Abstract:

It is very critical to make researches on the changes in water resources under the background of climate warming, in order to provide a scientific basis for the disaster prevention and mitigation, thus to promote the development of agricultural economy and food production in the region. The author estimated the evaporation with the empirical fomula of land evaporation by Koichiro Takahashi, using the monthly average temperature, precipitation sequence of data of Wafangdian, Dalian City from 1961 to 2010, and analyzed the charateristics of water resources change on precipitation, evaporation and the difference between precipitation and evaporation, using Mann-Kendall rank correlation test method, linear trend and other statistical methods. The result showed that the annual change of precipitation, evaporation and the difference between precipitation and evaporation trended to be consistent, among which, January was the minimum, July was the maximum. There were richest water resources in summer, richer in autumn and least rich in spring and winter. In crop growth season, precipitation as well as the difference between precipitation and evaporation approximate to 50 years trend to decrease. The change of evaporation was stable. Climate tendency rates were 6.588 mm/10 a, -7.684 mm/10 a and 1.096 mm/10 a, respectively. The annual precipitation as well as annual difference between precipitation and evaporation trended to decrease. The change of annual evaporation trended to be zero. Climate tendency rates were -9.537 mm/10 a, -8.741 mm/10 a and -0.796 mm/10 a, respectively. The annual difference between precipitation and evaporation reduced, with ultimate ratio reaching 13:1 which illustrated that in the meanwhile the water resources reduced, drought and flood frequency increased, reminding people of paying attention to the change of water resources and adjusting the agricultural structure accordingly.