Water Supply
Population Forecast
Project the design population using arithmetic, geometric and incremental increase methods. Enter past census data and the design year.
Past population data
Year
Population
Forecast Resultslive
- Forecast period, n
- 25 years
- Average increment, Ia
- 168 / yr
- Average geometric rate, r
- 2.306 %
- Incremental increase, Ii
- 40 /yr²
- Arithmetic Increase
- 15,388
- Geometric Increase
- 19,803
- Incremental Increase
- 28,388
Geometric tends to give the upper bound for fast-growing settlements; arithmetic gives the lower bound. The incremental-increase method is commonly used for urban water-supply design in Nepal.
Methods: Arithmetic: Pn = Po + n·Ia. Geometric: Pn = Po·(1+r)n. Incremental: Pn = Po + n·Ia + n(n+1)/2 · Ii.