RHESSYS FOR SANDHILLS REGION OF NORTH

CAROLINATom CravenMatt SimonAnne Trainor

Objective 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.

Study AreaThe Sandhills, NC

Study AreaSandhills Vegetation and Critters

Sub-basin – Cape Fear 14, Part of the Cape Fear River Basin

DataSub-basin

DataCatchment Topography – Flat Creek Watershed

DataCatchment Elevation – Flat Creek Watershed

DataCatchment Soils– Flat Creek Watershed

DataWetness Index– Flat Creek Watershed

DataMet and Stream Data

DataMet and Stream Data

MethodsArc Hydro Delineation

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.

MethodsReclassified 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

MethodsLand Use Type 30 m pixels Percentage Cumulative %

Evergreen Forest 11623 50.57% 50.57%

Grassland/Herbaceous 4003 17.41% 67.98%

Barren Land (Rock/Sand/Clay) 3431 14.93% 82.91%

Woody Wetlands - Deciduous 1796 7.81% 90.72%

Developed, Open Space 1228 5.34% 96.06%

Developed, Low Intensity 277 1.21% 97.27%

Deciduous Forest 248 1.08% 98.35%

Mixed Forest 238 1.04% 99.38%

Shrub/Scrub 114 0.50% 99.88%

Cultivated Crops 12 0.05% 99.93%

Emergent Herbaceous Wetlands 6 0.03% 99.96%

Open Water 6 0.03% 99.98%

Developed, Medium Intensity 4 0.02% 100.00%

Totals 22986 100.00%

Methods 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 idsRaster calculator: LULC + WI*10

Model Output

Future Steps

Get the model running Incorporate variation in soil types and

depths Use explicit routing to examine

hydrologic connectivity

Newbie User Reflections 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