Towards a watershed health and vulnerability index

The watersheds of the Mount Makiling Forest Reserve, an ASEAN Heritage Park (MMFR-AHP), were evaluated on the basis of land cover and land use changes, hydrologic regimes and how these factors and their interactions impact the health of the watersheds of Laguna de Bay. This study focused on three watersheds namely; Molawin-Dampalit, Cambantoc and Tigbi. Initial results revealed that among the three watersheds, Tigbihas the highest forest cover in terms of its total area (5096%) followed by the Molawin-Dampalit, with the longest major tributary, (29.48%) and then the Cambantoc watershed (25.47%). Based on the 2015 Census of the Philippine Statistics Authority, Tigbi watershed which drains through the City of Calamba has a population of 454,4668, the Molawin-Dampalit watershed which drains through the town of Los Baños has a population of 112, 008, and Cambantoc watershed which drans throught the town of Bay has a population of 62,143. The sustainability of the provisioning and regulating services depend on the maintenance of health of these watersheds. A healthy watershed can provide sufficient water and productive soils that are requisites of the populace, agriculture sector, including fisheries. As watersheds reflect the intricate connections among land, water and other resources, an integrated assessment of the health of a watershed shouls include, at least the following: water quality, hydrology, geomorphology, connectivity, biological, multi hazards and ecological footprint. This study assessed these factors using Geographical Information System (GIS) and remote sensing. Research results revealed that portions of the study watersheds are prone to drought between the months of January to July covering an area of up to 950 ha in 13 and 6 barangays [villahes] in Los Baños and Bay [Laguna, Philippines], respectively (Bantayan et al., 2014). In terms of landslide, the same study showed an estimated of 210 ha (3.51%) covering three barangays and two barangays in Los Baños and Bay are vulnerable.