Tiro as the source of water supply. The reservoir provides water for irrigating and supplying domestic water in Baro (11.950 ha) and Tiro (6.330 ha) areas. There are 13 districts (216718 inhabitants) use the water from this reservoir. Given the population growing at rate of 0.52% then the water demand in the region increases. The aim of study was to estimate the volume of water entering the reservoir using the tank model. Calibration curve between the tank model output and observation data showed good correlation (R<sup>2</sup> = 0.7). The calibrated model was then used to calculate the discharge at Krueng Baro Geunik. A water balance analysis showed that the highest deficit occurred in September and the highest surplus in November. Based on this analysis, the capacity of Krueng Rukoh reservoir is able to fulfill its function assuming the rate of population growth and the irrigation area are constant.</em>


2021 ◽  
Author(s):  
Mehmet Umit Taner ◽  
Dimmie Hendiriks ◽  
Lieke Huesken ◽  
Niels Mulder ◽  
Diana Morales Irato ◽  
...  

&lt;p&gt;An increasing number of mega-cities, such as Cape Town, Lima, and S&amp;#227;o Paulo, are confronted with increasing droughts as well as an increase in water demand. Inevitably, this leads to increasing pressure on the available water resources and associated risks and economic impact for the water-dependent sectors (eg. drinking water supply, industry, energy production, agriculture, nature) and different user groups within the sectors (eg. low, middle- and high-income households, self-subsistence farmers, large farms). To address these problems and to develop targeted mitigation strategies, risk analyses are required that quantify the impact of water scarcity on the various sectors and users-groups in different parts of the catchment.&lt;/p&gt;&lt;p&gt;Here, we present the Water Gap Risk Index (WGRI) that quantifies water scarcity and its impacts on a variety of economic sectors and user groups. The WGRI provides a normalized score to reflect high spatial and temporal variability typical for urban catchments that apply to different settings and problems. Index calculation involves the combination of unmet water demand and its characteristics with socioeconomic aspects related to vulnerability and exposure. The Water Gap term quantifies water system performance over a defined time period taking into account the frequency, persistence, and severity of unmet water demand.&amp;#160; Vulnerability metrics provide a score for each sector and user-group separately using context-specific vulnerability indicators of each sector and user-group.&lt;/p&gt;&lt;p&gt;In the novel WGRI special attention is paid to the vulnerability of different water user-groups, based on their socio-economic status level (expressed in income, consumption, or other indicators) and respective water use. We consider that 1 liter of water does not have the same utility for different user groups, based on the principle of the diminishing marginal utility curve. As a result, the impact of water scarcity and mitigation measures will also play out differently for these different user groups.&lt;/p&gt;&lt;p&gt;The novel WGRI is being applied in the context of the WaterLOUPE approach[1], to the catchment of Sao Paolo, Lima, and Chennai.&lt;/p&gt;&lt;p&gt;[1] https://doi.org/10.5194/egusphere-egu2020-20505&lt;/p&gt;


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