Action Plan for the Development of Watershed and Sub-Watershed Boundaries for northwestern Mississippi : Delineating in

1. Action Plan for the Development of Watershed and Sub-Watershed Boundaries for northwestern Mississippi :Delineating in Problematic Areas Claire E. Rose, K. Van Wilson, Richard A. Rebich U.S. Geological Survey Mississippi Water Science Center 308 S. Airport Rd. Jackson, MS 39208 in cooperation with Mississippi Department of Environmental Quality

2. Background and Issues

3. Acquisition of LiDAR enables delineation of subtle topographic features Philipp, MS 7.5-minute topographic map, USGS 1981 LiDAR imagery, US ACE 2009

4. Purpose of Study • To develop sub-watershed boundaries for watersheds in northwest Mississippi. • Complete the WBD for the state of Mississippi to the sub-watershed level. • Watershed and ecosystem health restoration depend on completed sub-watershed boundary dataset.

5. Map of Current delineation to sub-watershed level(all are in Mississippi Delta region)37: Number of 10-digit HUC watersheds in Northwest MS that need to be delineated down to the 12-digit HUC sub-watershed boundaries.~185: Approximate number of12-digit HUC sub-watershed boundaries that would be developed for NW MS

6. Flowchart of Data Objectives

7. Errors in the Yazoo River Basin Phase 1 LiDARDataset

8. Explanation of LiDAR Errors • USGS NGTOC: Responsible for reviewing LiDAR data before approval for inclusion in NED. • Goal of QA/QC: Assure data are sufficient quality for scientific analysis. • Errors, anomalies and other issues were documented in the LiDAR Data from the Yazoo River Basin (Phase 1). • 147 Errors were found including: • Floating water bodies • Mismatched seams • Bridge remnants • Missing data • Incomplete tiles • Steep shorelines • Spikes

9. Methods- Arc HYDRO Snake Creek Watershed– Upper BoguePhalia • Layers Needed to Auto-delineate using Arc Hydro: • LiDAR exported to DEM • NHD • Watershed boundaries • Aerial imagery

10. Methods- ArcHYDRO • Fill sinks • Use stream network (NHD) for pour points • Flow direction and flow accumulation • Stream definition and segmentation • Catchment grid delineation and polygon processing • Drainage processing • Joint catchment processing • Set nodes using NHD • Watershed processing – batch delineation • Section off by watershed leveland buffer itso it won’t change • Compare to NHD and aerial and previous watershed delineations

11. Quality Control • Compare to aerial imagery • Compare to NHD • Compare to previously-delineated watershed boundaries

12. Stewardship between USGS and WBD • Contact made with WBD • Web Seminars at each major step in the process • Guide the GIS specialist in the method and technique • Will ease WBD certification process in the future

13. Requirements and Standards of WBD • WBD Standards will be updated in March 2012 • Use current standards until the update

14. Timeline • Objective 1: LiDAR burned into USGS NED and QA/QC • Objective 2: Testing of auto-delineation methods, pilot basindelineation • Objective 3: Completion of sub-watershed delineation of NW MS, submission to National WBD

15. Questions or Comments? • WBD- Watershed Boundary Dataset • NGTOC- USGS National Geospatial Technical Operations Center • LiDAR- Light Detection and Ranging • EROS- USGS Earth Resources Observation and Science Center • NED- National Elevation Dataset • NHD- National Hydrography Dataset • DEM- Digital Elevation Model

16. Abstract: • Title: Development of Watershed and Sub-Watershed Boundaries for Northwestern Mississippi • The National Watershed Boundary Dataset (WBD) for the state of Mississippi lacks sub-watershed delineation in northwestern Mississippi, an area of intense agricultural production locally referred to as the Delta. Previous attempts to delineate watersheds in the Delta to the sub-watershed boundaries were unsuccessful due to topographically-uniform, low relief land elevations; land management practices employed by land owners and growers who frequently change drainage patterns; and the fact that the area did not previously have a sufficient scale of digital elevation data that would allow delineation of subtle topographic features. • Since the publication of the Mississippi WBD by the U.S. Geological Survey in 2009, the entire Delta region has been mapped using Light Detection and Ranging (LiDAR) technology, which has a vertical land surface accuracy of 8.5 centimeters (bare earth). With the availability of LiDAR data, it is now possible to delineate the Delta to the sub-watershed level. The U.S. Geological Survey, in cooperation with the Mississippi Department of Environmental Quality, will delineate the sub-watershed boundaries for northwestern Mississippi. • The preferred process to delineate river basins in the Delta to the sub-watershed level and to include these into the National WBD is as follows: (1) LiDAR data must be quality-control checked for errors by the USGS-National Geospatial Technical Operations Center (NGTOC) in Rolla, MO, and then integrated into the National Elevation Dataset (NED) by the USGS-Earth Resources Observation System (EROS) Data Center in Sioux Falls, SD; (2) after inclusion into the NED, the approved Digital Earth Model (DEM) from the NED can be auto-delineated using ArcHYDRO GIS software; (3) the auto-delineated boundaries are then manually checked and corrected to the DEM, aerial imagery, and the National Hydrography Dataset(NHD); (4) once the auto-delineated boundaries are corrected, WBD tools will be used to re-digitize the boundaries to eliminate line fragments; and (5) names and numbers will be assigned to each sub-watershed polygon and then submitted to the National WBD for certification.

17. Definition of Terms • HUC: Hydrologic Unit Code (Indicates size of watershed). • DEM: Digital Elevation Model • LiDAR: Light Detection and Ranging (Remote sensing technology that can measure distance). • Watershed: 10-digit HUC (~227 square miles). • Sub-watershed: 12-digit HUC (~40 square miles). • 5: Average amount of 12-digit HUCs within one 10-digit HUC

18. Acronyms • WBD- Watershed Boundary Dataset • NGTOC- USGS National Geospatial Technical Operations Center • LiDAR- Light Detection and Ranging • EROS- USGS Earth Resources Observation and Science Center • NED- National Elevation Dataset • NHD- National Hydrography Dataset • DEM- Digital Elevation Model