基于DPeRS模型的渭河典型断面汇水区面源污染评估及污染成因分析

近年来甘肃渭河桦林断面月度水质不稳定达标的问题引起了管理部门的广泛关注，掌握桦林断面汇水范围面源污染现状，对控制流域面源污染和促进水质稳定达标具有重要意义。采用遥感分布式污染估算（DPeRS）面源污染评估模型，对2018年黄河流域甘肃桦林断面汇水区面源污染空间分布特征进行分析，开展多类型污染量产排特征解析。结果表明：农业面源污染量方面，2018年甘肃桦林断面汇水区总氮（TN）、总磷（TP）、氨氮（NH⁺₄-N）、重铬酸盐指数（COD_Cr）面源污染排放量分别为11 591，2 697，7 141和1 458 t，入河量分别为2 184，512，1347，263 t；空间分布上，氮型（TN和NH⁺₄-N）排放负荷高值区主要分布在陇西县、武山县县段和岷县县段；武山县县段TP排放负荷较为突出;COD_Cr型面源污染高负荷区主要分布在陇西县、渭源县县段和武山县县段。农业面源污染物入河排放负荷空间分布差异明显，氮磷型（TN、NH⁺₄-N和TP）入河高负荷区主要分布在武山县县段、陇西县、临洮县县段；COD_Cr型面源污染入河高负荷区呈分散分布。漳县西部地区水土流失量较高，漳县西部、陇西县和渭源县县段北部局部地区泥沙负荷量较高。枯水期污染治理仍是保障水质稳定达标的关键期，农田径流是渭河桦林断面所在汇水区氮磷型面源污染的首要污染类型，畜禽养殖是COD_Cr型面源污染的首要污染类型。

Estimation and Pollution Cause Analysis on the Typical Basin of Weihe River Based on DPeRS Model

In recent years, the problem of unstable monthly water quality in Hualin section of the Weihe River in Gansu has attracted extensive attention from the management department. Understanding the current situation of non point source pollution in the watershed of Hualin section of the Weihe River in Gansu is important to control the non point source pollution and to promote the water quality to meet the standard. This paper used the DPeRS (Diffuse Pollution estimation with Remote Sensing) non point source pollution assessment model to analyze the spatial distribution characteristics of non point source pollution in the watershed of Hualin section of the Yellow River Basin in Gansu in 2018, including analysis on production and discharge characteristics of multi type pollution amount. The results showed as follows: in 2018, non point source pollution discharge loads of total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH₄⁺-N), and dichromate index (COD_Cr) in the watershed of Hualin section in Gansu were 11 591, 2 697, 7 141 and 1 458 t, and the amount of pollutants entering into river were 2 183 t, 512 t, 1 347 t, and 263 t, respectively; in terms of spatial distribution, the high value areas of nitrogen type (TN and NH₄⁺-N) discharge loads mainly distributed in sections of Longxi County, Wushan County and Minxian County. The TP emissions from non point source varied greatly among different county level administrative districts, and theTP discharge load in Wushan County was more prominent; the COD_Cr emissions in sections of Longxi County, Weiyuan County and Wushan County were more prominent. There were significant differences in the spatial distribution of non point source pollution discharge load in the watershed. The high load areas of nitrogen and phosphorus type (TN, NH₄⁺-N and TP) mainly distributed in Wushan County, Longxi County and Lintao County. High load area of COD_Cr type non point source pollution showed a scattered distribution. The soil erosion in the west of Zhangxian County causes high sand load of west Zhangxian County, Longxi County and north Weiyuan County. Pollution control in dry season is still the key period to ensure stable water quality. Farmland surface runoff is the primary pollution type of nitrogen and phosphorus non point source pollution in the catchment area of Hualin section of Weihe River in Gansu Province, and livestock and poultry breeding is the primary pollution type of COD_Crtype non point source pollution.