1. Ecosystems  Climate  Energy and Minerals  Natural Hazards  Environment and Human Health  Water U.S. Department of the Interior U.S. Geological Survey 1 GeoSFM / Water Balance Workshop August 2010 USGS Iraq Project - Analysis of one Year of Image Data for Keban Reservoir Assessing Trans-boundary Flow Potential

2. 2 Purpose Data Sets Digital Elevation Model (DEM) – SRTM 90m Satellite Imagery – Landsat 30m (5 scenes - 2003) Volume Lookup Tables The purpose of this hands-on exercise is to familiarize you with the basic technique being used for modeling reservoir height levels through time and deriving surface area and volume measurements based on these estimates.

3. 3 Hands-on Exercise Digital Elevation Model (DEM) –Load the GRID named Keban_srtm (Data directory) into ArcView –Display the GRID and adjust the color ramp to either elevation #1 or elevation #2

4. 4 Hands-on Exercise Digital Elevation Model (DEM) –Zoom into the lower right portion of the Keban reservoir (opposite of the dam location) –Note - most of the reservoir area falls into the lowest elevation class.

5. 5 Hands-on Exercise Digital Elevation Model (DEM) –Keeping the same color scheme, modify the value range to more discreetly map elevations adjacent to the reservoir –Note - most values near the reservoir fall into the 801- 850 classes

6. 6 Hands-on Exercise Satellite Imagery –Now we’ll consider these elevations relative to a series of Landsat images for the 2003 season. –Load the Landsat image acquired in March as an ‘image analysis data source’ into the same view as the DEM (p173_r33_mar20_2003.tif) Turn the Landsat image on and off to compare what you see in the image, especially the blue/black water body of the reservoir, with the DEM. What is the light blue on the image?

7. 7 Hands-on Exercise Satellite Imagery –Add the other 4 Landsat images to the view in chronological order (i.e. may07, jul18, aug19,oct22). –Spend some time turning different images on and off and comparing the spatial extent of the lower portion of the reservoir. Which image appears to show the maximum storage level? Now we’ll take a closer look at how these varied storage levels relate to the elevation variability and thus surface area/volume estimations.

8. 8 Hands-on Exercise Satellite Imagery –Add the keban_2m_contour.shp file from the data directory…this may take a little while to display. –With the contours turned off, zoom to the lower left portion of the reservoir extent…this is where we’ll select our points for measurement.

9. 9 Hands-on Exercise Satellite Imagery –Turn the 2m contour layer back on. –One contour line appears to define the extent of the reservoir (in the Aug 19 example) better than the others…the contours will not confine exactly to the reservoir…we need to approximate the elevation. Close approximation of reservoir height

10. 10 Hands-on Exercise Satellite Imagery –As in the earlier exercise, make the keban_srtm layer active, but have the image displayed on top of it. Using the “identify” tool, make point selections along the edge water pixels and make an estimate of the reservoir height for that date The yellow markers at left were added to show approximate point sampling locations…your identify tool will not leave these as permanent marks, but will provide a list of results (above) that allow you to review the elevation values at each.

11. 11 Hands-on Exercise Satellite Imagery –A review of the identify results for this example showed the majority of elevations sampled were 841m –Make the keban_2m contour active and use the selection tool to select the contour that most approximates the reservoir extent With the attributes of the contour shapefile displayed, use the promote button to show the selected contour line at the top of the list. In this case, the selected contour is 842m…very close to our point samples and reasonable given the over estimation in some areas.

12. 12 Hands-on Exercise Satellite Imagery –Follow this same process to determine height elevations for each time period of 2003 imagery. Be sure to record your estimations for each image, so we can reference your findings in the lookup tables. March 20 May 7July 18 August 19 October 22 You should finish with 5 reservoir height elevation estimates associated with each period of imagery.

13. 13 Hands-on Exercise Volume Lookup Tables –Open the Res_lookup_tbls.xls spreadsheet found in the “data” directory –Be sure you select the Keban reservoir tab Scroll to the elevation range corresponding to the height elevations you’ve identified.

14. 14 Hands-on Exercise Volume Lookup Tables –In addition to the lookup tables spreadsheet, open the Analysis_2003 spreadsheet in the “data” directory Cut/paste the elevation, pixel count, pixel sum, surface area, and volume from the lookup tables for each date analyzed into the 2003 spreadsheet.

15. 15 Hands-on Exercise Volume Lookup Tables –If time allows, graph the results of surface area and volume throughout the 2003 image series and/or answer the following: What period showed the highest reservoir storage volume? What period showed the least? Is the seasonal variability in the estimates what you would expect?

16. 16 Hands-on Exercise Congratulations, you’ve completed the Keban analysis exercise. This was a simplistic example of how the combination of satellite imagery, elevation data, and volume lookup tables can be used to estimate seasonal changes in reservoir surface area and volume. Our ultimate intention was to develop these techniques into a more standardized format that could be used in an operational manner. Still, these straightforward methods can be employed to assess inter-annual and intra-annual changes in reservoir storage in the absence of a formalized monitoring system. The importance of accounting for reservoir storage will be discussed in more detail as we work through other aspects of conducting a water balance for the region and in reference to it’s incorporation into the GeoSFM.