Both the Philippines and Thailand experienced their most economically devastating floods in recent memory. The worst in half a century, the floods in Thailand submerged two-thirds of its land area, damaging crops and infrastructure to the extent of over US$3 billion and affecting 8.2 million people.

In both Thailand and the Philippines, these disasters raised old issues anew. Dam managers are being criticized, if not threatened with legal suits, for not releasing water earlier during the rainy season, instead of during the flood itself, driving up floodwaters further.

In the two countries, poor land use planning and management are being taken to task as among the flood's social culprits. In the case of Thailand, academics are insisting that the industrial estates, that assemble electronic products for export and which were shut down by the floods, should not have been constructed where they are in the first place, as they block the natural draining out of floodwaters out into the sea. In the case of the Philippines, scientists similarly point to the building of fishponds and fishpens in river deltas as among the man-made reasons why the floodwaters were holed up rather than drained away quickly.

In Thailand, Capt. Somsak, director of the government's National Disaster Warning Center, is candid in admitting that the land use plans were flawed and that deforestation contributed to the disaster. In the Philippines, government officials have not openly admitted as much. However, President Benigno Aquino's and environment chief Ramon Paje's decision to either review or revise the dams' management protocol seem to suggest that they regard it to be outdated, at the least.

In Central Luzon in the Philippines, local officials and residents complain that excess water from the six large dams in the region, Ambuklao, Binga, San Roque, Angat, Ipo and Bustos, was released at the same time, flooding areas not previously experiencing floods at all. The irony of the situation is heightened by the fact that these dams, the operation of which it is now accused of worsening the floods, were originally built not merely to generate electricity and provide water for irrigating farms, but for controlling floods as well.

The Bulacan governor, and other residents of the province even threaten to file a class suit against the National Power Corporation (Napocor), which manages the Angat Dam in Bulacan.

For its part, the Napocor denied the accusation that it erred at all in releasing water in the Angat, Bustos and Ipo Dams in Bulacan during the flood and thus exacerbated the situation. Napocor officials argued that they simply followed the protocol that when the water level in Angat Dam breaches its spill level of 210 meters above sea level (masl), the excess water has to be discharged to prevent the dam from breaking.

From the viewpoint of engineering, the policy of releasing water to save the dam is perfectly logical. But this response ignores the question: Can water level in the dam be adequately and successfully controlled and managed in the first place so that even during severe typhoons, it need not be released at all, thus preventing floodwaters from being raised any further? Can a dam management protocol ensure that this will not happen?

In systems of managing large multipurpose dams such as those in Central Luzon, water level is ideally maintained at a level called the flood control pool level. As suggested by some engineers in the Philippines, this level should be low enough to absorb one or two severe typhoons per year at four to six meters per storm. It is recommended that as water level rises above this food control pool level, the surplus water is discharged on a pre-emptive basis and at a maximum safe rate so as not to avoid catastrophic releases later.

However, historically, such flood control pool levels were not managed efficiently. Frequently, in the past, these were managed largely through a trial-and-error process. The difficulty largely lies in the sheer complexity of the river basins and the hydrological systems, including forest moisture, climate, weather, rainfall and water flow, as well as soil erosion, in which large dams operate.

This complexity is among the reasons cited against the building and operation of large dams, aside from the fact that they usually involve the large-scale displacement of communities, inundation of river valley farmlands, and great losses in biodiversity.

These large dams are also made more complex in that they involve multiple purposes, from electricity generation to piped water supply to irrigation to flood control. In the past, these purposes often tend to conflict with each other, as fears of future water shortage compete with fears of excessive floodwater. The inability to predict factors that affect dam management has resulted in a number of faulty decisions, including failure to release water pre-emptively during the early rainy season.

For a long period, scientists have admitted that the science needed to be adequately understood and the management of such complex dam-related systems had not yet been reached. However, progress made in this science seem now to encourage some scientists and engineers to propose that that stage is now already attained.

These developments in science and technology include the emergence of Doppler radars that supply hourly real-time tracking data, together with sophisticated computers and new algorithms based on advanced computer science. These factors are now said to enable powerful simulation of hydrological patterns and optimization of dam flood control systems.

Whether or not the preventive flood control functions of the Central Luzon dams can be managed efficiently by adopting this new science and technology and a corresponding new protocol is itself hard to answer. First of all, there are other factors that come into play outside the focus of dam management, such as deforestation and soil erosion resulting in siltation of the dams themselves, or the downstream of rivers. These and other social factors have to be addressed as well as part of a holistic approach to the problem, involving major land use changes and forest regeneration.

As with the problem of flooding, the solutions to these problems are all complex, requiring even more research and social analysis that can enable appropriate action by communities affected by such floods. How we, and others, undertake this mission will have a bearing on whether or not such floods as those in Thailand and the Philippines will occur and exact a social toll on the same enormous or even greater destructive scale.