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. Iloilo Province
Panay Island

4. Project Area: The Tigum Aganan Watershed

5. 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. CONCEPTUAL
FRAMEWORK

7. 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

8. Natural Storage
Storage in Groundwater
Storage in Forest Soil

9. Storage in
Ground Water
Only 10% of the runoff
reaches the ground water

12. 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:

13. 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

14. STORAGE IN
FOREST SOIL
Rain on
Land
Surface
Runoff
Evaporate
Infiltrate
In Sub-surface soil
Through the soil profile

15. Trees at Maasin Watershed 90.6%
survival rate at sub project

17. 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

18. Dry Busay Creek

19. Dry Bungol Waterfall

20. A Dry Fishpond

21. Witnesses to a Lost Swamp
Tigbaw, Kagang, Tabun-ak,
Badyang

22. 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.”

23. POLICY DIALOGUE AT IWMC
Revisited Assumptions and their
Scientific Bases

24. 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.

25.  “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.

26. 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.”

27. Reference # 3 Internet Posting
http:/www.guardian.co.uk
“Research Pours Cold Water on
Moisture Conservation Role for
Forests.”
By Tim Radford, science editor
Friday, July 29, 2005, The Guardian

28. 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”

29. 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.

30. 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.

31. 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.

32. 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

33. INTEGRATION OF
RAINWATER HARVESTING

34. 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.

41. 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

42. RWH Applications for the
Maasin Watershed to Mitigate
Impact of Exotic Tree Plantation

43. 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

44. Plantation creates dry soil. Rainwater ponds could help enrich soil and
help growing trees in commercial plantation
Water pits

45. Rainwater Harvesting
Technology

46. Some types
of rainwater
catchment
facilities
Natural Depression
Infiltration
ponds &
canals
Dry Pond
Detention Ponds

47. 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.

48. 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

49. Income Diversification

50. Artificial
Recharge

52. 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

53. IMPACT of
EXTREME WEATHER
VARIABILITY

54. 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.

55. World’s Major Flooding

56. 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)

57. 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

58. 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

59.  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

60. 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


61. Stakeholders’
Assembly to raise
awareness and
generate
recommendations

62. 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

63. PROJECT
RECOMMENDATIONS
submitted to the
PROVINCIAL
LEGISLATIVE BODY

64. 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

65. 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

66. 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

67. e n d