Year Established: 2014 Start Date: 2014-03-01 End Date: 2015-02-28
Total Federal Funds: $22,272 Total Non-Federal Funds: $40,515
Principal Investigators: Ashley Helton
Abstract: Nitrogen (N) export from streams and rivers to coastal areas, including the Long Island Sound, is a primary cause of seasonal hypoxia, or dead zones. Nonpoint sources of N, particularly during storm events, can contribute substantially to excessive N loads, but predicting where and when nonpoint source N loading occurs from landscapes is difficult. Increases in surface water runoff and associated issues have already been experienced in our region, and future increases in runoff intensity will require storm water treatment strategies that better correspond with locations and timing of large N fluxes from the landscape. Thus, in this proposal we ask: How do storm magnitude, intensity, and frequency affect the magnitude and distribution of N export? And, how do those relationships change with land use conditions, specifically with urban development? To answer these questions, we will measure how both the distribution and overall magnitude of N flux vary within and among storm events and between land uses. Our objectives are to quantify 1) the temporal distribution of N flux and 2) the magnitude of N flux within discrete storm events, and then to compare the temporal distributions and magnitudes of N fluxes 1) across storm events that vary in their magnitude, seasonal timing, and antecedent conditions, and 2) across catchments that vary in their impervious cover. We will select five 2nd to 3rd order streams that range in their catchment land covers from undisturbed to highly developed. For each stream, we will measure continuous stream discharge and nitrogen (ammonium, nitrate, dissolved, and particulate) concentrations during biweekly grab samples and automated flow-weighted storm sampling. We will quantify the relationships within each catchment between N fluxes (magnitude and distribution) and storm characteristics (magnitude, intensity, duration). We will evaluate how the “first flush” response of N loading to storms, the relative amount of N load that occurs during the beginning of a storm, changes with storm characteristics and land use. This research addresses a critical scientific management need for expanding our understanding of N export to include storm events in Connecticut streams, and these results will be directly relevant for future planning of storm water management under a changing climate that includes more intense storm events.