Calculation of Dry Weather Flows in Pumping Stations to Identify Inflow and Infiltration in Urban Drainage Systems

The performance of most urban drainage systems is adversely affected by unintended connections of groundwater and surface water, often denoted as inflow and infiltration (I&I). Various methods exist to locate and characterise these effects. Yet, it remains difficult to quantify them accurately, especially in terms of spatial distribution over a larger drainage area. One of the reasons for this is the lack of sufficient high-quality sewer flow measurements at a high temporal resolution, which would enable the calibration of detailed spatio-temporal relationships between rainfall and I&I flows. In this paper, a methodology is presented for deriving sewer flow time series from operational measurements at pumping stations, and the results from four pilot locations are discussed. It shows the potential of the methodology to be implemented at a large scale and to contribute to a better understanding and remediation of I&I in urban drainage management planning.

Automated summary

The performance of urban drainage systems is negatively impacted by unintended connections of groundwater and surface water, known as inflow and infiltration (I&I). Although various methods exist to locate and characterize these effects, accurately quantifying them, particularly in terms of spatial distribution over a large drainage area, remains challenging. This is partly due to the lack of sufficient high-quality sewer flow measurements at a high temporal resolution. This paper presents a methodology for deriving sewer flow time series from operational measurements at pumping stations and discusses the results from four pilot locations, highlighting the potential of the methodology for large-scale implementation and its contribution to better understanding and remediation of I&I in urban drainage management planning.