A Study On Groundwater Flow System Using Three-dimensional Models In The Interior Drainage Region Of The Ordos

WITH the development of groundwater numerical simulation technology,the three-dimensional characteristics of groundwater flow system at the basin scale have attracted more and more attention from researchers in the field of hydrogeology.The regional groundwater flow system theory proposed by Tóth in 1963 is the basis for studying the law of groundwater circulation and evolution in the basin scale,and directs the study of groundwater flow field,groundwater source of the lake,and age characteristics of groundwater in the basin.The study area is located in the plateau lake-concentration area in the northeastern part of the Ordos inland area.The water well and lake data are used to correct the threedimensional groundwater flow numerical model of the upper boundary of the flux.The characteristics of groundwater flow field were analyzed by typical things and the northsouth section,and the relationship between the source range of groundwater recharge and the surface watershed of Dakebo and the characteristics of groundwater contours were studied.Streamlined tracking of Dakebo and Hutongchahannao,and determined the boundary area between Dakebo and Hutongchahannao groundwater flow line.Streamline reverse tracing and geophysical methods verify that there are three differe nt levels of flow systems in the local,intermediate and regional sections of the Dakebo,Mukainao and Hutongchahannao sections.Streamline reverse tracking of Dakebo and Hutongchahannao,and analysis of groundwater convective age characteristics.The tracking particles near Dakebo Lake are relatively close to each other,the groundwater age is smal;the tracking particles near the western,southern and northern borders of the Dakebo small watershed,the groundwater age is older;the farthest tracking particles in the northern part of Dakebo,groundwater The age reaches 56 ka.The groundwater age of the local flow system of the Hutongchahannao is younger,the groundwater age of the intermediate flow system is larger,and the maximum groundwater age of the regional mobile system reaches 109 ka.According to the topographic cybernetic discriminant formula proposed by Haitinj ie ma and Mitchell-Bruker in 2005,the applicability of topographic cybernetics in the study area is demonstrated.According to the diving surface of the three-dimensional model of flux,a numerical model of three-dimensional groundwater flow for a given head is established.At the same depth of the drainage zone,the head of the given threedimensional model of the head is larger than the head of the three-dimensional model of the flux.At the same depth of the recharge zone,the head of the flux threedimensional model is larger than the head of the three-dimensional model of the given head.The difference between the recharge area and the discharge area of the two models is smal.The groundwater age is less than 1 ka in the surface recharge area and the lake raft discharge area is greater than 10 ka.The groundwater age in the depths of the Chadengmuer Formation is more than 20 ka,the groundwater age in the depths of the Hutongchahannao Formation is greater than 70 ka,and the deepest groundwater age in Bayannaoer is greater than 20 ka.In the two-dimensional model of the given water head,the groundwater age in the deep roots of the Hutongchahannao is greater than 80 ka;in the three-dimensional model of flux and the two-dimensional model of the given head,the groundwater age in the deep stratum of the southeastern part of Hutongchaha nnao is more than 80 ka.