Water yield response to changes in land-use and climate in a semihumid/-arid transition region (Jinghe basin, Northwest China)

近几十年来，植被恢复对控制土壤侵蚀是有效的，但伴随而来的是黄河主要支流产水量的急剧减少。这导致了一场新的辩论，特别是关于森林发展的辩论。气温升高和降水减少也可能是导致产水量减少的原因之一。制定土地利用和水资源综合管理办法的一个关键是了解和区分对土地利用和气候变化的水文反应。在这项研究中，将在从单木到流域的多个尺度上，在选定的具有该地区典型植被的样地上调查和持续监测水分平衡成分、植被结构动态和土壤水力特性。本研究将在黄河重要支流--泾河半湿润/半干旱过渡区开展。在一个有代表性的子流域中，我们沿着上游/下游情况对地块和流域的比例采用嵌套方法。在我们测量的基础上，将实施面向过程的模型BROOK90，以根据地形和土壤条件预测气候和植被变化对产水量的响应。从小区研究中获得的结果将被用于分布式模型游泳的参数化。下一步，将在集水区的排水口安装SWIFE，并评估不同土地利用和植被管理对产水量的影响。这项评估将为通过森林管理恢复植被以维持一定程度的供水安全以确保更可持续的区域发展而改变多少集水区提供坚实的基础。

The effort of vegetation restoration in recent decades has been effective for soil erosion control, but accompanied by a drastic reduction of water yield in the main tributaries of the Yellow River. This has led to an emerging debate notably about forest development. Increased temperature and decreased precipitation may also have contributed to water yield reduction. An essential key for developing an integrated land-use and water management approach is to understand and separate the hydrological response to changes in land use and climate. In this study on multiple scales ranging from single tree to watershed, water balance components, vegetation structure dynamics, and soil hydraulic properties will be investigated and continuously monitored on selected plots with vegetation typical to the region. Our research will be carried out in the semihumid/-arid transition region of Jinghe which is an important tributary of the Yellow River. We follow a nested approach on scales of plots and watersheds along a upstream/downstream situation in a representative subbasin. On the basis of our measurements, the process-oriented model BROOK90 will be implemented for predicting the water yield response to changes in climate and vegetation depending on relief and soil conditions. The results obtained from plot studies will be used to parameterize the distributed model SWIM. In a next step, SWIM will be fitted to the catchment discharge and to assess the effect of different land use and vegetation management on water yield. This assessment will provide a solid foundation for how much of the catchment area can be changed by vegetation restoration through forest management to maintain a certain level of water supply security that will ensure a more sustainable regional development.