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

目前迫切需要评估地中海山区集水区的有关水文过程及其由于土地利用和气候变化而可能改变的供水功能。因此，我将与巴塞罗那idaa - csic的主办机构合作，研究植被、土壤和地下水如何影响西班牙瓦勒塞布雷长期研究集水区的集水区储存、混合和通过径流和蒸发蒸腾释放水。idaa - 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、通流、干流、溪流、地下水、土壤和植被。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，以提高我们对集水区内水流和运输的理解。我将首先测试存储选择函数（Rinaldo et al., 2015）如何帮助描述高度随时间变化的集水区水通量（径流和蒸散）。然后，我的目标是应用“年轻水分数”（Kirchner, 2016）和“新水分数”（Kirchner, 2017）的新概念来更好地描述旅行时间分布的短期成分。这些方法尚未在地中海环境中进行测试，但是Vallcebre集水区的广泛数据集允许对集水区同位素水文学中当前的问题进行解释：如何通过高降雨径流采样频率和考虑贯穿/茎流、根系水分吸收和土壤水流来改善水年龄研究？最后，我将包括土壤水同位素深度剖面，以约束示踪剂辅助模型，并将土壤中的移动时间与集水区的移动时间联系起来。后者是我博士论文和目前正在进行的博士后工作的后续。

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.