Implications of Vegetation Dynamics for Semi-Arid Hydrology: A Basis for Predicting Climate Impacts on Water Resources

植被动态对半干旱水文的影响：预测气候对水资源影响的基础[i]: John D. Albertson，杜克大学合作者：Nicola Montaldo，意大利卡利亚里大学摘要：本项目研究半干旱地中海流域的耦合生态水文动力学，其中雨季地表饮用水水库几乎完全依赖于地面水流，植被生长受到水分限制。动机集中在观测到的和预估的冬季降水减少，这是由大尺度大气环流模式的变化引起的。目前，预测这些系统未来水文行为的能力受到对植被覆盖变化如何与降水动力学相互作用以控制水文响应的理解差距的限制。拟议的研究将在撒丁岛的一个研究盆地中测试一组五个重点假设，该盆地已经配备了仪器，并广泛代表了半干旱的地中海流域。该项目建立在PI和意大利合作者过去几年在地中海第二大岛屿撒丁岛进行的实验和模型研究的基础上。该项目将增加坡面流试验，以捕捉不同草被和降雨强度对入渗和产流的影响。分析将在三个重叠的时间段进行，分别是：1)密集野外试验记录（~ 5+年），2)卫星记录（~ 20+年），3)径流和降水记录（~ 80年）。分析将包括入渗和蒸散之间可能的权衡。智力价值：该项目旨在揭示季节性降水模式的变化和变异如何激发植被动态，以及这些变化如何反过来影响半干旱流域的水文收支。开发的工具将能够严格预测生态水文系统对气候强迫的反应。这些结果与大尺度环流指数的联系有望提高季节时间尺度上的可预测性。此外，地中海气候（如加利福尼亚）的广泛流行简化了方法和结果的可转移性。更广泛的影响：拟议活动的结果将为在面对地中海降水制度的系统变化时规划水资源需求提供直接支持。本项目培养的本科生和博士生将有广泛而有意义的跨学科研究经验，包括在国外的合作时期。初步的努力是由杜克大学对PI的启动支持资助的。杜克大学将为本科生研究员提供资助（普拉特奖学金）。

Implications of Vegetation Dynamics for Semi-Arid Hydrology: A Basis for Predicting Climate Impacts on Water ResourcesPI: John D. Albertson, Duke UniversityCollaborator: Nicola Montaldo, University of Cagliari, ItalyAbstract:This project addresses the coupled eco-hydrologic dynamics of semi-arid Mediterranean watersheds, where the surface drinking-water reservoirs depend almost exclusively on overland flow in the rainy season and where the vegetation growth is water limited. The motivation centers on the observed and projected decreases in winter rainfall, stemming from shifts in large-scale atmospheric circulation patterns. Presently, the ability to predict future hydrologic behavior of these systems is limited by gaps in understanding of how changes in the vegetation cover interact with precipitation dynamics to control the hydrological response. The proposed research will test a set of five focused hypotheses in a Sardinian study basin that is already instrumented and broadly representative of semi-arid Mediterranean watersheds. This project builds on experimental and modeling studies that the PI and Italian collaborator have been conducting for the past several years on Sardinia, the second largest island in the Mediterranean. This project would add overland flow experiments to capture the effect of variable grass cover and rainfall intensity on infiltration and runoff generation. Analysis will be conducted over three overlapping time periods, representing: 1) the intensive field experiment record (~ 5+ years), 2) the satellite record (~ 20+ years), and 3) the streamflow and precipitation record (~ 80 years). Analysis will include possible tradeoffs between infiltration and evapotranspiration. Intellectual Merit: This project is designed to reveal how change and variability in seasonal precipitation patterns excite vegetation dynamics and how these changes in turn impact the hydrological budget of semi-arid watersheds. The tools developed will enable rigorous prediction of the response of eco-hydrological systems to climate forcing. The connection of the results to the large-scale circulation indices is expected to lead to improved predictability at the seasonal time scale. Furthermore, the broad prevalence of Mediterranean climates (e.g. California) simplifies the transferability of the approach and findings.Broader Impacts: The results of the proposed activity will provide direct support for planning water resources needs in the face of systematic changes in Mediterranean precipitation regimes. The undergraduate and Ph.D. students trained on this project will experience broad and meaningful interdisciplinary research experience, including collaborative periods abroad. Preliminary efforts were funded by Duke start-up support to the PI. Duke will provide funding (Pratt Fellowship) for summer support of the undergraduate student researcher.