Biology Centre of the Czech Academy of Sciences, v.v.i., Institute of Hydrobiology, Na Sádkách 7, České Budějovice 37005, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 31, České Budějovice 37005, Czech Republic.
Biology Centre of the Czech Academy of Sciences, v.v.i., Institute of Hydrobiology, Na Sádkách 7, České Budějovice 37005, Czech Republic.
Sci Total Environ. 2018 May 15;624:24-33. doi: 10.1016/j.scitotenv.2017.12.061. Epub 2017 Dec 12.
Man-made reservoirs are common across the world and provide a wide range of ecological services. Environmental conditions in riverine reservoirs are affected by the changing climate, catchment-wide processes and manipulations with the water level, and water abstraction from the reservoir. Long-term trends of environmental conditions in reservoirs thus reflect a wider range of drivers in comparison to lakes, which makes the understanding of reservoir dynamics more challenging. We analysed a 32-year time series of 36 environmental variables characterising weather, land use in the catchment, reservoir hydrochemistry, hydrology and light availability in the small, canyon-shaped Římov Reservoir in the Czech Republic to detect underlying trends, trend reversals and regime shifts. To do so, we fitted linear and piecewise linear regression and a regime shift model to the time series of mean annual values of each variable and to principal components produced by Principal Component Analysis. Models were weighted and ranked using Akaike information criterion and the model selection approach. Most environmental variables exhibited temporal changes that included time-varying trends and trend reversals. For instance, dissolved organic carbon showed a linear increasing trend while nitrate concentration or conductivity exemplified trend reversal. All trend reversals and cessations of temporal trends in reservoir hydrochemistry (except total phosphorus concentrations) occurred in the late 1980s and during 1990s as a consequence of dramatic socioeconomic changes. After a series of heavy rains in the late 1990s, an administrative decision to increase the flood-retention volume of the reservoir resulted in a significant regime shift in reservoir hydraulic conditions in 1999. Our analyses also highlight the utility of the model selection framework, based on relatively simple extensions of linear regression, to describe temporal trends in reservoir characteristics. This approach can provide a solid basis for a better understanding of processes in freshwater reservoirs.
人工水库在世界各地很常见，提供了广泛的生态服务。河流型水库的环境条件受到气候变化、集水区范围内的过程以及水位调控和水库取水等因素的影响。与湖泊相比，水库环境条件的长期趋势反映了更广泛的驱动因素，这使得水库动态的理解更加具有挑战性。我们分析了捷克共和国小型峡谷型里姆诺夫水库 36 个环境变量的 32 年时间序列，这些变量描述了天气、集水区土地利用、水库水化学、水文学和光照条件，以检测潜在的趋势、趋势反转和状态变化。为此，我们使用线性和分段线性回归以及状态转移模型拟合了每个变量的年平均值时间序列和主成分分析生成的主成分时间序列。使用 Akaike 信息准则和模型选择方法对模型进行加权和排名。大多数环境变量表现出时间变化，包括时变趋势和趋势反转。例如，溶解有机碳呈线性增加趋势，而硝酸盐浓度或电导率则表现出趋势反转。水库水化学中所有的趋势反转和时间趋势的停止（总磷浓度除外）都发生在 20 世纪 80 年代末和 90 年代，这是由于社会经济的急剧变化。20 世纪 90 年代末的一系列暴雨之后，由于行政决定增加水库的防洪蓄水量，1999 年水库水力条件发生了显著的状态变化。我们的分析还突出了基于相对简单的线性回归扩展的模型选择框架来描述水库特征的时间趋势的实用性。这种方法可以为更好地理解淡水水库的过程提供坚实的基础。
