Lapulapu LGU Inks Mactan Bubble Project with MCWDThe Mactan Bubble Project has finally been signed after it was postponed last December 11, 2008.
Mactan Island:
Its Water Situation
In the 1970’s, Mactan Island was already experiencing rapid development in terms of urbanization and industrialization. Along with development came the need to supply the island’s most basic necessity: WATER.
Based on previous reports (USC-WRC, 1979; USC-WRC, 1988; USC-WRC, 1993), Mactan Island was perceived to be limited in terms of its fresh groundwater resources due to over-pumping of wells within the island.
The Findings
However, recent findings (Walag, 2005a; Walag, 2005b; WRKC, 2006) showed that freshwater lens are still evident from as high as 24m at Barangay Bangkal to as low as 6m at Barangay Buaya. The location of the brackishwater zones are found mostly outside of the Mactan Circumferential Road.
The Focal Point
Main Objective
To establish a monitoring scheme that will comprehensively provide prompt and accurate data for developing decision-support information, maintenance, and conduct appropriate design for remediation measures on identified critical areas.
The Project Phases:
Pre-Project Phase
Rapid Assessment of Water Resources
This activity will use secondary information mostly taken from the 1992 study entitled “Water Resources Inventory for Mactan Island: An Update” conducted by the University of San Carlos-Water Resources Center (USC-WRC) (USC-WRC, 1993). The rapid assessment will be able to come-up with a water resources potential profile, extraction rate of the groundwater resources, identification of the location of high extraction areas and identification of data gaps to accurately determine water resources in the area. Data will be evaluated to partially characterize the aquifer system if the existing available information allows such analysis.
Inventory and Detailed Assessment of Water Resources
Well Survey
A well inventory is necessary to provide current data about the groundwater utilization. The data will be used to determine the current freshwater reserve and extent of groundwater utilization in the area both by private, public, and industrial entities (springs, open dug wells, handpumps, and electric-driven pumps). All data will be recorded in the standard National Water Resources Board (NWRB) well records. The result of the well survey will be used to identify possible control wells for water level monitoring.
Water Level Monitoring
Water level of selected control wells will be monitored simultaneously for a period of two days per well. The data will provide information on the accessibility and potential of the groundwater. The effect of the tide will also be observed. Selected control wells in the USC-WRC 1992 study will also be used for monitoring. However, in the event that these wells can no longer be located, another well within the proximate distance (about 50m radius) will be selected as substitute.
Differential Leveling
Water level elevation of control wells will be determined by conducting differential leveling. Reference points or Bench Marks (BM) must be established and referred to the mean sea level.
Conductivity Measurements
Electrical conductivity and chloride content of the water from the control wells shall be determined in relation with the water level. In this way, the fresh and brackish water zones can be determined and delineated.
Consumption Study
The rate of consumption for the different type of wells (handpumps - public and private; open dug well - public and private; electrically operated wells - public and private; industrial/commercial and agricultural) will be determined. For each well type a minimum of ten samples will be considered. The data will be used to update the current groundwater withdrawal which is an important parameter in the computation of the island’s actual water balance.
Equipment, Instruments, and Personnel Requirements
A minimum of two survey teams consisting of two members with a basic knowledge in the field of water resources will be assigned in the area under the close supervision of the MCWD water experts. Hydro-geologic equipment like water level indicators, divers, TDS / conductivity / salinity meters, geo-electrical resistivity meter, leveling instruments, global positioning system (GPS) rovers, and drilling machine will be used in this study.
Computerization of Output Using GIS
All gathered data will be stored in a computerized databank using dBase and Microsoft Excel programs. Working maps will be digitized with the aid of a Geographical Information System (GIS) tool for easy interpretation and analysis.
Expected Output
Well Map
A computer generated Well Map showing the exact location of all water sources found in the island with symbols and assigned numbers.
Well Records
The well record consists of Well Schemes and Well Logs to keep permanent records of new and old wells. New wells (installed after the 1992 study) will be assigned with well numbers in relation to the old one.
Expected Output s
Water Level Map
A computer generated Water Level Map featuring the elevation of the static groundwater in the area. The map is a direct guide in determining the critical areas where groundwater could be lower than the sea.
Water Quality Map
A computer generated Water Quality Map featuring the position of the fresh-brackish zone in the area by correlating conductivity with chloride. Seawater intrusion can be seen, if any. Likewise health risk zone will also be delineated.
Groundwater Extraction Map
A computer generated Groundwater Extraction Map featuring the current groundwater extraction in the area. The map can serve as a direct guide in locating the most heavily pumped areas, thus further exploitation can be prevented.
The result of the above activities will be analyzed and evaluated to come up with a proper design of groundwater monitoring network to effectively manage the groundwater resources in the island.
Post-Project Phase
Capacity-Building Activities
A water and environment team which composed of the representatives from the Local Government Unit (LGU) of Lapu-Lapu City will be created. As part of the capacity building, the team will undergo a seminar on the basic principles of hydrology and hydro-geologic measurements.
Design of Groundwater Monitoring Network
Data from Chapter 2.1 – 2.2 will be analyzed and evaluated to come up with a proper design of ground water monitoring network in the entire island. Areas identified for heavy groundwater extraction must be installed with monitoring station.
Long-Term Monitoring Activities
Once the design of the monitoring network will be implemented based on the results of the study, a long-term quantitative and qualitative groundwater monitoring will be done. Groundwater quantity and quality measurements will be done at least once a month to have better results. Monthly groundwater data will be evaluated and analyzed to detect possible trend to help ensure that groundwater will be protected from any damage at an early stage.
Joint Inspection
Monthly groundwater monitoring will be done jointly by the MCWD staff and the Water and Environment team of the Lapu-Lapu City. Each party should have its own records indicating the measured parameters and the corresponding date of measurements.
Scenarios and Remedial Measures
The monitoring activities will be used to compare the actual patterns versus the scenarios presented on the Pre-project phase. Abnormal trends will be subjected to investigation and conduct appropriate remedial measures.
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