By FAYE VELASCO          MAY 11, 2016

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This photo shows a well pump owner being interviewed regarding the well pump and the water extracted from it.

A series of hydrogeological surveys was conducted by the Mines and Geosciences Bureau Regional Office No. IV-A (CALABARZON) in the municipalities of Lobo and San Luis, Batangas Province. Four (4) MGB IV-A personnel were involved in the fieldwork for the periods of April 19-23, 2016 and April 26-29, 2016.

The groundwater survey consisted of well and spring inventory using a GPS instrument to determine their geographic location. Water well data were obtained from interviews of the well owners and/or barangay officials. These data are: (1) barangay, (2) geographic coordinates, (3) well owner name, (4) water level, (5) age of well, (6) other information (i.e. salinity, sediment content, lithology of nearby outcrops, yield fluctuation).

The well  locations were plotted on a topographic and geologic map and were used in the interpretation of groundwater conditions of each municipality.

In Lobo, the wells are hosted by the following rock formations: Talahib Andesite, Lobo Agglomerate, Taal Tuff, Quaternary Alluvium, and patches of coralline limestone. Most of these wells, except those on the first two rock types, are relatively shallow and are generally productive. However, protection of the watershed and the “Forest Zone” is encouraged to ensure the continuity of favorable recharge-discharge conditions.

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These photos show representative outcrops of the Talahib Andesite (left) and coralline limestone (right) which are two of the possible groundwater hosts in Batangas Province.

In San Luis, only the Talahib Andesite, Taal Tuff, and Quaternary Alluvium host the dominantly deep wells of the municipality. These wells are moderately productive with some wells drying up or recharging slowly. Thus, it is recommended that the groundwater extraction of San Luis be strictly monitored by the LGU and the San Luis Water District.

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The photo shows the water level data collected during the hydrogeological survey in Lobo, Batangas plotted on top of the area’s geologic map.

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The photo shows the water level data collected during the hydrogeological survey in San Luis, Batangas plotted on top of the area’s geologic map.