Design discharge 2030, Surkhet village

Survey year 2015, design year 2030, so $n = 15$ years.

Design population

$$P_{2030} = 1500\times(1.02)^{15} = 2{,}019$$

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.

Losses and wastage $= 15\%$ of net demand $= 20{,}625$ l/day

$$Q_{avg} = 137{,}501 + 20{,}625 = 158{,}126\ \text{l/day} = 158.13\ \mathrm{m^3/day} = 1.83\ \text{l/s}$$

Design discharge

• Maximum day demand $= 1.5\times1.83 = 2.75$ l/s (source, intake and transmission main).
• Peak hour demand $= 3\times1.83 = 5.49$ l/s (distribution).

Answer: Design discharge (maximum day) = 2.75 l/s; average demand = 1.83 l/s (158.1 m$^3$/day); peak hour = 5.49 l/s.