Contents

1. GENERAL BACKGROUND

1.0 Rainfall
1.1 Rainwater infiltration and run-off
1.2 What happens to water that infiltrates into the soil?
1.3 Springs and wells are sources of infiltrated water
1.4 What happens to water run-off?
1.5 Swamps, lakes and streams are sources of water run-off
1.6 Catchment basins and stream networks
1.7 Water requirements for a fish pond
1.8 Water supply for a fish pond

The water table as a water supply
Other sources of water supply : springs, streams and rivers
Measuring the water flow
When to build a reservoir

2. ESTIMATES OF WATER REQUIREMENTS

2.0 Water to fill the pond

How to calculate the surface area of the pond
How to calculate the average water depth of the pond when it is empty
How to calculate the average water depth of the pond when it is full
How to calculate the volume of water in the pond

2.1 Water losses by seepage

How to calculate water losses caused by seepage
Reducing seepage water losses by puddling
How to calculate water needed for puddling and water losses by seepage after puddling

2.2 Water losses by evaporation

Evaporation rates
Evaporation rates by Class A Pan
How to calculate water losses by evaporation using Class A Pan evaporation rates
Evaporation rates by the Penman Formula

2.3 Total water requirements

Pond size and water flow required
Pond volume and the number of ponds possible will depend on the water flow available
Volume of each pond to be built
Number of ponds to be built
Planning for future expansion
Losses by seepage and evaporation

3. ESTIMATES OF WATER FLOW

3.0 Introduction
3.1 Quick rough estimate
3.2 Bucket method
3.3 Float method

Prepare a float
Where to measure
Find the average water velocity
Find the average width
Find the average depth
Calculate the water flow

3.4 Float and cross section method

Where to measure
Find the average cross-section
Find the average water velocity
Calculate the water flow

3.5 Dye and cross section method
3.6 Weir methods

What is a weir
Advantages and disadvantages of weirs
Where to install a weir
How to choose a suitable weir
How to design a triangular weir
How to design a rectangular weir
How to build and install a weir

In a flowing stream
By diverting the water

Position of the weir in a stream
Building a weir of wood

Triangular weir
Rectangular weir

Building a weir with other materials

Sheet metal
Corrugated roof sheeting

Using a weir to determine water flow

Preparing an upstream point to measure the head when you have diverted the water flow
Preparing an upstream point to measure the head when you have not diverted the water flow

Maintaining a weir
How to calculate water flows using a weir

Triangular weir
Rectangular weir

3.7 Water flow through a straight pipe
3.8 Water flow through a siphon

How to make a siphon
How a siphon functions

4. ESTIMATES OF WATER STORAGE

4.0 Amount of water to be stored

Your source provides a supply of water throughout the year
Your water source dries up completely at certain times of year
Water losses by seepage and evaporation from a reservoir

4.1 Selecting a site for a reservoir
4.2 Determining the characteristics of a reservoir

Estimating the volume for a reservoir without a spillway
Estimating the volume for a reservoir with a spillway