Application of SWAP model to analyse the impact of drought and climate change on water demand and apple fruit crop yield in the Kromme Rijn area, The Netherlands.

Abstract

Drought is defined as water shortage. Future climate scenario predicts that average daily temperature will rise with less rainfall leading to higher evapotranspiration. Many studies have shown that in the future, drought is expected to be more severe compared to the past. Drought will affect ground water level and water demand for irrigation of agricultural area in order to maintain optimum crop yield.

De Stichtse Rijnlanden (HDSR) is responsible to supply sufficient water for irrigation of Kromme Rijn area which is one of the important fruit crop plantations in The Netherlands. In order to ensure the capability of HDSR to supply sufficient water supply to the Kromme Rijn in the future, an estimation of water demand for irrigation is needed.

This thesis tried to analyze the impact of future climate changes on ground water level, water demand for irrigation and relative crop yield in the Kromme Rijn area. Soil-Water-Atmosphere-Plants (SWAP) program is used. A SWAP model for the study area is was built and calibrated.

The calculation using the calibrated model for the future climate scenario showed that, to maintain optimum apple crop yield in the Kromme Rijn area, surface irrigation will need to be increased from 0.05 to 1.5 mm per day (1.8 – 55 cm/year) in 1986 – 1995 to about 0.5 to 4 mm per day (18 – 150 cm/year) in 2046-2055. The water demand in the future predicted by the SWAP model is between 0.05 to 0.60 m3/sec. Compared to the maximum water supply applied today (0.3 m3/sec), based on the calculation results obtained during this study, HDSR need to double the amount for irrigation with a factor of 2 in the future.