An open source version of the Nonpoint-Source Pollution and Erosion Comparison Tool Climate Tools Café Webinar Dave Eslinger, Ph.D. 3 May, 2012

What is OpenNSPECT? Water quality screening tool Spatially distributed (raster-based) pollutant and sediment yield model Compares the effects of different land cover and land use scenarios on total yields User friendly graphical interface within a GIS environment

Processes Simulated Topography determines flow direction and slope Soil characteristics, land cover, and precipitation determine runoff Runoff, land cover, and pollutant coefficients determine pollutant loads Runoff, topography, soil characteristics, and land cover determine sediment loads

Uses Existing Approaches Rainfall runoff –Soil Conservation Service (SCS) curve number technique Nonpoint pollutant –Event mean concentration technique Sediment erosion –Universal Soil Loss Equation (USLE) Modified (MUSLE) Revised (RUSLE)

Assumptions/Limitations Omitted processes – Stormwater drainage – Stream diversions – Snowmelt – Landslides No time component for – Runoff dynamics – Sediment redeposition – Pollutant dynamics Source: NASA Earth Science Enterprise

Usage Example Kingston Lake Watershed Association, near Conway, SC Nutrient loads under different growth scenarios

Data Needs National sources* –Land cover data –Topography –Precipitation –Soils data –Pollutant coefficients –Rainfall erosivity Local sources –Water quality standards –Additional pollutant coefficients *Local “tuning” improves accuracy

Topography Defines flow direction, stream networks, watersheds Default –U.S. Geological Survey (USGS) 30 m resolution digital elevation model Resolution impacts processing speed and file size

Land Cover Foundation for runoff quantity, sediment yield, pollutant yield Default –Coastal Change Analysis Program (C-CAP) –30 m resolution Flexible –Can easily substitute any land cover grid

Soils Runoff and erosion estimates are dependent upon soils and land cover Default –SSURGO soils † –County level resolution Infiltration rate –Hydrologic group Soil erodibility –K-factor † Soil Survey Geographic Database provided by the Natural Resources Conservation Service

Precipitation Derived from point estimates or modeled –OSU PRISM data Annual average Single event rainfall

Pollutants Pollutant coefficients –Event mean concentrations –Land cover specific Defaults –Nitrogen –Phosphorus –Lead –Zinc User–definable –New pollutants –New coefficients –Different criteria

Outputs Runoff volume Accumulated runoff Sediment yield Accumulated sediment load Pollutant yield Accumulated pollutant load Pollutant concentration

Baseline Runoff Flow directions derived from topography Precipitation grid provides amount of rainfall Uses soils and land cover data to estimate volume of runoff Validated Flow direction

Baseline Erosion Estimates total annual sediment load delivered to coast Provides a conservative estimate –A “worst-case” scenario

Baseline Nitrogen Estimates total annual pollutant load delivered to coast Focuses attention on source areas

Baseline Nitrogen Estimates total annual pollutant concentration Focuses attention on source areas

Example Application Makaha Valley, Oahu, Hawaii Annual time scale “What-if” scenario 1. Baseline 2. Land cover change New residential development 3. Climate change Change in rainfall characteristics

Land Cover Change Scenario Develop a subdivision Change scrub/shrub vegetation to low intensity development

Nitrogen (Pre-Change) Baseline –Low nitrogen runoff Add scenario

Nitrogen (Post-Change) Compare baseline estimate to the new estimated load 138 percent increase in annual nitrogen load

Climate Change Scenarios Same amount of rainfall, but change the number and intensity of the storms –7 raining days, Type I –14 raining days, Type IA –3 raining days, Type II

Questions? Download OpenNSPECT: nspect.codeplex.com Esri 9.x version at csc.noaa.gov/nspect Project Contacts: Dave Eslinger, Project lead Shan Burkhalter Matt Pendleton