Investigation of point source and non-point source pollution for Panjiakou Reservoir in North China by modelling approach

Abstract

Panjiakou Reservoir is the main water supply source for Tianjin City, which has a population of over 14 million. In order to develop a watershed management strategic plan for source water protection, it is necessary to have reliable information on point source (PS) and non-point source pollution (NPS). The modelling approach has been frequently used in the study of partitioning of PS and NPS pollution on a basin scale. This study employed the Loading Simulation Program in C++ (LSPC) model to investigate the PS and NPS source pollution loadings to Panjiakou Reservoir. The hydrological model and the water quality model were developed and validated using field data from 2006 to 2010. It has been found that the PS pollution is still the major source for chemical oxygen demand (COD) loadings, accounting for about three-quarters of the total annual loadings to the reservoir; while near half of the total nitrogen (TN) and total phosphorus (TP) total annual loadings are from NPS pollution. There is a large seasonal variation for TN and TP loadings from NPS pollution. The contribution of TN and TP from NPS in the flooding seasons can reach 70%, whereas the contribution can also be as low as 4% during the dry season in the winter.