Monitoring of an urban level spreader as part of the collaborative adaptive management process

Abstract

Irregular flows, such as the high flows caused by stormwater runoff after a rain event are a major cause of stream impairment in urbanized watersheds. The Hinkson Creek CAM (Collaborative Adaptive Management) approach is doing long-term monitoring of a level spreader system in the Hinkson Creek watershed to determine the effectiveness of this stormwater best management practice (BMP) as a method to regulate flow in asmall tributary to Hinkson Creek by forcing more infiltration and evaporation of urban stormwater runoff. Monitoring equipment placed at the site measures the level of water in the level spreader basin and swale, and climate data including precipitation, temperature and solar radiation. Measurements taken by the equipment are used together to characterize behavior of water as it moves through the level spreader system after a rain event, and to begin to define the water balance into and out of the level spreader. Based on measurements collected from 2016 to the present, the level spreader functions well to increase infiltration and decrease outflow of water to the tributary. By diverting water from the stream and into the level spreader, higher flows in the stream during rain events are reduced. We will present methodology used to estimate a water balance for the level spreader system, and how the results of this study may inform where "urban" level spreaders may be used to improve hydraulics of a watershed.