基于SWAT模型的黑河流域不同土地利用情景的非点源污染研究

SWAT model of non-point source pollution under different land use scenarios in the Heihe river basin

以卫星遥感影像为基础,运用GIS与环境模型(SWAT2000)相结合的技术手段和景观生态学的研究方法,探讨了黑河流域土地利用与非点源污染的关系;从土地利用恶化与改善出发,对模型进行水量、泥沙和营养负荷部分的参数率定和验证并分析其在黑河流域的适用性,在此基础上通过对不同土地利用情景下非点源污染负荷的定量化分析,研究了土地利用/土地覆被变化对黑河流域非点源污染的影响过程.结果表明,随着流域林地面积的增加,流域径流深逐渐减少,水土流失量逐渐减少,从而使得流域产沙量也相应减少.林地的非点源污染单位负荷为:氮0.67kg·hm-2·a-1,磷0.11kg·hm-2·a-1;耕地的单位负荷为:氮8.85kg·hm-2·a-1,磷4.2kg·hm-2·a-1;当流域全部为林地时,总氮与总磷的负荷量分别为99.001t和17.145t.在2000年土地利用情景下总氮与总磷的负荷量分别为173.334t和38.653t;随着对植被的破坏,即土地恶化,会导致流域非点源污染的急剧增加;反之,随着退耕还林、水源涵养林保护工程的实施,流域水环境会得到极大的改善.

GIS data was combined with environment model SWAT2000 and landscape ecology in order to determine the relationship between land uses and non-point source pollution（NPS） in the Heihe River basin. Considering land use deterioration and improvement, the discharge,sediment and nutrient load parameters of the model were verified and calibrated. The model was tested by applying it in the Heihe river basin. Through quantitative analysis of the non-point source pollution （NPS） load of different land use scenarios, the influence of land use and land cover changes in the water environment of the Heihe River Basin was studied. The results showed that with the increase of forest area of the watershed, gradual decrease of depth of runoff of watershed and the gradual decrease of the amount of soil and water loss,sediment yields of the watershed also decreased. The NPS nitric unit-load of forest land was 0. 67 kg·hm^-2· a^-1, the NPS phosphorus unit-load of forest land was 0. 11 kg·hm^-2· a^-1. The NPS nitric unit-load of cultivated land was 8.85 kg·hm^-2· a^-1 and the NPS phosphorus unit - load of cultivated land was 4.2 kg·hm^-2· a^-1. The total nitrogen and total phosphorus loads were 99. 001 t and 17. 145 t, respectively, under pure forest land. The total nitrogen and total phosphorus loads were 173. 334 t and 38. 653 t, respectively, under the land use scenario in 2000. With vegetation destruction, degradation of land resources and non-point source pollution（NPS） of the watershed will increase rapidly. Conversely, with the conversion of farmland to forests and the implementation of water conservation and forest protection projects, the water environment of watershed would greatly improve.