Completed: September 2010
Prepared by: Dr. Emelina G. Regis
Funded by: University Research Council, ADNU
A dam is a structure constructed across a stream to capture water in order to obtain various benefits. These are for irrigation of arid land, control of flooding in lowland areas, generation of hydroelectric power, water supply for towns and cities as well as for recreation. The impounding area for water is called a reservoir and dams above 15 meters high are considered large dams (Miller 2000). With this additional structure, the river is considered regulated (Smith & Smith 1998). Some regulated rivers however can result to negative impacts. A dam for instance can reduced downstream flow of water causing several ecological effects. These are 1) accumulation of silt behind the dam eventually filling up the reservoir; 2) nutrients from silt then become unavailable to plants along the riparian zone downstream making farmers dependent on commercial fertilizer; 3) accumulated salts (International River Network, 2001) resulting from the silt could not be flushed downstream, salinization then follows with consequent disappearance of wildlife, thereby reducing biodiversity in the water and riparian zones in both the reservoir and backwater as well as downstream portion of the dam (Smith & Smith 1998, Miller 2000).
The most devastating impact of dam construction is flooding of areas at the backwater of the dam. These areas may be forest, agricultural land or worst, human habitation. It is in this context that the study of the Libmanan-Cabusao Dam Project (LCDP) of the National Irrigation Administration (NIA), Region V was done. LCDP was approved by the national government with the following objectives: “1) to optimize the use of water and land resources by replacing the pump used to irrigate the present system with a concrete diversion dam [in general], and 2) [specifically] to cut down the cost of operation and increase farm income in aid of farmer beneficiaries.”
What is disturbing about this dam is that, it is not being constructed in the Municipalities of Libmanan and Municipality of Cabusao which are lowland areas and have ample supply of water within their jurisdictions. Rather, it is being constructed upstream in Sipocot River with backwater intended to inundate the town proper of Lupi and some agricultural areas along the Lupi and Sipocot Rivers. It was also difficult to understand that while, Sipocot River is connected downstream to Libmanan and Cabusao and this segment is known as Libmanan River which is already being used for irrigation purposes, the proponent opted to create a dam where its reservoir will convey water through a canal that will still connect to a pumping station downstream. This was the reason for the fear of concerned citizens of Lupi who requested for assistance from INECAR, Ateneo de Naga University and Bishop Jose Rojas, Jr. of the Diocese of Libmanan which includes the Municipality of Lupi. INECAR’s initial investigation in October 2009 concluded that the dam is not needed to provide irrigation water for Libmanan and Cabusao since these municipalities have rivers and creeks within their land territories. It is also unjust to sacrifice the people of Lupi and Sipocot and their ecosystems just to provide this need. There are also other alternatives to obtain water for irrigation that are less costly with less impact to the environment and to the human communities.
Objective of the study
This study intends to strengthen the initial investigation conducted by the INECAR in October 2009 by determining the specific and extent of the areas that will be impacted upon completion of the dam. These are: a) areas to be inundated by water, b) agricultural areas, c) fishery resources in the rivers/creeks, and d) wildlife resources.
Scope and delimitation
The research covered only certain concerns that will be directly impacted by the dam, thus the parameters are only limited to the physico-chemical attributes of sediments and rocks and areas of inundation. Only the agricultural crops of farms along Lupi (Sulong) River and Sipocot (Sipocot-Polantuna) River were included in the assessment. For wildlife resources, fish and bird species were observed and photographed and/or documented whenever possible but species identification was not done; instead, the local names based on usage by local communities were obtained from the respondents. Additional information such as a mammal and a unique aquatic plant which may be important, were also photodocumented.
Review of related literature
The construction of a dam becomes problematic when no proper and thorough study has been done to determine appropriateness before its approval and construction. These problems range from extinction of some species to destruction of a forest or human villages. Experiences by many countries have surfaced these problems such as those mentioned in the Blue Nile River (Hammerton 1972), the North Swedish River (Englund et al. 1997), the Answandam in the Nile (Hargrave 1991), the Colorado River (Newson 1994), the River Haddeo in Southern England (Webb and Walling 1993) and rivers in Africa and Tropical Latin America (Giller & Malmqvist 1998) to name a few.
When a dam is built, the problem on pollution by toxic phytoplankton begins. In areas dominated by sand, silt and clay, these loosened materials erode from the river bank during rains. Strong rainfall during typhoons even caused landslides and strong currents downstream will trap these materials at the back wall of the dam and accumulate there (Tahmiscioğlu et al. PDF file). Nitrates from household activities and other organics will accumulate and encourage the growth of phytoplankton (microscopic plants and plant-like organisms), especially toxic species that are not eaten by fishes. A process called eutrophication follows resulting from abnormal growth of phytoplankton known as algal bloom which eventually uses up the oxygen and suffocates the fishes. Toxic phytoplankton and deprivation of oxygen will consequently reduce productivity of the river (Corrales ,R.A. 1991; Manahan, 1994; Nebel and Wright1996, Miller 2000). Movement of some fishes upstream for breeding and feeding is hindered causing fish population to decrease (Stott and Smith, 2001).The depletion of fishes will decrease biodiversity because many organisms such as birds that sow seeds through their droppings replenish vegetation. Mammals, such as a vegetarian cloud rat that fertilizes the soil will leave or perish. Some fishermen also depend on fishery for added income or daily sustenance.
A study by Ampongan and Fraginal (2004) in Barit River, the river that drains Lake Buhi, Camarines Sur, suggests that the Hydraulic Control Structure, which is somewhat like a dam with a small opening on one side to release water in the Barit River, is one of the causes of the deterioration of the water quality of the same river. At the Lake side of the control structure, water is polluted having toxic alert Level II. This means that the number of toxic phytoplankton per liter of water is high, thus unsafe for human consumption. Toxic phytoplankton also causes a lot of skin diseases called contact dermatitis to people. They are not also eaten by fishes.
A. Preliminary activities
This involved the basic protocol in giving direction and preparing procedures to achieve the objectives of the study such as the map analyses, equipment needed, review of the Environmental Impact Statement (2009) made by the proponent National Irrigation Administration (NIA), literature search and past studies pertinent to the current research. Other activities included hiring of the research and field/laboratory assistants, preliminary communications and arrangements with the local communities for boats, lodging, and the standardization of methodology through training in the field. The location of the study sites is shown in Figure 1.
Figure 1. Location (red circle) of the study sites (Lupi and Sipocot) in relation to the rest of the Bicol Region
Three study sites were selected – Sulong River in Lupi, Sipocot River segment connected with Sulong River until the dam site, and Yabo River of Sipocot. The following were documented and/or photodocumented: a) elevation of sampling sites and their geographic coordinates using GPS, b) possible inlets along the three rivers and their geographic coordinates, c) pH, salinity and temperature of water of the rivers, d) location using GPS and elevation of agricultural areas that may be affected, and e) wildlife such as birds, fishes, and other interesting organisms.
Identification and/or characterization of soil, sediments and rock samples were also done. Some samples were brought to the Geological Oceanography Laboratory, UP Marine Science Institute (UPMSI), Diliman, Quezon City for identification. Other samples were characterized at the INECAR Extension Laboratory, Ateneo de Naga University using the methods of Fanning and Fanning (1989). A geologist and a geodetic engineer from UP, Diliman were consulted for some of the methods used and for assistance in finding out the inundation potential of dam construction to the areas that will be affected. The locations of the various sampling points are shown in Appendix A1. The location of the dam based on geographic coordinates and GoogleEarth map is also shown in Appendix A2.
Lupi River is locally known as Sulong River while Sipocot River is actually a downstream segment of a major connected to Polantuna River. This major river also connects Libmanan River downstream. In this study, the name Sulong River and Sipocot River was used. The connected tributary rivers to both Sulong and Sipocot rivers were determined during actual visits to the sites. A geologist from the National Institute of Geological Sciences (NIGS) of the University of the Philippines – Diliman also assisted in determining the flooding potential of the sites. Elevation reaching 15 – 23 meter above sea level (masl) with their geographic coordinates were measured by a Global Positioning System (GPS) and an altimeter (Suunto model with precision at 1 m change in elevation). Thus, study stations for sampling were established. The level of water at the dam site was initially measured at 15 m asl and the maximum level of water after the dam construction was set by NIA at 22.49 m asl (based on the EIS 2009). However to make up for possible surges during heavy rainfall, the minimum height of 23 m asl was used. Data on geographic coordinates were sent to the geologist who then processed the data using a digital elevation image from Advanced Spaceborne Thermal Emission and Reflection (ASTER) software to generate a simple topographical map for inundation potential of the study sites.
The number and locations of the inlets of water as well as other creeks connected with the two rivers where water could enter if the dam is constructed were determined with the assistance of a geodetic engineer from AGHAM, also connected with UP-NIGS, while joining the INECAR team during one of its visits. All inlets within the potentially inundated areas were photograph and their location determined by GPS.
Results and Discussion
In determining the specific problems and extent of the areas that will be impacted upon completion of the dam, the following are the findings:
A. Areas to be inundated by water
A.1. If the dam will be constructed, three main rivers will be affected. These are Sipocot River at Barangay Malaguico and Yabo River of Sipocot, and Sulong River of Lupi. A total of 18 openings and 1 canal will become inlets along Sulong River (6 inlets), Sipocot River (8 inlets and Malagatas Creek), and Yabo River (2 inlets). These inlets are places where floodwater will enter resulting in more areas to be inundated with water (Appendix B).
A.2. Figure 2a below presents the extent of the inundation water in Lupi and part of Sipocot if the dam is constructed. Other areas may also be affected if there are additional inlets connected to Sulong River and Sipocot River upstream. These include the areas going towards Colacling and Casay in Lupi and towards Polantuna River upstream. The image below was generated Advanced Spaceborne Thermal Emission and reflection (ASTER) software by the Geologist.
Figure 2a. A map showing the points with elevation 0-23m above sea level. The reddish brown contour lines represent 23m above sea level elevation. These are the possible inundation of the Poblacion (red circle) and agricultural areas (blue box) of Lupi when the dam is constructed. (source: C. Abon 2010)
A.3. If the dam fails, all the water that were impounded in the rivers/creeks of both Lupi and part of Sipocot will rush downstream towards the lowland areas of Sipocot and Libmanan (Figure 2b). More areas will be flooded in these places.
Figure 2b. Extent of inundation water (red arrows) in Sipocot and Libmanan if the dam fails. Gray arrows point to floodwater that recedes when dam fails. The points 16 meters and below represent the downstream of the dam area which is most of Sipocot and Libmanan. This shows that a larger extent of areas lower than 16m above sea level are found on the downstream area and they can be very vulnerable to flooding when the dam breaks. (Source: C. Abon 2010)
Appendix C also presents two maps alongside each other. These maps show the location of the flooding in relation to the town proper and various barangays of the Municipality of Lupi. Note that at critical elevation of 22.49 meter above sea level (asl), most of the town proper of Lupi along the Sulong River will be permanently inundated with water. This means that all areas having the same elevation just a little below the church ground (23.8 m asl) will be flooded. Likewise, a large area of agricultural land in Lupi along Sulong and Sipocot-Polantuna Rivers) and in Sipocot along Yabo River will also be permanently inundated . These include San Pedro, Barrera Jr., Cristo Rey, San Isidro and Haluban of Lupi, and Yabo of Sipocot.
Assuming that the dam is constructed and it failed resulting to flood water rushing downstream, the scenario of flooding is presented in Appendix D. Note that it is not only Sipocot that will be affected but also part of Libmanan.
The above scenarios are bleak for Lupi and part of Sipocot if the dam is constructed because all areas having the same elevation of 22.49 m asl will be inundated permanently. However, the probability of dam collapse is likely because of the kind of sediments and rocks as well as soil in the inundated areas are weak and prone to landslide. Calcarenitic type is limestone (Andriani and Walsh 2002) which is easily weathered by slightly acidic rain. Appendix E (Figures E1 to E5a and E5b) presents the kind of rocks present near the dam site and documented by the geologist Ms. Catherine Abon from UP NIGS-Diliman.
A.4. In support of the findings above, Tables 1 and 2 below present the result of the analysis and characterization conducted at the Geological Oceanography Laboratory, UP Marine Science Institute – Diliman and at the INECAR Extension Laboratory respectively.
Table 1. Sediments collected from the study sites and described at the Geological Oceanography Laboratory, UP Marine Science Institute (UPMSI), Diliman, Quezon City
Table 1 above describes the sediments analyzed at the Geological Oceanography Laboratory, UP Marine Science Institute (UPMSI) as predominantly muddy soil that has been compacted into mudstone, and some coarse and fine-grained sand. This condition indicates soft sediments as well as loose aggregates of sand particles which when submerged in water will easily give way to landslides. Likewise, Table 2 below shows that the kind of soil and sediments are clay, clay loam, sand, loam, sandy clay loam and loamy sand. These types indicate soft sediments that are easily eroded by floodwaters. Although values show normal temperature for a shallow river and those segments that are deeper, the pH values seem neutral but the slanting towards alkaline condition indicates contribution from limestone character of the river bottom and immediate shore and wall.
Table 2. Results of sediment characterization on sediment samples collected from the Study Sites
The physico-chemical condition of water in the study sites also influences the inundation potential and dam failure in the study sites. For instance, although Table 3 below show also normal temperature, yet the pH values are predominantly alkaline, indicating limestone character. Salinity values ranging from 1 – 4 also suggest erosion of riverbanks that are calcarenitic or limestone. The effects of erosion can be seen in the way rainwater, which is normally slightly acidic due to the presence of carbonic acid, reacts with calcium carbonate, the component of limestone and calcarenitic sediments, dissolving them in the process. This is the very reason why limestones are weak and can easily become porous and/or broken into fragments thus, increasing the probability of dam failure.
Table 3: Physico-Chemical conditions of the water in the different locations of Lupi/Sulong River and Sipocot River
B. Agricultural areas that will be affected
Appendix F presents the names of some farmers as key informants and the crops that they are raising in the study sites. Those mentioned include bamboo, coconuts, citrus, eggplant, “monggo”, squash, “parapa-gulong”, corn, string-beans, and “ampalaya” as examples of the resources that will be affected by the inundation water if the dam is constructed.
C. In terms of history and culture, the town of Lupi is a very old settlement found by the Spanish colonizers when they came to the Philippines. The first church was founded in Oct. 17, 1726 in Barangay San Pedro (based on Church exhibits 2009).
D. Fishery resources in the rivers/creeks that will be disturbed
The fishery resources of Lupi (Sulong) and Sipocot (Sipocot/Polantuna) Rivers are as follows: 1) bakla, 2) balanak, 3) burirawan, 4) carpa, 5) casili, 6) hito or catfish, 7) Japanese carp, 8) mirapina or gurami, 9) puyo, 10) talosog (mudfish, and 11) tilapia. The fishing methods that they are using are a) Tuldong (spear), b) pangki or laya (net), and banwit (hook and line). These are the fishery resources that will be affected is the dam is constructed.
E. Other wildlife resources that will be impacted
1) Pictures of birds documented are presented in Appendix G together with the location, features and activity of the birds when they were documented. Birds are indicators of weather disturbances, thus, critical in monitoring climate change. The inundation of these areas could affect the habitat and ecological range of these birds.
2) A giant vegetarian cloud rat (Figure 3) was found by a resident of Lupi. It is a vulnerable and endemic species (PAWB, 2000). There are only 6 species of Cloud Rats in the world and all of them are found only in the Philippines. Its critical habitat, the Malagatas creek is connected to the Sipocot River, and will be flooded. Thus, some surviving individuals of this species will be affected because it is near Malagatas where the rats get their food.
Figure 3. The cloud rat found in Malagatas Creek is one of the 6 species endemic to the Philippines and found nowhere else in the world.
3) A unique submerged aquatic flowering plant. The right photo shows the underwater flower (encircled) of the aquatic flowering plant.
The above findings clearly show warning signs that the dam should not be constructed not only because it is not needed, but also because of the danger it will bring to Lupi, Sipocot and Libmanan. All evidences in the geology of the area such as the nature of sediments and rocks, the presence of many inlets in such short segments of the three rivers in this study, the physico-chemical condition of the sediments/rocks and water, the rainy climate considered receiving high rainfall most times of the year point to an inevitable disaster. Appendix H shows the current condition of the dam site after Typhoon Basyang visited the Bicol Region.
Similarly, in terms of permanently inundating human habitations, their livelihood in agriculture and fishery, the historical very old settlement found by the Spanish colonizers when they came to the Philippines and where the first church was founded in Oct. 17, 1726 at Barangay San Pedro, cannot be justified by providing an irrigation water for another group of people who have the same source of water at their doorsteps. On the issue of biodiversity conservation, the Philippines is one of the signatories in the 1992 Convention on biological diversity concluded at Rio de Janeiro which specifically states the responsibility of the signatory countries to conserve biological diversity and sustainable use of resources. Inundation of the areas can cause the death of endemic species and probably other rare species in the area not yet studied and identified as indicated by the presence of cloud rat and colorful birds, and a submerged aquatic flowering plant.
The presence of limestone, coarse sand, fine-grained sediments, and mostly mudstone, including the soil and sediments, when soak in water will trigger landslides affecting many areas of Lupi primarily, and some areas in Sipocot when water rises with the dam in Sulong and Sipocot Rivers including Yabo and Colacling Rivers and their tributaries. The clear water of Sipocot will be replaced with turbid water affecting the fishes and bird habitats. The addition of sediment load from landslides will increase pressure on the dam wall with possibility of dam failure during typhoons and unusually strong rainfall. A probable outcome will be that floodwater carrying silt and sediments will rush downstream and destroy some areas of Sipocot and Libmanan.
Mr. Alex San Jose, Research Assistant; Mr Pedro Prima, Field/Laboratory Assistant, and Field Assistants Ms. Shane Bimeda, Ms.Charmaine Bustarga, Ms. Niño Cañaveral and Mr. Jay Abawag
The concerned citizens of Lupi, Camarines Sur, represented by Former Mayor Sebastian Perez, Ms. Melai Asma, and Ms. Minerva Bombita.
Ms. Catherine Abon of AGHAM, and working at the National Institute of Geological Sciences (NIGS) of the University of the Philippines – Diliman, Quezon City
Ms. Anne Mae Edrosolam of AGHAM, and working at the National Institute of Geological Sciences (NIGS) of the University of the Philippines – Diliman, Quezon City
Siringan, Fernando, Head of the Geological Oceanography Laboratory, University of the Philippines Marine Science Institute, for the free analysis of the sediments collected by INECAR and Ms. Janneli Lea Soria who made the actual analysis of the sediments. Special thanks to Ms. Yvainne Yacat for facilitating the request.
Fr. Joel E. Tabora, S.J., President and the University Research Council (URC), Ateneo de Naga University for providing the funds for the study
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