--- title: "Demand of rural municipality, base period 3 years" subject: "Water Supply Engineering" chapter: 3 key: "semester_5/water_supply_engineering:demand-bk79" source: https://www.bctengineer.com/q/semester_5/water_supply_engineering/demand-bk79 site: BCT Engineering --- # Demand of rural municipality, base period 3 years Water Supply Engineering · Chapter 3: Quantity of Water - Asked in: 2079 Baisakh, 8 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/water_supply_engineering/demand-bk79 - Whole chapter: https://www.bctengineer.com/md/semester_5/water_supply_engineering/chapter-3 ## Question Baseline survey of a newly developing rural municipality in 2021 AD has the following information: Population = 6000 with annual growth rate of 2%; No. of cows = 3050; No. of buffaloes = 2000; No. of goats = 2500; No. of ducks = 1000; No. of chickens = 6000; No. of rural municipality = 1 and no. of students in a school = 150 boarders and 1500 day scholars. Neglecting the fire demand, calculate the water demand of the area considering a base period of 3 and design period of 20 years. ## Short answer With 2% annual growth, design population in 2044 is 9,461. Summing domestic (45 lpcd), livestock, school, and office demands, then adding 15% losses, average daily demand = 784 m³/day (9.1 L/s) and maximum day demand = 13.6 L/s. ## Answer Survey year 2021; base period 3 years and design period 20 years, so the design year is $2021+3+20 = 2044$, i.e. 23 years after the survey. #### Population forecast (geometrical, r = 2%) $$ P_{2044} = P_0(1+r)^{n} = 6000\times(1.02)^{23} = 9{,}461 $$ #### 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. Livestock and school numbers are taken as constant. Fire demand is neglected. | Demand | Quantity | Rate | Demand (l/day) | |---|---|---|---| | Domestic (45 lpcd) | 9,461 | 45 l/c/d | 425,763 | | Boarders | 150 | 45 l/c/d | 6,750 | | Day scholars | 1,500 | 5 l/c/d | 7,500 | | Cows + buffaloes | 5,050 | 45 l/d | 227,250 | | Goats | 2,500 | 5 l/d | 12,500 | | Ducks + chickens | 7,000 | 0.2 l/d | 1,400 | | Rural municipality office (10 staff) | 10 | 45 l/staff | 450 | | **Net demand** | | | **681,613** | Losses and wastage $= 15\%$ of net demand $= 102{,}242$ l/day $$ Q_{avg} = 681{,}613 + 102{,}242 = 783{,}855\ \text{l/day} = 783.85\ \mathrm{m^3/day} = 9.07\ \text{l/s} $$ Peak (maximum day) demand $= 1.5\times783.9 = 1{,}175.8\ \mathrm{m^3/day}$. **Answer: Design population = 9,461; average daily water demand = 784 m$^3$/day (9.1 l/s); maximum day demand = 13.6 l/s.** ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Survey 2021, base period 3 and design period 20 years. How many years of growth? A. 20 B. 3 C. 23 D. 26 Answer: C. Design year = 2021+3+20 = 2044, so n = 23 years. (Key point: Design year) 2. What is the design population at 2% growth? A. 9,461 B. 8,000 C. 12,000 D. 6,000 Answer: A. 6000 x 1.02^23 = 9,461. (Key point: Population) 3. What rates are used for animals? A. Cows and buffaloes 5 l/d, goats 45 l/d B. All animals 45 l/d C. Cows and buffaloes 45 l/d, goats 5 l/d, poultry 0.2 l/d D. All animals 5 l/d Answer: C. Big animals 45, small animals 5, poultry 0.2 l/d. (Key point: Livestock rates) 4. How are losses and max day demand applied? A. Losses 15% of net demand; maximum day = 1.5 x average B. Losses 15% of domestic only; max day = 3 x average C. Losses ignored; peak = 1.5 D. Losses 50% Answer: A. Net demand 681,613 + 15% = 783,855 l/day, and max day = 1.5 x average. (Key point: Losses and design flow) ## Related in Water Supply Engineering - [Demand of rural area survey 2019, 1.77% growth](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-b78) — Water Supply Engineering, chapter 3 - [Rural village demand, survey 2070 BS, base year 2073](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-as70) — Water Supply Engineering, chapter 3 - [Demand of rural municipality 2018, 15,000 pop](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-c74) — Water Supply Engineering, chapter 3 - [Demand of village 2070 BS, base period 5 years](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-c70) — Water Supply Engineering, chapter 3 - [Population in survey year from design demand 800 m3](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Apop-s73) — Water Supply Engineering, chapter 3, asked 2× - [Average demand, village survey 2013, design 25 years](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ademand-c73) — Water Supply Engineering, chapter 3, asked 2× ## Related in other subjects - [Prove mean annual flood has 2.33-year return period](https://www.bctengineer.com/question.md?key=semester_5%2Fengineering_hydrology%3Agumbel-mean-flood-2-33yr) — Engineering Hydrology, chapter 6 - [5th year peak load with population growth](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Afifth-year-peak-load-population-growth) — Transmission and Distribution System Design, chapter 6, asked 7× - [Asphalt Institute design: 1.888×10³ ESAL/day, 10 years](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Aasphalt-institute-design-1-888e3-esal) — Transportation Engineering II, chapter 2 - [5th year peak load, incremental growth rate](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Afifth-year-peak-load-incremental-growth) — Transmission and Distribution System Design, chapter 6, asked 7×