With climate change, water may become limited for intensive agriculture even in regions presently considered “water-rich”. Information about the potential water requirement and its temporal and spatial variability c...With climate change, water may become limited for intensive agriculture even in regions presently considered “water-rich”. Information about the potential water requirement and its temporal and spatial variability can help to develop future water management plans. A case study was carried out for Switzerland with its highly complex pre-alpine topography and steep gradients in climate. The hydrological model WaSiM-ETH was used to simulate net irrigation requirement (NIR) for cropland, grassland and orchards using criteria to define irrigation periods based either on the water stress level (expressed by the ratio of actual (aET) to potential evapotranspiration ((pET) (Method 1) or on thresholds for soil water potential (Method 2). Simulations for selected catchments were carried out with a daily time step for the period 1981-2010 using a 500 × 500 m spatial resolution. Catchment-scale NIR ranged between 0 and 4.3 million m3 and 0 and 7.3 million m3 for the two methods, respectively, with no trend over the observation period in any catchment. During the heat wave in 2003, NIR increased by a factor of 1.5 to 2.3 relative to the mean, and in catchments where discharge is directly dependent on precipitation, NIR in the summer of 2003 reached the limits of river water availability. In contrast, in a region with water supply from glacier melt water, highest NIR in 2003 still remained far below total river discharge. The results show that NIR varies strongly between years and across the landscape, and even in a presently cool-temperate climate, irrigation may put pressure on regional water resources under extreme climatic conditions that may become more frequent by the end of the 21st century.展开更多
Under climate and land use changes,water cycle is expected to be intensified.This will likely result in frequent hydrometeorological extremes events such as droughts and floods,and affect the water balance components....Under climate and land use changes,water cycle is expected to be intensified.This will likely result in frequent hydrometeorological extremes events such as droughts and floods,and affect the water balance components.A distributed model(WaSiM)was calibrated and validated to evaluate water resources and flood hazard in the Zou catchment,Benin,for the period 1991–2009.The model was calibrated and validated at a threshold of 120 m3/s and its performance in simulating lower discharge was evaluated.The results show that the model was able to satisfactory simulate streamflow using different thresholds with the Kling and Gupta efficiency(KGE)between 0.5 and 0.85.The model performance decreases with increasing discharge threshold.The overall water balance predicted by the model is consistent with the hydroclimatic condition of the basin.The runoff coefficient varies between 15%and 18%(11%and 14%respectively)of the total annual rainfall during the calibration(validation)period.By considering the discharge above the threshold of 120 m3/s the model performances were acceptable with regards to the uncertainties in discharge measurement mainly in peak discharge.Hence,the model is able to reproduce satisfactorily the hydrological processes in the study area and could be used for impact assessment.展开更多
文摘With climate change, water may become limited for intensive agriculture even in regions presently considered “water-rich”. Information about the potential water requirement and its temporal and spatial variability can help to develop future water management plans. A case study was carried out for Switzerland with its highly complex pre-alpine topography and steep gradients in climate. The hydrological model WaSiM-ETH was used to simulate net irrigation requirement (NIR) for cropland, grassland and orchards using criteria to define irrigation periods based either on the water stress level (expressed by the ratio of actual (aET) to potential evapotranspiration ((pET) (Method 1) or on thresholds for soil water potential (Method 2). Simulations for selected catchments were carried out with a daily time step for the period 1981-2010 using a 500 × 500 m spatial resolution. Catchment-scale NIR ranged between 0 and 4.3 million m3 and 0 and 7.3 million m3 for the two methods, respectively, with no trend over the observation period in any catchment. During the heat wave in 2003, NIR increased by a factor of 1.5 to 2.3 relative to the mean, and in catchments where discharge is directly dependent on precipitation, NIR in the summer of 2003 reached the limits of river water availability. In contrast, in a region with water supply from glacier melt water, highest NIR in 2003 still remained far below total river discharge. The results show that NIR varies strongly between years and across the landscape, and even in a presently cool-temperate climate, irrigation may put pressure on regional water resources under extreme climatic conditions that may become more frequent by the end of the 21st century.
基金funded by the German Federal Ministry of Education and Research(BMBF)through the West African Science Service Centre on Climate Change and Adapted Land Use(WASCAL).
文摘Under climate and land use changes,water cycle is expected to be intensified.This will likely result in frequent hydrometeorological extremes events such as droughts and floods,and affect the water balance components.A distributed model(WaSiM)was calibrated and validated to evaluate water resources and flood hazard in the Zou catchment,Benin,for the period 1991–2009.The model was calibrated and validated at a threshold of 120 m3/s and its performance in simulating lower discharge was evaluated.The results show that the model was able to satisfactory simulate streamflow using different thresholds with the Kling and Gupta efficiency(KGE)between 0.5 and 0.85.The model performance decreases with increasing discharge threshold.The overall water balance predicted by the model is consistent with the hydroclimatic condition of the basin.The runoff coefficient varies between 15%and 18%(11%and 14%respectively)of the total annual rainfall during the calibration(validation)period.By considering the discharge above the threshold of 120 m3/s the model performances were acceptable with regards to the uncertainties in discharge measurement mainly in peak discharge.Hence,the model is able to reproduce satisfactorily the hydrological processes in the study area and could be used for impact assessment.
