With the presence of rivers, streams and brooks in the majority of the barangays, erosions are common occurrences in many areas. Lack of water shed maintenance aggravated by rampant cutting of trees is the common cause of erosion, it contributes to flooding due to siltation of rivers and streams. Erosion endangers many agricultural lands, residential and commercial areas. Construction of flood control dikes are being undertaken but then they are not a long term solution to erosion problems, however, dredging and tree planting activities are seen to be the solution to this problem.
Areas prone to landslide are located in five barangays (Imelda,Mabuti Lydia, Daquioag and Elizabeth), rolling to mountainous terrain with minimal vegetation and forest cover. With an area of 1.8764 has. Or .01% of the Municipal land area is covered with tin natural hazard.
Flood Control and Drainage System
It is of a common knowledge that cutting of trees in the upland areas is uncontrolled and this poses a significant degradation of forest cover, which results to serious environmental problems in the future like flooding, erosion and landslide.
In the urban area and adjacent areas, these are catchment places of run-off water that needs canal waterways are needed to be constructed, this will prevent the occurrences of severe damages on properties both on lands and buildings.
Flood Prone Areas
Mostly, all barangays are flood prone areas, affecting agricultural lands, roads, bridges, as well as residential houses and commercial establishment. Earth roads and wooden bridges incurred damages due to scouring. But damages to agricultural crops is described as moderate because water subsides within 4 hours.
The DENR has identified the western part of Marcos as siltation prone of flood prone areas (possible debris flows and mudflows) and the eastern side being prone to accelerated soil erosion Furthermore, the same source revealed that the eastern part of the town is traversed by a normal fault. The won experiences earthquake due to its geographical location.
Typhoon is also often experienced and the whole population is exposed to drought.
While it is true that Marcos is generally siltation prone and accelerated soil erosion prone area considering its hilly and mountainous terrain, at present, only certain steep and loose soil in Barangays Elizabeth and Cacafean are erosion prone; and the depressed areas near rivers in Barangay Valdez, Daquioag, Fortuna, Pacifico, Escoda and Tabucbuc area are flood prone.
Except the erosion in certain parts of the mountains caused by slash-and-burn farming and illegal logging in the past, there are no man-made risk areas in Marcos.