| In recent years, with the development of industry and agriculture and theimprovement of people’s living standard, the contradiction between supply anddemand of water resources have become increasingly prominent. Therefore, Ourrational exploitation and utilization of groundwater resources put forward higherrequirements, that is to carry out the evaluation of groundwater resources from thequantitative point of view, and establish the reasonable development and utilizationscheme. While the groundwater dynamics is an important index to reflect the relevantinformation of groundwater resources in an area, through the study of the dynamicrule, that can help us to understand the evolution of groundwater resource and predictthe future trends of various elements in a certain extent, which provide scientific basisfor the rational development and utilization of groundwater resources. Thereforerevealling of space-time groundwater dynamic evolution is an important support forthe realization of sustainable utilization of groundwater resources and regionalsustainable development.Chengdu Plain is located in West Sichuan Basin, surrounded by mountains, is thelargest plain in southwestern, whose area widely distributed. The whole is fan, fan toplocated in the North West, fan tail line is longer, from North to South West clockwisedistribution.Narrow, Chengdu Plain includes the Min-jiang River, Tuo-jiang Riveralluvial plain, with Du jiangyan, Mian zhu, Luo Jiang, Jin tang, Xin jin and Qiong laias the boundary, the total area of8640km2, constitute the main part of the WesternSichuan plain.Plain subject is in NNE trending, long200km, wide42km, likediamond, and in which the Quaternary sediments accumulated. Where open flatterrain, high-lying north-west, southeast of the low, at an elevation of460~730m, thenatural gradient is small, about4~5‰. Then narrow selection of the Chengdu Plain asthe research object, to study the changes of the underground water level.This paper studies from the Chengdu plain natural conditions and geologicalconditions, investigated the hydrogeological conditions of groundwater system inChengdu plain and its hydrodynamic characteristics, on the basis of which, analysiscycle of change and influence factor of underground water level Chengdu plain byusing the mathematical model. And further according to the geographical and time,respectively we find the change rule of the groundwater level in different area and rainfall conditions. Finally, that inject relevance into history data of the two biggestcity in Chengdu plain, and analyse the influence of underground water level changesin the process of city.The main research result are as follows:(1) The main water supply respectively is the vertical infiltration recharge andlateral runoff recharge in the Chengdu plain area, among them, the vertical infiltrationrecharge can be divided into theatmospheric rainfall, surface water supply andagriculture irrigation water supply. Groundwater mainly migrate along the plain tiltdirection, from north west to south east after infiltration. To the eastern plain,groundwater begins to discharge into the river in east of Three weir, Pi xian, Wenjiang and Chong qing line, excretion to Qing baijiang nearby Cheng xiang, Shuang liu,Zhong xing field and Xin jin.(2) In Chengdu plain area, changes of phreatic water dynamic can be divided intotwo parts, namely the change of variation within the year and years. Based on thestatistical results of124groundwater level observation, we discover that the mostsignificant period is64months and128months in chengdu plain area, in addition tothe obvious within year cycle, about30%of the observations had shown the existenceof many years period; Secondly, for256months, display about16.9%observationpoints; Finally, for the85months’ period, about12.9%of point is in the cycle.(3) According to analysis of underground water level years period of three unitsof the Tuo-jiang River, Min-jiang River and Xi River respectively, which reveals theonly observations of Peng zhou City area Showed two cycle of64months and128months, the cycle of85months and128months are not reflected in Tuo-jiang Riverarea; The main period is64months and128months in Min-jiang River area, but alsoreflects the long years period of85months and256months, although the proportion isonly half of the previous two, it is still more prominent; The main period is128months,64months is the second in Xi River area, there are also many years period of85months and256months at the same time, frequency of occurrence of the latter twois less than128months and64months to half, but it is still reflected.(4) After screening more than700water level observation data in the ChengduPlain, who give related nalysis by selecting124representative data of observation ofwater level point and rainfall. The results showed significant correlation betweenunderground water level and rainfall of78.3%exist.(5) Respectively discussing the relationships of underground water level andrainfall according to three different years of the wet period: average water period andthe dry period, there was a gradual decline in three period of each year the extent of the affected by the rain, namely the wet years affected by rainfall dominated thehighest degree, is0.7, and there are a two function relationship between the two,rainfall as the factors of groundwater level fluctuation whose weight is56.1%of allfactors; average water years is the second, is0.47, and there are a three functionrelationship between the two, rainfall as the factors of groundwater level fluctuationwhose weight is47.5%of all factors; dry years is minimum, function relation betweenthe two can be expressed with several main function form: linear, logarithmic, twoand composite, comprehensive consideration, selecting four kinds of R mean valuefrom functions as the regression results of the area, whose value is approximately0.41.rainfall as the factors of groundwater level fluctuation whose weight is31.5%of allfactors.(6) After correlation analysis of the underground water level fluctuation and cityurbanization in the Chengdu City and Deyang City, we found that there was nosignificant correlation between urbanization and groundwater level in Chengdu City,and a weak negative correlation existing between urbanization and fluctuation ofgroundwater level in Deyang City, is about36.4%. |
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