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Wetland spatio temporal change analysis and ecosystem services in two urbanizing cities

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Presented by IWMI's Daniel Van Rooijen at the TropiLakes2015 Conference, September 23-29, 2015, Bahir Dar, Ethiopia.

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Wetland spatio temporal change analysis and ecosystem services in two urbanizing cities

  1. 1. Wetland spatio-temporal change analysis and ecosystem services in two urbanizing cities Research team: Priyanie Amerasinghe, Matthew McCartney, Kiran Apsunde and Kanika Mehra Bahir Dar, Ethiopia, 23-29 September 2015 Daniel Van Rooijen International Water Management Institute
  2. 2. Contents • Introduction • Methods • Case study city characteristics
  3. 3. Introduction: Wetlands in India • A wealth of ecosystem service benefits • Inadequate attention in the national water sector agenda • Urbanization, population increase, land-use changes have impacted • Emphasis has been on ecologic and limnologic studies • Hydrological, landscape and wetland spatio- temporal change analysis studies are sparse
  4. 4. Methods • Two cities (2014): Kolkata, West Bengal Nagpur, Maharashtra • Landsat 7 and 8 satellite images 2000 and 2013 (November/December – post monsoon/winter) • Supervised Image classification and Modified Normal Difference Water Index (MNDWI); • TEEB’s approach (The Economics of Ecosystems and Biodiversity) to assess ESS – A total of 27 ESS were selected, based on observations and surveys. • 4 wetlands were investigated to validate the ESS and wetland dependence by poor communities
  5. 5. Photo:DavidBrazier/IWMIPhoto:TomvanCakenberghe/IWMI Kolkata Nagpur City type Metropolitan City Metropolitan City Population KMC- 4.49 million KMDA-14.77 million NMC- 2.41 million Population density 24,000 persons/ sq. km 11,000 persons/ sq. km Area KMC-185 sq. km KMDA-1886 sq. km NMC- 217 sq. km NMA- 3780 sq. km Main industries IT industry Mining and agriculture (Orange City of India) Population Growth rate 1.73% n.a. Climate Annual rainfall:1,582 mm Annual mean temperature 250 C Annual rainfall: 1,205 mm Annual temperature 20-330 C City characteristics
  6. 6. Location of study sites 0 3 6 9 121.5 Kilometers Kolkata Area: 87,500 ha Nagpur Area: 92,500 ha
  7. 7. CLICK TO EDIT MASTER TITLE STYLE Mapping Natural and Built Infrastructure • TCWI = Tasselled Cap Wetness Index • MNDWI = Modified Normalized Difference Water Index • NDVI = Normalized difference Vegetation Index • DN = Digital Number MNDWI was found to be the most suitable index. The water bodies therefore were extracted using MNDWI Field Validation of mapped features Post Validation Changes Final Maps Landsat 7 -2000 Landsat 8 - 2013 Mapped & Classified 2000 & 2013 Field Validation Change Analysis at City and Watershed Level
  8. 8. Wetland Selection and Field Surveys (HH & FGDs) Ecosystem Services Check-listing / Scoring Wetland Selection based on ES Score & Community dependence Questionnaire Preparation, Validation, Revision and Field Surveys. For each of the ES identified, a score of 1 was given and summed-up to give a final score for the wetland.
  9. 9. Legend Hoogli River KMC_Boundary Built-up Water Bodies Open Spaces/ Wastelands Orchards/Trees Agriculture/Shrubs Map_Area ± 0 3 6 9 121.5 Kilometers 0 3 6 9 121.5 Kilometers November 2000 November 2013 Land Cover Changes: 2000 and 2013 – Kolkata
  10. 10. Results from Kolkata 1/2 • Size class of 0.36 ha and above were mapped (over 3,300 wetlands) • Built up areas (6%) and waste/open lands increased (1%) • Water bodies (3%), orchards and trees (5%) Agriculture and shrub lands (10%) decreased • 4 types of wetlands tanks, aquaculture/paddy rice, riverine marsh/lagoons and treatment units (10,645 ha) • Area-wise tanks constituted 12%, only 1.2% (127 ha) were natural. Rest was the EKW (East Kolkata Wetland)
  11. 11. Results from Kolkata 2/2 • 50% reduction in wetland area over a 12 year period • 37 wetlands were scored for ES. 30 in urban and 7 periurban • Number of reported Ecosystem Services (ES) varied between 4-20 per wetland • High number of ES provided by a majority of wetlands (75% fell within 15-17 range)
  12. 12. Distribution of ES (%) 1 Bathing and washing 2 Recreation 3 Religious activities 4 Medicinal plants/food 5 Fishing 6 Firewood 7 Construction Material 8 Agriculture 0 20 40 60 80 100 1 2 3 4 5 6 7 8 Urban Wetlands Peri-Urban Wetlands
  13. 13. 0 4 8 12 162 Kilometers ±Land Cover in Nagpur City Legend Stream Network Watershed BOundary NMC_Boundary Subwatersheds GRIDCODE Built-up Water Bodies Vegetation/Forest Agriculture/Scrubs Open/Fallow Sand Mine Ash Pond River Bed Year 2000 Year 2013
  14. 14. Results – Nagpur 1/2 • Size class of 0.36 ha and above were mapped (182 wetlands) • Built-up area (5%) agriculture/shrub land area (3%) increased • Marginal changes in water bodies • Forest area (5%) open fallow land (3%) decreased • 4 types of wetlands: tanks, reservoirs, water logged areas in quarries and treatment plants (844 ha)
  15. 15. Results - Nagpur 2/2 • 90% of wetland area were tanks and reservoirs • 0.4% were classified as natural • Loss of natural tanks (70%) was significant (was obscured by water in quarries) • ES scores varied from 15-23, and the distribution was very similar that found in Kolkata
  16. 16. Conclusions • Wetlands in Kolkata and Nagpur support a rich diversity of ES • No other studies available on wetland spatio– temporal changes that can evidence wetland losses • Wetland conservation plan is necessary (Wetland conservation policy drafted but not implemented) • Engagement of decision makers and users is important to develop policies that are relevant to wetland conservation.
  17. 17. Thank you • WLE program for funding • Daniel van Rooijen (IWMI - Ethiopia) • Anuradha Adikari and Aruna Jyoti (IWMI- Hyderabad) • Stakeholders in Kolkata and Nagpur • South Asia Forum for Environment, Kolkata • Centre for Rural Research and Community Development, Nagpur For more info contact Dr. Amerasinghe (p.amerasinghe@cigar.org)

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