Urban hydrological modeling of the Malden River using the Storm Water Management Model (SWMM)

Abstract

The portion of the Malden River in Malden, Massachusetts, has a long history of industrial activity and urbanization, which has degraded the water quality and ecosystem of the River. Following years of water quality testing, community groups are concerned about the River's current state of ecological health and its safety for recreational use. A first step to understanding the River's current state is to understand its hydrology and the effect of rainfall on stormwater discharge to the River. This thesis develops a site specific model to characterize runoff from rainfall as it flows across the watershed, through the drainage system, and into the River. The Storm Water Management Model (SWMM), developed by the Environmental Protection Agency (EPA), was used because it was deemed the most appropriate of the readily available models for this urban setting. This model characterizes the impervious nature of the land surface in the study site. Both the Curve Number and Green-Ampt infiltration methods were used for the runoff processes, with the Curve Number methods producing higher runoff values. For the hydraulic processes used to calculate flow in the drainage system, kinematic wave routing was used. The results showed substantial internal flooding within the drainage system. Since such flooding has not been observed, this is an indication that the hydraulics portion of this model requires further refinement in order to achieve fully accurate simulation. However, this model does achieve the goal of providing insight into the watershed's hydrology, and develops a foundation from which more robust analyses can done to model water quality and pollutant loadings, which may be used in support of remediation strategies for the Malden River.