A Numerical Modeling System of the Hydrological Cycle for Estimation of Water Fluxes in the Huaihe River Plain Region, China

Abstract

To analyze the water budget under human influences in the Huaihe River plain region in China, the authors have developed a numerical modeling system that integrates water flux algorithms into a platform created by coupling a soil moisture model with the modular three-dimensional finite-difference groundwater flow model (MODFLOW). The modeling system is largely based on physical laws and employs a numerical method of the finite difference to simulate water movement and fluxes in a horizontally discretized watershed or field. The majority of model parameters carry physical significance and can be determined by field and laboratory measurements or derived from watershed characteristics contained in GIS and remote sensing data. Several other empirical parameters need to be estimated by model calibration. The numerical modeling system is calibrated in the Linhuanji catchment (2 560 km2) to estimate surface runoff, groundwater recharge, and groundwater loss for evapotranspiration and stream baseflow. Model validation is conducted at a small runoff experimental field (1.36 km2) in the Wuduogou Hydrological Experimental Station to test the model?s capability to simulate hydrological components and estimate water fluxes using observed stream stage and groundwater data, as well as lysimeter-measured precipitation recharge and groundwater loss. As proven by the promising results of model testing, this physically based and distributed-parameter model is a valuable contribution to the ever-advancing technology of hydrological modeling and water resources assessment.