Such water-bearing strata or levels of permeable rock, sand, or gravel are most suitable for shallow tubewell (STW) development, pointed out four researchers of the Mariano Marcos State University (MMSU). Currently headed by Dr. Miriam Edulian-Pascua, president, MMSU is a multi-campus tertiary institution in Ilocos Norte whose seat of administration is the main campus in Batac town.
The research done by Rodel Utrera, Nathaniel Alibuyog, Rodolfo Natividad, and Reynold Caoili with funding support from the Department of Agriculture-Regional Field Unit-I was started in July 1999 and completed in 2005. The results of the study were presented at a recent technology forum sponsored by the DA-Bureau of Agricultural Research (BAR).
The researchers said that the productive aquifers in Pangasinan are indicated by the lithologic and hydraulic characteristics of the area. (Lithology is the study of rocks while hydraulic means something operated, moved, or affected by means of water.)
"Therefore, Pangasinan has a good potential and most suitable for shallow tube well development," they stated.
Results on the groundwater quality indicated that it is still safe to use STW as a source of irrigation water to grow crops in the region.
The researchers added that the maps developed in the study can be used by farmers and well drillers in locating potential sites for STW development and serve as guide in selecting suitable diameter (three-inch and four-inch) of pipes applicable in the area.
Safe well spacing in the area based from 10 hours of continuous pumping ranges from 14 meters to 842 m. Radius of influence must be considered for the proper spacing of wells to avoid well interference and land subsidence.
On the other hand, acquifers in Ilocos Norte, Ilocos Sur, and La Union are less productive and moderately suited for STW. The groundwater resources in these areas may be tapped using smaller diameter (two-inch and below) and low capacity pump to minimize abrupt drop of the groundwater level. – RAF