Characteristics And Causes Of Temporal-Spatial Variation Of Groundwater Depth In Handan City

Groundwater is an important part of water resources.Global groundwater exploitation accounts for about 33%of freshwater production.About 35%of the world's population depends on groundwater resources.Groundwater shortage has been a global issue.From 2006 to 2015,groundwater supplied in China accounts for about 18%of total water supply.Groundwater supplied in Hebei Province accounts for about 78%of total water supply,while groundwater supplied in Handan City accounts for about 85%of the total water supply.Groundwater is the main component of water supply in Handan City.At the same time,the groundwater resources in Handan City are relatively scarce.Long-term groundwater exploitation results in a series of problems such as groundwater depletion,water level decline,water quality decline,salinization,and surface subsidence.This not only causes the destruction of the natural environment,but also affects the social environment.The problem of groundwater has become a hot issue in Handan City.It is of great significance to explore the change of groundwater depth and its influencing factors for the rational development and protection of groundwater resources.Based on the groundwater depth observation data of Handan City from 2006 to 2015,this paper analyzed the temporal and spatial characteristics of groundwater depth in Handan City.Based on variation of groundwater depth in temporal and spatial,we quantified the influence of factors which include natural factors(elevation,slope,aspect,soil type,precipitation variation and soil texture type)and socio-economic factors(land use and land cover type,GDP,population,agricultural groundwater use variation,industrial groundwater use variation and domestic groundwater use variation)on groundwater depth changes using Geo-detector.The main research contents and related conclusions are as follows:(1)The characteristics of groundwater temporal variation in Handan from 2006 to 2015,?Inter-annual variation.The average annual groundwater depth in Handan City shows an increase trend,so the groundwater level in Handan City has shown a decrease trend in recent 10 years.?Seasonal variation.The groundwater depth in Handan is the lowest in winter and the highest in summer.The groundwater in spring and autumn are between summer and winter.This is consistent with the geographical environment of Handan City and the large-area irrigation of summer crops.?Monthly variation.The monthly variation of groundwater depth can be divided into three dynamic periods:groundwater depth increase period(March to June),groundwater depth decline period(June to October),and groundwater depth stable period(October to February).(2)The spatial distribution characteristics of groundwater depth in Handan from 2006 to 2015.?The groundwater depth high-value zone(groundwater depth is more than 60 meters)is the two connected areas formed by the northern part of the She-the south of Wu'an-the Fengfeng mining area-the west of Ci.The groundwater depth low-value area(with a depth less than 10 meters)is formed by Handan City-Handan County region-the east of Ci;?Spatial distribution characteristics of groundwater depth change.The rate of groundwater depth variation is between-4.75 and 15.53m/a.In the central and eastern parts of Handan city,the groundwater depth increases.In the southwest,the depth of water level declines seriously.In the northwest,the depth of groundwater generally shows a downward trend.(3)Groundwater depth variation attribution analysis.Using Geo-detector to analyze the influencing factors of groundwater depth variation.The results of the Factor Detector show that,as far as the whole city is concerned,the explanations for groundwater depth variation are more important for elevation,land use and land cover type,agricultural groundwater use variation and domestic groundwater use variation;the explanatory power of the various factors in the plain area and the mountainous area is quite different.The main influencing factors in the plain area are industrial groundwater use variation and precipitation variation,while the mountainous areas are land use and land cover type.The results of the Ecological Detector show that the impact of domestic groundwater use variation on groundwater depth is significantly greater than that of industrial groundwater use variation,elevation is significantly greater than precipitation variation,agricultural w groundwater use variation,industrial groundwater use variation and domestic groundwater use variation;Land use and land cover type is significantly greater than precipitation variation,industrial groundwater use variation,domestic groundwater use variation,slope,and aspect;The soil type is significantly greater than the industrial groundwater use variation and aspect;There is no significant difference in the influence of other factors on the groundwater depth variation.The results of the Interaction Detector show that there are interactions among the impact factors,which are mainly represented by the relationship between bi-enhancement and nonlinear enhancement.