GIS BASED FLOOD MODELING OF SOANRIVER AND DISASTER RISK REDUCTION                        By          Muhammad Nadeem      ...
INTRODUCTION    Background     Importance of flooding due to rainfall     Development of housing societies and embankmen...
STUDY REACH3
DATA SETS                    DATA SETS FOR MODEL PREPARATION        Data type                Specification             Sou...
GENERAL METHODOLOGY      Field Height          Data        DEM                            Satellite Image      Comparison ...
MATERIALS AND METHODS
MATERIALS AND METHODS     Input Datasets       Terrain height       Land-cover information       Magnitude of 100 year...
FIELD DATA COLLECTION8
X-Section 4                                                  DEM VS Field Heights                1460                1450 ...
X-Section 10                                              DEM VS Field Height                1460                1450     ...
X-Section 12                                              DEM VS Field Height                1440                1430     ...
X-Section 23                                                  DEM VS Field Height                1430                1420 ...
X-Section 30                                              DEM VS Field Heights                1410                1400    ...
DEM VS FIELD HEIGHT      Cross     No. of Points    Mean Field      Mean DEM       Mean Height     Section                ...
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LAND COVER CHANGE ANALYSIS                  1600                                                                          ...
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INSTANTANEOUS PEAK DISCHARGED 100000i 90000sc 80000h 70000ar 60000g   50000e   40000(C    30000us    20000e    10000cs    ...
FLOOD FREQUENCY ANALYSIS      Extreme value type I distribution also known as Gumbel       distribution was used for floo...
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RESULTS AND DISCUSSION
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Manning Coefficient                                .014          .035                         .014                      14...
100 YEAR FLOOD 2011 MODEL26
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CALIBRATED MANNING VALUES     •   DD&C’s flood map area was 388 hectares                                                Wa...
Manning Coefficient                                .014          .035                         .014                      14...
100 YEAR FLOOD 2011 MODEL32
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INUNDATION RESULTS      100 year flooding event inundated total area of 249 Hectares           Area Class        Inundate...
37
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CONCLUSIONS &                        RECOMMENDATIONS     •   Since large number of cross sections are required for flood m...
LIMITATIONS      Satellite images for the peak discharge days were not available for       more reliable validation of mo...
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Gis based flood modeling of soan river and disaster risk reduction

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Gis based flood modeling of soan river and disaster risk reduction

  1. 1. GIS BASED FLOOD MODELING OF SOANRIVER AND DISASTER RISK REDUCTION By Muhammad Nadeem GIS Specialist at Survey of Pakistan
  2. 2. INTRODUCTION Background  Importance of flooding due to rainfall  Development of housing societies and embankments Objectives  Hydraulic modeling of 100 year flood in Soan river  Land survey for taking cross sections of the river  Selection of best suitable height data for 1D flood modeling  Calibration of the model and production of flood maps  Multi-temporal satellite image classification and change detection2
  3. 3. STUDY REACH3
  4. 4. DATA SETS DATA SETS FOR MODEL PREPARATION Data type Specification Source ASTER Digital (GDEM) 30m Spatial Resolution Elevation Model website SPOT 5 Image 2.5m Spatial Resolution Survey of Pakistan LandSat Images 30m Spatial Resolution USGS Website Annual Instantaneous Discharge Data SWHP, WAPDA Peak Values DATA SETS FOR VALIDATION Data type Specification Source Field Survey & Cross Section Data 5 Cross Sections DEM DD&C, E in C’s Flood Extent Map 1997 Flood Event Branch4
  5. 5. GENERAL METHODOLOGY Field Height Data DEM Satellite Image Comparison Land-cover Classification TIN Creation Calibration Flood Frequency Analysis Time Series Discharge Data FLOOD MAPS5
  6. 6. MATERIALS AND METHODS
  7. 7. MATERIALS AND METHODS  Input Datasets  Terrain height  Land-cover information  Magnitude of 100 year flood  RAS geometry  Acquisition Methods  Field survey  Satellite image classification  Flood frequency analysis  Digitizing satellite images7
  8. 8. FIELD DATA COLLECTION8
  9. 9. X-Section 4 DEM VS Field Heights 1460 1450 1440 1430Height (Feet) 1420 Height_Field 1410 Height_DEM 1400 1390 1380 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 Station Number from Left Bank to Right Bank facing Downstream 9 0 10 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Meters
  10. 10. X-Section 10 DEM VS Field Height 1460 1450 1440 1430 1420Height (Feet) 1410 1400 Height_Field 1390 Height_DEM 1380 1370 1360 1350 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142434445464748495051 Station Number from Left Bank to Right Bank facing Downstream 10 0 30 60 120 180 240 300 360 420 480 540 600 660 720 Meters
  11. 11. X-Section 12 DEM VS Field Height 1440 1430 1420 1410Height (Feet) 1400 1390 Height_Field Height_DEM 1380 1370 1360 1350 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 Station Number from Left Bank to Right Bank facing Downstream11 0 30 60 120 180 240 300 360 420 480 540 600 660 720 780 Meters
  12. 12. X-Section 23 DEM VS Field Height 1430 1420 1410 1400 1390Height (Feet) 1380 1370 1360 HEIGHT_FIELD HEIGHT_DEM 1350 1340 1330 1320 1310 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 Station Number from Left Bank to Right Bank facing Downstream 12 0 1020 40 60 80 100 120 140 160 180 200 220 240 260 280 Meters
  13. 13. X-Section 30 DEM VS Field Heights 1410 1400 1390Height (Feet) 1380 1370 HEIGHT_FIELD HEIGHT_DEM 1360 1350 1340 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 Station Number from Left Bank to Right Bank facing Downstream 13 0 15 30 60 90 120 150 180 210 240 270 300 330 Meters
  14. 14. DEM VS FIELD HEIGHT Cross No. of Points Mean Field Mean DEM Mean Height Section Height (ft) Height (ft) Difference (ft) 4 62 1414 1440 26 10 51 1403 1429 26 12 41 1393 1418 25 23 67 1380 1387 7 30 39 1367 1385 18  DEM heights were on average 21 feet higher than the field heights  Cross section profiles’ plots were similar except at a few locations  DEM was selected for taking cross sections for flood modeling14
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  18. 18. LAND COVER CHANGE ANALYSIS 1600 1394 1400 1200 1118 1128 1016Area (Hectares) 1000 831 842 Builtup 800 710 Vegetation Water 600 Barrenland 404 400 323 200 135 147 65 0 1998 2003 201118 Year of Image Acquisition
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  20. 20. INSTANTANEOUS PEAK DISCHARGED 100000i 90000sc 80000h 70000ar 60000g 50000e 40000(C 30000us 20000e 10000cs 0) Year20 Courtesy: Surface Water Hydrology Project (SWHP), WAPDA
  21. 21. FLOOD FREQUENCY ANALYSIS  Extreme value type I distribution also known as Gumbel distribution was used for flood frequency analysis  Magnitude of peak discharge for 100 year flood 118130 cusecs  This estimate was considered acceptable because DD&C has had previously used 110000 cusecs21
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  23. 23. RESULTS AND DISCUSSION
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  25. 25. Manning Coefficient .014 .035 .014 1480 Legend 1475 WS 100 Year Ground 1470 Bank Station 1465 Elevation (ft) 1460 1455 1450 1445 1440 2000 2500 3000 3500 4000 Distance (ft)25
  26. 26. 100 YEAR FLOOD 2011 MODEL26
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  30. 30. CALIBRATED MANNING VALUES • DD&C’s flood map area was 388 hectares Water Area Barren land Built-up Vegetation % Difference Channel (Hectare)Set 1 0.027 0.015 0.031 0.035 439 +13.21Set 2 0.025 0.014 0.029 0.035 410 +5.72 • Calibrated model area was 5.72% greater than DD&C’s map area • In other words, model result was almost 94.28% correct30
  31. 31. Manning Coefficient .014 .035 .014 1480 Legend 1475 WS 100 Year Ground 1470 Embankment 1465 Elevation (ft) Bank Station 1460 1455 1450 1445 1440 2000 2500 3000 3500 4000 Distance (ft)31
  32. 32. 100 YEAR FLOOD 2011 MODEL32
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  36. 36. INUNDATION RESULTS  100 year flooding event inundated total area of 249 Hectares Area Class Inundated Area Inundated Area (Acre) (Hectares) Barren land 70 174 Built-up 55 137 Vegetation 72 17936
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  39. 39. CONCLUSIONS & RECOMMENDATIONS • Since large number of cross sections are required for flood modeling and it is very hectic and time consuming task to take them all from field survey so DEM is the best option for taking cross sections for flood modeling • Floodplain of the river has been narrowed down due to urban developments and construction of protection embankments, further studies can be conducted to investigate issues related to floodplain management to avoid further narrowing • Flood inundation maps show that already constructed protective structures can withstand against 100 year flood making right bank safe but some areas on the left bank are still under risk of inundation. Therefore, new protection structures should be constructed on the left bank at suggested locations to make these areas safe • DTM or LIDAR data can also be used for flood modeling and floodplain management39 studies which can enhance the accuracy and results to make them more reliable
  40. 40. LIMITATIONS  Satellite images for the peak discharge days were not available for more reliable validation of model results  High resolution DEM was not available, if available, too much costly. So it was a binding to use 30m Aster DEM only  Lot of changes have taken place in terrain after the acquisition of aster DEM  Same type of data is being maintained by various organizations, so getting knowledge of what data is available from where is a tough job  Therefore, it is recommended that flood discharges should be observed, recorded and disseminated by a single organization40
  41. 41. Thanks
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