THE SYNCHRONIZATION OF STORM DISCHARGE PEAKS AND THEIR ASSOCIATED FLOOD HAZARDS IN A SMALL, URBANIZED WATERSHED IN NEW JERSEY

The study installed a series of depth sensors in the main stem and two tributaries of a small watershed, the Peckman River, in northeastern New Jersey. This small (~30 square kilometers), urbanized watershed has had recent flooding problems, especially with Tropical Storm Irene in 2011. By studying the timing of the flood peaks at different points in the watershed, flood mitigation strategies can be developed to reduce and desynchronize the peaks. The depth sensors, along with two USGS sensors (#01389550 and #01389534) measured water depth every fifteen minutes, recording the rise and fall of the river. Initial data from spring and summer 2014 recorded seven storm events in the watershed. The timing of the storm peak was determined for each rain event at each location. The flood peaks are occurring generally either simultaneously, or within fifteen to thirty minutes of the farthest downstream station. There is a small reservoir in the upper part of the watershed, and the peaks are especially synchronized downstream of it. With the river rising at each of the points almost simultaneously, this would cause the most damage in flooding situations, and synchronized flood peaks also contribute to increased channel erosion, altered aquatic habitats, and other aspects of “urban stream syndrome”. Future data will be collected to determine whether the synchronized flood peaks continue into fall and spring, or whether the synchronized peaks is a seasonal issue. This research project will also propose solutions that would be made specifically for the study areas, however they could be modified for rivers with similar flooding issues and be applied to other areas.