Changes in water demands under adaptation actions to climate change in an irrigation district

Abstract

Climate change will affect the water balance of irrigated agriculture. Therefore, farmers and irrigation managers should consider adapting to new scenarios. Changes in water demands in a Mexican irrigation district were studied using an irrigation-scheduling model. The impact on water demands of two potential adaptation actions, adjusting planting season and using longer-season varieties (LV), was estimated and compared with a baseline scenario. Two cropping plans (wet and dry) for the last 15 water years were considered. Cumulative and daily irrigation demands were estimated for each agricultural season and each adaptation action. The reference period (1961–1990) and three future climate projections (2011–2040, 2041–2070, 2071–2098) under A1B scenario were used. Results indicated that without adaptation water demands will decrease as temperatures increase and season lengths will shorten. However, as farmers respond with adaptation actions to maintain actual yields, water demand can be higher than non-adaptation action. The impacts of climate change on water demands depend on the adopted adaptation actions and have a greater effect on peak and cumulative demands. The water demands increased by 2.4% when LV were used and 16.3% when this is combined with adjusting planting season. Thus, adaptation actions should be chosen carefully to minimize future agricultural risk.