基于GIS的小流域养分流失预测

GIS-BASED PREDICTION OF NUTRIENT LOSS FROM A SMALL WATERSHED

在GIS技术的支持下 ,将流域划分为多个独立的坡面单元 ,运用室内人工降雨实验坡面养分流失的研究结果和通用土壤流失方程 (USLE)进行了重庆市丰都三合小流域的养分流失预测与评价。研究结果表明 ,利用流域泥沙流失量进行流域养分流失预测时 ,只能对流域全量养分 (有机质、全氮、全磷、全钾 )的流失进行较为准确的预测 ,而对流域速效养分 (有效氮、有效磷、有效钾 )流失量进行预测时 ,径流携带流失的部分不能被忽略。要对流域养分流失量进行准确的预测与评价 ,必须通过建立流域分布式径流模型 。

The Sanhe small watershed was divided into many slope units with the aid of GIS and its nutrient loss was assessed on the basis of the results of the study slope nutrient loss by means of simulated rainfall,using the universal soil loss equation(USLE). Results showed that the total nutrient(organic matter,TN,TP,TK)loss could be well and truly estimated by calculating sediment in the small watershed,but in estimating of the available nutrients(available nitrogen,available phosphate,available potassium),the nutrients in runoff should not be neglected. In order to accurately estimate the nutrient loss in the small watershed,a runoff distribution model of the watershed should be established and used in combination with the soil erosion model with the aid of GIS. In the Sanhe small watershed,the average quantity of soil loss per year was 5 839t and for the average quantity of nutrient loss per year,the organic matter,TN,TP and TK reached 197.9,7.42,3.91,and 174.0 t,respectively.