Target ET computing of ground water over-exploited area: the case of Jiexiu

Traditional water resources allocation theory of “to increase income and to reduce expenditure”
ignores water resources cycles, transformation and consumption, therefore does not satisfy the needs of
society. Allocation of water resources based on target evapotranspiration (water consumption during regional
sustainable development) can proceed from regional hydrologic cycle, to determine regional water balance, to
ascertain available amount of regional water resources, and to control water loss of at its roots. In the present
work we applied the basic theory and method of target ET computing to over-pumping ground water area of
Jiexiu. Ground water recovery was included in target ET calculations. Comprehensive, itemizing and post
evaluations were used to calculate target ET of Jiexiu in 2020, which were found to be 480.9 mm in normal
flow years and 433.0 mm in low flow years.Total regional water resources consumption, together with
different combinations of water resources conditions and water transfer volume and ground water exploitation
were applied to nine computational schemes to compute comprehensive ET. Different water saving methods for
agriculture irrigation and reclaimed water reuse measures were proposed for corresponding itemized ET
schemes. Coordination analysis and calculation evaluation then gave rise to recommendated scheme and
target ET.