SEAWATER intrusion due to over-extraction of groundwater in Cebu remains a serious threat that needs to be solved, an expert said.
Engineer Maria Nenita Jumao-as, a hydrologist and chief of the University of San Carlos–Water Resources Center (USC-WRC), said that over-pumping of groundwater within the Cebu mainland’s aquifer has worsened the intrusion of saltwater inland over the years.
In her presentation at the Cebu Water Summit at the Bai Hotel Cebu in Mandaue City on Monday, March 27, Jumao-as said the Metropolitan Cebu Water District (MCWD) has been reliant on extracting groundwater of around 235,000 cubic meters per day, while it extracts only 44,800 cubic meters of surface water per day.
But she said MCWD supplies only 215,000 cubic meters of water per day to 2.5 million customers in its franchise area from the municipality of Minglanilla up to the town of Compostela, or a difference of 64,000 cubic meters per day, because of its 23 percent unaccounted-for water (UFW) or leakage and loss in production.
According to Jumao-as, Metro Cebu demands 639,889 cubic meters of water every day for both domestic and non-domestic purposes.
She said 424,780 cubic meters of water come from total domestic demand, or 134 cubic meters of water that an individual consumes every day.
Jumao-as said Metro Cebu’s natural water resources can store around 1.3 million cubic meters of freshwater per day.
She said 747,000 cubic meters of this water per day come from the surface water supply, while 559,000 cubic meters of water per day come from the aquifers — an area below the ground where groundwater can be extracted.
Jumao-as said over-extraction of groundwater will lead to inevitable water shortages and other environmental issues.
So she proposed the formulation of policies that must be implemented immediately to address this concern.
This includes Integrated Water Resource Management with key strategies of increasing the supply, lowering the demand, protecting the sources, efficient water governance, intensified research and development, and education.
On the other hand, engineer Emmanuel Espina, MCWD corporate planning management officer, said that aside from seawater intrusion and over-extraction of groundwater, the agency is also facing other problems such as the clogged rainwater recharge areas (the places where water is able to seep into the ground and refill an aquifer because no confining layer is present), nitrate contamination, rapid demand growth, climate change, and calamities that affect the water supply deficit in Cebu.
Espina said MCWD produced 255,000 cubic meters of water per day, with 70 percent or 177,443 cubic meters of water extracted from groundwater.
With a demand of 563,245 cubic meters of water per day, it has a supply gap of 338,245 cubic meters of water that needs to be addressed.
Twenty-one percent or 55,861 cubic meters of water come from surface water and nine percent or 21,695 cubic meters from the brackish water.
With the lingering threat of saltwater intrusion, Espina said MCWD stands firm on installing 11 desalination plants spread in Cebu City, Cordova, Lapu-Lapu City, Consolacion, Liloan, Mandaue and Talisay City.
If MCWD cannot fully utilize other sources of water such as desalination, the supply and demand gap would rise to 420,291 cubic meters of water needed per day, according to Espina.
Desalination plants use seawater to be treated and turned into freshwater for human consumption.
On other hand, Espina said inadequate toilet and septage waste collection and treatment facilities in Metro Cebu have worsened the nitrate contamination of groundwater.
In 2017, MCWD had a septage collection rate of only 8.1 percent, which was low.
However, with the help of the Japan International Cooperation Agency in the installation of the septage waste treatment plant at the North Reclamation Area, MCWD has a goal of improving the waste collection to 57.9 percent in 2025.