Figure 2. Generalized schematic diagram of the simulation area
The actual area on which this quasi-ideal model relies is the plain area
of the Baiyangdian Basin in the North China Plain, wetland degradation
refers to the degradation of the Baiyangdian wetland, and the lake set
up is Baiyangdian Lake. The aquifer in this study area is a phreatic
aquifer, which is divided into one layer in the vertical direction with
a thickness of 60 m. In this model, precipitation infiltration recharge
is the main source of groundwater recharge in the North China Plain. The
coefficient of precipitation infiltration recharge α is approximately
0.17–0.35, which is taken as 0.2; the lateral recharge in the study
area is 25% of the rainfall infiltration recharge. The average depth of
Baiyangdian Lake is 3.5 m, the elevation of the lake surface is 10.5 m,
and the elevation of the lake bottom is 7 m. The water-bearing medium is
a sand layer, the hydraulic conductivity is set as 25 m/d, the specific
yield μ=0.20, and the bottom of the phreatic aquifer is a clay layer,
taken as the confining bed.
According to the above
hydrogeological conceptual model, the
groundwater flow in the study area is generalized to a homogeneous
isotropic submerged two-dimensional transient flow model, and the
corresponding mathematical model is as follows: