By FAYE VELASCO            JUNE 13 2016

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

Two (2) geotechnical personnel of the Mines and Geosciences Bureau Regional Office No. IV-A (CALABARZON) conducted a hydrogeological survey in the Municipality of Ibaan, Batangas Province last May 17 – 21, 2016.

The groundwater survey consisted of well inventory using a GPS instrument to determine the geographic location of each well. Well data were obtained from interviews of the well owners and/or barangay officials. These data includes: (1) barangay name, (2) geographic coordinates, (3) well owner’s name, (4) groundwater depth, (5) age of well, (6) other information (ie. salinity, yield fluctuation and possible subsurface materials).

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The photo on the left shows an outcrop of the bedded tuffaceous sandstone member of the Taal Tuff in Ibaan. The photo on the right shows the sediments that comprise the alternating siltstone and sandstone members of the same formation from a drilling site.

Thirty-eight (38) well and three (3) spring locations were plotted on a geologic map and were used in the assessment of the groundwater conditions of Ibaan.

The wells of Ibaan are hosted solely by the tuffaceous sandstone member of the Taal Tuff. Most of these wells are moderately deep to deep and are generally productive. Meanwhile, the springs form through fractures within the agglomerate member of the same formation.

The concentration of groundwater flow within the municipality is toward the central portion that includes Poblacion, Salaban II, Malainin, Lapu-Lapu, Palindan, Pangao, and San Agustin despite a uniform southward decrease in elevation toward the Calumpang River. This irregular flow pattern can be explained by the occurrence of aquitards within the tuffaceous sandstone aquifer unit.

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The photo on the left shows a representative spring in Ibaan while the photo on the right shows a close-up of the agglomerates hosting the springs.