Mudanças climáticas e impactos na demanda de água para irrigação na bacia do Jaguaribe

Abstract

Climate change has a potential to impact hydrological cycle processes such as rainfall that affects run off temperature and air humidity which are related to evaporation river flow and plant evapotranspiration They may also affect water availability and crop water requirement The purpose of this research was to assess climate change impacts on irrigation water demand on Jaguaribe river basin Ceará future scenarios derived from the PRECIS (Providing Regional Climates for Impacts Studies) using boundary conditions of the HadAM3P global circulation model submitted to a dynamic downscaling nested to the Hadley Centre regional circulation model HadRM3P Monthly time series for average temperature and rainfall were generated for 1961 to 90 (baseline) and for the future (2040) The reference evapotranspiration was estimated using Penman Monteith FAO methodology using limited climate data Projected climate change impacts were mapped and show an increase on irrigation water demand as a result of evapotranspiration (increase from 11 to 12%) and rainfall trend (decrease from 31 to 37%) Impacts were mapped over the target region by using geostatistics methods An increase of the average irrigation water needs was estimated to be 30% and 31% higher for 2040 A2 and B2 scenarios respectively Even though it has been shown that climate change has impacted the irrigation water demand increase, sensitivity analysis has indicated that water demand is more sensible to final irrigation efficiency revealing itself as an important adaptation measure to be considered