03_dilg_salintubig - supply and demand gap analysis

7/28/2019 03_DILG_Salintubig - Supply and Demand Gap Analysis

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SUPPLY AND DEMAND

GAP ANALYSIS


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SUPPLY AND DEMAND GAP ANALYSIS

Existing Situation Present Facilit ies and State of Facil it ies

(include observed defects, operational requirements,needed improvements for present si tuation, cash flow

problems)

- Maps (areas currently served, areas under proposedproject, probable ultimate service area)

- Water Users (domestic, commercial, industrial,institutional and publ ic faucet)

- Population (served)

- Statistical Information (% of population served)- How Served (% metered, % unmetered, % PublicFaucets)

- Historical Data (metered water consumption, NRW,Water production)


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Existing Situation- Per Capita Consumption (historical data, evidence of

unsatisf ied demands, consumption restricted by

inadequate water distr ibution capacity)

- Will connection increase if distribution capacity is

expanded?- Historical dates of exist ing WSS (planning,

construction, abandonment, expansion source,

intake, transmission, treatment, booster pumping

stations, distribution main/network, storage)

- Capacities and present conditions- Existing surface water source data (catchment area,

rainfall, Water quality, river flow data, water rights,

watershed condition)

- Exist ing Groundwater (well & spring locations,capacities, GW aquifer capacity, water quality


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Demand Projections

Population Projections

Water Consumption

Demand Variation (ADD, MDD, PHD)


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Population Projections

(Geometrical Method Formula)

Pn = Po (1 + i)n

Where:

Pn = Design Population

Po = Present Population

i = Growth Rate

n = Design Period


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Growth Rate/Annual Rate Increase

The analysis of ARI should be on city/municpal to

barangay level:

Determine growth patterns/trends

Take note of extraordinary increase or decrease andreason for such. (zoning plan or a master development plan,physical limits and or geographical barriers, possibility ofindustrial development, proposed new arterial roads ortransportation facilities, proposed regional facilities

universities, military base)

Examine official historical population data(1990,1995,2000,2005)


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Water Consumption Rate (Wc):

Domestic ConnectionIndividual connection = 100 to 120 lpcdPublic Faucets = 30 to 60 lpcd NRW = 20% to 25%

Institut ional Connection = 3 to 6 cumd

Commercial Connection = 1 to 2 cumd

Industrial Connection = 1 to 3 cumd


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Demand Variations

ADD = used in the design of basic water

facilities. Reservoir capacity is usually 25% of

ADD.

MDD = used in determining the transmission

main and pump capacity for a water source to be

acceptable.

PHD = used in determining the size of

distribution mains.


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Peak Hour Demand)

Maximum Day Demand)

Average Day Demand)


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Estimate of Water Demand

ADD = Wrqt / (1-NRW)

Wrqt= Pn x Wc

MDD = 1.3 x ADD PHD = 2.0 x ADD (Population > 1000) PHD = 2.5 x ADD (Population > 600,


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Water Demand Factors

ADD = (Design Population x Water ConsumptionRate) /(1-NRW)

Figures multiplied to the ADD to determine other demand

variations for purposes of analyzing and designing thewater supply system.

MDD = 1.2 to 1.5 (For Transmission Main and

Well yield)

PHD = 1.5 to 2.0 (For design of distribution

pipes)


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PRESENT SITUATION

Total Population = 3,000

Population withinthe service area = 2,700

Estimated served

population = 2,200

Number of persons

per household = 5

Level 2 Water Supply

Water Demand = 60 lpcd

NRW = 20%

Year 1 215 CMD 2.48 lps



Water Reqt = Population xWater Demand

ADD = Water Reqt/(1-NRW)

MDD = 1.3xADD

PHD = 2.0xADD

WATER DEMAND TABLE:


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03_dilg_salintubig - supply and demand gap analysis

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