Development of an internet-accessible tool for the identification of hydrologically sensitive areas (HSA’s) and the calculation of New York State phosphorous indices Helen Dahlke, Daniel R. Fuka, Zachary M. Easton Tammo S. Steenhuis

Introduction hydrologically sensitive areas (HSA‘s) are preferred flowpath in the landscapes of the humid Northeast of the US connect mostly agricultural land to streams and lakes need of estimation of the risk of nutrient loads in surface waters: CNMP planner help producer to identify high risk transport areas when applying manure current tools use a fixed distance setting from a watercourse and/or soil wetness indicators need of tools that consider the landscape position of saturation areas and their spatial-temporal dynamics tool must be user-friendly and easy accessible

study areas Salmon Creek: 227 km² (87.7 mi²) Fall Creek: 326 km² (126 mi²) Six Mile Creek: 102 km² (39 mi²)

model approach rainfallET If rainfall > ET, soil wets up If rainfall > soil storage, excess overland flow flowaccumulation slope soil depth soil hydraulic conductivity DEM Soil topographic wetness index Calculation of the fractional area of the watershed prone to saturation terrain analysis hydrology

Google Earth-based HSA-tool Google Earth ( is free software that provides a virtual globe program it maps earth by superimposition of satellite images, aerial phorographs and GIS maps over a 3D globe user can program their own data overlays of vector or raster data using the Keyhole Markup Language (KML) maps can be animated based on a time stemp  ideal for time series application such as simple hydrological models

realization of the HSA-tool in Google Earth Soil topographic wetness index [Geo-Tiff] Soil topographic wetness index [GRID] reclassification into 255 classes of equal area export into Geo-Tiff HSA image [png] modelled fractional area of HSA‘s [table] conversion to web-image *.png file 1% incremental area images KML-file for Google Earth

realization of the HSA-tool in Google Earth control bar for timeseries simulation loaded images of HSA‘s for each day of simulation Six Mile Creek

realization of the HSA-tool in Google Earth daily estimated level of phosphorous load is displayd at the outlet of the catchment