Developing GIS indicators and metrics

Developing GIS indicators and metricsDeveloping GIS indicators and metrics

David TheobaldNatural Resource Ecology Lab

Colorado State University

Goals of indicator developmentGoals of indicator development

Develop and evaluate landscape-level indicators suitable for spatial and temporal analyses of EMAP data

Investigate limitations of currently-available data and offer new, robust methodologies

Current effortCurrent effort

1. Linkage between watershed and hydrologic networks

2. Refine surrogates with direct measures of area and discharge

3. GIS-based toolsa. RWTools for ArcViewb. Catchment delineation & discharge in

ArcGIS

1. Watershed–hydrological 1. Watershed–hydrological network linkagenetwork linkage“…in every respect, the valley rules

the stream.” – Hynes 1975Indirect measures based on

hydrological properties (e.g., Strahler order, drainage density, etc.)

Distance:Distance:

As the crow flies (Euclidean)

Distance:Distance:

As the crow flies As the seed floats

(downstream)

Distance:Distance:

As the crow flies As the seed floats As the fish swims

(down & up stream)

Distance: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:Distance:

As the crow flies As the seed floats As the fish swims Upstream length Network (dams,

fragmentation)

What indicators measure What indicators measure watershed-stream linkage?watershed-stream linkage?Length of stream line– Dam alteration of flow at a downstream

gauge?

RWTools extension (ArcView v3.2)

Upstream66 km

Downstream298 km

MainstemUpstream37 km

Network16 km (down)6 km (up)

2. Direct measures of discharge 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 catchmentsDelineate 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 dischargeStream discharge

PrecipitationD = C * P

10 acft

8 acft20 acft

R2=0.7282

P-value=3.407e-006

Stream dischargeStream discharge

Encouraging preliminary resultsAdditional factors (Infiltration, E.T.): – Geology– Land cover– Exposure

D = f(C, G, L, E)

3. GIS-based tools3. GIS-based tools

Interactive query and analysis of watersheds (RWTools) (ArcView v3.2)

ArcGIS Geometric network

Plans for next yearPlans for next year

Initial release of GIS tools:– RWTools for ArcGIS– Functional-based spatial weights

Spatial weightsSpatial weights

11 2

3 54

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

1 0 1 0 0

0 1 0 1 0

W =

Functional weighting Functional weighting

1

1 2 3

54

0 0 0 0 0 0 0

0.7 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

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

W =

6 7

E.g., downstream hydrology

Functional weighting Functional weighting

1

1 2 3

54

0 1 0 0 0 0 0

1 0 0 0 1 1 0

0 0 0 0 0 0 0

0 0 0 0 1 0 0

0 1 0 1 0 1 0

0 1 0 0 1 0 1

0 0 0 0 0 1 0

W =

6 7

E.g., macroinvertebrates

Plans for next yearPlans for next year

Initial release of GIS tools:Perennial/intermittent frame

problem in western USDevelopment of network

fragmentation indices