Estimation of Evapotranspiration (ET_c) from Agricultural Land in the Lower Delta of the Amudarya River

Abstract

Environmental water needs are particularly unmet during the spring and summer seasons (April to August), when ecosystems are most vulnerable to water changes (e.g., due to shallow coastal fish spawning), but agricultural water demands are also at their highest. Thus, the expected impact of climate change on the status of deltaic wetlands is a worsening of conditions, especially in the lakes identified as vulnerable above. The shift from cotton and rice to wheat would result in an estimated 30% reduction in cotton yields compared to today, even assuming increased yields and wheat substitution for rice. Overall, agricultural production will also in-crease (assuming improved yields/hectare). This loss in cotton production is offset by increased productivity of wheat production and other ecosystem products and services such as fish, game birds, muskrats, and grazing. When all planned measures are fully implemented, the area of wetlands is expected to in-crease by 234,000 hectares. In the current scientific research work, ET_c was calculated for the area based on the phases of crop development for cotton, grain, and rice crops grown in the irrigated lands of the lower Amudarya River delta. The highest ET_c was found to be evapotranspiration of 22.7 mm/ha and 21.4 mm/ha corresponding to the middle development phase of cotton and wheat, respectively. The lowest ET_c value corresponds to the maximum development phase of rice, with evapotranspiration of 6.3 mm/ha.