Skip to main content

Total demand, village survey 2013, design 15 years

Short answer

Survey year 2013, design year 2031. Population forecasted 327 by geometric growth. Total water demand: 34.6 m3/day (0.40 l/s) after adding 15% losses.

The survey data collected for a water supply scheme in a village of Nepal is given below:

Survey year = 2013; Base period = 3 years; Design period = 15 years; Population = 250; No. of cows = 200; No. of goats = 500; No. of chickens = 5000; Annual population growth rate = 1.5%; No. of day scholars in school = 100; No. of boarders in school = 10; No. of health post = 1; No. of tea shop = 1; VDC office = 1.

Calculate total water demand for design year.

Survey year 2013; base period 3 years and design period 15 years: design year 2031, n=18n = 18 years.

Design population

P2031=250×(1.015)18=327P_{2031} = 250\times(1.015)^{18} = 327

Water demand

Design values assumed (Nepal rural water supply practice): domestic 45 lpcd (public taps); day scholar 5 l/d; boarder 45 l/d; office staff 45 l/d with 10 staff per office; big animal (cow, buffalo) 45 l/d; small animal (goat, pig) 5 l/d; poultry 0.2 l/d; health post 1000 l/d; tea shop 500 l/d; losses and wastage 15% of net demand; maximum day factor 1.5 and peak hour factor 3.

DemandQuantityRateDemand (l/day)
Domestic (45 lpcd)32745 l/c/d14,708
Day scholars1005 l/c/d500
Boarders1045 l/c/d450
Cows20045 l/d9,000
Goats5005 l/d2,500
Chickens5,0000.2 l/d1,000
Health post11000 l/d1,000
Tea shop1500 l/d500
VDC office (10 staff)1045 l/staff450
Net demand30,108

Losses and wastage =15%= 15\% of net demand =4,516= 4{,}516 l/day

Qavg=30,108+4,516=34,624 l/day=34.62 m3/day=0.40 l/sQ_{avg} = 30{,}108 + 4{,}516 = 34{,}624\ \text{l/day} = 34.62\ \mathrm{m^3/day} = 0.40\ \text{l/s}

Answer: Design population = 327; total water demand = 34.6 m3^3/day (0.40 l/s).

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Water Supply Engineering chapter 3 questions →