Department of Hydrology, Faculty of Geography and Regional Studies, University of Warsaw, Krakowskie Przedmieście 30, 00-927 Warsaw, Poland.
Sci Total Environ. 2019 Mar 15;656:458-467. doi: 10.1016/j.scitotenv.2018.11.331. Epub 2018 Nov 23.
Considering the growing recognition that human activity and climate variability are critical stressors influencing river regimes, there is an urgent need to identify the contribution of these fundamental factors. Here we examine the runoff changes of a wastewater-effluent dominated river flowing in a heavily modified urban environment. The study concerns the Utrata River basin (727 km), central Poland, a challenging human-natural system for investigating changes in hydrological processes. The new insights into the present-day functioning of a system are provided through the quantification of runoff changes resulting from the following factors operating simultaneously: climate, wastewater, and urbanization. We adopted and applied the water balance and elasticity-based methods to assess the contribution of particular factors. Climatic data were provided by the gridded observational dataset, while runoff comes from observed daily streamflow values at the stream gauging station. Satellite-derived estimates of evapotranspiration acquired from Operational Simplified Surface Energy Balance (SSEBop) were assimilated into the conceptual framework to provide a robust representation of the system. To determine the changes in urban water budget components, two distinct periods were determined: the baseline period (1951-1960), with a relatively low level of urbanization (9.8%), and the change period (2007-2016), with controlled wastewater inflow and urbanization reaching almost 20%. The results show that in the change period, the mean annual runoff increment attributed to climate variability amounted to 68 mm; the contribution of wastewater inflow - 36 mm; and the contribution attributed to urban-induced changes - -43 mm. Thus, the relative contributions of human activity and climate were estimated as 54% and 46%, respectively. The results demonstrate that in a heavily modified environment, the hydrological effects of human activity can exceed those caused by climate variability. Moreover, wastewater inflow and climate impact can mask decreases in the streamflow induced by urban land fragmentation and land management practices.
考虑到人类活动和气候变化是影响河流状况的关键胁迫因素这一认识不断增强，因此迫切需要确定这些基本因素的贡献。在这里，我们研究了一条在高度人工化的城市环境中流动的以废水为主要来源的河流的径流量变化。本研究涉及波兰中部的乌特拉塔河流域（727 平方公里），这是一个极具挑战性的人-自然系统，可用于研究水文过程的变化。通过量化同时作用的以下因素导致的径流量变化，为当前系统的运行提供了新的见解：气候、废水和城市化。我们采用并应用了水量平衡和弹性方法来评估特定因素的贡献。气候数据由网格化观测数据集提供，而径流量则来自于河流流量站的观测日流量值。从运行简化表面能量平衡（SSEBop）获取的卫星衍生蒸散量估算值被同化到概念框架中，以提供系统的稳健表示。为了确定城市水预算组成部分的变化，确定了两个不同的时期：基线时期（1951-1960 年），城市化水平相对较低（9.8%），以及变化时期（2007-2016 年），该时期控制了废水流入且城市化率达到近 20%。结果表明，在变化时期，归因于气候变率的年平均径流量增量为 68 毫米；废水流入的贡献为 36 毫米；归因于城市化引起的变化的贡献为-43 毫米。因此，分别估计人类活动和气候的相对贡献为 54%和 46%。结果表明，在高度人工化的环境中，人类活动的水文效应可能超过气候变率造成的影响。此外，废水流入和气候变化的影响可以掩盖由于城市土地破碎化和土地管理实践导致的径流量减少。
