Developing GIS indicators and metrics - Colorado State University

eveloping GIS indicators and metric
avid Theobald
atural Resource Ecology Lab
olorado State University

FUNDING SOURCE
This presentation was developed under the STAR
Research Assistance Agreement CR-829095
awarded by the U.S. Environmental Protection
Agency (EPA) to Colorado State University. This
report have not been formally reviewed by EPA.
The views expressed here are solely those of its
author and the STARMAP Program. EPA does
not endorse any products or commercial services
mentioned in this presentation.

Goals of indicator development
Develop and evaluate landscape-level
indicators suitable for spatial and
temporal analyses of EMAP data
Investigate limitations of currentlyavailable
data and offer new, robust
methodologies

Current effort
• Linkage between watershed and
hydrologic networks
• Refine surrogates with direct
measures of area and discharge
• GIS-based tools
• RWTools for ArcView
• Catchment delineation & discharge in
ArcGIS

1. Watershed–hydrological
network linkage
• “…in every respect, the valley rules
the stream.” – Hynes 1975
• Indirect measures based on
hydrological properties (e.g.,
Strahler order, drainage density,
etc.)

Distance:
As the crow flies
(Euclidean)

Distance:
As the crow flies
As the seed floats
(downstream)

Distance:
As the crow flies
As the seed floats
As the fish swims
(down & up stream)

Distance:
As the crow flies
As the seed floats
As the fish swims
(down & up stream)
Upstream length
- mainstem (2)
- arbolate (1+2+3+4)

Distance:
As the crow flies
As the seed floats
As the fish swims
Upstream length
Network (dams,
fragmentation)

What indicators measure
watershed-stream linkage?
• Length of stream line
– Dam alteration of flow at a downstream
gauge?
• RWTools extension (ArcView v3.2)

Upstream
66 km
Mainstem
Upstream
37 km
Downstream
298 km
Network
16 km (do
6 km (up)

2. Direct measures of discharge
• Surrogates developed, e.g. Strahler
order:
The usefulness of stream order assumes,
with a sufficiently large sample, that order is
proportional to stream discharge
– Strahler 1957
• Alternatives:
- basin area
- discharge

Delineate reach catchments
• Robust method (no pre-processing)
• 1 to 1 relationship NHD reach and
catchment
• “Grow” watershed from reach line
based on flow direction iteratively

Stream discharge
Precipitation
D = C * P

8 acft
20 acft
10 acft

R 2 =0.7282
P-value=3.407e-006

Stream discharge
• Encouraging preliminary results
• Additional factors (Infiltration, E.T.):
– Geology
– Land cover
– Exposure
D = f(C, G, L, E)

3. GIS-based tools
• Interactive query and analysis of
watersheds (RWTools) (ArcView
v3.2)
• ArcGIS Geometric network

Plans for next year
• Initial release of GIS tools:
– RWTools for ArcGIS
– Functional-based spatial weights

Spatial weights
11
2
W =
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
1 0 1 0 0
3
4
5
0 1 0 1 0

Functional weighting
W =
0 0 0 0 0 0 0
0.7 0 0 0 0 0 0
0 0 0 0 0 0 0
1
0 0 0 0 0 0 0
4
1
5
2 3
6 7
0 0 0 0.7 0 0 0
0.2 0.8 0 0.2 0.8 0 0
0.1 0.2 1.0 0.1 0.2 1.0 0
E.g., downstream hydrology

Functional weighting
W =
0 1 0 0 0 0 0
1 0 0 0 1 1 0
0 0 0 0 0 0 0
1
0 0 0 0 1 0 0
4
1
5
2 3
6 7
0 1 0 1 0 1 0
0 1 0 0 1 0 1
0 0 0 0 0 1 0
E.g., macroinvertebrates

Plans for next year
• Initial release of GIS tools:
• Perennial/intermittent frame
problem in western US
• Development of network
fragmentation indices