Linking elevated rainfall with sewage discharge volume

Abstract

Abstract The intricate hydrological processes elucidating the interplay between rainfall and flow manifest through rainwater's traversal along diverse routes, encompassing surface runoff and subsurface flow. While the foundational association between these entities is discernible, the convoluted intricacies characterizing this correlation defy straightforward comprehension. Examining the data between 2019 and 2022, the average daily sewage outflow was 12,518 m3/d, with occasional peaks of up to 50,440 m3/d. The wastewater treatment plant's capacity of 35,000 m3/d was usually not exceeded. Overall, average daily sewage outflows varied between 11,716 m3/d and 13,969 m3/d during the studied period. Comprehending this interrelationship holds pivotal significance for the optimization of water-resource-management strategies. A moderate correlation (r = 0.42) between daily rainfall levels and sewage discharge was found in the dataset covering 2018–2023. When categorizing daily rainfall into groups labelled “A” through “G” and comparing them to sewage flows, a pattern emerged: Rain-free days in group “A” had the lowest average sewage flow (10,996 m3/d), while heavy rain days in group “G”, had the highest average flow (22,112 m3/d). This observation underscores a significant correlation between intensified rainfall and increased volume of sewage discharge. Through a comprehensive analysis of factors such as sewage composition, meteorological dynamics and chronological sequences, we will gain an enhanced ability to prognosticate and govern sewage systems. The significance of this is heightened within the context of evolving climatic dynamics.