Construct a RHESSys ecohydrologic model for Sandhills Region
Sandhills Eight-County Area. Shown on a blue to red color ramp is an 20 foot elevation model of the region. Dashed black lines indicate primary roads, blue lines - major hydrology. Ft. Bragg (right) and Camp Mackall (left) boundaries are shown in fuchsia.
The entire sub-basin was processed using Arc Hydro in ArcGIS 9.2 using a LiDAR-derived digital elevation model (DEM) created from the North Carolina Floodplain Mapping Program (NCFMP) by the North Carolina Department of Transportation (NCDOT This DEM has a 20 ft spatial resolution or roughly 6 meters.
Reclassified LULC from 15 to 4 classes – Hardwood Deciduous Forest Shrub/Scrub Woody Wetlands – Evergreen Evergreen Forest Mixed Forest – Open/Barren Developed (open space, low and medium intensity) Barren – Herbaceous Grassland Herbaceous Cultivated Crops Emergent Herbaceous Wetlands Open Water
Land Use Type30 m pixelsPercentageCumulative % Evergreen Forest1162350.57% Grassland/Herbaceous400317.41%67.98% Barren Land (Rock/Sand/Clay)343114.93%82.91% Woody Wetlands - Deciduous17967.81%90.72% Developed, Open Space12285.34%96.06% Developed, Low Intensity2771.21%97.27% Deciduous Forest2481.08%98.35% Mixed Forest2381.04%99.38% Shrub/Scrub1140.50%99.88% Cultivated Crops120.05%99.93% Emergent Herbaceous Wetlands60.03%99.96% Open Water60.03%99.98% Developed, Medium Intensity40.02%100.00% Totals22986100.00%
Arcview (Arc2World) to construct world file Template File Parameters Single Soil Type: Sandy Loam Land use: Undeveloped 4 Vegetation Types from 30 m LULC Topography DEM, Hill slope, Wetness index, Slope, Aspect Patch Identification Composite of hill slope, wetness index and LULC Trial 1: 4,161 discrete patch ids Raster calculator: LULC + WI*100 + hill slope * 100000 Trial 2: 91 discrete patch ids Raster calculator: LULC + WI*10
Get the model running Incorporate variation in soil types and depths Use explicit routing to examine hydrologic connectivity
Add option to write a logfile with state variables Examine templates and create worldfiles in class for the example watershed Initial gray areas Exact method for creation of useful grids Headers in.def files Going from scratch was difficult but yields a better understanding of the inner workings