FLOOD COUNTERMEASURES UNDER TIGHT BUDGET

In the Philippines, the design parameters in the preparation of master plans and feasibility studies, implementation, operation and maintenance of flood control projects are greatly influenced by the economy of the country. For Metro Manila, 30 year return period for river improvement, and mostly less than or equal to 10 year for drainage works are implemented on a phase to phase basis. Budget comes in trickles resulting to delays in the implementation. Optimal operations of flood control appurtenances are not attained. The equipment; which necessitate immediate replacement or rehabilitation, outlast the efficiency level over years of use.

Due to growing population, topographical changes, and the impact of climate change, structural measures limited to design flood level cannot cope under extreme condition, and the master plan and feasibility studies are becoming less and less feasible. Land subsidence due to water demand, land use changes due to development in the upstream and downstream reaches, encroachment of waterways both by influential and marginal groups, are considerations to update and revise the master plans and feasibility studies. However, the financial capability of the government and the duration to implement the priority projects are still uncertain.

As vulnerability of the people in the flood prone areas increases, viable alternatives affordable through local resources should be pursued. Some innovative measures require short term implementation that can increase the security of the affected populace. Flood forecasting and warning system are becoming more popular and acceptable as private entities begun to get involved and cooperate. However, some significant aspects, such as those which relate to political and social factors , are hard to change in a short term. Urgent works should be sourced from available local funds which are low cost in nature to supplement the non-structural countermeasures. Though conceptual, these may include heightening of the house in highly susceptible areas, viaduct for mobility and passage during flood time, maintenance of waterways engaging community participation, accessible and safe evacuation centers, etc.

Philippine Strategies to Mitigate Flood Disasters

For the past decades, the Philippines has been experiencing climate variability with extreme rainfall. Some areas, especially the southern part, are now frequented by typhoons and heavy rains where before such phenomena were rarely experienced resulting to disastrous run-off to a surprised populace. In reaction to series of disasters, the government has been formulating and implementing measures to alleviate the negative impact of these calamities. Among these are reviewing and enforcement of policies dealing with river easement and  flood control, establishment of nationwide early warning system through improvised hydrological sonar gauges linked through SMS and internet, acquisition of LiDar digital elevation maps for flood modeling and flood forecasting, and production of hazard maps as guides for land use planning,  and formulation and revision of master plans and feasibility studies for flood management in prioritized river basins. At this stage in a changing environment, accuracy and reliability of each measure is still rudimentary.

While the country is developing flood disaster management, there are still many issues to resolve. At present flood plain management is governed by the current policy on river easement.  It is enforced hardly as there are many encroachments legally and illegally in the waterways. At the same time, river boundaries are not clearly established even in urbanized areas and especially where river shifting is experienced. Another issue is the watershed where settlers are uncontrollably falling down trees and bushes for agricultural purpose, for firewood and as means of livelihood.

It is indeed a big challenge to clear the high risk areas in flood plain and watershed areas where more often available budget for relocation and political interest are big stumbling blocks. These could be one of the foreseeable reasons for poor implementation of land use and watershed management.

On modeling, flood hazard mapping, flood forecasting, warning, and planning, the country has spatially sparse hydrological data plus the changing norms due to climate change. Also, data sharing even among government agencies is not cohesive. Dissemination of warning information becomes confusing also, because many players are now involved in processing and in media release. It is also found out that there are discrepancies between the actual and the acquired data. As there are few local experts on modeling, calibration to get more efficient results may take some time.

Lastly, due to limitation of budget, flood management implementation in different river basins is prioritized according to risk and necessity. At the rate of occurrence of disasters on nationwide scale, priority ranking will be revised soon.

Each key issue is examined to recommend improvement of measures adaptable and fitted to the communities at risk.