Assessment of current and projected stormwater runoff dynamics before major land use changes at SUNY Purchase College

Abstract

Excess stormwater in urbanized settings is a risk to local ecosystems and inhabitants. Impervious surfaces in urban areas are the largest contributors to excess stormwater, since water cannot be transpired or infiltrate into the ground the way it would in a vegetated space. Current stormwater runoff conditions were analyzed in two sections of the SUNY Purchase College campus, the least-developed of which will be altered during building for the Broadview Senior Living facility. The timing and duration of runoff events was measured on both sites with water level sensors accessed remotely from May through October of 2020. Both sites were assessed for three characteristics of stormwater runoff delay to initial runoff (Di), delay to peak runoff (Dp), and runoff duration (RD). Characteristics of rain were additionally assessed total rain, rainfall average, rain duration, peak rain, and an index of storm size. The results of unpaired t-tests show that runoff from West 2 is faster than East-West Road in many of the characteristics studied. Because expected change in impervious surface at East-West Road is known, predictions were made for future runoff times. Showing that East-West Road will become 25% faster overall and more like West 2 than it is now, which could increase instances of flooding downstream from Purchase without proper abatement.