A New Method of Predicting Rainfall Dependent Inflow and Infiltration
There are many hydrological models available to quantitatively characterize rainfall dependent inflow and infiltration (RDII) in a sanitary sewer system, most of which were first derived for quantifying rainfall surface runoff process and later found many applications in studying the issues of combined sewer overflows (CSO). However, it has been long recognized that profound differences do exist between sanitary sewer overflows and combined sewer overflows from the perspective of their duration and unique pattern, which renders the application of existing hydrological methods, such as SWMM routing, to sanitary sewer overflow a challenge, sometimes even unattainable goal. This paper is written to introduce a new methodology to predict rainfall dependent inflow and infiltration, and compare its pros and cons to the existing methods. The “ground infiltration” model proves to be highly effective and efficient in simulating
sanitary sewer overflow in exceedingly porous system with surprisingly long duration as demonstrated in the case study.