1 / 25

An integrated hydro-topographic model for Viti Levu Gau

An integrated hydro-topographic model for Viti Levu Gau. Conway Pene 2012 Pacific GIS&RS Conference 27-30 November 2012, Suva. Hydro- topo integration. Water flows downhill... Hydro – surface water, stream network ... plus ... Topo – surface shape, slope and aspect ... equals ...

alayna
Download Presentation

An integrated hydro-topographic model for Viti Levu Gau

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. An integrated hydro-topographic model for VitiLevuGau Conway Pene 2012 Pacific GIS&RS Conference 27-30 November 2012, Suva

  2. Hydro-topo integration • Water flows downhill... • Hydro – surface water, stream network • ... plus ... • Topo – surface shape, slope and aspect • ... equals ... • A catchment model

  3. Test site • Gau island, central Fiji

  4. The big picture • Create a Digital Elevation Model (DEM) • Process the DEM to find breaklines • Streams and ridges • Create hydro network • Logical network – junctions, streams, catchments • Integrated model for hydro flow analysis

  5. Step 1 - DEM using terrain-specific tools • Traditional terrain data • Contours, spot heights, cliffs • PLUS… • Hydrological data • Streams, lakes, sinkholes • Hydrology easy to follow on air photos, thus higher accuracy • hydrology ‘enforce’ the terrain shape i.e. breakline

  6. Need to do some cleaning first...

  7. Completed DEM

  8. Step 2 – Process DEM • DEM • Flow direction from each cell to next (slope) • Flow accumulation • Stream segments (accumulation threshold) • Catchment boundary

  9. Flow directions

  10. Flow accumulation

  11. Stream segment

  12. Catchment boundary

  13. Step 3 –Hydro network • Convert raster from DEM processing • Stream segment to vector line network • Catchment boundary to vector polygons • Points created at stream junctions

  14. Stream segments

  15. Catchment polygons

  16. Network junctions

  17. Flow tracing using the model

  18. Runoff calculation • Predict volume of water at end of catchment • Amount of rainfall • Size, shape, slope of catchment • Surface characteristics (vegetation, soil)

  19. Amount of rainfall • WorldClim climate raster

  20. Catchment characteristic • Curve number – hydrological parameter • 0 – 100% of rainfall runoff • Function of land cover and soil type • Land cover – vegetation layer • Soil type – made up (no soils layer for this island)

  21. Vegetation + soils

  22. Curve number

  23. Curve number x rainfall = runoff

  24. Clip runoff to a catchment

  25. What next?... • Apply to larger island (VitiLevu) • Heavy data load for desktop computer • Calculate realistic curve numbers • Make dynamic runoff query tool • Hover over map and pop-up runoff value

More Related