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Realizing the benefits from P686-B investments in irrigation (Part IV)

Concrete Lining of Irrigation Canals

We are realizing only about a third of the potential benefits from the P686 billion worth of investments in irrigation and drainage systems. This is based on the reported cropping intensity of 1.37 versus the target of 2.00. These unrealized benefits are equivalent to 764,000 hectares of unplanted rice fields which should have produced 3.7 million tons of palay worth P51.8 billion each year.

A significant part of the firmed-up service areas (FUSA) of the irrigation systems run out of water during the dry season. After the rains, the water available for irrigation in the rivers and dams gradually diminish. This seasonal decline in the water supply in made worse by water losses in the canals due to seepage.

The aggregate length of the canals of our national (NIS) and communal (CIS) irrigation systems is in the order of 21,000 kilometers of which about 7,900 kilometers have been lined with concrete (pers. comm. B Labiano, NIA). The standard trapezoidal canal with a base width of 1.00 meter and a top width of 1.80 meters reportedly costs about P7,000 per lineal meter or P7 million per kilometer. Thus, P92 billion would still be needed to fully line with concrete the balance of 13,100 kilometers of unlined canals. This can be reduced significantly if the farmers volunteer their labor, bayanihan style. With the canals lined with concrete, there will be less need for maintenance after they take over the irrigation system.

As our population continues to grow and as our economy expands, there will be more intense competition for fresh water. Agriculture which for now draws something like 80 percent of available water must prepare to produce more and more food with less and less water. We really have little choice but to make those additional investments in the lining of canals with concrete to conserve water.

Conjunctive Use of Small Irrigation Units in the NIS and CIS Service Areas

The downstream farms in the large irrigation systems (NIS+CIS) have sufficient water to start a second crop of palay but many run out of water towards the middle of the season. Not assured of water to complete the crop cycle, farmers refuse to take the risk and opt not to plant.

The remedy is to install small farm reservoirs, shallow tube wells and small water pumps in the service areas of the large irrigation systems as supplementary sources of water during the dry season.

But even more importantly, the installation of small irrigation units in conjunction with the large systems allows the farmers direct control of the volume and timing of delivery of water. The large irrigation systems are designed for rice and are ill-suited for the water needs of other crops. This precise control of water makes feasible the introduction of higher value crops into the cropping sequences.

In fact, in terms of gross value added to the economy as well as in terms of incomes of farmers and creating more employment, greater benefits can be derived from irrigation by shifting from rice monoculture into higher value crops like vegetables, fruits and ornamentals in a common farming practice called relay cropping.

Most annual crops mature in 70 to 120 days (exceptions are pechay and mustard which are harvested in only 30 days). Provided there is sufficient water during the dry season, there is time to grow three to five crops a year on the same piece of land.

Because of excessive water at the height of the rainy season, the first crop is normally devoted to palay which is tolerant of water logging. The next plantings could be a second crop of palay, or a number of possibilities and combinations of crops like tomato, pepper, eggplant, mungbean, squash, watermelon, sweet and glutinous corn, pechay and mustard depending upon access to market.

Some of the popular cropping sequences among the more progressive rice farmers are: rice-rice-mungo; rice-rice-pechay; rice-tomato/pepper/eggplant; rice-squash/watermelon musk melon/honey dew; rice-sweet/glutinous corn-pechay.

An irrigated, reasonably managed rice field with a yield of six tons palay per hectare will give a rice farmer a net income of R30,000 to R40,000 per hectare. In comparison the income from these other crops could be 2x to 10x as much, depending upon market prices at time of harvest.

Unfortunately the government programs for irrigation are lodged with separate agencies – National Irrigation Administration (NIA) for large systems and the Bureau of Soils and Water Management (BSWM) for small irrigation projects. The BSWM projects are installed in upland areas not serviced by NIS and CIS.

This artificial dichotomy between large versus small systems is counterproductive and should be abandoned. However, in order to minimize confusion BSWM should continue to confine itself to designing and constructing small irrigation projects outside the NIS and CIS service areas. There is so much yet to be done and BSWM will have its hands full in the decades to come.

Installing small irrigation units should be added to the mandate of NIA. Part of its annual budget should be realigned to constructing small irrigation units in its service areas to provide supplementary water during the dry season and facilitate diversification and relay cropping.


As our population continues to rise and our economy expands, we will need more fresh water for domestic and industrial uses. Even now Metro Manila and Metro Cebu are already water stressed. This can only get worse as the other major urban centers grow.

Thus, share of water for food production purposes (irrigation) will have to be moderated to accommodate the needs for drinking and for industry. Agriculture will have to adjust to the challenge of producing produce more and more food with less and less water. Hence the imperative to raise the efficiency of our irrigation systems.

To date, we have developed 1.73 million hectares out of the 3.02 million hectares potentially irrigable farm lands at an approximate cost of R686 billion in 2000 prices. However, the reported cropping intensity of our irrigation systems is only 1.37 versus the objective of 2.00, meaning we are realizing only about a third of the potential benefits from our investments

Even as we invest more resources in irrigation and drainage systems for our long term water and food needs, the immediate priority for now is rehabilitation/restoration and proper operation and maintenance of existing irrigation systems.

Four complementary measures are needed to achieve higher irrigation use efficiency: First is to further strengthen the NIA’s role in irrigation development and management. In particular for NIA to devote more attention for now to rehabilitation and operation and maintenance (O&M). Its budget should be realigned to devote more resources to its Irrigation Management Transfer program which devolves partial responsibility for O&M to the farmer-users themselves and their irrigators associations.

Second is the convergence of efforts of stakeholders in seeing to the proper maintenance and operation of the irrigation systems. NIA cannot bear that responsibility alone. The farmers themselves, the relevant local governments, the NGOs and private sector, the state colleges and universities, and NIA’s sister agencies in the Department of Agriculture (DA) like BSWM, the Philippine Rice Research Institute (PhilRice), the Bureau of Plant Industry (BPI) and the Philippine Center for Postharvest Development and Mechanization (PhilMech) should pitch in.

Third, is to minimize systems losses in the canals that convey water to the fields. Of the aggregate 21,000 kilometers of canals about 7,900 kilometers have been lined with concrete. The remaining 13,100 kilometers of canals would require additional investments of R92 billion at a unit cost of R7 million per kilometer. That cost could be significantly reduced if the farmer-beneficiaries volunteer their labor, bayanihan style.

And finally the installation of small irrigation units like farm ponds, shallow tube wells and small pumps, in the service areas of the NIS and CIS irrigation systems to provide supplementary water during the dry season to raise cropping intensity.

But more importantly to facilitate diversification away from rice and relay cropping with other higher value crops to generate greater value added, more employment and raise farmer’s income.


Dr. Emil Q. Javier is a Member of the National Academy of Science and Technology (NAST) and also Chair of the Coalition for Agriculture Modernization in the Philippines (CAMP). For any feedback , email