Starting in 1999, the Grain‐for‐Green Programme has been implemented in the Loess Plateau to alleviate the severe soil erosion by converting steeply sloping croplands to forestlands or grasslands. To quantify the effects of these conservation efforts, this study identified the land‐use changes between 2000 and 2015 and quantified their impacts on runoff and erosion using the Soil and Water Assessment Tools (SWAT) and a typical hilly basin, the Yanhe River basin as a case‐study. To heighten the applicability of SWAT to the region, major model parameters were localized and calibrated for the period of 1975–1980 and were then validated for 1981–1987. The R² and NS validation indices were 0.70 and 0.65 for the monthly runoff and 0.67 and 0.61 for the sediment load, indicating that the model performance was acceptable. Between 2000 and 2015, the slope croplands were reduced by 39.9%, the forestlands increased by 90.2%, and the grasslands increased by 12.9%. These land‐use changes were simulated using SWAT to reduce the basin runoff by 13.8% and the sediment load by 50.7%. Spatial analyses using ArcGIS indicated that the simulated reduction in water yield due to cropland conversion to forestland was more obvious than that due to the conversion to grassland, but the reductions in the sediment yields were similar. The results suggest that the Grain‐for‐Green practice during this period was effective for preventing soil and water losses.

中文翻译：

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黄土高原沿河丘陵流域土地利用变化对径流和土壤侵蚀的影响评价

从 1999 年开始，黄土高原实施了以粮换绿计划，通过将陡坡耕地转为林地或草地来缓解严重的水土流失。为了量化这些保护工作的效果，本研究确定了 2000 年至 2015 年之间的土地利用变化，并使用土壤和水评估工具 (SWAT) 和典型的丘陵流域延河流域量化了它们对径流和侵蚀的影响。案例研究。为了提高 SWAT 在该地区的适用性，主要模型参数在 1975-1980 年期间进行了定位和校准，然后在 1981-1987 年期间进行了验证。月径流的 R² 和 NS 验证指数分别为 0.70 和 0.65，泥沙负荷为 0.67 和 0.61，表明模型性能是可以接受的。2000 年至 2015 年间，坡耕地减少39.9%，林地增加90.2%，草地增加12.9%。这些土地利用变化是使用 SWAT 模拟的，使流域径流减少 13.8%，泥沙负荷减少 50.7%。使用ArcGIS的空间分析表明，由于农田转林导致的模拟出水量减少比转草地更明显，但沉积物产量的减少量相似。结果表明，这一时期的以粮换绿实践对防止水土流失是有效的。使用ArcGIS的空间分析表明，由于农田转林导致的模拟出水量减少比转草地更明显，但沉积物产量的减少量相似。结果表明，这一时期的“以粮换绿”实践可有效防止水土流失。使用ArcGIS的空间分析表明，由于农田转林导致的模拟出水量减少比转草地更明显，但沉积物产量的减少量相似。结果表明，这一时期的“以粮换绿”实践可有效防止水土流失。