La Union geohazard maps complete, says MGB
By Jennilyne C. Role
San Fernando City, La Union (12 September) -- "The geohazard maps for the province of La Union are already complete after series of consultations and assessment made in each barangays of the province," Dr. Karlo L. Queaño, Supervising Science Research Specialist of the Department of Environment and Natural Resources ? Mines and Geo-Science Bureau (DENR-MGB) said during the press conference held recently at ORT Training Center, this city.
In a weeklong seminar-workshop conducted by DENR-MGB on September 2-8, 2010 for the local government units and barangay captains of the province of La Union, results of the geohazards mapping conducted for the province were presented for consultations and discussions.
Based on the results, among the identified geohazards in La Union presented by MGB include rock slides brought about by fractured rocks in the mountains, collapsed cavern and earthquake induced rockfall.
Tsunami is also one considering that the province is situated along the China Sea, along with sand bar on river delta, coastal erosion due to raised water surface and mud flow.
La Union is also prone to flooding due to unplanned urban development. Liquefaction, flashfloods, landslides, volcanic hazards and sink slides and rock slides are among the other hazards the province is experiencing.
Interventions cited by DENR-MGB to prevent the impact of these geohazards are to consider the structural/engineering measures and the non-structural/non-engineering measures.
For the structural mitigation, it was noted that for the blocks to become stable, the resisting forces should be greater than the driving forces. There is a need for rib concreting, shortcutting, retaining wall and the like.
Under the non-structural mitigation, it was suggested to avoid settlements below/on steep slopes, avoid settlements at the mouth of rivers especially those that are deeply incised, avoid structures on top of an old landslide deposit, and avoid areas that had previously experienced landslides.
Queano added that the geohazard maps produced were categorized into highly susceptible to flooding, highly susceptible to landslides, highly susceptible to earthquake and the like which means that the identification of certain areas to the different categories will warn the local government units and the people alike to take precautions and further advance actions prior to the occurrence of such calamities.
He further identified that 58 barangays in the province will be highly susceptible to landslides while 59 barangays will be highly susceptible to flooding considering the province' location and composition.
In closing, Queano quoted Oakeshott statement that says, "There are no geologic hazards without an. The hazards arise from man's unwise, inept, use or abuse of the geologic environment". (PIA Region 1/La Union) [top]