Flooding of the sewage system is an environmental hazard often caused by illegal connections between drainage and sewage systems. The timely detection of such illicit connections, often done by property owners in an attempt to remove rainwater promptly from their private courtyards, is a complex task due to the high cost of field surveying and limited manpower of environmental law-enforcement authorities. This paper suggests an empirical approach to the identification and characterization of localities with an elevated likelihood of illegal connections between runoff and sewage systems. The proposed approach is implemented in three stages. First, the association between rainfall and the amount of wastewater arriving to sewage treatment facilities from different localities is analyzed. Next, regression residuals are investigated, to identify localities with an especially strong association between the amount of rainfall and sewage surplus. The identified localities are then analyzed, to determine their geographic location, physical and socioeconomic attributes. In the present study, the proposed approach is tested using data for 623 urban and rural localities in Israel. As the study shows, the probability of association between the amount of rainfall and sewage surplus, which we consider as an indicator of pirate connections between drainage and sewage systems, tends to increase as a function of socioeconomic welfare of the local residents, surface slope, and the level of urbanization. The proposed approach can help law-enforcement authorities to focus their efforts on specific locations and to reduce economic and environmental damages associated with illegal connections between drainage and sewage systems.

中文翻译：

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径流和污水系统之间存在非法连接的可能性很高的地区特征

污水系统泛滥是一种环境危害，通常由排水系统和污水系统之间的非法连接引起。由于实地调查的成本高昂和环境执法部门的人力有限，及时发现此类非法连接（通常由业主试图从其私人庭院中迅速清除雨水）是一项复杂的任务。本文提出了一种经验方法来识别和表征具有较高的径流和污水系统之间非法连接可能性的地方。建议的方法分三个阶段实施。首先，分析降雨量与从不同地方到达污水处理设施的废水量之间的关系。接下来，研究回归残差，确定降雨量和污水盈余之间具有特别强关联的地方。然后分析确定的地点，以确定它们的地理位置、物理和社会经济属性。在本研究中，所提出的方法使用以色列 623 个城市和农村地区的数据进行了测试。正如研究表明的那样，降雨量和污水盈余之间的关联概率，我们认为这是排水和污水系统之间海盗联系的一个指标，随着当地居民的社会经济福利、地表坡度、和城市化水平。