10/1/2007 NC Water Quality

Mapping Headwater Streamsin

North Carolina

North Carolina Division of Water QualityNorth Carolina State UniversityNorth Carolina Department of Transportation

10/1/2007 NC Water Quality

Background

Problem: Existing Maps Inaccurate and InconsistentCritical to NC Division of Water Quality 401 program and other public agencies and private sector

Tributaries shown on one map and not the other

Headwater stream shown on one map and not the other

Solution: Make better mapsTake advantage of state-wide LiDAR (LIght Detection And Ranging) coverageStream Mapping Project began early 2004 (NCDWQ, NCSU, NCDOT)

10/1/2007 NC Water Quality

Approach

•Use LiDAR data acquired from the NC Floodplain Mapping Program to create new topographic maps

•Conduct field identification and mapping of intermittent and perennial streams and their origins in headwater areas

•Conduct spatial analysis using GIS data and field data

•Use field data and other GIS data to create predictive models of streams and origins

10/1/2007 NC Water Quality

What are we trying to predict with spatial models?

•Presence/Absence of stream in a valley•Stream length•Flow Duration –ephemeral, intermittent or perennial

What are the influencing factors?What processes do these factors represent?How do factors and processes vary spatially?

10/1/2007 NC Water Quality

Methods: Field Data

•Walk streams

•Locate Origins

•Determine flow regime (DWQ Stream ID, 2005 )

•GPS origins (sub-meter accuracy)

http://h2o.enr.state.nc.us/ncwetlands/regcert.html

10/1/2007 NC Water Quality

Methods: GIS Data

Create Digital Elevation Models (DEMS)

•Generate Terrain Derivatives

•Acquire existing GIS Data, ex. Soils, geology…

Spatial patterns and analysis

10/1/2007 NC Water Quality

•23 watersheds•600 + origins

10/1/2007 NC Water Quality

Little Creek, Yadkin BasinStanley County, North Carolina

Streams

IntermittentPerennial

Origins

High : 230

Low : 169

Elevation (ft)

10/1/2007 NC Water Quality

Variables used (or to be used) in Analysis

•Level IV Ecoregion•Local Slope•Average Slope•Contributing Drainage Area•Local Curvature, profile and plan•Average Upslope Curvature, profile and plan•Soils•Geology•Land use•Indices (roughness, stream power…)

10/1/2007 NC Water Quality

General Description

Ephemeral to intermittent 46 %Intermittent to perennial 36 %Ephemeral to perennial (all mtns) 14 %Other, wetlands and modified 8 %

does not include outer coast

First order intermittent stream lengthmountains 33 %piedmont 22 %inner coast plain 32 %outer coast plain 56 %

44 origins/1 site

*Data for 21 sites, 542 origins

10/1/2007 NC Water Quality

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Contributing Drainage Area Int/Per Within EcoregionAll exceptEastern Blue Ridge &Group B-Slate Belt

Between Ecoregions*Rolling Coastal Plain*Triassic & Eastern BR*Slate Belt & N. Outer Piedmont

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Landscape Process…..

Trend Plots Average Slope and Contributing Drainage Area against Topographic Relief by Site

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Range (max-min)

Avg Slope Relief

Drainage Area Relief

10/1/2007 NC Water Quality

Distribution of Intermittent and Perennial Origin Contributing Drainage Area (acres)

Carolina Slate Belt-A

Carolina Slate Belt-B

Eastern Blue Ridge Foothills

Northern Outer

Piedmont

Rolling Coastal Plain

Triassic Basin

int per int per int per int per int per int per

Min 0.20 0.72 0.05 2.04 0.23 0.24 1.55 2.54 0.16 7.16 0.10 0.13

10% 1.47 7.53 0.77 2.39 2.17 1.02 1.80 4.07 7.52 10.76 1.24 1.89

25% 2.85 11.58 4.89 9.52 3.72 2.91 4.48 10.05 11.15 28.82 1.95 3.27

50% 7.36 15.99 23.80 37.50 4.60 4.98 8.82 16.18 25.67 84.00 3.70 6.85

Mean 11.20 23.74 50.86 60.85 5.16 5.27 12.72 20.52 40.66 95.59 5.11 10.40

75% 14.47 35.40 69.96 68.16 6.34 7.04 15.06 27.11 55.15 122.00 7.16 15.79

90% 27.39 43.33 142.41 187.26 8.16 9.81 22.99 41.31 101.33 217.34 11.87 27.80

Max 74.63 107.00 322.27 328.28 14.60 15.85 115.95 64.81 173.65 343.66 16.51 32.49

10/1/2007 NC Water Quality

Much to be Done!