Department of Aquatic Ecosystem Analysis, Helmholtz-Centre for Environmental Research - UFZ, Brückstraße 3a, 39114, Magdeburg, Germany.
Institute of Urban Water Management, Technische Universität Dresden, Bergstraße 66, 01069, Dresden, Germany.
Environ Monit Assess. 2023 Nov 23;195(12):1517. doi: 10.1007/s10661-023-12027-6.
Leaky urban drainage networks (UDNs) exfiltrating wastewater can contaminate aquifers. Detailed knowledge on spatiotemporal distributions of water-dissolved, sewer-borne contaminants in groundwater is essential to protect urban aquifers and to optimize monitoring systems. We evaluated the effect of UDN layouts on the spreading of sewer-borne contaminants in groundwater using a parsimonious approach. Due to the UDN's long-term leakage behavior and the existence of non-degradable sewer-borne contaminants (equivalent to a conservative and constant contaminant source), we employed a concept of horizontal line sources to mimic the UDN layout. This does not require the consideration of bio-degradation processes or temporal delay and effectively bypasses the vadose zone, thus reducing computational requirements associated with a full simulation of leakages. We used a set of synthetic leakage scenarios which were generated using fractals and are based on a real-world UDN layout. We investigated the effects of typical leakage rates, varying groundwater flow directions, and UDN's layouts on the shape of the contaminant plume, disregarding the resulted concentration. Leakage rates showed minimal effects on the total covered plume area, whereas 89% of the variance of the plume's geometry is explained by both the UDN's layout (e.g., length and level of complexity) and groundwater flow direction. We demonstrated the potential of applying this approach to identify possible locations of groundwater observation wells using a real UDN layout. This straightforward and parsimonious method can serve as an initial step to strategically identify optimal monitoring systems locations within urban aquifers, and to improve sewer asset management at city scale.
渗漏的城市排水管网（UDN）渗出的废水可能会污染含水层。详细了解地下水中文献中溶解在水中的、来自污水的污染物的时空分布情况，对于保护城市含水层和优化监测系统至关重要。我们采用简约的方法评估了 UDN 布局对污水在地下水扩散的影响。由于 UDN 长期泄漏行为和存在不可降解的污水污染物（相当于保守和恒定的污染物源），我们采用了水平线源的概念来模拟 UDN 布局。这不需要考虑生物降解过程或时间延迟，并且有效地绕过了包气带，从而减少了与完全模拟泄漏相关的计算需求。我们使用了一组基于分形并基于实际 UDN 布局的合成泄漏场景来生成。我们研究了典型泄漏率、不同地下水流动方向和 UDN 布局对污染物羽流形状的影响，而不考虑由此产生的浓度。泄漏率对总覆盖羽流面积的影响最小，而羽流几何形状的 89%的方差由 UDN 的布局（例如，长度和复杂程度）和地下水流动方向解释。我们展示了该方法应用于利用实际 UDN 布局识别地下水观测井可能位置的潜力。这种简单而简约的方法可以作为战略性识别城市含水层中最优监测系统位置的初始步骤，并改善城市规模的污水资产管理。
