Water age dynamics in a Mediterranean catchment and their ecohydrological implications in a changing environment

迫切需要评估地中海山区集水区的相关水文过程及其可能因土地利用和气候变化而改变的供水功能。因此，我将与巴塞罗那IDAEA-CSIC的东道主机构合作，研究在西班牙Vallcebre的长期研究流域中，植被、土壤和地下水如何通过径流和蒸散影响集水区的蓄水、混合和释放水。IDAEA-CSIC小组收集了不同水文集水区的水文和稳定同位素(d2H，d18O)数据，包括降雨、穿透雨、树干径流、溪流、地下水、土壤和植被的水。我计划使用这个广泛的数据集来应用最近提出的旅行时间估计方法，以提高我们对流域内水流和运输的理解。我将首先测试存储选择函数(Rinaldo等人，2015)如何帮助描述高度时变的集水通量(径流和蒸散)。然后，我的目标是应用“年轻含水率”(基什内尔，2016)和“新含水率”(基什内尔，2017)的新概念来更好地描述旅行时间分布的短期组成部分。这些方法尚未在地中海环境中进行测试，但Vallcebre流域的大量数据集可以解释目前流域同位素水文学中的问题：如何通过高降雨-径流采样频率并考虑穿透雨/干径流、根吸水量和土壤水流动来改进水龄研究？最后，我将包括土壤水同位素深度剖面，以约束示踪剂辅助的模型，并将土壤中的旅行时间与集水区的旅行时间联系起来。后者是我博士论文的后续，目前正在进行博士后工作。

There is an urgent need to assess the relevant hydrological processes of Mediterranean mountain catchments and their potential altered functioning for the water supply due to land-use and climate changes. I will, therefore, study in collaboration with the host institution from the IDAEA-CSIC in Barcelona, how vegetation, soils and groundwater influence the catchment storage, mixing and release of water via runoff and evapotranspiration in the long-term research catchments in Vallcebre, Spain.The group of IDAEA-CSIC gathered hydrometric and stable isotope (d2H, d18O) data of the different hydrological catchment compartments, including the water of rainfall, throughfall, stemflow, stream, groundwater, soils and vegetation. I plan to use this extensive data set to apply recently proposed methods for travel time estimations to improve our understanding of the water flow and transport within the catchment. I will first test how Storage Selection functions (Rinaldo et al., 2015) can help to describe the highly time variable catchment water fluxes (runoff and evapotranspiration). Then, I aim to apply the new concepts of “young water fraction” (Kirchner, 2016) and “new water fraction” (Kirchner, 2017) to better describe the short-term component of the travel time distribution. These methods have not yet been tested for Mediterranean environments, but the extensive data set for the Vallcebre catchments allows accounting for current questions in catchment isotope hydrology: How can water age studies be improved by high rainfall-runoff sampling frequency and taking throughfall/stemflow, root water uptake and soil water flow into account? Finally, I will include soil water isotope depth profiles to constrain tracer-aided models and relate travel times in the soil to catchment travel times. The latter is a follow up to my PhD thesis and currently ongoing postdoctoral work.