Question

A small village is located near a stream which is to be used as the source of water supply for

the community. The minimum flow in the stream is 550 m3/h. The population analysis

reveals that the population is expected to increase linearly from a population of 10,000 in

2008 to 30,000 in 2058.

The water consumption of the community is estimated to reach an annual average demand

of 300 L/capita/day, a maximum daily demand of 1.8 times the annual average and peak

hourly demand of 1.5 times the daily average.

Would you be able to supply these demands directly from the stream? If not, what would

you recommend?

a) In the year 2030

b) In the year 2058

Answer 1

According to the linear increment of population, there will be a low supply than demand in 2023.

In 2008 the supply from stream will be = 550 m3/h = 550 x 10000 (L/hr) = 55 x 104 L/hr.

Now, population of 10000 with an annual average demand of 300 LCD =(300 x 10000) / 24 (L/hr) = 12.5 x 10 4 L/hr

Now Maximum daily demand is 1.8 times annual average demand then, maximum demand = 1.8 x 12.5 x 104 L/hr

= 22.5 x 104 L/hr in the year 2008

The maximum demand need to be fulfilled by the supply. With increase in the population linealy, the supply of 55 x 104 L/hr will match the maximum demand of water in 2030. Then after the further increase of population would not be able to get fulfilled by the supply.

IN AND AFTER 2030.

Either the supply needs to be increased of the methods of rain water harvesting needs to be adopted. The authority needs to plan an additional supply source to meet the requrired demand for further and upcoming needs.