A PROGRAM FOR OQei 4AAAAQ~A 0* .1 cs~ PIOAAA­ et *-Woc-Q,"-v --- 4111; PAMPANGA 0-AG NO COTABATON9 mIILOG- HILABANGAN -iBICOL --- mmAGU SAN atA& CAGAYAN RIVER BASINS HAROLD E. HEDGER INTERNATIONAL COOPERATION ADMINISTRATION NATIONAL ECONOMIC COUNCIL REPUBLIC OF THE PHILIPPINES A PROGluM FOR FORMULATION OF PLANS FOR MULTI-PURPOST DEVELOPM4ENT OF WATER RESOURCES OF THE PAMPANGA, AGNO, COTABATO ILOG-HILABANGAN, BICOL, AGUSAN AND CAGAYAN RIVER BASINS OF THE PHILIPPINE ISLANDS Prepared by HAROLD E. HEDGER Consultant INTERNATIONAL COOPERATION ADI'TISTRATION F or NATIONAL ECONOMIC COUNCIL Republic of the Philippines Manila, Philippines June, 1961 D 5421 A PROGRAM FOR THE FORMULATION OF PLANS FOR MULTI-PURPOSE DEVELOPMENT OF WATER RESOURCES OF THE PAMPANGAs AGNOs COTABATO, ILOG-HILABNGAN;, BICOL, AGUSAN AND CAGAYAN RIVER BASINS OF THE PHILIPPINE ISLANDS Harold E. Hedger Flood Control Consultant June 1961 At the urgent request of President Garcia, resulting from serious flood losses in the Pampanga and Agno River Basins in Central Luzon in iAugust 1960, a cooperative project was sub­ mitted to ICA/W by USOM/Philippines with the concurrence of the Philippine National Economic Council which originally con­ templated review and recommendation by flood control consultants of flood control plans heretofore prepared by Philippine Government agencies for protection of this area, but which was later expanded to include investigation of the desirability of combining flood control measures with other types of water utilization, such as hydro-electric power generation, water supply, etc. The program was also expanded to include the basins of the Cotabato, Ilog- Hilabangan, Bicol, Agusan and Cagayan Rivers, the locations of which are shown on the accompanying map. It was tentatively expected to involve the services of a 5-man team of experts over a period of 18 months, plus the supply of certain commodibies and services, all at an estimated cost of about 4,4OOOOO. The appointment of a short-term flood control consultant was authorized by ICA/W for the purpose of conducting a pilot -2 ­ survey of the basic data, plans and other material available for review, and the formulation of a definite action program for the subsequent guidance of a consulting team. The fol­ lowing report presents this consultant's findings and recom­ mendations. Initial review of the problems involved was accomplished by study of hydrologic data and analyses, hydraulic plans and economic material developed by the River Control and Drainage Section, Division of Irrigation, Bureau of Public vWorks (BPW); followed by consultation with officials and engineers of the National Power Corporation (NPC), National Waterworks and Sewerage iuthority (NWSA) and with various sections of the BPW, including River Control, Irrigation, Ground-Water Investigation and Hydrology Sections and the Irrigation Service Unit of the Department. Field inspections of all of the basin watersheds was also undertaken to insure adequate understanding of the many problems involved. Availability of Data The availability of basic data, bydrologic studies, mapping, surveys and engineering data for water resources planning, as disclosed by this review is presented as follows: Pampanga River Basin - Central Luzon Maps: Aerial photos and mosaics (controlled) of the basin, scale 1:40,000. - 3 - Topographic, general, scale 1:1,000,000 contour interval 150 m. Topographic, general, scale 1:250,000 contour interval 100 m. Topographic, general, scale 1:50,000 contour interval 20 m. Topograchic, special, Candaba Swamp, scale 1:90,000 contour interval 1 m. Topographic, special, of dam sites on Angat, upper Pampanga and Talavera Rivers. Rainfall records: from 19 stations within the basin, all standard ;ages; length of records, from 4 years to a maximum of 30 years, broken in continuity. Runoff records: from 32 automatic recorders and 23 staff gages, data published 1953-54 3nd 1956-57, unpublished 1957 to date. Suspended sediment data obtained at 9 points during last 2 years. Some recent data on evaporation, salinization and ground water level is available. Field surveys, with location plan and cross sections are available for Rio Chico, Pampanga and Parua River Channels. Field surveys, analysis and report on flood damages at­ tributable to the 1937, 194, 1950 and 1960 floods are available, with computation of average annual damage. Flood Control studies made to date include: Isohyetal maps and charts for major storms of record; for mean annual and monthly precipitation, with frequency analysis, and for estimated 100 year 1-day through 7-day rainfall. Derivation by unit hydrographs, infiltration capacity curves, and per cent runoff curves of the design maxidmum storm for Pampanga basin; and for Rio Chico and Angat Rivers separately. Flood routing studies of basin runoff assuming natural storage in San Antonio and Candaba Swamps only, and also with storage assumed at Angat and other proposed damsites. Alternative plans and estimates for conveying design maximum storm discharge from Candaba Swamp to Manila Bay, with and without regulating storage at Angat dam. Complete hydrology, design, plans and construction data for proposed Angot dam and hydro-electric oroject. Preliminary studies for proposed Pantabangan Dam. Data on irrigation systems operated and proposed in basin. Data on water supply systems in basin. Reports on "Rainfall and Runoff in Central Luzon" and on "The Pampanga River Flood Control Project" by A. A. Villanueva and A. B. Delefa; also "Report on Surface Water Supply of Central Luzon" by Tomas Saddam. Agno River Basin Maps: Aerial mosaics (controlled) of watershed, scale lil5,000 and 1:42,000. Aerial mosaics (controlled) of Viray-Dipalo River System, scale 1:30,000. Topographic maps, scale 1:1,000,000 contour interval 150 m. Topographic maps, scale 1:400,000. it it " 1:250,000 contour interval 50 m. Topographic maps, scale 1:50,000 contour interval 10 m. Location plan and profile of Agno River, San Manuel to Lingayen Gulf. Rainfall date: from 19 stations with standard gages and 1 with automatic recorder; length of records, from 7 years to maximum of 52 years, broken in continuity. 11 standard gages are located within the wutershed, the others are located - 6 ­ around the perimeter. Runoff data: from 6 staff gages and 3 automatice recorders. Length of record - from 1 to 16 years, broken. Maximum flood heights for 10 major flood periods. Suspended sediment s3mples have been taken at 2 points for period of about 21 years. Some ground water elevations and evaporation data are available. Field surveys, analyses and estimates have been made of flood damage during 1935, 1937, 1947, 1948 and .1960 flood periods, also estimate of average annual damage "Report on Surface 'later Supply of Central Luzon" by Tomas Saddam and report on "Rainfall and Runof* in Central Luzon" by A. A. Villanueva and A. B. Delefla. Flood Control Studies: Isohyetal maps of mean annual and monthly rainfall in watershed with expectancies computed for 5, 10, 20 and 50 year frequencies. Isohyetal charts of watershed showing design storm pattern for 1-day through 7-day rainfalls. Same for Agno River above San Manuel, and for Tarlac River. - 7 - Derivation of design maximum storm discharge from unit hydrographs for Agno River at San Manuel and Wawa, and for Tarlac River. lydro-electric studies: Hydrology, design and construction plans and other data for existing projects at Ambuklao and Binga and preliminary studies for proposed projects at Tabu, Tayum, Kalipkip and Lubas sites. Irrigation studies relative 6 existing and proposed systems in this basin. Water supply data concerning municipal and barrio systeims, both existing and proposed. Cotabato River Basin (Rio Grande de Mindanao) - Mindanao laps: Aeri3l mosaic (uncontrolled) of basins, scale 1:16,000 and 1:35,000. Topographic, general, scale 1:1,000,000 contouir interval 150 m. Topographic, general, scale 1:250,000 contour interval 100 m. Topographic, general, scale 1:50,000 contour interval 20 m. Topographic, general, (Mindanao) scale 1:200,oc 0 1:600,000 1:50,000 Topographic, special,,of City of Cotabato in progress. - 8 - Rainfall records: from 14 standard gages, 7 of which are within the watershed; length of records from 6 years to maximum of 4 years, broken in continuity. Runoff records: from 8 automatic recording and 12 staff gag-s located on various tributaries; length of records from 1 yr. to maximum of 11 years, broker Field surveys: Profiles and cross-sections of the tributary Pulangui and 1aridagao Rivers and cross-sectioning of lower Cotabato River now in progress; also profile and cross-sections of 7 pro­ posed cut-off channels and one pro­ posed floodway. Flood damage surveys, analyses and estimates of damage during 1955, 1956 and 1958 flood periods with estimates of average annual damage. Flood control studies: Isohyetal maps of Mindanao for maximum 1-day through h-day rainfalls for major storm periods of 1955 and 1956. Depth-area curves for 1955 and 1956 major storms. For Pulangui River, at Pikit bridge - discharge rating curves, rainfall hydrographs, computation - 9 ­ of maximum probable discharge by unit hydrograph and depth-area methods, rainfall frequency curves for maximum 1-day through 7-day periods. Hydro-electric studies: preliminary only, for 1 large and 1 small proposed projects on Pulangui River. Several other sites due for investigation. Irrigation studies relative one system under construction and 8 proposed systems within this basin. Water supply data as to several waterworks systems and numerous barrio wells and springs. log-Hilabangan River Basin - Negros Occidental Maps: Aerial photos and mosaic (uncontrolled) of the basin, scale 1:40,000. Topographic, general, 1:1,000,000 contour interval 150 m. Topographic, general, 1:250,000 contour interval 100 m. Topographic, general, 1:50,000 contour interval 20 m. Topographic, special, flood plain and irrigation maps of Ilog and Hilabangan Rivers. Rainfall records: from 4 standard gages all of which are located outside the watershed; length of records from 3 years to max­ imum of 43 years, broken in continuity.