Selge F, Matta E, Hinkelmann R, Gunkel G
Department of Water Quality Control, Technical University of Berlin, Straße des 17. Juni 135, Berlin 10623, Germany E-mail:
Chair of Water Resources Management and Modeling of Hydrosystems, Technical University of Berlin, Gustav-Meyer-Allee 25, Berlin 13355, Germany.
Water Sci Technol. 2016 Oct;74(7):1671-1679. doi: 10.2166/wst.2016.342.
Large flow-through reservoirs and lakes possess environmental gradients and monitoring programs are mostly adapted for cost and time effectiveness. Bay areas are often more isolated from the main water body and are likely to have unobserved different environmental processes and impacts. This study was performed at the Itaparica Reservoir, São Francisco River, located in semi-arid Northeast Brazil, with dendritic form. Water residence time in the Icó-Mandantes Bay was estimated by hydrodynamic flow and transport simulations. The P-chlorophyll a relationship was used to develop the P use efficiency coefficient for critical P load estimation of 25 μg P L. Phosphorus sources and input rates into a bay and the respective reservoir were calculated and compared regarding their different origins for the period after flooding (1988) and for 2013. After impoundment, the P load highly exceeded the carrying capacity because of leaching and mineralization processes. In 2013, P inputs were still above this threshold, whereas inflow and sub-basin P export during the rainy season were crucial. But eutrophication processes have increased in the bay relative to the main water body. Hence, water in hydraulic isolated parts is prone to eutrophication processes, thus, bays have to be specially considered in water resource management.
大型径流水库和湖泊具有环境梯度，监测计划大多是为了成本和时间效益而制定的。湾区通常与主要水体隔离程度更高，可能存在未被观测到的不同环境过程和影响。本研究在位于巴西东北部半干旱地区、呈树枝状的圣弗朗西斯科河伊塔帕里卡水库进行。通过水动力流动和输运模拟估算了伊科-曼丹特斯湾的水停留时间。利用磷与叶绿素a的关系来确定磷利用效率系数，以估算25μg P/L的临界磷负荷。计算并比较了洪水后时期（1988年）和2013年湾区及相应水库的磷源和输入速率，考虑了它们不同的来源。蓄水后，由于淋溶和矿化过程，磷负荷大大超过了承载能力。2013年，磷输入仍高于该阈值，而雨季的入流和次流域磷输出至关重要。但相对于主要水体，湾区的富营养化过程有所增加。因此，水力隔离区域的水体容易发生富营养化过程，所以在水资源管理中必须特别考虑湾区。
