Meteorologische Zeitschrift (Sep 2016)
Irrigation water demand of common bean on field and regional scale under varying climatic conditions
Abstract
Crop irrigation plays an important role in the world's food production and its role is expected to increase still further. For policy makers, the quantification of the irrigation water demand and the water availability on a regional scale is crucial. In the project ‘SAPHIR’, a new stochastic framework was developed to upscale crop yield and crop water demand from irrigation experiments with common bean to the regional scale using the one-dimensional mechanistic crop model Daisy. The crop model parameters – derived based on a comprehensive experimental data collection and a sound calibration of the crop model – were used to simulate potential bean yield, yield reduction due to drought stress, and crop water demand in mid and northern Saxony, Eastern Germany, using the dominant soil characteristics. The stochastic relationship between irrigated water and crop yield (stochastic crop water production function) enabled the prediction of the crop productivity on a regional scale. Furthermore, the available water resources for irrigation on the catchment scale were compared to the predicted irrigation water requirements to estimate the degree of local water self sufficiency. The simulation results show that an irrigation of common bean has high yield effects especially in locations with low precipitation during the growing season or for soils with a low water storage capacity. Especially in the drier northern parts of Saxony with its lower soil water storage capability, a decrease in non-irrigated fresh matter bean yield up to 40 % is predicted for the future. Irrigation and the projected increasing temperature can enhance the bean yield in southern Saxony. However, the required amount of irrigation water in northern Saxony can only be delivered by down to 20 % and less from the local precipitation. The presented framework enables policy makers to compare water demand and available water which allows a precise estimation of relevant indicators for a considered region, e.g., the degree of local water self sufficiency.
Keywords
