With the power crisis looming our heads, we immediately look at our water bodies for rescue. Dams have been romanticized by our leaders to be the cure of all our woes. However, is building dams for power generation a sustainable path towards power stability in Mindanao?
My assessment: It is not.I will give three reasons for my contention. Climate uncertainties, siltation and inappropriate land use, and social costs.
Climate uncertainties. We have witnessed in Luzon how difficult it is to manage dam operations given climatic extremes. Manila suffered from water crisis due to inadequate dam water levels at Angat. On the other extreme, dam releases were also blamed in floodings like that of Ondoy. Given that power generation is highly dependent on high water level, maintaining it at such is already a challenge. How sure are we that a dam along Pulangi can ensure a water level stable enough to generate power? Drought in the 1990s slowed down power generation for the Mindanao grid. Dams therefore is not reliable in terms of power generation. Given uncertain hydrometeorology, we will still expect power shortage in the future.
Siltation and inappropriate land use. Much of our lands in the heart of Mindanao (see previous article), has been devoted to agriculture. Our current agricultural practices are highly erosive. This means sediments were carried away from our farmlands towards our rivers. The challenge of dam management has been siltation. Dam's operational life has been shortened due to siltation. This has been a concern in the Magat Dam in Isabela. Magat's upper watersheds (Ifugao and Nueva Vizcaya) are slowly being populated, tilled, and deforested. In designing dams, hydrology and siltation have been factored in. However, uncontrolled land use change and the unpredictability of precipitation makes it a problem. We were told that our current hydroelectric power plants were below the design capacity due to siltation. Dredging and dam clean-up is expensive. If our current dams experience this problem, why are we going to build more dams just to be silted. As if we build something just to fail later. If only we have good management of our watersheds. Nueva VIzcaya and Ifugao (for Magat) are still sparsely forested compared to Bukidnon (for Pulangi). Since my childhood, I have always seen Pulangi river being turbid unlike that of Magat river where you still can see clear waters. If Magat suffers from siltation, it is not difficult to conclude that the worse is expected on the envisioned Pulangi Dam project. Dams with intact watershed is an excellent source of power. But in the case of Pulangi, it is otherwise.
Social costs. The proposed dam will flood a significant portion of Pres. Roxas and sadly part of it maybe the lands of my ancestors. One question lingers my mind. Why my people have to suffer again for the benefit of the majority? Is this part of the democratic assertion of majority rules? The moro insurgency and settlers' development aggression has pushed us up to the mountains. And even that last scratch of our lands has to be flooded to quench the thirst of energy and the excesses of the majority.
Friday, May 4, 2012
Monday, January 9, 2012
disconnect between forecasts and vulnerability maps
After storm Sendong and the landslide in Compostela Valley, several maps propped out in the open. Experts flaunt their respective vulnerability and hazard maps. LGUs supposedly knew this and were blamed for not having implemented precautionary measures to avert these disasters. I guess much have been said about poor governance and the biophysical vulnerabilities we are in. In this case, I will try to digest the relevance of these maps and try to analyze why despite all of these information, we are caught unaware when disaster strikes.
Flood maps supposedly showed inundation areas once 1-meter, or 2 meter flood levels come rushing in. Maps are good for planning. They give us idea of the spatial dynamics answering the important question of "where disaster may strike". But what these maps fail to say is "when disaster may potentially strike". Addressing temporal dynamics is also an important consideration in addressing disasters.
I think there is a disconnect between our appreciation of maps and digesting forecasts. What I mean is that we know where areas can be inundated by a 1-m flood stage but we do not know when this flood level may occur. At what rainfall can we say that 1-m flood stage may occur. For example, 180 mm would be destructive for CDO and Iligan. This would mean that rainfall forecast beyond 180 mm has to be watched out for CDO and Iligan (please see my previous article for Iligan: how rainfall can save from flooding). Every watershed respond differently, so preparedness would be different. For example, 180 mm would be minimal if situated in the Cagayan River in Luzon but would be destructive for Cagayan river in Mindanao. So communities have to be careful in listening to forecasts. Previously, I called for revising our alert system by focusing mainly on rain instead of wind (typhoon warnings: switching from wind to rain). This time, I believe it is high time to categorize our watershed and other water bodies that correspond to its response to rainfall volume, intensity, and duration.
For example, a watershed can be categorized as high risk if floods may occur at very small rainfall amounts. Conversely, areas which can absorb high volume of rainwater can be categorized as low risk. It is not enough to say where areas can be flooded by a certain flood height but also when this height could possibly occur given rainfall amounts. I longed for weather forecast that states, "we expect rainfall up to 50 mm therefore areas under category A should be vigilant". I guess stating just "low lying areas" is not enough to warn because other low-lying areas may not have the topography vulnerable to floods.
In categorizing watersheds, topography and land use has to be considered. Areas with the impounding potential and "choked" topography would be different from really flat areas. Cultivated areas would respond differently from closed forest. Our current hazard maps are static in nature and does not into account changes in land cover. Hazard maps have to be revised as often as possible to reflect actual land use. Actually, maps generated ten years ago may not be applicable today because substantial land use change might have occurred during this duration. On the other hand, if vulnerability maps were based on historical hydrological data, it may not be able to capture future scenarios brought about climate change.
There is a substantial stride in climate forecasting in recent times. For example, it has been predicted that above than normal rainfall is expected in Mindanao for December, January and February (La Nina). "Above than normal rainfall" may not sound alarming. But we need to understand that DJF period is when floodings "normally" occurred in Maguindanao, Caraga, and Davao. In this case, this would mean "above normal flooding".
My point here is that forecast is nothing if we do not reflect that with the vulnerability on the ground. We need to repackage our alert systems enough to warn. Vulnerability maps are nothing if we cannot connect that with forecasts. PAGASA, LGUs, and the so-called climate experts should try ways on how to connect their information that is understandable by the common tao. Please do not flood us with bytes, grids, pixels and weder-weder lang yan.
Flood maps supposedly showed inundation areas once 1-meter, or 2 meter flood levels come rushing in. Maps are good for planning. They give us idea of the spatial dynamics answering the important question of "where disaster may strike". But what these maps fail to say is "when disaster may potentially strike". Addressing temporal dynamics is also an important consideration in addressing disasters.
I think there is a disconnect between our appreciation of maps and digesting forecasts. What I mean is that we know where areas can be inundated by a 1-m flood stage but we do not know when this flood level may occur. At what rainfall can we say that 1-m flood stage may occur. For example, 180 mm would be destructive for CDO and Iligan. This would mean that rainfall forecast beyond 180 mm has to be watched out for CDO and Iligan (please see my previous article for Iligan: how rainfall can save from flooding). Every watershed respond differently, so preparedness would be different. For example, 180 mm would be minimal if situated in the Cagayan River in Luzon but would be destructive for Cagayan river in Mindanao. So communities have to be careful in listening to forecasts. Previously, I called for revising our alert system by focusing mainly on rain instead of wind (typhoon warnings: switching from wind to rain). This time, I believe it is high time to categorize our watershed and other water bodies that correspond to its response to rainfall volume, intensity, and duration.
For example, a watershed can be categorized as high risk if floods may occur at very small rainfall amounts. Conversely, areas which can absorb high volume of rainwater can be categorized as low risk. It is not enough to say where areas can be flooded by a certain flood height but also when this height could possibly occur given rainfall amounts. I longed for weather forecast that states, "we expect rainfall up to 50 mm therefore areas under category A should be vigilant". I guess stating just "low lying areas" is not enough to warn because other low-lying areas may not have the topography vulnerable to floods.
In categorizing watersheds, topography and land use has to be considered. Areas with the impounding potential and "choked" topography would be different from really flat areas. Cultivated areas would respond differently from closed forest. Our current hazard maps are static in nature and does not into account changes in land cover. Hazard maps have to be revised as often as possible to reflect actual land use. Actually, maps generated ten years ago may not be applicable today because substantial land use change might have occurred during this duration. On the other hand, if vulnerability maps were based on historical hydrological data, it may not be able to capture future scenarios brought about climate change.
There is a substantial stride in climate forecasting in recent times. For example, it has been predicted that above than normal rainfall is expected in Mindanao for December, January and February (La Nina). "Above than normal rainfall" may not sound alarming. But we need to understand that DJF period is when floodings "normally" occurred in Maguindanao, Caraga, and Davao. In this case, this would mean "above normal flooding".
My point here is that forecast is nothing if we do not reflect that with the vulnerability on the ground. We need to repackage our alert systems enough to warn. Vulnerability maps are nothing if we cannot connect that with forecasts. PAGASA, LGUs, and the so-called climate experts should try ways on how to connect their information that is understandable by the common tao. Please do not flood us with bytes, grids, pixels and weder-weder lang yan.
Tuesday, December 20, 2011
The heart of Mindanao needs hydrological surgery
Hydrologically speaking, the most ideal land use is that of closed forest stands represented by dark green colors in Figure 1. Unfortunately, only the northeastern part of Bukidnon and the eastern part of Lanao del Sur (as of 2003) have closed forest covers. What I mean of hydrologically ideal situation is the capacity of a certain land cover type to retain or delay runoff caused by rains. Once these closed forest stands are disturbed its retention capacity is diminished significantly (in the order of 30 to 50%). These are the areas represented by light green or the open forest stands in Figure 1. Even reforestation cannot revert the hydrological capacity back to its original capacity. Virgin forest once lost has no hope for recovery. Closed forests have an ecosystem structure perfected through centuries of evolution. The hydrological capacity is not only about trees but also include the species assembly underneath the canopy. Thus, reforestation is better if done in such a way that shrubs, grasses, bushes are included in the program not just trees. In biosystems engineering, we call it biomimicry.
Similar in hydrological capacity to open forest is the wooded grasslands represented by the peach color. Though not as effective as the closed forest, this land cover type is better than the cultivated annual crops cover represented by yellow colors. It is worthy to note that wooded grasslands, closed and open forests in the eastern portion of Bukidnon have made the hydrology of Davao river stable and tamer. But once the agricultural activities in the Cabanglasan and San Fernando in Bukidnon intensifies, it will be a nightmare for Davao City. I heard that a road is being constructed in the areas that would connect Bukidnon with Davao del Norte. This would mean intensified economic activities in this Bukidnon territory. And if Davao City will open their northern frontier to economic activities (conventional agriculture, etc.), it would be a disaster waiting to happen.
The prevalence of annual crops (yellow areas) has disabled ecosystem services that Bukidnon provides in terms of hydrological regulation (flood delay, and water during drought). This makes the receiving provinces of North Cotabato, Maguindanao and CDO at the mercy of Bukidnon waters (from different watersheds!). This is demonstrated by the perennial problem of flooding in Maguindanao and Cotabato City. Unfortunately, we tried to solve Cotabato floods by controlling the water lilies. Personally, I believe it is better to start seriously looking at the land use practices in the heart of Mindanao. The erratic nature of weather patterns needs adaptive interventions that transcends boundaries and academic disciplines.
Here are some weak points, I believe we need to address:
1) We need to review the different land use plans of the municipalities (CLUP). Does it conform to the whole river basin hydrodynamics? Does the projected land use take into account the possible consequences it may impose on our hydrology? Several accounts would point to CLUPs being a "copy and paste" plans. This is where the LGUs need to craft their respective land use plans that conforms with the ecological dynamics beyond their territorial limits.
2) There is a need to delienate the final limits of forest lands and those alienable and disposable. It can be gleaned in Figure 1 that a lot of forestlands were already cultivated. For example, in Bukidnon, 491,579 hectares were classified as forestlands but only about 170,000 hectares are with forest covers with over 100,000 hectares already open.
3) DENR, DAR, and DA should work hand in hand in developing upland agriculture that focusses on land and water conservation. DA and DAR refuse to work on forestlands eventhough agricultural activities are evident simply because it is within the domain of DENR. DENR are "tree - oriented" and may be not technically conversant with appropriate agricultural technologies that farmers need. On the other hand, agricultural professional are "plantation-oriented" and may not be technically equipped in dealing with smallholder sloping agriculture. If only DENR, DAR, and DA creates a liason office that deals with rigors of upland and sloping agriculture or agroforestry. I think it is no longer possible to reforest the whole 491,579 forestlands but agricultural and environmental agencies can work together in developing economic activities in the uplands that can maintain vital ecosystem water resources services.
4) Built up areas (red colors) should be redesigned that considers storm water regulation. Our preference to pavements in real property development makes a concrete jungle that has the worst hydrological capacity. This is demonstrated by Typhoon Ondoy. Rainwater harvesting and stormwater retention facilities can be embedded in urban structures.
5) Enforce forestry laws to maintain the integrity of the last remaining closed forest. I guess a total log ban is in proper. A log ban for both legal and illegal logging of natural forests. In order to supply our timber needs, tree planting should be encouraged in non-critical parts of the watersheds.
6) Downstream provinces and cities need to reconsider their "dikes and dams" mentality as flood control. Engineering designs are usually based on hydrological analysis. Unfortunately, some of our historical data (if there is such data existing for specific locality) do not capture uncertainties brought about by climate change and the faster land use transitions brought by human activities upstreams. And so our usual dam and dikes solution may not work in the long run. There should be plan B - and that is adaptation and mitigation. What I learned from Dutch water engineering is that water is difficult to control and so they make do of floating structures (bridges, houses, etc.). Instead of relying much on dikes, they make more "room for rivers" and "space for waters". They keep on studying their situation and propose solutions beyond engineering realms.
There is a need to rehabilitate our river basins. Let the heart of Mindanao pump life again. A transboundary natural resources management is imperative that addresses the biophysical and social dynamics of the river basins. A participative and adaptive mechanism that connects stakeholders from different spatial scales and technical backgrounds. Let us remember that water knows no boundary.
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