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

Iloilo Province

Panay Island

Project Area: The Tigum Aganan Watershed

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

CONCEPTUAL FRAMEWORK

Rainwater Potential

CommunityApplication

Annual Average RainfallDry Season RainfallRainy Season RainfallDry 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 forestedUpland agriculture: Alimodian, Cabatuan, Sta. BarbaraLowland agriculture: OtonPavia, Built Up areaIloilo City, Built up area

PROJECT

CONCEPT

FRAME

WORKProvide Man-made storage: in soil & cisterns

Natural Storage

Storage in Groundwater

Storage in Forest Soil

Storage inGround Water

Only 10% of the runoff

reaches the ground water

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:

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

STORAGE IN

FOREST SOILRain on

Land

Surface Runoff

Evaporate

Infiltrate

In Sub-surface soil

Through the soil profile

Trees at Maasin Watershed 90.6% survival rate at sub project

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

Dry Busay Creek

Dry Bungol Waterfall

A Dry Fishpond

Witnesses to a Lost Swamp

Tigbaw, Kagang, Tabun-ak, Badyang

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.”

POLICY DIALOGUE AT IWMC

Revisited Assumptions and their Scientific Bases

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.

“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.

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.”

Reference # 3 Internet Postinghttp:/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

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”

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.

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.

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.

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

INTEGRATION OF RAINWATER

HARVESTING

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.

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

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

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

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

Water pits

Rainwater Harvesting Technology

Some types of rainwater catchment facilities

Natural Depression

Infiltration ponds & canals

Dry Pond

Detention Ponds

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.

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

Income Diversification

Artificial Recharge

Potential Benefits of IntegratingRainwater 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

IMPACT ofEXTREME WEATHER

VARIABILITY

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.

World’s Major Flooding

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)

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

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

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

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

Stakeholders’ Assembly to raise awareness and generate recommendations

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

PROJECT RECOMMENDATIONS

submitted to the PROVINCIAL

LEGISLATIVE BODY

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

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

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

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