Southeast Asia Conference 08


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Regional Conference for Southeast Asia on Rainwater Harvesting in IWRM: An ExChange of Policies and Learnings

November 25-26, 2008
Davao City

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  • What is a wtershed. Watershed divide, sub basin, channel
  • Highest vol SB 25, SB05 (Pavia), Maasin W. Total of 4 subbasin 72
  • Southeast Asia Conference 08

    1. 1. A REPORT TO THE SANGGUNIANG PANGLALAWIGAN NG ILOILO Rainwater Harvesting in IWRM for Climate Change Adaptation Project UNEP- IWMC-TAWMB, 2007-2008 By Jessica Calfoforo Salas, Project Manager
    2. 2. Iloilo Province Panay Island
    3. 3. Project Area: The Tigum Aganan Watershed
    4. 4. The Tigum-Aganan Watershed  Area – 52,669 ha  Population – 419,973 persons, 391 villages  Rainfall, Rainy Season, 6 mos. – 1600 mm  Rainfall, Dry Season, 6 mos. - 345 mm  Overseeing Body - The Tigum Aganan Watershed Management Board: Municipalities of Maasin, Alimodian, Cabatuan, Sta. Barbara, Pavia, San Miguel, Oton, Iloilo City, NIA, DPWH, PIA, MIWD, CPU, KSPFI, Irrigators’ Association, KAPAWA
    6. 6. Rainwater Potential Community Application Annual Average Rainfall Dry Season Rainfall Rainy Season Rainfall Dry Season Rainfall – 50% Rainy Seaso Rainfall + 50% Average Annual Rainfall +/ - 50% Protect Natural Storage: Old Growth Forest & Groundwater Projections in Sub Basin 17, 14, 12, 10 and 6 GIS Maps Sub- Basin Maps Mianas Micro Watershed:f forested Upland agriculture: Alimodian, Cabatuan, Sta. Barbara Lowland agriculture: Oton Pavia, Built Up area Iloilo City, Built up area PROJECT CONCEPT FRAME WORK Provide Man-made storage: in soil & cisterns
    7. 7. Natural Storage Storage in Groundwater Storage in Forest Soil
    8. 8. Storage in Ground Water Only 10% of the runoff reaches the ground water
    9. 9. Maraget Sandstone aquifer Recharge Dry Season Ave540 mm/year or . 054m3 7,781.9 CMD MIWD DATA EXTRACTION 2007 = 10,380 CMD Max. 1 pump capacity @ 20 lps = 15,552 CMD. Capacity of total present facility (9 pumps) = 205 lps Outcrop area is 52.6 km2 Since MIWD is serving only 24% of the city population, it is possible that total actual extraction is far more than the recorded extraction of MIWD. An example:
    10. 10. Ground Water Supply Condition “Although a relatively large amount of deep ground water exists at the center of the Iloilo plain, its development has already exceeded the sustainable level.” p.15 JISRADP study  Low efficiency in MIWD wells indicates lowering ground water level (Engr. Calasara, MIWD Operations Manager).  “It would be difficult to develop the deep groundwater in the other area because of its low potential as investigated by the test well in the field survey.” p. 18 JISRADP study  Further studies may be needed to define the aquifer
    11. 11. STORAGE IN FOREST SOIL Rain on Land Surface Runoff Evaporate Infiltrate In Sub-surface soil Through the soil profile
    12. 12. Trees at Maasin Watershed 90.6% survival rate at sub project
    13. 13. Issues: Poor biodiversity Mono-cropping in large areas: bamboo, mahogany, gmelina Accelerated spread of invasive species No cutting of harvestable stands in a plantation-8 to 12 yrs old Drying of rivers & creeks during summer & drought Observations Today 33-year old plantation 7-12 year old trees
    14. 14. Dry Busay Creek
    15. 15. Dry Bungol Waterfall
    16. 16. A Dry Fishpond
    17. 17. Witnesses to a Lost Swamp Tigbaw, Kagang, Tabun-ak, Badyang
    18. 18. Influence of Ground Cover on Surface Runoff and Soil Loss Taken from Study on Sediment Condition in the Jaro and Iloilo River Basins, Iloilo Flood Control Project. , DPWH. Fig. 4.2, p84.”
    19. 19. POLICY DIALOGUE AT IWMC Revisited Assumptions and their Scientific Bases
    20. 20. Reference No. 1. Fact Sheet, Tree and Forest (Dept of Environment Conservation, New York State)  “Trees provide protection for our watersheds.  The forest floor, to which trees add leaves and decaying wood, acts as a sponge and store water.  “If the forest floor is a SPONGE, a tree is a PUMP that transpires water into air make rain for the land.  “A medium-sized tree (40 to 50Ft tall) will drink 10,000 gallons of water from the soil in a growing season.  “Forest soil 36-inches deep can absorb and hold as much as 18 inches of rain, or nearly 1 million gal per hectare.
    21. 21.  “A medium-sized tree (40 to 50Ft tall) will drink 10,000 gallons of water from the soil in a growing season.  “Baltimore City Watershed experimented with converting open areas to young pine forests. The result was a decline in water yield of 283,000 gallons per year.  If the forest floor is a SPONGE, a tree is a PUMP that transpires water into air make rain for the land.
    22. 22. Reference # 2. Media Release by Ellen Wilson, Jeff Haskins/ Coimbra Sirica at Business Communications  “Trees Overplayed as Solutions to World’s Water Problems, Finds Sweeping Report from UK’s Tropical Forestry Research Programme  Misguided Views on Water Management Have Encouraged Major Investments in Water Resource Projects that are Ineffective or Counterproductive, says Report.  Calls on Policymakers to Design Water Projects Based on Scientific Evidence of Benefits.”
    23. 23. Reference # 3 Internet Posting http:/ “Research Pours Cold Water on Moisture Conservation Role for Forests.” By Tim Radford, science editor Friday, July 29, 2005, The Guardian
    24. 24. Reference # 4: Mallin Falkenmark, “Water Management and Ecosystems” Living with Change, TEC Background Papers No. 9. Global Water Partnership Technical Committee. “Motherhood statements on forests and water which are against scientific evidence: Forests increase rainfall – Forests increase runoff – Forests regulate flows – Forests reduce erosion – Forests reduce floods. “A more questioning attitude is advised. The challenge of Adaptive Management is to uphold two incompatible imperatives: Respect the ecosystem imperative and commit to a set of human livelihood imperatives”
    25. 25. Reference # 5 – Watershed Magazine, Jan-June, 2005 “Flip flop Hydrology” by Albert Nauta Expert meeting led by Director Romeo T. Acosta (FMB-DENR, ) drafted joint statements which included:  “Plantation forestry or forest regeneration on grassland or crop will greatly reduce annual water yields (approx 400-700 mm/yr) due to their high water use.  “Forest clearing leads to increased annual water yield but seriously impairs infiltration opportunities. This is due to gradual soil degradation or extensive compacted areas.
    26. 26. Reference 6: GWP TEC # 9  Terrestrial ecosystems consumed 2/3 of the rainfall over the continents, a total of 71,000 km3/year and temperate and tropical forests/woodlands consume 40,000km3 of this or 56%. Other areas consuming rain are croplands, grasslands, swamps and marshes, tundra and desert and other systems.
    27. 27. Reference # 7. Calder, The Blue Revolution: Land Use and Water Resources Management. Earthscam, London, UK, 1999  The perception that forests are good for the water environment and for water resources has grown out of observation that linked land degradation with less forest and rehabilitation and conservation with more forest. Reference # 8. Savanije, “New Definition for Moisture Recycling and Relationships with Land- Use Changes in the Sahel” Journal of Hydrology, 1995.
    28. 28. Recommendations to Enhance Storage in Natural Forest Understand forest soil  Use natural Regeneration  Assisted natural regeneration  Rainforestation  Protect biological diversity  Protect forest from exotic and invasive species  Create buffer zones  Study erosion pattern, protect rivers
    30. 30. Steps Taken Rainwater Harvesting Project UNEP & IWMC-TAWMB  GIS Mapping/ study of the rainfall and the land characteristics of the watershed  Stakeholders’ assembly and planning  Identification of demonstration areas for rainwater harvesting  Integration of rainwater harvesting in the municipal and provincial development plans.
    31. 31. Demo for Lowland agriculture Demo for artificial recharge Demo for forest enhancement Demo for upland agriculture Demo for household storage Demo for Forested Area Demo for Household Storage Demo for Upland Storage Demo for Lowland Storage Demo for Built Up Area Storage
    32. 32. RWH Applications for the Maasin Watershed to Mitigate Impact of Exotic Tree Plantation
    33. 33. A Watershed Planted with Exotic Trees May take 20 years for trees to stabilize and trees may stop drinking much water but no storage in forest soil may be formed due to inability of organisms to decay exotic leaves. (University of Minnesota, Cornell University & ESSC (Ateneo University opinions). Fast growing exotic species mature and die in 15 to 20 yrs
    34. 34. Plantation creates dry soil. Rainwater ponds could help enrich soil and help growing trees in commercial plantation Water pits
    35. 35. Rainwater Harvesting Technology
    36. 36. Some types of rainwater catchment facilities Natural Depression Infiltration ponds & canals Dry Pond Detention Ponds
    37. 37. Camilo Sacupon Rainfed farm: Yield – 120 sacks/cropping x 3 cropping or 6 tons a year for 2 hectares. NIA average is 3.3 tons/hectare With 1,250 m2 mother tank and 100 m2 daughter tank, water can support 3 cropping of rice in a 2 ha. service area.
    38. 38. Andres Calfoforo Jr. Yield of 1.5 ha., 120 sacks / ha. or 6 tons for 1.5 hectares With 2,500 sq.m pond, water can support 3 croppings of rice and other selected crops such as pepper, tomatoes, etc. NIA’s cost to provide irrigation to 1 hectare of riceland is P250,000 to P600,000 / hectare
    39. 39. Income Diversification
    40. 40. Artificial Recharge
    41. 41. Potential Benefits of Integrating Rainwater Harvesting  Retains and stores rainwater during rainy season  Helps mitigate flooding: urban & rural  Reduces use of processed public system water  Reduces use of river stream flow to allow downstream use  Recharges shallow ground water  A tool for managing water demand
    43. 43. Extreme weather; major disasters  Increase in frequency and magnitude  76% of the 100-year flood events occurred during the last half of the century  Cost of direct damage increased 5 times since 1980  Drought areas on earth surface doubled from 1970 to 2000.
    44. 44. World’s Major Flooding
    45. 45. The most vulnerable ones  Are those in developing countries, because of  High poverty level  Poor financial resources  High dependence on ecosystem functions for livelihood:  Agriculture  Fishing  Tourism  Weak institutions  Limited awareness re. Climate Risk Resiliency  High prevalence of communicable diseases (HIV, TB)
    46. 46. Philippines’ Inherent Vulnerability to Extreme Weather Variability  Geographical location – an archipelago in a ring of fire  Large mountainous terrain  Narrow coastal plain  Interior valleys UNDP Report on disaster:  Philippines is highest in # of tropical cyclones with average of 20 cyclones a year.  Third highest in terms of people impact
    47. 47. Impact of Typhoon Frank on the natural resources of the Tigum- Aganan Watershed  Leon – total eroded land is 660 m with 30-40 m high  Wells covered with soil  Aganan River changed course  San Miguel  800 meters length, eroded land, 2-6 m wide  Pavia  Household water resources contaminated
    48. 48.  Maasin  Waterfalls eroded, 3 hectares wide  River embankment erosion, 300 m long  River width 50 m.widened  30,000 trees damaged in plantation  Creeks damaged, decreasing 20% surface water supply  Observation that terraced farms have less damage
    49. 49. How may RWCS help communities adapt to climate variability  User has to manage demand (discipline in use of water)  Low cost  Adaptable to individual situation, needed in extreme weather variability.  Control of own’s resources  Encourages total community involvement  Protects river & ground water ecosystems  Green house gas contribution is 50% less compared with urban piped water system/ lesser than centralized irrigation system 
    50. 50. Stakeholders’ Assembly to raise awareness and generate recommendations
    51. 51. Steps in the integration process: 1. TAWMB Planning to integrate rainwater harvesting recommendations to the TigumAganan Watershed Management Plan. 2. Approval of the ammended Watershed Management Plan 2008- 2010 by the Tigum-Aganan Watershed Management Board. 3. Municipal Planning Workshops in 5 municipalities to integrate stakeholders’ recommendations in the municipal development plan. 4. Approval of the Municipal Development Plan and the Annual Investment Plan
    53. 53. Surface Water – Storage in the Forest  Restoration of damaged areas in the forest (slopes and riverbanks).  Restoration of endemic species and biodiversity at the Maasin Watershed  Soil enhancement in afforested areas and agro- forestry areas.  Use of appropriate farming methods, especially in the upland.  Institutional support: ordinances, sustainable upkeep of the upland through payment for environmental services
    54. 54. Ground Water Storage  Inventory and monitor ground water extraction  Limit sealed areas as part of CLUP  Pre-decision as to the volume of ground water to be used/ extracted  Use artificial ground water recharge, where needed, provide incentives and create a TWG to implement program  Institutional Support – IEC, ordinances, creation of a Ground Water TWG at IWMC
    55. 55. Rainwater Harvesting  Integrate rainwater harvesting in municipal and provincial development plan  Create a program to promote and provide fund for rainwater harvesting in government buildings.  Require rainwater facilities for all new buildings as part of permit requirement.  Require upland farms to use appropriate farming methods to control erosion, particularly use of terraces and ponds  Encourage farmers and provide incentives to use rainwater ponds to irrigate their farms.  Integrate Rainwater Harvesting in water and sanitation programs to provide water to households in rural and remote areas
    56. 56. e n d