Application Of High-density Electrical Resistivity Tomography In Construction Of Paleochannel Groundwater

The development of Paleochannel Groundwater Reservoir is based on exploitation of shallow fresh water in paleochannel,it attempt to take the paleochannel sand body as storage capacity and increase available water resource quantity.Usually,in region of alluvial plain,the paleochannel is primary channel of groundwater for storage and transportation,as for the construction of groundwater reservoir,paleochannel play the crucial role in regulating water resources,groundwater recharge and restoring groundwater table.Because of uneven water inflow and low efficiency in surface water,both regional groundwater overexploitation and decline of groundwater table are in serious condition,at present,there is already come into being many territorial large funnel,besides,the D-value between saltwater hydraulic head and freshwater hydraulic head is increasing day by day,based on good formation conditions in paleochannel,the phenomenon that saltwater in north intrude into inland aquifer becomes more and more serious.In order to reduce the region of groundwater fuunel,uplift territorial groundwater level and take advantage of the ground dike to prevent saltwater from intrusion,intercept freshwater into the sea,we attempt to take some sediments in paleochannel like sand gravel or the other porous media as water srorage space to construct groundwater reservoir,and divert surface water for storage and irrigation,thus keep north sea(salty)water from furher intrusion.so,to study the watery and structure of paleochannel within groundwater reservoir area is a important content,the ascertainment of feature such as location,depth and thickness of paleochannel can provide references for construction of groundwater reservoir in slection,scale,structure and also the research in ground diaphram wall crucial parameters.This paper mainly completed the following aspects of work:(1)By collecting materials of hydrology,meteorology,topography and hydrogeology in MI river alluvial fan area,ascertain geological structures and hydrogeological condition in study area,make certain of aquifer distribution characteristic and dynamic characteristics of groundwater;(2)Make use of numerical simulation of geological model,investigate the influence on ERT explain resistivity accuracy result especially in device type and inversion iteration times or the other aspects;(3)Arrange ERT surveying lines to scan and measure in research area,obtain the distribution information of rock massin electrical characteristics,and acquiretwo dimensional resistivity image and electrical sounding curveby data preprocessing,inversion calculation and drawing,then,analyze the location and shape of paleochannel and other releated parametersThrough the above research,the following research results have been obtained:(1)The paleocurrents in the study area are characterized by high resistivity resistivity.In the unshaped diagenetic area,the resistivity is in the range of 20-40? · m,and the lithology is mainly composed of fine sand and fine sand.The resistivity value is in the range of 0-20? · m,and the lithology is dominated by surface cover soil and clay layer.The resistivity is in the range of 0-20? · m.In the 16,17,18,19 line drawing interpretation of the ancient river,the area is located in the town of Taitou town Jijiaqiaozi Village and Taipingzhuang Village area,in 2014 to the south of the brackish water line,but the region's groundwater level is long Over-picking state,groundwater level drop serious.(2)Based on the two-dimensional high-density resistivity image analysis,the section of the ancient river is WS-EN direction,east-west width of 1400 m,the east and west shore position is more clear;sand layer in the middle of the river buried depth,buried at both ends of the depth is small "U" shape distribution,the distribution of a very typical river bed characteristics,sand layer thickness changes in line with the characteristics of the ancient river bed kinetic products;sand layer around the interpretation of the accumulation of residual clay,the presence of clay blocks on the accumulation of sand Or to promote the formation of a good sand layer deposition area,in order to further clarify the form and regularity of the ancient river bed deposition is of great significance.(3)Based on the analysis of the electro-sounding curve,the apparent resistivity values of the sedimentary zone of the ancient river channel are in three sections,and the surface is mostly flattened or declining,and the clay layer is judged to be rising.The middle curve is increasing and the apparent resistivity value is increased.For the sand layer to reflect the bottom curve slow or decline,to determine the clay layer or clay,sand interbed.