Environmental monitoring in Sundarbans: A Bangladesh Perspective

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Environmental monitoring in Sundarbans: A Bangladesh Perspective

  1. 1. ENVIRONMENTAL MONITORING OF THESUNDARBANS: BANGLADESH PERSPECTIVE Abu Saleh Khan Deputy Executive Director IWM, Bangladesh
  2. 2. FarakkaBarrage
  3. 3. N North Central• Area - 40,500 sq km North West North East• Population - 30 million Farakka• 62% land cultivable Barrage South North Central• 10% Forest, Sundarbans Centra• Only remaining habitats for the Royal Bengal Tiger South West South Central South West Sundarbans CAM Bay of Bengal Bay of Bengal
  4. 4. Driving forces on the ecosystem REDUCED RIVER FLOW Agriculture Shrimp farming - - Manure - - - - POLDERING URBAN AREASFARMING (Groundwater) Development in the upstream catchment & freshwater flushingMicro-topographic changes due to deposit of sediments carried by rivers or tidal currentsIndustrial, maritime and agricultural pollution MONGLA PORT KNM SUNDARBANS Sea level rise due to global warming Extreme wave attack due to cyclone and tidal surges
  5. 5. Declining Ganges DistributariesSalinityTop Dying of SundarbansGroundwaterFisheriesAgricultureDesertificationChannel Siltation
  6. 6. Mathabhanga offtake Chandana now closed inland river Arial Khan-Buriswar J am una Rive r Ga n ges Riv er System r Go iv e r ai R Ri hna ve Ch r eg an d rM Ku na ma pe Pa rR Up R i ver d iv e m Na b a a gan r Ri ga R ve rGorai-Passur/Sibsa Gorai-Madhumati System Baleswar System
  7. 7. J amuna Riv erIndustrial units suffered aprogressive damage due to Ga ng e sR ive r Crop damage andincreased corrosion r Go ive ra yield reduction aR iR iv g hn Ch er an Me dn Ku pe r m aR ar Pa R Up iver dm ive Na b a a r g an Ri ga R ve r River water turned impotableIndustrial operation neededto carry fresh water from along distance Increased water borne diseasesTop-dying of Sundari trees Degradation of public health
  8. 8. Increased salinity and associated sedimentation has raised the river banks. Raised river banks resulted in permanent bowl-shaped depressions inside the forestRoot Zone Nuematophores are exposed to extended period of inundation resulting in top- dying of trees
  9. 9. Static water table dropped down to 23 ft(7.01m), which caused• High pumping cost• Saline intrusion in shallow water table• Effect on surface water treatment plant• Now surfaced ARSENIC pollution in groundwater
  10. 10. Arsenic59 out of 64 districts are affected
  11. 11. Fish catch reduced: • Ganges by 88% Hilsha fish totally absent • other rivers by 90% • Beels by 31% Total loss of Tk. 4 BillionAlready some local species of fish: Sarputi, Nandai,Aeer, Belemach are no more available
  12. 12. Salinity at Khulna 20 15Salinity (ppt) 10 5 0 Febraury March April May Date Measured 2000 Measured 1999 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
  13. 13. Water supply to G K Project drastically reducedImplementation of Mathabhanga, Baral Basin andNorth Rajshahi Irrigation Project suspended
  14. 14. Decrease in surface water enhances Desertification Increased moisture deficiency down to even wilting point and added soil salinity result in severe damage to soil fertility
  15. 15. About 1/4 th of the countrysuffer water stress in dry season
  16. 16. “When only water is diverted atupstream point with no sediment, downstream reach undergosevere morphological imbalances and siltation occurs randomly” Number of islands increased in the Ganges river from 14 to 24 between 1973 and 1996
  17. 17. Heavy SiltationModerate SiltationSlow Slitation
  18. 18. P W Hydro-Morphological Aspect 14 13 Hardinge W a t e r L e v e l ( m Bridge 12 • Monthly discharge, Jan-May reduced by 25% • Monthly discharge, Jul-Sep increased by 8% 11 10 GK • Min. WL dropped from 6.98m to 5.34m PWD Intake 9 1960s 8 • Post-monsoon recession reduced from 4 to 2 months 7 6 Recent 5 0 30 60 90 120 150 180 210 240 270 300 330 360 Days (from 1 April) Talbaria SelaidhaL e v e l ( m , P W D ) 15 13 Kushtia Max. WL at Talbaria 11 Gorai Rail Bridge 9 Bed Level at Gorai Offtake 7 5 Min. WL at Talbaria 3 1964 1968 1972 1976 1980 1984 1988 1992 1996 18 Feb 1997 Year
  19. 19. • Rainfall: 5 locationsData Collection under SBCP • WL: 15 locations • Salinity: 26 locations • Sediment: 1400 nos. at 15 place • River flow: 15 places, 1 – 3 rounds • Water Quality: 10 parameters at 16 pl • Detailed Study: at 3 pilot areas • Land topography: at 3 pilot area • River Sections: at 178 locations • Secondary: collected from 1991 onward
  20. 20. Data collection inside the Sundarban Inundation of forestland Fall velocity measurementSiltation on forestland River water level
  21. 21. Seasonal Fluctuation of Water Level East West
  22. 22. Distribution of Rainfall in the Forest Area 2002 Mongla Supati Hironpoint Jhalia Notabaki 1200 1000Rainfall in mm 800 600 400 200 0 May Jun Jul Aug Sep Oct Nov Month
  23. 23. Seasonal Salinity variation During 2002 Salinity observation during 20023025201510 5 0 4/1/02 5/3/02 4/5/02 3/7/02 1/9/02 31/10/02 30/12/02 Date Supati Nalianala Hiron Point Notabaki
  24. 24. Salinity Distribution in September 2001
  25. 25. Salinity Distribution in March 2002
  26. 26. Salinity Distribution in April 2002
  27. 27. Salinity Distribution in May 2002 Non Sundari Area
  28. 28. Impact on Salinity Due to the Gorai Dredging
  29. 29. Monitoring of Water Quality Parameters Dissolved oxygen (DO) Biochemical oxygen demand (BOD) Chemical oxygen demand (COD) Ammonia as NH3-N Ammonium as NH4-N Nitrate as NO3-N Total phosphate as PO4-P Mercury (Hg) Chromium (Cr) Lead (Pb) Oil and grease
  30. 30. BOD Concentration observed during 2002 Monthly average of obseved BOD during 2002 25 20BOD in mg/l 15 10 5 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Eastern Part Western Part One sample with erroneous result has been excluded
  31. 31. Monthly Average of Observed DO value Monthly average of observed DO (Random Sample) during 2002 while profiling along channels during 2002 7.00 6.00 5.00DO in mg/l 4.00 3.00 2.00 1.00 0.00 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Total Sample: 1140 Minimum Allowable Limit: 5
  32. 32. Pb Concentrations: Eastern Sundarban 0.25 0.2 Harbaria HarintanaPb (mg/l) 0.15 Dudmukhi Shwarankhola 0.1 Jafa 0.05 Mrigamari 0 Jan02 Feb02 Jun02 Jul02 Jan03 Mar01 Mar02 Oct02 Apr01 Apr02 Sep02 Nov01 May02 Aug02 Nov02 Dec02 Months
  33. 33. Pb Concentrations: Western Sundarban Nalianala Arpangasia Bal Malancha Dingimari Kaikhali Kobadak 0.25 0.2 0.15Pb (mg/l) 0.1 0.05 0 Jul02 Jun02 Aug02 Jan02 Feb02 Sep02 M ay02 M ar01 M ar02 Nov01 Apr01 Apr02 Oct02 Dec01 Months
  34. 34. Erosion/Sedimentation of rivers inside the Sundarban
  35. 35. Patakata Khal, Chainage 0.81km 4 0 -4Level, m -8 -12 -16 -20 0 50 100 150 200 250 Width of the River, m Surveyed in 2000 Surveyed in 1995 Erosion of river bank
  36. 36. Bhola River , Chainage 39.31km 2Level, m -1 -4 -7 0 100 200 300 400 Width of the River, m Surveyed in 2000 Surveyed in 1995 Siltation on river bed
  37. 37. Selagang River, Chainage 40.67km 2 -3Level, m -8 -13 -18 -23 -28 0 200 400 600 800 1000 Width of the River, m Surveyed in 2000 Surveyed in 1995 Erosion of river bed and bank
  38. 38. FLOODING IN THE SUNDARBAN
  39. 39. Inundation in Jangra Pilot Area at high and low tide
  40. 40. Inundation in Jangra Pilot Area at high and low tide
  41. 41. Inundation in Jangra Pilot Area at high and low tide
  42. 42. SALINITY VARIATION WITHUPSTREAM FRESH WATER FLOW AND SEA LEVEL RISE
  43. 43. Existing dry period salinity
  44. 44. Op1: Minimum 100 m3/s in Gorai River
  45. 45. OP2: Minimum 200m3/s in Gorai River
  46. 46. Op3: Minimum 200m3/s in Gorai & 50 m3/s in Kobadak, Hari, Harihar & Betna
  47. 47. Op4: 50 cm Sea level rise
  48. 48. Long profile of maximum salinity concentration along Pussur-Rupsa river system for different option scenarios Maximum Salinity in March 02 for different Options (River: Rupsa-Pussur) 30 25 Hiron Point Mongla 20 Salinity(ppt) 15 Khulna 10 Bardia SUNDARBAN 5 0 0 20 40 60 80 100 120 140 160 180 200 Distance from Bardia (km ) BASE op-1 op-2 op-3 Op1: minimum 100 m3/s in Gorai Op2: minimum 200 m3/s in Gorai Op3: 50 m3/s in Kobadak, Hari, Harihar and Betna in addition to Op2
  49. 49. Mongla (Pussur-16.84 km) 7 6 5Salinity (kg/m 3) 4 3 2 08-Feb-02 10-Feb-02 12-Feb-02 14-Feb-02 16-Feb-02 18-Feb-02 20-Feb-02 22-Feb-02 Tim e Base Option-1 Option-2 Option-3 Op1: minimum 100 m3/s in Gorai Op2: minimum 200 m3/s in Gorai Op3: 50 m3/s in Kobadak, Hari, Harihar and Betna in addition to Op2
  50. 50. NOTABAKI (JAMUNA_35.57) 24 23 22 21 Salinity (kg/m ) 3 20 19 18 17 16 15 23-Feb-02 25-Feb-02 27-Feb-02 1-M ar-02 3-M ar-02 5-M ar-02 7-M ar-02 9-M ar-02 11-M ar-02 13-M ar-02 15-M ar-02 Time Base op-4 op-5Increase in salinity at Notabaki due to sea level rise (Op4: 50 cm SLR &Op5: 20 cm SLR)
  51. 51. Result of Hydrodynamic Model Showing the impact of Re-opening of Khorma Khal Bhola River , Chainage 39.31km Cross-section of Bhola River in 1995 and 2000 2 Level, m -1 -4 -7 0 100 200 300 400 Width of the River, m Surveyed in 2000 Surveyed in 1995 Proposed Bed Level Under Option Scenario 4 2 BASE BED-PROFILE Note: Before drawing any 0 Level(m/pwd) conclusion, this result obtained -2 from 1-D hydrodynamic model -4 OPTION BED-PROFILE -6 should be verified with that of a -8sediment transport model (under -10 development at present) 0 10 20 30 40 Chainage(km) 50 60 70 80 BASE OPTION-1
  52. 52. Result of Hydrodynamic Model Showing the impact of Re-opening of the Khorma Khal COMPERISON OF DISCHARGE AT CHAINAGE 23 KM COMPARISON OF WATER LEVEL 150 3.5 Change in Flow Volume 3 Change in Water Level 100 2.5 WATER LEVEL (m.PWD) 50 2DISCHARGE (M 3/S) base Q23km 1.5 0 Option Q23km 1 -50 0.5 -100 0 -0.5 16/9/01 17/9/01 18/9/01 19/9/01 20/9/01 21/9/01 22/9/01 23/9/01 24/9/01 25/9/01 26/9/01 -150 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 16/9/01 17/9/01 18/9/01 19/9/01 20/9/01 21/9/01 22/9/01 23/9/01 24/9/01 25/9/01 26/9/01 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 0:00 TIME TIME COMPARISON OF VELOCITY Base Option 1.5 Change in Flow Velocity 1 Note: Before drawing any 0.5 conclusion, this result Velocity(m/s) 0 obtained from 1-D -0.5 hydrodynamic model should -1 be verified with that of a -1.5 sediment transport model) 16/9/01 0:00 18/9/01 0:00 20/9/01 0:00 Time 22/9/01 0:00 24/9/01 0:00 26/9/01 0:0
  53. 53. [meter] Water Quality Modelling495000.0490000.0485000.0480000.0475000.0470000.0465000.0460000.0455000.0450000.0445000.0 DO mg/l440000.0435000.0430000.0425000.0420000.0415000.0410000.0405000.0400000.0 380000.0 400000.0 420000.0 440000.0 460000.0 480000.0 500000.0 520000.0 [meter] Modelled DO level on 17-8-2001 03:00 (Monsoon) in the Forest area
  54. 54. [meter] Water Quality Modelling495000.0490000.0485000.0480000.0475000.0470000.0465000.0460000.0455000.0450000.0445000.0 DO mg/l440000.0435000.0430000.0425000.0420000.0415000.0410000.0405000.0400000.0 380000.0 400000.0 420000.0 440000.0 460000.0 480000.0 500000.0 520000.0 [meter] Modelled DO level on 09-12-2001 19:00 (Post-monsoon) for the Forest area
  55. 55. [meter] Water Quality Modelling495000.0490000.0485000.0480000.0475000.0470000.0465000.0460000.0455000.0450000.0445000.0 DO mg/l440000.0435000.0430000.0425000.0420000.0415000.0410000.0405000.0400000.0 380000.0 400000.0 420000.0 440000.0 460000.0 480000.0 500000.0 520000.0 [meter] Modelled DO level on 28-6-2001 01:00 (Dry) for the Forest area
  56. 56. SWIMSSundarban Water Information Management System
  57. 57. Achievement at a glance Comprehensive data collection on water level, salinity, sediment, discharge and water quality Introduction of hydrological data collection on the forestland Improvement of Hydrodynamic and AD Model Introduction of non-point load assessment and Development of Water Quality Model (indicative)Application of HD & AD model for development of different option scenarios Development of SWIMS database and incorporation of available data and maps prepared
  58. 58. Unfinished Tasks of SBCP • Inundation/siltation study on forest land at more areas • Improvement of HD model incorporating additional channels/creeks and updated x-sections • Improvement of Salinity & WQ model to simulate scenarios with more confidence• Development of Cohesive Sediment Transport Model to study sedimentation process • Establishment of Bench Mark at Southern Boundary Stations• Exploring possibility of increasing flow in the western river system- Ganges Barrage Option
  59. 59. Thank You

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