The Challenges of Developing Conservation Planning Tools Using LIDAR Topographic Data M.D. Tomer, D.E. James, D.B. Jaynes National Soil Tilth Laboratory, USDA-ARS T. M. Isenhart, and S. Krogh Iowa State University

Map of research site showing sampling transects, and the wetness index which indicates the relative frequency of saturated soil conditions.

Placement of buffers Placement of wetlands Terrain analysis tools to target specific conservation practices

Precision Conservation Effective targeting of conservation practices to improve water quality requires knowledge of what pollutants are being transported, pathways they are being transported along, timing of their transport, and what opportunities exist to trap or treat them.

Effective targeting of conservation practices to improve water quality requires knowledge of

what pollutants are being transported,

pathways they are being transported along,

timing of their transport, and

what opportunities exist to trap or treat them.

Aspects of targeting Dosskey et al. (2002) Helmers et al., 2005 Where? When? What pathway? TILE DRAINAGE SUBSURFACE OVERLAND

Using LiDAR data to plan and target conservation practices Source: USGS

Delineation of nutrient interception wetlands

Issues to address: Accuracy analysis, patterns/implications of errors. Appropriate scale of analysis may vary not only with scale of planning, but type of practice being planned. Hydrologic routing: Across vegetation boundaries–moving from field to watershed scales raises issues inherent to method of data acquisition. Across glacial terrain with potholes and subsurface drainage. Across existing terraces

Accuracy analysis, patterns/implications of errors.

Appropriate scale of analysis may vary not only with scale of planning, but type of practice being planned.

Hydrologic routing:

Across vegetation boundaries–moving from field to watershed scales raises issues inherent to method of data acquisition.

Across glacial terrain with potholes and subsurface drainage.

Across existing terraces

Lidar coverage of Walnut Creek

Accuracy/error analysis

Accuracy/error analysis

Influence of scale: Flow accumulation pathways on 1, 5, and 10 m grids. “ Channel” thresholds shown are identical at each scale. Scale

Hydrologic routing Lidar image: processed DEM at 1 m grid Note detail shown in roads, ditches, fence lines, tillage, and vegetation boundaries. This affects flow routing!

Hydrologic routing - boundaries Grass Waterways

Hydrologic routing - boundaries

Mapped changes in surface elevation from 2002 to 2005 Hydrologic routing - boundaries

Landscape connectivity: In tile drained landscapes, ponded areas often have a surface inlet and direct conduit to the stream Terrain Modeling: Ponding Runoff Hydrologic routing - potholes

Terrain Modeling:

Ponding

Runoff

Hydrologic routing - potholes

Hydrologic routing - potholes

Effect of existing conservation practices on hydrologic flow routing Hydrologic routing - terraces

Learning to use Lidar terrain data for conservation planning How to represent / model hydrologic modifications and conservation practices already placed on the landscape? May be most important question at both field and watershed scales. Extraordinary detail may or may not represent actual flow routing, especially along boundaries (fences, buffers, etc.). “Scaling up” may or may not address this issue, depending on the particular application.

How to represent / model hydrologic modifications and conservation practices already placed on the landscape? May be most important question at both field and watershed scales.

Extraordinary detail may or may not represent actual flow routing, especially along boundaries (fences, buffers, etc.). “Scaling up” may or may not address this issue, depending on the particular application.

Learning to use Lidar terrain data for conservation planning Accuracy assessment - need to document error effects? Contracted accuracy assessments generally on hard surfaces, not in tall grass, forests, and tilled and untilled fields. Lidar DEMs have great potential as powerful conservation planning aide but are not a substitute for first hand knowledge gained by site visits and landowner contacts.

Accuracy assessment - need to document error effects? Contracted accuracy assessments generally on hard surfaces, not in tall grass, forests, and tilled and untilled fields.

Lidar DEMs have great potential as powerful conservation planning aide but are not a substitute for first hand knowledge gained by site visits and landowner contacts.