Catchment Delineation Workflow

Transcription

1 Catchment Delineation Workflow Slide 1

2 Given is a GPS point (Lat./Long.) for an outlet location. The outlet could be a proposed Dam site, a storm water drainage culvert on a rural highway, or any other feature that is believed to be attacked by a stream. It is required to define the catchment that attacks the outlet point: Compute catchment parameters (area, slope, length, etc) Slide 2

3 Steps: 1. Preparation Preparing the DEM, Satellite images,.. etc 2. Delineating the Catchment Initial Delineation inside WMS 3. Streams Verification Correcting the streams as needed 4. Visualizing the Catchment Slide 3

4 Software Needed: Global Mapper WMS Google Satellite Maps Downloader Google Earth Latitude N Longitude E Slide 4

5 Step1: Preparation Slide 5

6 Software Needed: Preparation Global Mapper WMS Google Satellite Maps Downloader Google Earth Latitude N Longitude E Slide 6

7 Preparation - Open Google Earth. (Make sure that you use the latest version) Slide 7

8 Preparation - Now add a Placemark. Place it Anywhere. Slide 8

9 Preparation Latitude N Longitude E - Adjust the name of the Placemark to be GPS Point - Adjust the Latitude and longitude to be the same of the outlet point - Press Enter. (The placemark location will change automatically to be near Makkah) Slide 9

10 Preparation Stream visually identified from sporadic vegetation - Now to the GPS point and inspect nearby streams from the picture. - Images in Google earth are usually high resolution images that allows for close lookups. - The area looks to be flat at the outlet Slide 10

11 Preparation Flow direction identified visually from Satellite Image and Elevation in Google Earth - It is required to prepare the DEM and satellite images needed to cover the catchment boundary feeding this stream. - To get a preliminary estimate of the stream boundary, free GIS data shall be used Slide 11

12 Preparation - Go to the Geocommunity website - Press S from the Data Country Index - Select Saudi Arabia from the country list Slide 12

13 Preparation - Select Nation Wide Data - Select the Hydrography 1M E00 Format. Slide 13

14 Preparation - Select to download the Drainage Network E00 file. Data is free of charge. - You will need to have a geocommunity account in order to download the data. - The downloaded file is located on the CD and named KSA- DNNET.E00 Slide 14

15 Preparation - Open Global Mapper Program - Drag and Drop the KSA Dnnet.e00 file that we have just downloaded into the main window. - Press OK on the error message that appears Slide 15

16 Preparation - Global mapper needs to know the projection of the incoming data to align it correctly - Select the Geographic (Latitude/Longitu de) as the Projection - Select the WGS84 as the Datum - Press OK Slide 16

17 Preparation - All drainage network of Saudi Arabia shall appear now on the screen - The delineated streams are of low resolution however they give a good indication of the catchment extents Slide 17

18 Preparation - Go to File > Export Vector Format - Select to export vector data as KML / KMZ. This is to view the data on Google Earth Slide 18

19 Preparation - Leave all the export options the same and press OK. - Name the file KSA Drainage Network Slide 19

20 Preparation - Double click the KSA Drainage Network file. It shall open up in Google earth and the streams shall appear on the image - Now zoom back to the GPS point and inspect the stream network - Try to define approximately the extent of the catchment Slide 20

21 Preparation - Add a Polygon in Google earth covering an area more than the catchment extent and name it DEM Boundary - Use the controls in the Upper Right corner to pan and zoom while drawing. Slide 21

22 Preparation - The polygon may appear as in the figure to the left. Slide 22

23 Preparation - Right click on the DEM Boundary polygon feature that appears in the places tree and select Save Place As.. - Save the polygon as DEM Boundary.kmz so we can use it later in Global Mapper Slide 23

24 Preparation - Go to ar.org/ in order to download the latest SRTM 3 DEM tile for the catchment boundary - There are many ways to download the SRTM data. - Scroll down the page and download the SRTM KML file SRTM41.kmz Slide 24

25 Preparation - Double click on the SRTM41.kmz file. It shall open up in Google earth - For viewing purposes, uncheck the box near the KSA Drainage Network and make sure that all the SRTM4.1 boxes are checked on Slide 25

26 Preparation - Now zoom out - You will find a grid lines drawn on the earth showing the boundary of each SRTM tile. - The file name covering the catchment boundary is srtm_45_08 - Click on Data for srtm_45_08 to see download options Slide 26

27 Preparation - A popup window shall appear. - Scroll down to the Download section - Select to download HTTP: Download the DATA tile in zipped GEOTIFF format (from London server) - Save the file on your computer srtm45_08.zip Slide 27

28 Preparation - Extract data from srtm45_08.zip on your computer - Drag and drop the srtm_45_08.tif file into global mapper. - Elevation data shall appear now in global mapper as a color relief box and an elevation scale shall appear on the left Slide 28

29 Preparation - No go to Tools > Control Center and uncheck the box beside the KSA dnnet.e00 file to close its layer. - Press Close Slide 29

30 Preparation - Now Drag and Drop the DEM Boundary.kmz that we have previously created. - The boundary shall appear as in the figure to the left. Slide 30

31 Preparation - Now press on the Feature Info Tool - Press OK to the Tip that will appear - Select anywhere inside the DEM boundary polygon. It should get highlighted in white - Close the info screen that shall appear. The boundary will remain selected Slide 31

32 Preparation - Go to File > Export Elevation Grid Format Slide 32

33 Preparation - Select DEM for the Export Format. This is supported by WMS - Press OK to the Tips that will appear - On the DEM Export Options, go to Export Bounds and select Crop to the Selected area feature and press OK. - Name the saved file Cropped DEM.dem Slide 33

34 Preparation - Open Google Satellites Map Downloader - Adjust the settings and download bounds as in the image to the left. - image bounds can be obtained approximately from Google Earth - Zoom 15 will result in about 4m resolution image - Press Download Slide 34

35 Preparation - When Download is finished, go to Tools > Combine Images - Select the project file SaudiDAM.gmid to combine the images into one big bitmap file Sat Image.bmp. - Press Combine - The final image will be located inside the C:/Downloads/ SaudiDAM/ folder Slide 35

36 Preparation - Go to C:/Downloads/ SaudiDAM/ folder and Drag / Drop the SAT Image.bmp file into Global mapper. - Press OK to the message that will appear - Select Geographic as the projection and WGS84 as the Datum - Press OK Slide 36

37 Preparation - The image will appear to be placed correctly in the drawing. However, it is not orthorectified correctly. Slide 37

38 Preparation - Go to Tools > Control Center and right click on the SAT Image.bmp file. - Select RECTIFY - Press OK to the Tip that will appear. Slide 38

39 Preparation - Press the Select Projection button in the Ground Control Point (GCP) Projection section Slide 39

40 Preparation - Select the Mercator as the projection and WGS84 as the Datum - Press OK Slide 40

41 Preparation - Press YES to Reproject the GCPs to the new projection. This is very important. - Press OK to the RECTIFY dialogue window. - Now the image is correctly placed and projected. - Now close all layers except the SAT Image.bmp layer Slide 41

42 Preparation - Go to Tools > Configure. - In the Projection tab adjust the projection of the file to be UTM zone 37 North and the datum to be WGS84. - Press OK - This will project all the data in the file into the UTM zone 37 projection Slide 42

43 Preparation - Go to File > Export Raster/Image Format Slide 43

44 Preparation - Go to File > Export Raster/Image Format - Press OK to the Tips window - Leave the JPG Export options unchanged and press OK - Save the file as SAT Image.jpg - A.prj and.jgw files will be saved automatically with georeference information Slide 44

45 Step 2: Working inside WMS Slide 45

46 Working inside WMS - Open WMS version 7.1 Slide 46

47 Working inside WMS - Drag and Drop the Cropped DEM.dem file into the WMS main window - Uncheck the Smooth DEM on Import - Press OK to start importing elevation data Slide 47

48 Working inside WMS - Remember that the original M data was in Geographic projection (Lat/Long degrees). - WMS requires to project the data into a plainimetric coordinate system for delineation. - Press YES Slide 48

49 Working inside WMS - Now edit the Project Coordinate system first to be Geographic, WGS84, North and East. - Then edit the project coordinate system to be UTM Zone 37, WGS84. - Press OK Slide 49

50 Working inside WMS - Now contour lines are displayed in the main window. - The file is projected in UTM zone 37 now - Coordinates X,Y, and Z of any point is displayed in the lower left bar. Slide 50

51 Working inside WMS - Go to the drainage Module - Go to DEM > Compute TOPAZ Flow Data to calculate the flow accumulations Slide 51

52 Working inside WMS - Leave all options the same and press OK Slide 52

53 Working inside WMS - Adjust the Basin Areas to Square Kilometers and the Distances to Meters - Press OK Slide 53

54 Working inside WMS - When Done, Press Close to the Model wrapper window Slide 54

55 Working inside WMS - Now streams appear on the plan. - The default threshold value for drawing streams is 1.0 square kilometers. This value can be changed from the Display options. Slide 55

56 Working inside WMS - Now we need to place the GPS point in side WMS. - Given coordinates of the PS point in geographic Lat/long while WMS file now is in UTM Projection - First open Global Mapper to find the GPS point coordinates in UTM zone 37 coordinates. - Go to Tools > Coordinate Convertor Slide 56

57 Working inside WMS - Edit the Input Coordinates and the Output Coordinates as in the figure to the left. - Write the long/lat of the outlet point - Press Convert to - Values written in the X and Y fields are the new coordinates to be used in WMS Slide 57

58 Working inside WMS - Open the Terrain Module in WMS - Select the Create Feature Point button Slide 58

59 Working inside WMS - Place the point anywhere inside the contour lines - Copy and paste the X and Y coordinates from Global Mapper to the X and Y Fields inside WMS and press enter - The feature point location will be changed automatically Slide 59

60 Working inside WMS - Go to the Drainage Module again - Zoom in to the Feature Point Location Outlet Point - Create an outlet point on the stream (blue) nearest the feature point location Feature Point Slide 60

61 Working inside WMS - Go to DEM > Delineate Basins Wizard - Check the Display feature arc creation option - Leave the threshold value to 1.0 km2 and press OK Slide 61

62 Working inside WMS - Press OK to calculate the Basin Data Slide 62

63 Working inside WMS - Catchment Delineation is Done - Save the WMS file in a new folder Slide 63

64 Working inside WMS - Select the Select drainage unit or basin button. - Double click anywhere inside the catchment boundary - Press on Unit Hydrograph Method button Slide 64

65 Working inside WMS - Press on Basin Geometrical Attributes - The calculated Basin Data will appear. - When done press Cancel to return to the main WMS window Slide 65

66 Step 3: Verifying the Catchment Slide 66

67 Verifying the Catchment - Drag and Drop the SAT Image.jpg file into the WMS main window - The image shall appear in its place overlaid over the catchment and streams - Carefully verify the streams and catchment boundary delineated by WMS with the satellite image. Slide 67

68 Verifying the Catchment Stream A Flat Area Catchment Boundary Outlet - For Some reasons, it is decided to include stream A in the figure to the left inside the catchment - The could be because the elevation difference between the stream ad the catchment boundary is small such that water is expected to overtop the boundary Slide 68

69 Verifying the Catchment - Go to the Terrain Module - Press on the Select DEM Points button to use this tool - We are going to manually edit the DEM cells Slide 69

70 Verifying the Catchment Cell 4 Cell 1 Cell 2 - We need to manually reverse the flow direction of the shown 4 DEM cells to include the additional stream inside the catchment. Cell 3 Slide 70

71 Verifying the Catchment - First Double click on Cell 3. Before - Adjust the flow direction to be downwards - Press OK After Slide 71

72 Verifying the Catchment - Uncheck the three boxes and press OK - We shall perform these calculations when all edits are done Slide 72

73 Verifying the Catchment Before - Repeat the same with Cell 2 then cell 1 After Slide 73

74 Verifying the Catchment - Repeat the same with Cell 4 Before After Slide 74

75 Verifying the Catchment - This time check all the boxes to recalculate everything Slide 75

76 Verifying the Catchment - Stream Direction is modified - However, the catchment boundary is not - Go to DEM > Delineate basin wizard and repeat the delineation process again. Press ok to the warning message that shall appear. Delineation will be repeated using the same outlet point Slide 76

77 Verifying the Catchment - Stream Direction is modified - However, the catchment boundary is not - Go to DEM > Delineate basin wizard and repeat the delineation process again. Press ok to the warning message that shall appear. Delineation will be repeated using the same outlet point Slide 77

78 Verifying the Catchment - Stream Direction is modified - However, the catchment boundary is not - Go to DEM > Delineate basin wizard and repeat the delineation process again. Press ok to the warning message that shall appear. Delineation will be repeated using the same outlet point Slide 78

79 Step 4: Visualizing the Catchment Slide 79

80 Visualizing the catchment - Go to the Map Module - Go to CAD > Data -> CAD Slide 80

81 Visualizing the catchment - Go to the Map Module - Go to CAD > Data -> CAD - Save the file. - An AutoCAD drawing shall appear in the WMS file folder with the same name Slide 81

82 Visualizing the catchment - Drag and drop the AutoCAD drawing file into Global Mapper - Press OK - Define the projection of the CAD drawing as UTM Z37 and WGS84 as datum - Press OK Slide 82

83 Visualizing the catchment - The delineated Catchment will appear in place in Global Mapper Slide 83

84 Visualizing the catchment - Go to Tools > Control Center - Close all layers except the ACAD Drawing Slide 84

85 Visualizing the catchment - Go to File > Export Vector Format - Select KML/KMZ for export format - Leave all export options the same - Save the file on your computer Slide 85

86 Visualizing the catchment - Open the KMZ file in Google Earth Slide 86

87 Additional Exercise Latitude N Longitude E Slide 87