2021 ◽  
Author(s):  
Ronan Abhervé ◽  
Clément Roques ◽  
Laurent Longuevergne ◽  
Stéphane Louaisil ◽  
Jean-Raynald de Dreuzy ◽  
...  

<p>While it is well understood and accepted that climate change and growing water needs affect the availability of water resources, the identification of the main physical processes involved remains challenging. It notably requires to filter interannual to interdecadal fluctuations and extreme events to isolate the underlying trends. Metropolitan areas are specifically subject to growing pressures because of the significant and increasing demand, combined with the strong anthropization of land uses.</p><p>The Meu-Chèze-Canut catchment supplies the city of Rennes with drinking water (680 km² - 500 000 users, Brittany, France). In this field laboratory, we explore the dynamics of the water cycle and water resources availability. In this context, water supply is mostly coming from reservoir storage for which levels shows a medium-term vulnerability in response to frequent relatively dry years. Based on retrospective data analysis, we describe the relationship between climatic forcing (precipitation, temperature) and water availability (aquifer storage, river discharge and reservoir storage) in different parts of the catchment that are characterized by distinct lithological and topographical settings. We then evaluate the resilience of both surface and groundwater resources, their past evolution and their resilience to climate change and increasing societal needs.</p><p>Water resources availability in these catchments relies on two geological formations with distinct hydrodynamics properties: the Armorican sandstone and Brioverian schist. To assess the resilience of the system, we specifically analyzed the relationships between monthly effective precipitation and stream discharge within nine sub-catchments over the past 30 years. We observe annual hysteresis relationships - that is, a time lag between precipitation and discharge highlighting the capacity of the landscape to temporarily store water - with significant variability in shapes across the catchments. We argue that topographic and lithological factors play key roles in controlling this variability through their impacts on subsurface storage capacity and characteristic drainage timescales. We propose perspectives based on the complementary use of calibrated groundwater models to leverage these results and provide adaptive water management strategies.</p>


2018 ◽  
Vol 22 (12) ◽  
pp. 6473-6491 ◽  
Author(s):  
Francisco Pellicer-Martínez ◽  
José Miguel Martínez-Paz

Abstract. Currently, climate change is a major concern around the world, especially because of the uncertainty associated with its possible consequences for society. Among them, fluvial alterations can be highlighted in basins whose flows depend on groundwater discharges and snowmelt. This is the case of the headwaters of the Tagus River basin, whose water resources, besides being essential for water uses within this basin, are susceptible to being transferred to the Segura River basin (both basins are in the Iberian Peninsula). This work studies the possible effects that the latest climate change scenarios may have on this transfer, one of the most important ones in southern Europe. In the first place, the possible alterations of the water cycle of the donor basin were estimated. To do this, a hydrological model was calibrated. Then, with this model, three climatic scenarios were simulated, one without climate change and two projections under climate change (Representative Concentration Pathways 4.5 (RCP 4.5) and 8.5 (RCP 8.5)). The results of these three hydrological modelling scenarios were used to determine the possible flows that could be transferred from the Tagus River basin to the Segura River basin, by simulating the water resource exploitation system of the Tagus headwaters. The calibrated hydrological model predicts, for the simulated climate change scenarios, important reductions in the snowfalls and snow covers, the recharge of aquifers, and the available water resources. So, the headwaters of the Tagus River basin would lose part of its natural capacity for regulation. These changes in the water cycle for the climate change scenarios used would imply a reduction of around 70 %–79 % in the possible flows that could be transferred to the Segura basin, with respect to a scenario without climate change. The loss of water resources for the Segura River basin would mean, if no alternative measures were taken, an economic loss of EUR 380–425 million per year, due principally to decreased agricultural production.


Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2330
Author(s):  
George Akoko ◽  
Tasuku Kato ◽  
Le Hoang Tu

Rice is an important cereal crop in Kenya, where it is mainly grown in the Mwea Irrigation Scheme, MIS. The serious challenges of MIS include low water use efficiency and limited available water resources. The objective of this study is to analyze the current and future irrigation water resource availability for the improvement of future water management. A Soil Water Assessment Tool (SWAT), a public domain software supported by the United States Department of Agriculture’s Agricultural Research Service in Bushland, TX, USA, was used to estimate the current and future water resources availability from the MIS’s main irrigation water supply sources (River Thiba and River Nyamindi). CropWat, a computer program developed by the Land and Water Division of the Food and Agriculture Organization (FAO), Rome, Italy, was used to estimate irrigation water requirements from 2013–2016 and into the future (2020–2060 and 2061–2099). Future climatic data for total available flow and irrigation requirement estimations were downloaded from three General Circulation Models (GCMs). The data was bias corrected and down-scaled (with observed data) using a Climate Change Toolkit, a toolkit for climate change analysis developed by the Water Weather and Energy Ecosystem, Zurich, Switzerland. The results indicated that the highest irrigation water deficits were experienced in July and August based on the existing cropping pattern. Under a proposed future pattern, estimates show that MIS will experience water deficits mainly from June to October and from January to February. This study recommends that MIS management should put into strong consideration the simulated future estimates in irrigation water availability for the improvement of water management.


2018 ◽  
Author(s):  
Francisco Pellicer-Martínez ◽  
José Miguel Martínez-Paz

Abstract. Currently, climate change is a major concern around the world, especially because of the uncertainty associated with its possible consequences for society. Among these can be highlighted the fluvial alterations in basins whose flows depend on groundwater discharges and snow melt. This is the case of the headwaters of the Tagus River Basin, whose water resources, besides being essential for water uses within this basin, are susceptible to being transferred to the Segura River Basin (both basins are in the Iberian Peninsula). This work studies the possible effects that the latest climate change scenarios may have on this transfer, one of the most important in southern Europe. In the first place, the possible alterations of the water cycle of the donor basin were estimated. To do this, a hydrological model was calibrated. Then, with this model, three climatic scenarios were simulated, one without climate change and two projections under climate change (Representative Concentration Representative 4.5 (RCP 4.5) and RCP 8.5). The results of these three hydrological modelling scenarios were used to determine the possible flows that could be transferred from the Tagus River Basin to the Segura River Basin, by simulating the water resource exploitation system of the Tagus headwaters. These hydrological modelling predict, for the simulated climate change scenarios, important reductions in the snowfalls and snow covers, the recharge of aquifers and the available water resources. So, the headwaters of the Tagus River Basin would be the loss of part of its natural capacity for regulation. These changes in the water cycle for the climate change scenarios used would imply a reduction of around 80 % in the possible flows that could be transferred to the Segura Basin, with respect to a scenario without climate change. The loss of water resources for the Segura River Basin would mean, if no alternative measures were taken, an economic loss of 330–380 million euro per year, due principally to decreased agricultural production.


2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Wenchao Sun ◽  
Jie Wang ◽  
Zhanjie Li ◽  
Xiaolei Yao ◽  
Jingshan Yu

The influences of climate change on water resources availability in Jinjiang Basin, China, were assessed using the Block-wise use of the TOPmodel with the Muskingum-Cunge routing method (BTOPMC) distributed hydrological model. The ensemble average of downscaled output from sixteen GCMs (General Circulation Models) for A1B emission scenario (medium CO2emission) in the 2050s was adopted to build regional climate change scenario. The projected precipitation and temperature data were used to drive BTOPMC for predicting hydrological changes in the 2050s. Results show that evapotranspiration will increase in most time of a year. Runoff in summer to early autumn exhibits an increasing trend, while in the rest period of a year it shows a decreasing trend, especially in spring season. From the viewpoint of water resource availability, it is indicated that it has the possibility that water resources may not be sufficient to fulfill irrigation water demand in the spring season and one possible solution is to store more water in the reservoir in previous summer.


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