Impacts of irrigation on annual potential evapotranspiration in Jingtai irrigation district

Changes in potential evapotranspiration will affect the projection of water dan and and the detemination of irrigation quota in a region.In order to evaluate the influence of irrigation on the maintenance and development of agricultural oasis, the impacts of irrigation on annual potential evapotranspiration in Jingtai irrigation district of Gansu province are quantitatively analyzed and projected using the advection aridity complem entary relationship in regional evapotranspiration.A declined trend has been observed from both annual pan evaporation records and estmiated potential evapotranspiration since the introduction of Yellow River irrigation in 1972.The observed aerodynamic forcing has been significantly weakened in the region, and the declined trend in potential evapotranspiration is likely due to the weakening in wind speed and increasing in relative humidity that is affected by irrigation Future variations in potential evapo transpiration with different water consumptions are smiulated using the long-term mean annual precipitation and the solar radiation conditions, and the results are presented.