The Characteristics Of Water-saving Irrigation Effects On Groundwater Recharge

As two kinds of resources, land and water in tYanQi Basin were over exploited during the end of last50thto the beginning of last70th, in which the flood irrigation was wildly spreaded in Yan Qi Basin whichcaused many adverse impacts on farm land and ecological environment. Nowdays, the irrigation systemuse both wells and diversion canals for fedding water to the farm regions in Yan Qi Basin. And in Yan QiBasin, the proportion of water saving irrigation that relys on groundwater is continuously rised up wherethe area of flood irrigation land is decrasing. Therefor, study on the impacts of the changing mode to thegroundwater system is urgently needed. In this paper, a villige named of Xiawuhao was choosen as a testsite in Yan Qi Basin for researching the combine influences of water-saving irrigation and flood irrigationto groundwater system, and the technical means include investigations, statistical analysis, numericalsimulation, etc.Soil moisture trend which measured in both water-saving irrigation land and flood irrigation land byneutron probe is regarded as the response variable for studying groundwater recharge. And therelationships between soil moisture trend with evapotranspiration, groundwater depth trend and waterquantity of irrigation have been analyzied by statisticl way. The result shows that water-saving irrigationhas non-contributes to groundwater recharge while the process of infiltration from flood irrigation togroundwater in test site will lasts7days in which the first3days contains the main water quantity(July16th,90mm, Augerst7th,50mm). The proportion of flood irrigation is calculated with empirical equation,and the conclusion is0.212.The groundwater depth of the whole villige was recorded by MINI-DIVER in3settled observationwholes that located in the region. The relation ships between groundwater depth trend with groundwaterextraction, flood irrigation, evapotranspiration and tempreture have been analyzied in SPSS. Theconclusion shows that, during the farming period time the groundwater depth trend reflects both floodirrigation and groundwater extraction accurately, in which the flood water-saving irrigation mode will raise the groundwater depth up quickly and anothe mode will make it deeper greately. During thenon-farming period time only tempreture has some relation ship with the groundwater depth trend.Both the generalized and mathematical modles have been built based on hydrogeological conditons ofthe test area, and it is simulated by the numerical modle that set up by Processing MODFLOW. Theappropriate scale of water-saving irrigation, groundwater quantity of extraction and the intake of floodirrigation for autum/winter irrigation is forcasted by the numerical models that examed in SPSS throughnon-parametric tests.