抄録
Non-point source pollution contribution is one of the major causes of water quality degradation in Chinese rivers and lakes. This research proposes a non-point source pollution modelling based on hydrograph separation by a distributed hydrological model and Time-Space Accounting Scheme. This method simulates spatially exported non-point source pollution nutrient loads by estimating flow discharge contribution rates from different spatial zones and source runoff concentrations of nutrients for each spatial zone. The source runoff concentrations can be estimated by field measurement or an inverse approach based on multiple stream flow samples. The proposed method was applied at the Pingqiao River Basin for a storm event. The inversely estimated source runoff concentrations showed satisfactory agreement with field measurement in the upstream area. The analysis suggested that this area (22.3 km2) exported about 2,630 kg of total nitrogen during an investigated storm event, and the urban area (5.3% of total area) contributed 18.5% of total nitrogen and 80.1% of ammonia nitrogen. The estimated source runoff concentrations were further applied for one-year simulation (2014/12/1 ～ 2015/11/30), which estimated 102,600 kg of total nitrogen export. The result was compared with the estimation based on measured source runoff concentrations (79,000 kg of total nitrogen) and revealed that the inverse method showed about 30% overestimation.
