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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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SUPPLY AND DEMAND GAP ANALYSIS
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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SUPPLY AND DEMAND GAP ANALYSIS
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
Year 5 234 CMD 2.71 lps
Year 10 265 CMD 3.07 lps
Water Reqt = Population xWater Demand
ADD = Water Reqt/(1-NRW)
MDD = 1.3xADD
PHD = 2.0xADD
WATER DEMAND TABLE:
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