Irrigation impact on annual water balance of the oases in Tarim Basin, Northwest China

摘要

By taking the sum of annual precipitation and lateral water input (in which irrigation water withdrawal is the main component)nfor water availability, the Budyko hypothesis and Fu’s formula derived from it was extended to the study of oases in the TarimnBasin, Northwest China. For both long-term (multi-year) and annual values on water balances in the 26 oases subregions, thenextended Fu’s formula was confirmed. Regional patterns on water balance on the 26 oases subregions were related to changenin land-use types due to increased area for irrigation. Moreover, an empirical formula for the parameter was established tonreflect the influences of change in land use on water balance. The extended Budyko framework was employed to evaluatenthe impact of irrigation variability on annual water balance. According to the multi-year mean timescale, variabilities innactual evapotranspiration in the oases were mainly controlled by variability in irrigation water withdrawal rather than potentialnevapotranspiration. The influences of variability on potential evapotranspiration became increasingly apparent together withnincreases in irrigation water withdrawal. Copyright  2010 John Wiley & Sons, Ltd..