Application field

Georesistivity evaluation of bgy.lindongan, baroy, lanao del norte as a requirement for salintubig funding

Back to list

Ⅰ、Introduction

This project was commissioned by Gintong Tubig Engineering Venture for the Municipality of Baroy, Lanao del Norte, as a pre-requisite for the proposed funding for water well drilling project under the Salintubig Program of DILG.

The Municipality of Baroy intends to provide potable water supply to Bgy. Bato which is a mountain barangay that has no access to a reliable water source. Drilling a well from a nearby barangay that has the potential to produce the needed groundwater to satisfy the requirement of Bgy. Bato is a practical solution to this situation. This evaluation will give confirmation on the potential of Bgy. Lindongan to host a well drilling project for Bgy. Bato.

Included in this report is a georesistivity survey and interpretation of results on three (3) sites nominated by the LGU personnel; a work program for well drilling and well costing for the proposed preliminary well drilling are also included in this report.


Ⅱ、Background of the study area

Bgy. Bato in Baroy Municipality is a mountain barangay that is deficient in water supply. It has neither spring source nor groundwater source. To be able to supply water to Bgy. Bato, the LGU of Baroy envisions to develop groundwater source at the nearby barangay (Bgy. Lindongan) that will be transmitted through pipeline to Bgy. Bato. Previous groundwater studies had 

been done in the past near the area, and this is one study of similar in nature.

Georesistivity can help determine the presence of potential aquifer underground that can be drilled and developed to supply groundwater. 

One well drilled to around 100m was drilled in the past in Bgy. Bato, but did not produce water at all.

In 2016 a georesistivity study in Bgy. Pindolonan was conducted but it only confirmed the absence of an aquifer that can support groundwater production.Bgy. Pindolonan is immediately southwest of Bgy. 

Bato.Bgy. Lindongan located south of Bgy. Pindolonan is a more promising location in terms of groundwater resource. At present there is an operating well in the barangay that supplies water to the barangay. This is the subject of this present georesistivity study.


Ⅲ、Resistivity measurement &analysis

Three VES stations were measured in Bgy. Lindongan as shown in the figure below.

图1.png


Location of Bgy. Lindongan


2.png

Location of VES Points

Description of VES Points

The raw fieldwork georesistivity data are given on the attachment as Annex A. 

• BA-01 is located at coordinates: 7.91363oN, 123.82167oE This VES station was executed at a bearing of northeast direction with a total 

wire spread of 600m. The effective depth of investigation at this station is 

120m to 180m.

• BA-02 is located at coordinates: 7.91201oN, 123.81955oN

This VES station was executed at a bearing of north to northeast direction with 

a total wire spread of 300m. The effective depth of investigation at this station 

is 60m to 90m.

• BA-03 is located at coordinates: 7.91616oN, 123.82271oE This VES station was executed at a bearing of northeast direction with a total 

wire spread of 300m. The effective depth of investigation at this station is 

60m to 90m.

Interpretation of Georesistivity Measurements

BA-01

3.png

BA-01 has the potential to produce a good amount of water. Based from the  interpretation

of the field georesistivity data, the identified water-bearing  layer is unconsolidated

sandstone formation with a true resistivity of 43.67  ohm.m and thickness of 133.4m. 

1.png2.png

BA-02

aaccb9696036b2b5ac0a85436eefc9ae.jpg

BA-02 is not a good site for deep well drilling. At best the weathered volcanics  identified at below 3.51m with true resistivity value of 160 ohm.m may be  good for shallow well drilling equipped with handpump, but not for high  capacity pumping. In addition, its proximity to the rice field makes it  vulnerable to fertilizer contamination, as can be observed from the very high  resistivity of 14343 ohm.m which corresponds to loose soil affected by ionic  charges probably from the long time application of chemicals and fertilizers to  the rice field.

3.png4.png

BA-03

Georesistivity Evaluation of Bgy Lindongan, Baroy,

BA-03 is already near Bgy. Pindolonan where the topography ascends towards  Bgy. Bato. The formation at this site is volcanic in origin and is quite a difficult  area to source groundwater. There may be chances of finding groundwater at  shallow depths not exceeding 5m but drilling for shallow wells using manual  tools may be very difficult.

5.png6.png



Ⅳ、Conclusion

BA-01 is the best site among the three (3) VES sites measured in the area. It is located near the boundary of Bgy. Curva and Bgy. Lindongan. A preliminary well design for 120m deep well is prepared in this report together with the corresponding cost. These two documents may form part of the work program