Three-dimensional Hierarchical Hydrogeological Modeling And Groundwater Resource Evaluation In The North China Plain

Accurately reconstructing the three-dimensional spatial distribution of hydro-lithologies plays an important guiding role in underground space utilization,water resources development and management.This paper studies the constraints of hydrogeological structure and hydro-lithologies on groundwater resources in the North China Plain,and reconstructs the model of the study area on two scales of stratigraphic structure model and hydrogeological model.And the three-dimensional sequential indicator simulation（SIS）hierarchical hydrogeological model was coupled with the water level to estimate the realistic groundwater and recharge area resources in the study area.The main research results obtained in this paper are as follows:（1）Based on the two-dimensional hydrogeological cross-section,the three-dimensional stratigraphic boundaries and the three-dimensional lithological sampling points were extracted.Using the DSI method,the stratigraphic boundary and the elevation contours of the aquifer group are used to establish a three-dimensional stratigraphic grid models of the whole area and four aquifer groups.（2）Based on the method of hierarchical modeling,the lithological sampling points of each aquifer group are extracted from the hydrogeological section of the whole region.The corresponding grid model of the aquifer group as the modeling space,and the hydrogeological models of the four aquifer groups in the study area were established using the indicator kriging estimation（IK）and sequence indicator simulation（SIS）.The global lithological data was also used to establish the global hydrogeological lithological model for comparative analysis,which highlighted the advantages of the layered model.（3）The 3D hierarchical hydrogeological model and the global hydrogeological model were quantitatively analyzed through the variogram,the sampling point histogram and the three-dimensional model histogram,and the absolute error percentages（APEs）of the hierarchical model and the global model were calculated.From the analysis of the lithological spatial distribution,the conformity of the shape and the profile,etc.,The hierarchical model can accurately express the lithological spatial properties and real distribution.（4）The hierarchical SIS hydrogeological model was coupled with the water level,and the realistic groundwater volume and recharge area of shallow and deep layers in the study area were estimated according to the groundwater calculation principle of unconfined aquifers and confined aquifers.The hydraulic properties,porosity and thickness of each aquifer group,the realistic total groundwater in the study area was 5.173×10¹¹m³.The idea of hierarchical modeling is applied in the 3D hydrogeological modeling of the North China Plain,and the 3D IK model and a 3D SIS model are obtained respectively.The structure model of the aquifer group is established,and the hydro-lithological model is established with the structural model as the constraint.This ensures the extension of lithology in this aquifer group,and the hierarchical model of the study area can provide advice and model support for groundwater management and development.