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，植被恢复在控制水土流失方面取得了成效，但同时黄河主要支流的出水量急剧减少。这导致了一场新的辩论，特别是关于森林发展的辩论。温度升高和降水减少也可能导致产水量减少。制定土地利用和水资源综合管理办法的关键是了解和区分对土地利用和气候变化的水文反应。本研究将在从单树到流域的多个尺度上，选择具有该地区典型植被的样地，研究并持续监测水分平衡成分、植被结构动态和土壤水力特性。我们的研究将在黄河重要支流泾河的半湿润/半干旱过渡区进行。我们在一个具有代表性的次盆地的上游/下游情况下，在地块和流域的尺度上采用嵌套方法。在我们测量的基础上，基于过程的模型BROOK90将被用于预测根据地形和土壤条件对气候和植被变化的水量响应。从地块研究中获得的结果将用于参数化分布式模型SWIM。下一步，将把SWIM应用于集水区排放，并评估不同土地用途和植被管理对水量的影响。这项评估将为通过森林管理恢复植被可以改变多少集水区提供坚实的基础，以维持一定程度的供水安全，从而确保更可持续的区域发展。

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.