Abstract Land use change is one of the dominant driving factors of hydrological change at the watershed scale. Thus, understanding the hydrological responses to land use changes can facilitate development of sustainable water resource management. The land use of the Wei River (the largest tributary of the Yellow River) Basin (WRB) has changed greatly due to the large-scale ecological restoration program in the Chinese Loess Plateau (e.g., grain-for-green program), causing dramatic impacts on the water cycle. This study was to simulate the impacts of land use and land cover change (LUCC) on the key hydrological components, using the Soil and Water Assessment Tool (SWAT). We investigated the spatiotemporal changes of LUCC from 1980 to 2010 in terms of four sub-regions (i.e., three subbasins and one mid-downstream area) and three landforms (i.e., mountain, hill, and plain), respectively. Then, we quantified the spatial heterogeneity of hydrological responses to land use change scenarios. Our LUCC analysis showed that cropland declined by about 0.8%, from 58,776 km2 in 1980 to 57,519 km2 in 2010, whereas the forest and grassland areas correspondingly increased 552 km2 and 16 km2, respectively. The urban area changed more dramatically in the middle and lower reaches of the Wei River owing to the faster socioeconomic development in this region than the rest areas. In mountain area, the main types of land use were forest and grassland, and the main transformation was from cropland to forest land and grassland. The area of cropland in plain could be over 50%, and it was mainly converted to urban land. The hydrological simulation indicated that LUCC from 1980 to 2010 caused 5.3% of decrease in the water yield and 6.2% increase in soil water content, but there was nearly no change in evapotranspiration (ET). Scenarios about slopping land use conversion (SLC) program showed that the conversion of cropland to grassland or forest (i.e., grain-for-green) resulted in negative effects on soil water content and water yield, with a greater effect by the reforestation. In addition, we found that the change of ET was clear in areas where cropland with slope > 15° was converted to grassland or forest, suggesting slope is also an important factor for hydrological responses to LUCC. This study can provide valuable decision support for land use planning and water resources protection in the WRB.

中文翻译：

---

黄土高原南部典型流域土地利用转换对水循环的影响

摘要 土地利用变化是流域尺度水文变化的主导驱动因素之一。因此，了解对土地利用变化的水文响应可以促进可持续水资源管理的发展。黄河最大支流渭河流域（WRB）的土地利用，由于黄土高原大规模生态修复工程（如以粮换绿），发生了巨大变化。对水循环的影响。本研究旨在使用土壤和水评估工具 (SWAT) 模拟土地利用和土地覆盖变化 (LUCC) 对关键水文组成部分的影响。我们从 4 个子区域（即 3 个子流域和 1 个中下游区域）和 3 个地貌（即，山、丘陵和平原），分别。然后，我们量化了水文响应对土地利用变化情景的空间异质性。我们的 LUCC 分析表明，耕地面积减少了约 0.8%，从 1980 年的 58,776 平方公里减少到 2010 年的 57,519 平方公里，而森林和草地面积分别相应增加了 552 平方公里和 16 平方公里。渭河中下游城区由于社会经济发展较其他地区快，因此城区变化更为剧烈。山区土地利用类型主要为林地和草地，主要由耕地向林地和草地转变。平原耕地面积可达50%以上，主要转化为城市用地。水文模拟表明，1980-2010年LUCC造成了5次。产水量减少 3%，土壤含水量增加 6.2%，但蒸散量（ET）几乎没有变化。坡地土地利用转换（SLC）计划的情景表明，农田转为草地或林地（即以粮换绿）对土壤含水量和产水量产生了负面影响，其中重新造林的影响更大。此外，我们发现坡度> 15°的农田转变为草地或森林的地区ET变化明显，表明坡度也是LUCC水文响应的重要因素。本研究可为水利局土地利用规划和水资源保护提供有价值的决策支持。坡地土地利用转换（SLC）计划的情景表明，农田转为草地或林地（即以粮换绿）对土壤含水量和产水量产生了负面影响，其中重新造林的影响更大。此外，我们发现坡度> 15°的农田转变为草地或森林的地区ET变化明显，表明坡度也是LUCC水文响应的重要因素。本研究可为水利局土地利用规划和水资源保护提供有价值的决策支持。坡地土地利用转换（SLC）计划的情景表明，农田转为草地或森林（即以粮换绿）对土壤含水量和产水量产生了负面影响，其中重新造林的影响更大。此外，我们发现坡度> 15°的农田转变为草地或森林的地区ET变化明显，表明坡度也是LUCC水文响应的重要因素。本研究可为水利局土地利用规划和水资源保护提供有价值的决策支持。我们发现坡度> 15°的农田转变为草地或森林的地区ET变化明显，表明坡度也是LUCC水文响应的重要因素。本研究可为水利局土地利用规划和水资源保护提供有价值的决策支持。我们发现坡度> 15°的农田转变为草地或森林的地区ET变化明显，表明坡度也是LUCC水文响应的重要因素。本研究可为水利局土地利用规划和水资源保护提供有价值的决策支持。