Research on surface water resources in Taihu Lake Basin based on zonal coupling model

Abstract

[Objective] The Taihu Lake Basin is a highly developed economic region in China and a typical area with prominent imbalance between supply and demand of water resources. The aim is to estimate the multi-year average surface water resources in the Taihu Lake Basin based on its geographical distribution, underlying surface types, and hydrometeorological conditions. [Methods] A zonal coupling modeling method was proposed, dividing the basin into the upstream hilly area and the middle-lower plain area. The Xin'anjiang three-source model and the runoff generation and concentration method based on underlying surface classification were used respectively to estimate the surface water resources from 1956 to 2020. The reliability of the result was verified through reservoir runoff simulation and a one-dimensional hydrodynamic model. [Results] The result showed that in the upstream hilly area, runoff simulation achieved an average coefficient of determination of 0.76, with relative errors controlled within ±7%. In the middle-lower plain area, water level simulation yielded an average coefficient of determination of 0.88, with better fitting performance in wet years. The model estimated the multi-year average surface water resources at 17.854 billion m³, which was 10.6% higher than the 16.15 billion m³ reported in the Second National Water Resources Survey and Assessment and 2.1% higher than the 17.481 billion m³ average in the water resources bulletins from 2006 to 2020. [Conclusion] The zonal coupling model demonstrates good applicability and reliability for estimating surface water resources in the Taihu Lake Basin. Differences between the model result and the “Second Survey” result primarily stem from the extended rainfall series, optimized runoff estimation method in the western lake area, and underlying surface changes. Future research should consider developing dynamic parameterization schemes to improve the model's estimation capabilities.

Keywords

Taihu Lake Basin / surface water resources / runoff simulation / Xinanjiang model / one-dimensional hydrodynamic model