The Need for High Resolution Digital Elevation Data for Precision Conservation in Minnesota Dr. David Mulla Professor and W.E. Larson Chair for Soil and Water Resources Department of Soil, Water, & Climate University of Minnesota

Precision Conservation Precision Conservation allows small portions of the landscape that have a disproportionate effect on water quality or wildlife habitat to be targeted with Best Management Practices (BMPs) Best Management Practices placed on critical landscapes can help treat small areas that produce disproportionate amounts of pollution Identifying critical landscape areas can best be achieved using high resolution digital elevation data, although information about existing management practices is also important

Precision Conservation allows small portions of the landscape that have a disproportionate effect on water quality or wildlife habitat to be targeted with Best Management Practices (BMPs)

Best Management Practices placed on critical landscapes can help treat small areas that produce disproportionate amounts of pollution

Identifying critical landscape areas can best be achieved using high resolution digital elevation data, although information about existing management practices is also important

Precision Conservation (compared to Precision Ag) (From Berry, 2008 )

Precision Conservation Example Source: Sharpley et al. 2006. Nutrient Management Practices. In Environmental Benefits of Conservation on Cropland: The Status of Our Knowledge. Schnepf and Cox (eds). Soil and Water Conservation Society, Ankeny Iowa.

Precision Conservation Example Sites of Biodiversity Significance Wildlife Management Areas 250m buffer around current WMAs and Biodiversity Sites

Clean Water Funding Initiatives Passage of the Clean Water Legacy Amendment provides badly needed funding for protection, restoration and enhancement of impaired waters and damaged wildlife habitat Funding from the Clean Water Legacy Amendment should be spent on the most critical landscapes and sources of degradation rather than spread evenly across the state There is a pressing need to identify critical sources of water quality degradation and their locations in order to select and implement BMPs

Passage of the Clean Water Legacy Amendment provides badly needed funding for protection, restoration and enhancement of impaired waters and damaged wildlife habitat

Funding from the Clean Water Legacy Amendment should be spent on the most critical landscapes and sources of degradation rather than spread evenly across the state

There is a pressing need to identify critical sources of water quality degradation and their locations in order to select and implement BMPs

The 2008 Impaired Waters list contains 1,469 impairments including: 500 lakes 25 listed for multiple pollutants 336 rivers & streams 603 “reaches” w/many pollutants

The 2008 Impaired Waters list contains 1,469 impairments including:

500 lakes

25 listed for multiple pollutants

336 rivers & streams

603 “reaches” w/many pollutants

Lake Pepin Watershed TMDL Sediment Phosphorus

Sediment

Phosphorus

Existing BMP Programs RIM program involved 203,000 acres enrolled in 5,300 conservation easements Program is heavily focused on Minnesota River Basin riparian areas and wetlands

RIM program involved 203,000 acres enrolled in 5,300 conservation easements

Program is heavily focused on Minnesota River Basin riparian areas and wetlands

Wildlife Management Areas (FY ‘07 & FY ‘08) Prairie Grassland Habitat 63,000 ac Wetland Habitat 201,000 ac Forest Habitat 32,000 ac

Prairie Grassland Habitat 63,000 ac

Wetland Habitat 201,000 ac

Forest Habitat 32,000 ac

Conservation Reserve Program Enrolled Acreage Expiration Patterns

Variable Source Areas The variable source area concept explains how small portions of the landscape, termed critical source areas, can contribute disproportionately to runoff and peak flows during storm events (Brooks et al., 2003) Q TIME Q TIME T2 T1 *Modified from Brooks et al., 2003 & references

The variable source area concept explains how small portions of the landscape, termed critical source areas, can contribute disproportionately to runoff and peak flows during storm events (Brooks et al., 2003)

Critical Source Areas Critical source areas can include upland depressions, riparian areas, open culverts and tile outlets, gullies, ravines, eroding stream banks and slumping stream bluffs

Critical source areas can include upland depressions, riparian areas, open culverts and tile outlets, gullies, ravines, eroding stream banks and slumping stream bluffs

Critical Area Problem Studies suggest that small areas of the agricultural landscape (5-25%) generate a disproportionately large amount of erosion or phosphorus The reduction of nonpoint source pollution loads at the outlet of agricultural watersheds is dependent on the implementation of best management practices (BMPs) in critical source areas of nonpoint source pollution Defining critical source areas is a challenge, but terrain analysis of digital elevation models (DEMs) is promising

Studies suggest that small areas of the agricultural landscape (5-25%) generate a disproportionately large amount of erosion or phosphorus

The reduction of nonpoint source pollution loads at the outlet of agricultural watersheds is dependent on the implementation of best management practices (BMPs) in critical source areas of nonpoint source pollution

Defining critical source areas is a challenge, but terrain analysis of digital elevation models (DEMs) is promising

Converging/Diverging Flows

Lidar Image of Beauford Watershed

Comparison Between Lidar and 30 m DEMs Lidar 30 m DEM

Terrain Attributes for Precision Conservation Terrain attributes can be derived from DEMs using… ESRI’s AcrGIS v. 9.2 TAUDEM v. 3.1 (Tarboton, 2005) D∞ method of flow routing (Tarboten, 1997) Critical source area data layers can be created by combining… Different thresholds applied to terrain attributes Ancillary GIS data (Soils drainage, Landuse/Landcover)

Terrain attributes can be derived from DEMs using…

ESRI’s AcrGIS v. 9.2

TAUDEM v. 3.1 (Tarboton, 2005)

D∞ method of flow routing

(Tarboten, 1997)

Critical source area data layers can be created by combining…

Different thresholds applied to terrain attributes

Ancillary GIS data (Soils drainage, Landuse/Landcover)

Slope (S) Specific Catchment Area (SCA) Slope and Specific Catchment Area 5% 0 % 30 10,000

Landscape slope Affects overland flow and erosion potential

Sheet & Rill Water Erosion Potential Duluth Bemidji Cambridge Twin cities Grand Forks Winona Rochester Pipestone Marshall Montevideo St. Cloud Roseau Moorhead Austin Mankato Morris Grand Rapids International Falls Ortonville Red Wing

CTI Values Smoothed CTI Compound Topographic Index 7 20 8 14 CTI = Ln (SCA / S) =

Characterizes soil water content and surface saturation zones Compound Topographic Index CTI = ln(As/tan S) As is specific catchment S is slope

Terrain Indices: Stream Power Index Ln (SPI Values) Smoothed Ln (SPI) -6 6 -2 4 SPI = SCA x S x =

Stream Power Index SPI = As tanS As is specific catchment area, S is slope Measures erosive power of overland flow

Stream Power Index

SPI = As tanS

As is specific catchment area, S is slope

Measures erosive power of overland flow

Types of Water Erosion Upland sheet and rill erosion Construction site erosion Gully and ravine erosion Stream bank erosion Stream bluff erosion

Upland sheet and rill erosion

Construction site erosion

Gully and ravine erosion

Stream bank erosion

Stream bluff erosion

Deposition from Sheet & Rill Erosion

Construction Site Erosion

Ravine Erosion

Ravines in Blue Earth county 3 m LiDAR Le Sueur 0 2500m

Ravines in Blue Earth county 30 m DEM Le Sueur 0 2500m

Eroding Stream Bank

Stream Bluff Erosion

Disproportionalities The Le Sueur contributes a disproportionate amount of non-point source pollution to the Minnesota River Only comprises 7% of the basin land surface area 53% TSS 31% Total P 20% NO 3 -N (MRBDC, 2005) Data Source: ESRI & MN DNR Le Sueur River Watershed N Km 0 15 30 0 100 200 Km

The Le Sueur contributes a disproportionate amount of non-point source pollution to the Minnesota River

Only comprises 7% of the basin land surface area

53% TSS

31% Total P

20% NO 3 -N

(MRBDC, 2005)

Cobb River Slumping Bluff

Appendix D

Ravine Sediment Sources Digitized from Blue Earth county Lidar by Patrick Belmont - NCED

8 14 Upland Depressions Delineation Smoothed CTI > 11.5 Drainage = “Poorly Drained” = Upland Depressions + Upland Depressions Critical Areas

Upland Depressions Covers nearly 20,000 ha (7%) in the Le Sueur Watershed 85% of upland depressions are in ag production Upland Depressions Critical Areas N Data source: MN DNR 0 20 40 Km

Covers nearly 20,000 ha (7%) in the Le Sueur Watershed

85% of upland depressions are in ag production

Upland Depressions Data source: MN DNR & MN LMIC N Upland Depressions Critical Areas 0 15 30 Km 0 2.5 5 Km 0 500 1,000 Meters

Riparian Critical Areas Delineation Smoothed SPI > 10 = Riparian areas 0 10+ Riparian Critical Areas

Critical Riparian Areas Riparian Critical Areas Covers over 25% of the watershed (~74,000ha) 59% of riparian critical areas are in ag production When combined with erosion potential, gives high priority areas needing BMPs N Data source: MN DNR 0 20 40 Km

Covers over 25% of the watershed (~74,000ha)

59% of riparian critical areas are in ag production

When combined with erosion potential, gives high priority areas needing BMPs

Conclusions Disproportionate amounts of sediment and phosphorus are generated from small areas of the watershed The effectiveness of BMPs depends on placing them in vulnerable portions of the landscape Precision conservation strategies involving terrain analysis may prove very helpful in the future to guide conservation efforts tailored to specific landscapes and to maximize efficiency of their placement Lidar based DEMs can help improve the accuracy of identifying critical landscapes and targeting BMPs to critical areas

Disproportionate amounts of sediment and phosphorus are generated from small areas of the watershed

The effectiveness of BMPs depends on placing them in vulnerable portions of the landscape

Precision conservation strategies involving terrain analysis may prove very helpful in the future to guide conservation efforts tailored to specific landscapes and to maximize efficiency of their placement

Lidar based DEMs can help improve the accuracy of identifying critical landscapes and targeting BMPs to critical areas

Thank You. Questions?