Groundwater Supply in Metro Manila

ADAMSON UNIVERSITY COLLEGE OF ENGINEERING CIVIL ENGINEERING DEPARTMENT CE 428-Water Resources Engineering

Groundwater Supply in Metro Manila Presented by: Dudas, Gladys Leigh Macasinag, John Brouxe Pajarillaga, Mary Margarethe Suyat, Allyssa Presented to: Dr. Tomas U. Ganiron Jr.

Outline Groundwater System Distribution

1 in Metro Manila

2 Environmental Issues and Analysis Economic Evaluation of Groundwater 3 Use

4

Groundwater Development and Management

Groundwater Depletion in Metro 5 Manila

3 4

Groundwater System Distribution in Metro Manila

Aquifer Systems • The aquifer system covers about 1400 to 1800 sq.km. • In general, the aquifers consist of the upper water table aquifer up to 30 m depth and the lower artesian aquifer of more than 500 m thickness, separated by semi-confining layer with thickness of up to 45 m.

Confined Aquifer The main aquifer is the one formed by the Guadalupe formation which covers 472 square km and which also covers much of the area of the NCR.

Unconfined Aquifer Alluvial sediments derived from erosion of the Guadalupe formation provide the medium or material for water table aquifers.

Recharge to Aquifer System • Pumping (for confined aquifer) • Precipitation (for unconfined aquifer) • Deep cone of depression (both) Total Annual Recharge to Groundwater System: 217 million m^3/year or 594,000 m^3/day Precipitation: 148 m^3/ year Induced flow from Laguna lake: estimated at 22 m^3/ year Inflow from North: 12 m^3/year Inflow form South: 10 m^3/ year MWSS pipeline leakage: estimated at 25 m^3/ year

Changes in Groundwater levels Pasig and Quezon City

Valenzuela an alarming 110 m below msl

50 to 60 m below msl

Las Pinas, Paranaque and Muntinlupa the piezometric surface is from 70 to 80 m below mean sea level

Sea water intrusion into the aquifer has reached up to 5 km from Manila Bay’s coastline.

Major Aquifer System in Metro Manila Marikina Valley Alluvium

Manila Bay Alluvium

Guadalupe Formation

Laguna Formation and Pre-Quaternary Formations

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The average value of the transmissivity coefficient in Metro-Manila Guadalupe formation is 58 sq.m./day

Geohydrology of Aquifers The storage coefficient (S) of the main aquifer varies from 0.1 (or 10%) in the southern end of NCR where phreatic (water table) aquifer is assumed to prevail to 0.0001 in the northern end.

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Higher values of 0.002-0.006 are found along the western and northern side of Laguna de Bay.

Geohydrology of Aquifers The upper water table is separated from the main artesian aquifer by semi-impermeable layer (aquitard) with thickness ranging from 15-45 m.

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South to Coastal Municipalities of Metro Manila negative piezometric heads (around -10 m) exist

Northeast of Metro Manila positive piezometric heads exist in Northeast of Manila which ranged from +10 to +180

Groundwater Potential refers to the total amount of permanent storage that exists in the aquifers.

It depends on:

Hydrogeology

Relative Surface Area

Amount of precipitation the area receive

Environmental Issu es and Analysis

Current Problems Associated with Groundwater Use Aquifer Depletion

Groundwater Pollution

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Land Subsidence

Salinization

Economic Evalua tion of Groundwa ter Use

Cost of Groundwater Pumping  1. JICA model JICA proposed a simple estimation procedure to determine the cost per cubic meter of water for rehabilitating or constructing new wells.

It is written as: C = (A*a + B) / Q

Where: C = cost of water per unit volume A = total project cost a = capital reduction rate B = annual operation and maintenance cost Q = annual pumpage.

The capital reduction rate (a) can be estimated from: a = (i(i+1)n/((i+1)n -1) Â Where: i = rate of interest n = useful life in years

 2. AIC model AIC can be regarded as a good approximation of the Long-Run Marginal Cost (LRMC) of water supply and is defined as the ratio of the present value of incremental costs of producing water over the present value of volume of incremental water produced

It can be defined further if we consider the average incremental cost of water produced at the headworks, which is written as:

T å (Ilt + Rlt) / (1 + r)t t=0 AICH = T+L å + r)t t=L

Qlt / (1

Where: Ilt is the investment at the headworks in year t Rlt is the incremental operating and maintenance (O&M) cost of the headworks in year t Qlt is the incremental water produced at the headworks in year t r is the discount rate (e.g. opportunity cost of capital).

Groundwater Dev elopment and Ma nagement

Groundwater Distribution Projects Metro Manila Groundwater Distribution System

Rizal Province Water Supply Improvement Project (RPWSIP)

Metro Manila Groundwater Distribution Sys tem

01

rehabilitation of 100 existing MWSS wells in MSA

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construction of 7 new deepwell pumping stations and 6 elevated water tanks in Antipolo

construction of 50 monitoring wells around MSA

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conduct detailed hydro geologic survey or study in Rizal province

Rizal Province Water Supply Improvement Projec t (RPWSIP) This project is aimed to improve and construct waterworks systems in 9 municipalities of Rizal such as Angono, Baras, Cardona, Jala-jala, Morong, Pililia, Tanay, Taytay and Teresa by utilizing groundwater and Laguna de Bay as sources.

Groundwater Dep letion in Metro M anila

Groundwater Depletion a term often defined as long-term water-level declines caused by sustained groundwater pumping

Groundwater Depletion high temperature

low precipitation

land subsidence

Causes

Effects

drying up of wells

deterioration of water quality excessive unregulated pumping

reduction of water in streams and lakes

Groundwater depletion by 2050 Land subsidence due to excessive groundwater utilization has contributed to the worsening Metro Manila flooding.

Solutions • Find alternative sources of water • Reduce use of chemicals and know how to properly dispose them • Conserve water • Regulation regarding pumping of water • Conduct more comprehensive research regarding groundwater depletion

References https://news.mb.com.ph/2018/08/16/flooding-subsiding-ground-caused-by-excessive -water-use-environmental-expert / https://www.manilatimes.net/groundwater-depletion-by-2050-filipino-expert/18329/? fbclid=IwAR3om9YU383F_h3VWzUCV0C80JatLy_XmKIcC-cdXY-FAojniAkw-tRibK0 https:// www.usgs.gov/special-topic/water-science-school/science/groundwater-decline-anddepletion?qt-science_center_objects=0#qt-science_center_objects https://www.researchgate.net/publication/24110829_Groundwater_Supply_in_Metr o_Manila_Distribution_Environmental_and_Economic_Assessment http:// citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.520.3200&rep=rep1&type=pdf https://www.conserve-energy-future.com/causes-effects-solutions-of-groundwater-de pletion.php