Technical University of Crete, Department of Environmental Engineering, University Campus, 73100 Chania, Greece.
TEI - Athens, Department of Civil Infrastructure Engineering, Agiou Spyridonos, 12210 Aigaleo, Greece.
Sci Total Environ. 2015 Dec 15;538:288-97. doi: 10.1016/j.scitotenv.2015.07.092. Epub 2015 Aug 24.
Mediterranean semi-arid watersheds are characterized by a climate type with long periods of drought and infrequent but high-intensity rainfalls. These factors lead to the formation of temporary flow tributaries which present flashy hydrographs with response times ranging from minutes to hours and high erosion rates with significant sediment transport. Modeling of suspended sediment concentration in such watersheds is of utmost importance due to flash flood phenomena, during which, large quantities of sediments and pollutants are carried downstream. The aim of this study is to develop a modeling framework for suspended sediment transport in a karstic watershed and assess the impact of climate change on flow, soil erosion and sediment transport in a hydrologically complex and intensively managed Mediterranean watershed. The Soil and Water Assessment Tool (SWAT) model was coupled with a karstic flow and suspended sediment model in order to simulate the hydrology and sediment yield of the karstic springs and the whole watershed. Both daily flow data (2005-2014) and monthly sediment concentration data (2011-2014) were used for model calibration. The results showed good agreement between observed and modeled values for both flow and sediment concentration. Flash flood events account for 63-70% of the annual sediment export depending on a wet or dry year. Simulation results for a set of IPCC "A1B" climate change scenarios suggested that major decreases in surface flow (69.6%) and in the flow of the springs (76.5%) take place between the 2010-2049 and 2050-2090 time periods. An assessment of the future ecological flows revealed that the frequency of minimum flow events increases over the years. The trend of surface sediment export during these periods is also decreasing (54.5%) but the difference is not statistically significant due to the variability of the sediment. On the other hand, sediment originating from the springs is not affected significantly by climate change.
地中海半干旱流域的气候类型特点是干旱期长，降雨稀少但强度大。这些因素导致形成了暂时性的支流，其形成的洪水过程具有反应时间从几分钟到几个小时不等、侵蚀率高且携带大量泥沙的特点。由于洪水现象，大量泥沙和污染物被携带到下游，因此对这种流域的悬浮泥沙浓度进行建模非常重要。本研究的目的是建立一个岩溶流域悬浮泥沙输移模型，并评估气候变化对水文复杂且管理密集的地中海流域的流量、土壤侵蚀和泥沙输移的影响。采用土壤和水评估工具 (SWAT) 模型与岩溶水流和悬浮泥沙模型耦合，模拟岩溶泉和整个流域的水文学和泥沙产沙量。模型校准采用了 2005-2014 年的日流量数据和 2011-2014 年的月泥沙浓度数据。结果表明，流量和泥沙浓度的观测值与模拟值吻合良好。洪峰事件占年输沙量的 63-70%，这取决于当年是旱年还是涝年。一组 IPCC“A1B”气候变化情景的模拟结果表明，在 2010-2049 年和 2050-2090 年期间，地表流量（69.6%）和泉水流量（76.5%）将大幅减少。对未来生态流量的评估表明，最小流量事件的频率多年来一直在增加。在这些时期，地表泥沙输出的趋势也在减少（54.5%），但由于泥沙的变化，差异并不具有统计学意义。另一方面，泉水产生的泥沙受气候变化的影响不显著。
