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本文以泾河水系的东川流域为例,应用分布式生态水文模型SWIM(Soil and Water Integrated Model)模型模拟比较了退耕还林和还草对流域径流的影响。结果表明:(1)高覆盖度草地与森林的产水能力相当,占流域面积10%的高覆盖度草地造林后,流域年径流深仅减少0.01mm(针叶林)和0.08mm(阔叶林),减少0.2%(针叶林)和1.2%(阔叶林);(2)低覆盖度草地造林后流域径流大幅下降,占流域面积10%的低覆盖度草地变为高覆盖度草地、针叶林和阔叶林后,流域年径流深分别减少8.0mm、8.2mm和6.7mm,减少了29.9%、30.4%和25.0%;(3)造林后流域径流减少量的70%发生在夏季。
Taking Dongchuan watershed in Jinghe River system as an example, this paper simulates and compares the effects of the conversion of cropland to forestland and grassland on runoff in this area by using distributed soil and water integrated model (SWIM). The results showed that: (1) The productivity of grassland and forest with high coverage was similar, and the annual runoff depth decreased only 0.01mm (coniferous forest) and 0.08mm (broadleaf Forest), 0.2% (coniferous forest) and 1.2% (broadleaf forest). (2) After the afforestation of low coverage grassland, the runoff of the basin dropped significantly, and the low coverage grassland accounting for 10% of the drainage area became high coverage grassland , Coniferous forest and broad-leaved forest, annual runoff depth decreased by 8.0%, 8.2mm and 6.7mm, respectively, decreased by 29.9%, 30.4% and 25.0%; (3) 70% of runoff reduction after afforestation occurred in summer.