Shallow lakes in the semi-arid climate zone of the Mediterranean are sensitive to drought due to the low annual precipitation and high evaporation. Changes in precipitation and temperature as projected by climate change scenarios will have an effect on the hydrology of these shallow lakes with secondary effects on nutrient dynamics and ecological state. In this study, we used a combined modelling approach that included the catchment model Soil and Water Assessment Tool (SWAT) and the lake model PCLake to study the possible effects of several climate scenarios on a shallow lake in semi-arid central Anatolia, Turkey. Our results show that lower precipitation and higher temperatures may reduce inflow rates and water levels drastically. Diffuse nutrient loading depended highly on precipitation and thus decreased as well. The lake model predicts an interaction between external nutrient loading and water levels. Low water levels benefited submerged macrophytes if nutrient concentrations were low, but low inflow rates and high evaporation during dry periods increased in-lake nutrient concentrations and chlorophyll-a. Cyanobacteria biomass was also higher in the drier and warmer scenarios. Overall, the results show that lower hydraulic loads and reduced flushing rates as a result of drier and warmer conditions lead to lower water levels and higher in-lake nutrient concentrations unless nutrient loading decreased as well. This implies that catchment-scale nutrient management is essential to maintain low nutrient concentrations in the lakes with increasing temperature and decreasing precipitation in a dry climate.

中文翻译：

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气候变化对地中海浅湖的影响：基于集水区和湖泊模型的见解

由于年降水量少和蒸发量高，地中海半干旱气候区的浅湖对干旱敏感。气候变化情景预测的降水和温度变化将对这些浅水湖泊的水文状况产生影响，并对养分动态和生态状况产生次要影响。在这项研究中，我们使用了包括流域模型土壤和水评估工具（SWAT）和湖泊模型PCLake在内的组合建模方法，以研究几种气候情景对土耳其半干旱中部安纳托利亚中部浅湖的可能影响。我们的结果表明，较低的降水量和较高的温度可能会大大降低流入量和水位。分散的养分含量在很大程度上取决于降水，因此也有所减少。湖泊模型预测外部养分负荷与水位之间的相互作用。如果养分浓度低，则低水位会使淹没的大型植物受益，但干旱时期的低流入量和高蒸发量会增加湖内养分浓度和叶绿素-a。在较干燥和较热的情况下，蓝细菌的生物量也较高。总体而言，结果表明，由于干燥和温暖的条件导致较低的水力负荷和较低的冲水速率导致较低的水位和较高的湖内营养物浓度，除非营养物负荷也降低。这意味着流域规模的养分管理对于在干旱的气候中随着温度升高和降水减少而保持湖泊中低的养分含量至关重要。