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Climate change effects on irrigation demands and minimum stream discharge: impact of bias-correction method

DOI: 10.5194/hessd-9-4989-2012

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Abstract:

Climate changes are expected to result in a warmer global climate, with increased inter-annual variability. In this study, the possible impacts of these climate changes on irrigation and low stream flow are investigated using a distributed hydrological model of a sandy catchment in western Denmark. The IPCC climate scenario A1B was chosen as the basis for the study, and meteorological forcings (precipitation, reference evapotranspiration and temperature) derived from the ECHAM5-RACMO2 regional climate model for the period 2071–2100 was applied to the model. Two bias correction methods, Delta Change and Distribution-Based Scaling, were used to evaluate the importance of the bias correction method. Using the annual irrigation amounts, the minimum stream flow, the median minimum stream flow and the mean stream flow as indicators, the irrigation and the stream flow predicted using the two methods were compared. The study found that irrigation is significantly underestimated and low stream flow in overestimated when using the delta change method, due to the inability of this method to account for changes in inter-annual variability of precipitation and reference ET and the resulting effects on irrigation demands. Additionally, future increases in CO2 are found to have a significant effect on both irrigation and low flow, due to reduced transpiration from plants.

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