Quantification of Climate Change Impact on Regional Agricultural Irrigation and Groundwater Demand

Climate change is expected to impact agricultural production conditions and groundwater resources. The climate change impacts are expected to be of particular importance for the German region North Rhine-Westphalia. Due to a high population density and intensive partial irrigation of agricultural production, future resource conflicts for groundwater are expected. An integrated model framework consisting of climate, crop-soils and groundwater models represents the regional heterogeneous climatic, geographic and agronomic conditions. The integrated model framework simulates the irrigation demand and groundwater recharge. An ex-post comparison between the simulated reference period (1961 to 1990) and statistical data prove a good model validity. The climate change scenario for the future period 2051 to 2080 assumes decreasing precipitation and increasing transpiration. The simulated total irrigation demand increases by nearly 20 times compared to the reference period (1961 to 1990) and increases regionally to more than 40 mm/ha. Decreasing groundwater recharge results in a tenfold increased share of irrigation water from groundwater. This share accounts regionally for more than 30 %. The results indicate important impacts for both agricultural production and other groundwater users.