Theme 7-5-Climate change, water supply and crop production.

Abstract

Changes in environmental components such as atmospheric composition, climate and land use may have major effects on water supply and food production. Hydrological models can be used to investigate the effects of various scenarios at different scales. Two linked hydrological models, SLURP (Semi-distributed Land-use Runoff Processes) and SWAP (Soil-Water-Atmosphere-Plant) were applied to a basin in Turkey. SLURP modelled the entire 17,200 km2 river basin and SWAP was used to model cotton within a particular irrigation scheme. The outputs from the models include the areal distributions of variables such as soil evaporation and crop transpiration over the basin and crop yield at the field level. The results show that, under a 2 x CO2 scenario, crop transpiration was reduced almost everywhere in the basin due to generally higher temperatures and lower precipitation. River flows to the sea were also reduced under the 2 x CO2 scenario as more water was diverted from the river to support crop production, urban and industrial water supplies. At the field scale, crop production was much reduced under the 2 x CO2 scenario because of an increase in the evaporative demand of the atmosphere.