Avgwlf-based estimation of nonpoint source nitrogen loads generated within long island sound subwatersheds

Nickitas Georgas, Srinivasan Rangarajan, Kevin J. Farley, Sarath Chandra K. Jagupilla

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

The Generalized Watershed Loading Functions (GWLF) model and its ArcView interface (AVGWLF) were used to estimate and examine the components of the total nitrogen (TN) nonpoint source (NPS) load generated within New York and Connecticut (CT) watersheds surrounding Long Island Sound (LIS, the Sound). The majority of data used as model inputs were generally available from online sources, and the work involved an overall calibration to streamflow and TN data in accordance with generic guidelines recommended in the GWLF manual. The GWLF model performance for three calibration and two validation watersheds in CT was compared with results of a detailed model, Hydrological Simulation Program in Fortran, developed in a previous study. The results of the application illustrate the usefulness of the relatively simpler, less parameter-intensive GWLF model in performing exploratory loading analysis in preparation for adaptive nutrient management in the LIS watersheds. The presented methodology is valuable for identification of priority watersheds for NPS pollution reduction and also for planning-level evaluation of best management practices to achieve the desired reductions. It is estimated that ground-water base flow may be the largest pathway for NPS TN to the Sound, contributing about 54% of the total NPS TN load, a finding with significant implications for LIS total maximum daily load reduction scenarios. In addition to ground water, septic systems are estimated to contribute about 17% of the total load, with the remaining TN load being mostly runoff from urban (17%), agricultural (5%), and low impact (e.g., forest) areas (6%).

Original languageEnglish
Pages (from-to)715-733
Number of pages19
JournalJournal of the American Water Resources Association
Volume45
Issue number3
DOIs
StatePublished - Jun 2009

Keywords

  • ArcView generalized watershed loading functions
  • Decision support systems
  • Generalized watershed loading functions
  • Long Island Sound
  • Nitrogen
  • Nonpoint source pollution
  • Total maximum daily load
  • Watershed modeling

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