Water Resources and Rivers of the Philippines

Water Resources in Phillipines

• Water is a basic resource, crucial for all life forms. Plants, animals, and humans are entirely dependent on it.
• The human body consists of roughly 70% moisture.
• Water is universally needed, globally distributed, and seemingly inexhaustible, influencing various human perspectives on its utilization.

Water Supply Sources

• Water sources include evaporation, runoff from rivers, lakes, rapids, and waterfalls, and penetration into the surface as groundwater.

Rivers of Northern Luzon

• The Cagayan River is the Philippines' longest river, rising in the Caraballo mountains.
• It traverses northward through the entire Cagayan Valley, flooding annually, which makes the Cagayan Valley fertile and ideal for tobacco cultivation.

Agno River

• The Agno River begins in the Central Cordillera and is partly developed for hydroelectric power.
• It supplies the Ambuklao and Binga hydroelectric plants.

Central Luzon Rivers

• The Upper Pampanga River Project is located at Pantabangan, Nueva Ecija; it serves multiple purposes, including irrigation, water power, water supply, and flood control.
• The Angat River flows through the Bulacan and Rizal provinces and has been developed for similar purposes.

Mindanao Rivers

• Rivers in Mindanao are typically short with high gradients due to the islands' terrain, originating from mountainous interiors and descending to coastal areas.

Groundwater

• Part of rainfall prevented from flowing to streams and seas, penetrates the earth's surface, forming groundwater
• The amount of groundwater and the depth of the water table depend on rainfall, land topography, vegetation cover, and soil porosity.

Springs and Wells

• Springs derive water from groundwater with location dependent on terrain and rock structure relating to the water table
• Most springs in the Philippines are located in mountainous or volcanic areas
• Springs on mountainsides are typically cold, while those near volcanoes are warm and mineralized.
• Pansol Spring in Pansol, Laguna has warm, medicinal water useful in treating diseases like rheumatism.
• Tiwi Spring in Albay's water can treat skin diseases.
• Springs should be developed for income and to address health and water needs.
• Wells are formed by digging or drilling into the ground to reach the water table.
• The term "artesian well" originated in Artois, France
• The water in many wells rises above the earth like a fountain, though today the term applies to any deep well where groundwater is brought to the surface, even if it doesn't flow naturally.

Industrial uses of water

• Water is utilized as a key ingredient, a cooling and impurity-removing agent, and a diluting medium for industrial waste

Historic facts about irrigation

• Irrigation in the Philippines dates back to pre-Spanish times.
• The Ifugao people constructed rice terraces in what is now Mountain Province.
• Showing skill in the use of irrigation water
• During three centuries of Spanish rule, the government didn't build irrigation systems.
• Irrigation systems in Friar Lands were established by churches around Manila and the Central Plain of Luzon.

Hydroelectric Power

• The amount of water power depends on water availability and stream, vertical fall, and the efficiency of water wheels/turbines
• The National Power Corporation (NPC) was tasked with comprehensive development, utilization, and conservation of Philippine water resources for beneficial uses, including power generation and electrification

Water Resources for Economic Development

• Conservation is important to prevent silting of dams and water reservoirs when used for irrigation or hydroelectric power
• The volume and height of water in reservoirs determine the life span and the irrigation and hydroelectric system.

Water Resources Situation

• Land area: 300,000 sq km
• Rivers and lakes: 1,830 sq km
• Bays and coastal waters: 266,000 sq km
• Average rainfall: 2,400 mm
• 12 Water Resources Regions exist with hydrological boundaries.

Per Capita Availability

• Surface water dependable supply: 125,790 MCM (80 dependability).
• Groundwater potential: 20,200 MCM (safe yield).
• Total dependable water supply: 145,990 MCM.
• 421 principal river basins are in the country.
• 18 are major river basins (DA ? 1,400 sq km).

Major River Basins

• Major River basins of the country include Abra-Ilocos, Cagayan-Cagayan Valley, Abulug-Cagayan Valley, Agno-Central Luzon, Pampanga-Central Luzon, Pasig-Laguna Bay-Southern Luzon, Bicol-Bicol, Panay-Western Visayas, Jalaur-Western Visayas, Ilog-Hilabangan-Western Visayas, Agusan-Northern Mindanao, Tagoloan-Northern Mindanao, Cagayan de Oro-Northern Mindanao, Tagum-Libuganon-Southeastern Mindanao, Davao-Southeastern Mindanao, Buayan-Malungon-Southeastern Mindanao, Agus-Southern Mindanao, and Mindanao-Southern Mindanao

Hard Facts for the Phillipines

• Nine major cities are at risk of water constraints.
• Eighteen river systems fall below water quality standards.
• 50 of the 421 rivers in the country are biologically dead.

Irrigation

• Irrigation is the artificial application of water to soil meeting crop water requirements, supplementing precipitation and ground water
• Main concerns of irrigation include:
  • How to apply?
  • How much to apply?
  • When to apply?

Benefits of Irrigation

• Irrigation development strengthens economy, increases employment opportunities, and ensures self-sufficiency in food production.
• Irrigation enables cultivation where it'd be impossible otherwise and makes growing more profitable crops.
• It increases crop yield and quality, improving the aesthetic value of landscapes.
• Benefits also include leaching of salts, wind erosion control, multiple cropping, and improved socioeconomic conditions, reduces risk of crop failures.

Disadvantages of Irrigation

• Excessive irrigation decreases crop yield and causes leaching/transport of chemicals.
• Can cause yield reduction in deficit irrigation
• Over saturation can lead to waterlogging and salinity

Irrigation Systems

• Irrigation is classified into national, communal, and private.
• National irrigation systems (NIS) are large, medium schemes operated and maintained by NIA requiring irrigation service fee rendered in the delivery of water
• Joint management of national systems with irrigators associations (IA) started in the 1980s.
• Communal irrigation systems (CIS) are small-scale schemes working with farmer-beneficiaries through their IAs.
• The operation and maintenance (O&M) is transferred to IAs upon project completion, subject to cost recovery, farmers can amortize the cost for up to 50 years at 0% interest, and repayment is agreed to by NIA and IA.
• Private irrigation systems are maintained by private individuals or groups with or without NIA or other government support

Comparison Between National and Communal Irrigation Systems

Types of Irrigation Methods

• The three schemes are: run-of-the-river diversion, storage or reservoir, and pump irrigation.
• Diversion projects draw water directly from river/stream flow with control measures.
• Reservoir projects impound water with storage dams to be drawn downstream; these projects include functions like power generation, flood control, fishery, and recreation.
• Pump projects involve lifting water from underground or surface sources. Environment and protection are highly important during the planning.

Status of Irrigation Development

• The Philippines has 10.3 million ha of agricultural lands; 3.1 million ha are deemed irrigable with a slope up to 3 percent, but the World Bank identified 6.1 million ha.
• As of December 2015, 1.731 million ha (57.33%), has been irrigated
• 754,665 ha are under NIS, 615,797 ha are under CIS, and 187,766 ha are in privately owned.

Reasons for Low Irrigation Efficiency

• Irrigation has low efficiency due to unlined canals, lack of field channels and communication networks, poor drainage and field leveling, and low water prices.