Assessing the resurgent irrigation development program of the Philippines : water resources component
Guillermo Q. Tabios, Tomas De Leon
This study is to assess the irrigation service areas of AMRIS and PDRIS benchmarked against design area water availability, land use (including flood vulnerability), and status of irrigation facilities, using resource assessment and watershed and irrigation modeling. Highlight of the findings are: irrigation area of NIA-AMRIS fell below design area due to urbanization, lowered height of Bustos Dam, complicated by competing use of water for hydropower. The PDRIS system has likewise only realized half of the target irrigation service area due to urbanization and flooding, as well as low diversion dam height of Cong Dadong Dam. The AMRIS irrigation canal network was thoroughly investigated through hydraulic modeling and simulation. There are areas within the system that may not at all be irrigated since most canals had reduced capacities due to sedimentation, rendering gravity flow inefficient. Thus, there is a need to develop effective canal maintenance scheme of the AMRIS and also to reassess the operation schemes for efficient canal operations. The following are major recommendations in this study. First is reassessment of the details of the operations should be done since the feasibility studies of these irrigation systems seem lacking in detailed technical assessment of performance of the irrigation systems with regard to reliability of water sources (in time and space). Second, periodic operational studies once the system is already built is practically never done but simply to make adjustments based on actual observations and experiences thus the need for periodic review and updating of operations schemes and strategies and preferably this is done every 3 years or as needed. It is important that periodic appraisal or assessment of the efficiency of irrigation water delivery operations as illustrated here through hydraulic model simulations should be conducted for proper maintenance and upgrade of irrigation facility as needed.
