3.1 Man and water
3.2 Man and livestock
3.3 Water and livestock
3.4 Livestock and rangeland
3.5 Concluding or summary statement
3.1.1 Creation or improvement of water supplies
3.1.2 Water lifting devices and maintenance
3.1.3 Cost of water
3.1.4 Water and rangeland management
Natural water supplies (small ponds during the rainy season, permanent lakes or rivers during the dry season) are the main source of water for livestock belonging to the extensive migratory animal production system. However, as a consequence of the growing number of livestock, artificial watering facilities have been created either for enabling livestock to graze larger areas and make full use of the forage resources of the rangelands or for watering livestock along the transhumance routes.
The different techniques of water development will be examined in chapters 5-6.
While the main function of the pumps and water lifting devices, which is to produce water, and especially groundwater, to make it available to livestock, they should also suit the habits and preference of the human users as well as their capacity to maintain mechanical devices and water structures. Some common devices are discussed in Chapter 6.
In an agricultural environment, water users are usually sensitive to the cost of water even in developing countries. The small farmer in Tunisia or the vegetable producer in an oasis of Mauritania are perfectly aware of what their well and their pump cost and how many litres of fuel they need to irrigate their garden every month. But in a rangeland environment of a developing country, cost of water is an abstract concept, since it is usually not related to a price stockbreeders have to pay to water their animals. Most of the investment and operating costs are borne by the national budget.
On the other hand cost of water is commonly used as an indicator to judge the economical feasibility of water development. Physical parameters (depth to water, type of rock to be dug or drilled) affect the cost of water. Costs are closely related to local conditions and to the proper financial and technical management of the project. It is often misleading to draw general conclusions on correlations between cost of water and hydrogeological or hydrological situations. This is the reason why this aspect of the water development is not discussed in this manual. In normal practice this analysis should be carried out for each case, especially when alternatives (surface water or groundwater, dug or drilled wells) are available.
Until recently it was considered that good management of a system including rangeland and water supply could only be attained through a single agency or authority, which would take care of the maintenance and repair of the water supply and pumps as well as of the conservation of the rangeland.
The disappointing results obtained so far by many of these organizations have led livestock development planners to use informal groups of livestock owners, pastoral associations or cooperatives as a channel for some of the development activities including partial financing of wells, maintenance and repair of pumps, and conservation of rangeland (fire protection essentially). The direct involvement of the population concerned is expected to improve the efficiency of the livestock development projects and in the meantime to lighten the financial weight of large projects on the national budgets. This trend observed during the last few years to assign more responsibility to the pastoral communities in managing their wells, pumps and rangelands, is unfortunately too recent to allow positive results to be observed. Additional creative efforts in this field are still needed. For example, why not to assign the task of monitoring ground-water (water level fluctuations, water use) to stockowners' groups or cooperatives?
The relationship between livestock and the human population is important and has considerable bearing upon the use of the rangelands and the type of distribution of the watering facilities.
There is a range of situations from the truly nomadic herdsmen who move with the animals together with their families and possessions, to the sedentary situation where the stockbreeder and his family has a permanent home, usually associated with a village. However, in order to stay within the general purpose of this manual, only the pure pastoral and semi-sedentary systems which include important movements of the herds will be considered.
a. Purely pastoral system
The purely pastoral system concerns the extensive migratory animal production system in use within the Near East, Sahel, Sudan and Sub-Saharian zones of Africa. The traditional pastoral communities own and manage the great animal resources in these regions. In this situation the herds constantly move in search of grazing areas and water. During and immediately after the rainy season, livestock move northwards (in Sahel area) in order to exploit the meagre grazing resources of the Sub-Saharian areas. When the dry season is well set up, herds move southwards in order to eventually stay for the rest of the dry season in the vicinity of the permanent water supply points. The permanent dry season water supply may come from the large river systems (Niger, Senegal, Chart, Logone) or permanent lakes (de Guiers in Senegal, Rkiz in Mauritania, Lake Chad). Permanent ponds are common in wetter regions while occasionally deep wells, either artesian or equipped with pumping facilities, may be used.
It is clear that the planning of the water supply layout must take into consideration the seasonal movements of the livestock as well as the possible competition between farmers and stockbreeders for the utilization of the watering facilities during the period in which the herds have to enter the agricultural areas.
b. Semi-sedentary system
In the areas where the average annual rainfall exceeds 350-400 mm, stockbreeders progressively settle and become agro-pastoralists. Their way of life based on the interaction between stockbreeding and agriculture includes four different periods:
i. as soon as the first rains take place - usually in June in the Sahel area), the herds move towards the high lands (plateaux) which are not used for agriculture. One herd is usually conducted by only one shepherd who may be either a stock owner or a wage earner. This period is commonly called "petite (small) transhumance" in the French literature;ii. immediately after harvesting - mid-September in Sahel area - part of the herds come back to the villages to eat the residues of the crops during approximately one month;
iii. when the crop residues are exhausted the livestock is taken back to the grazing areas which may be as far as 30 to 40 km away from the village. This period is commonly called "grande (great) transhumance" in the French literature, usually lasts until December-January when most of the natural ponds dry up;
iv. during the 4-5 months preceding the rainy season, the livestock uses the grazing areas located close to the villages and is watered from the village wells.
3.3.1 Water quality
3.3.2 Water requirement
3.3.3 Location of the water supplies
3.3.4 Watering facilities
a. Salinity tolerance in livestock varieties
Livestock needs fresh drinking water for normal health and high production. The total salt content of water is the most important characteristic in determining the suitability of water for stock and it is also the easiest water quality data to obtain even in the field. Other quality characteristics are usually of secondary importance.
Excessive intake of saline water may cause sickness and death. Adult sheep appear to be fairly tolerant, and indeed are often given free access to salt licks, obviously in circumstances where they do not ear enough to cause ill effects. Cattle are less tolerant than sheep but more tolerant than pigs and poultry.
The standards at present considered to be safe upper limits of total salts in water for stock in Western Australia are indicated in Table 1.
Table 1: UPPER LIMITS OF TOTAL SALT CONTENT OF WATER FOR LIVESTOCK
|
Livestock |
Total dissolved solids (in g/l) |
|
Poultry |
2.8 |
|
Pigs |
4.3 |
|
Horses |
6.4 |
|
Cattle (dairy) |
7.1 |
|
Cattle (beef) |
10.0 |
|
Adult dry sheep |
12.8 |
While most animals can therefore tolerant fairly high levels of total salts, the amount of magnesium in the water may be critical. The following concentrations of magnesium in water are considered to be safe upper limits for stock on dry feed. Higher levels can be tolerated when pastures are green and succulent:
|
Lactating cows and horses |
0.25 g/l |
|
Dry cattle and weaner sheep |
0.40 g/l |
|
Adult sheep |
0.50 g/l |
Another useful guide to animal water supply is shown in Table 2. This table is primarily intended for human drinking water, since people often drink the same water as animals.
b. Effect of excessive water or feed salt content on livestock
The amount of salt in the feed or water which will produce symptoms of salt poisoning in the various domestic animals are Indicated in Table 3.
Table 2: WATER QUALITY STANDARDS FOR ARID REGIONS
|
|
Suitability for permanent supply |
|||
|
good |
fair |
moderate |
poor |
|
|
Colour |
colourless |
colourless |
|
|
|
Turbidity |
clear |
clear |
|
|
|
Odour |
odourless |
hardly perceptible |
slight |
slight |
|
Taste at 20°C |
none |
perceptible |
pronounced |
unpleasant |
|
Total dissolved solids (mg/l) |
0-500 |
500-1000 |
1000-2000 |
2000-4000 |
|
EC m S/cm) |
0-800 |
800-1600 |
1600-3200 |
3200-6400 |
|
Na (mg/l) |
0-115 |
115-230 |
230-460 |
460-920 |
|
Mg (mg/l) |
0-30 |
30-60 |
60-120 |
60-120 |
|
|
0-5 |
5-10 |
10-20 |
20-40 |
|
Cl (mg/l) |
0-180 |
180-360 |
360-710 |
710-1420 |
|
SO4 (mg/l) |
0-150 |
150-290 |
290-580 |
580-1150 |
Source: Schoeller (1977)
Table 3: TOTAL QUANTITY OF SALT PRODUCING SYMPTOMS OF SALT POISONING
|
Livestock |
Total amount of salt per day (in g/l) |
|
Poultry |
4 - 8 |
|
Pigs |
100 - 200 |
|
Cattle |
1800 - 3600 |
|
Sheep |
100 - 200 |
The main symptoms in sheep and cattle are excessive thirst, abdominal pain, loss of appetite, diarrhoea and increased urination.
c. Deterioration of water quality
The water quality can deteriorate over the years (mainly groundwater) and even from season to season, and it is wise to check suspect water before letting stock have access to the supply.
During the warmest months, high evaporation increases the concentration of salt in the water standing in troughs or in ponds for a long time and it may be advantageous to place the water troughs in the shade to limit the water temperature.
d. Bacteriological water quality
Where possible animals should be given water which is bacteriologically clean as well as chemically satisfactory.
a. Factors affecting the water requirements
The water requirement of livestock is the total quantity of water required by animals for their metabolic processes as well as for the heat regulation of their body. They vary according to a number of factors such as the food intake, quality of the food, and air and water temperature.
b. Food intake
The demand for food varies according to the type and class of animal and the particular functions occurring such as during pregnancy, in lactation or whilst being fattened. Moreover the food requirement may be affected by the quantity of energy consumed by animals, mostly to reach the water supply from the grazing areas. The values of dry matter intake indicated in Table 4 correspond to a minimum requirement level for maintenance of animals on rangeland.
c. Quality of the food
Natural pastures are usually thought to be dry, but in many instances individual plants, or part of plants, remain green for long periods after rain has ceased and this moisture is of benefit in reducing the dependence of animals on water supplies. During the growth period (wet season), grass may contain as much as 80 percent water. The moisture content progressively decreases until the straw contains only 10 to 15 percent water. The green pods of Prosopis may supply an important part of water requirement of animals even under desert conditions.
Vegetation in arid areas may, unfortunately, have a high content of salt. The water consumption of sheep grazing on saltbush is two to three times greater than that of sheep on grasslands, and the importance of salt free water is greater.
d. Air temperature
The water requirement related to dry matter intake increases with air temperature. Table 4 shows the effect or air temperature on water requirement.
Table 4 WATER REQUIREMENT AND AIR TEMPERATURE
|
Air temperature (in °C) |
Water requirement (in l/kg of dry matter consumed) |
|
-17 to +10 |
3.5 |
|
10 to 15 |
3.6 |
|
15 to 21 |
4.1 |
|
21 to 27 |
4.7 |
|
more than 27 |
5.5 |
|
In the case of pregnant cows the quantities are multiplied by 1.5 and for lactating cows they are increased by 0.87 l per kg of milk produced. | |
Source: Agricultural Research Council (1965)
e. Voluntary water intake
The voluntary water intake is the quantity of water which has actually to be supplied to animals and corresponds to that part of the water requirement which cannot be provided by the moisture content of the forage. This is the parameter to be taken into account when planning a water supply system for livestock.
Table 5 summarizes the effect of the various factors governing the water requirement and gives an estimate of the voluntary water intake corresponding to the three main seasons in the Sahel.
The voluntary water intake has been calculated from the water requirement by assuming a water supply from the plants corresponding to:
i. 70 to 75 percent of moisture content of the plants during the wet season
ii. 20 percent of moisture content of the plants during the dry and cold season
iii. 10 percent of moisture content of the plants during the dry and hot season.
Table 5: ESTIMATED WATER REQUIREMENT AND VOLUNTARY WATER INTAKE OF LIVESTOCK UNDER SAHELIAN CONDITIONS
|
|
Tropical |
Mean |
Daily dry |
WET SEASON Air temp 27°C |
DRY COLD SEASON Air temp from 15-21 |
DRY HOT SEASON Air temp 27°C | |||
|
Animal |
Livestock Units (TLU) |
live-weight in kg |
matter intake in kg |
total water req. in l/day |
volun. water intake in l/day |
total water req. in l/day |
volun. water intake in l/day |
total water req. in l/day |
volun. water intake in l/day |
|
Camels |
1.6 |
410 |
9 |
50 |
15 |
37 |
35 |
50 |
50 |
|
Cattle |
0.7 |
180 |
5 |
27 |
10 |
20 |
19 |
27 |
27 |
|
Sheep |
0.1 |
25 |
1 |
5 |
2 |
4 |
4 |
5 |
5 |
|
Goats |
0.1 |
25 |
1 |
5 |
2 |
4 |
4 |
5 |
5 |
|
Donkeys |
0.4 |
105 |
3 |
16 |
5 |
12 |
11 |
16 |
16 |
Note: One Tropical Livestock Unit (TLU) is equivalent to an animal of 250 kg liveweight on maintenance. It corresponds to the "Unité Bétail Tropical (UBT)" of the French literature. In the Sahelian countries, 1 TLU is approximately equivalent to 1.4 cattle or to 10 sheep or goats.
The spacing of water supplies across the land is partly dependent on drinking frequency, but also affected by the walking ability of the animals, a requirement for uniform utilization of the forage resources and the maximim daily discharge of the water supply.
In terms of vegetation utilization, productivity is reduced by wider spacing because the areas close to water become overgrazed and those further from the water are undergrazed. In Australia, areas of 17 000 ha (circle of 7.35 km radius) for cattle and 4 000 ha (circle of 3.5 km radius) for sheep may be grazed from one water source, although shorter distances would seem desirable for maximum production and uniform use of vegetation.
In Sahelian countries, it is usually considered that cattle can walk 6 to 10 km from the grazing area to water and sheep and goats can walk 3 to 5 km from the grazing area to water.
These figures have however to be considered as rough optimal averages since livestock can easily walk twice as far in case of necessity.
Drinking frequency is another debated question among the stockbreeding specialists. It is usually thought that a daily water intake for cattle is necessary during the hot season while sheep and goats may be watered every second day only and camels can afford to stay without drinking for 4 to 5 days.
However recent observations made in Niger have proved that water intake every second day may be profitable for cattle too when the distance from the grazing area to water exceeds 5-6 km. Observations were made on two similar herds (Serres 1980) using grazing areas located 10 km away from the water supply. For the herd which was watered daily, an important part of the day was spent for the walking activity. Grazing has to take place partly during the night and very little was remaining for rest and ruminating. Table 6 shows the main results of the observations. For the herd which was watered every second day, the daily grazing time was increased as well as the time for ruminating, therefore facilitating the digestion of the straw. Moreover the animals which spent less energy for walking were less tired and could walk faster as shown on Table 6.
Table 6: RESULTS OF OBSERVATIONS MADE IN NIGER ON TWO SIMILAR HERDS ONE WATERED EVERY SECOND DAY AND THE OTHER ONE EVERY DAY
|
Activity |
WATER INTAKE EVERY SECOND DAY |
DAILY WATER INTAKE |
||||
|
Time spent first day |
Time spent second day |
Daily average |
Percent of total time |
Time spent |
Percent of total time |
|
|
Grazing |
6h 40 |
9h |
7h 50 |
33% |
6h 30 |
27% |
|
Walking |
7h |
2h |
4h 30 |
19% |
8h 30 |
37% |
|
Ruminating |
4h 50 |
5h 40 |
5h 15 |
22% |
3h 30 |
15% |
|
Rest |
5h 20 |
7h 20 |
6h 20 |
26% |
5h 20 |
22% |
|
Watering |
0h 10 |
0 |
0h 05 |
negligible |
0h 10 |
1% |
|
TOTAL |
24h 00 |
24h 00 |
24h 00 |
100% |
24h 00 |
100% |
Source: Serres (1980)
a. Design and organization
The design and organization of a watering facility for permanent use must usually be different from that for temporary or seasonal use. The drying up of a pond or reservoir can be used to control grazing, while permanent boreholes may ensure overgrazing in a considerable area around the borehole. Control methods near boreholes must be based on locally available thorn shrubs which are used to make paths to the borehole. Permanent installations may provide a basis for one or a few families to settle if the borehole produces enough water for gardening as well as stock. Considerable efforts are needed to resolve the problems related to design of the watering facility and for the organization to operate and maintain it, since it must be an integral part of the animal production system.
b. Watering troughs
In order to allow livestock to drink easily and in order to avoid crowding around the watering place, the use of watering troughs properly build and set up is advisable even if the water source is an impounding surface reservoir or a simple dug well.
Shape
Circular and rectangular troughs are commonly used for cattle. Circular troughs provide the greatest storage capacity per unit of material used, while rectangular troughs give the greatest drinking space in proportion to their capacity. V or U shaped troughs are commonly used for sheep.
Material
If properly constructed, reinforced concrete troughs are usually the most satisfactory for permanent use because of their durability.
Wooden troughs constructed from 5 cm thick material, well braced and preferably painted with non-toxic paint are satisfactory if they are not exposed to frequent drying out.
Reinforced galvanized metal troughs are durable, lightweight and usually of moderate cost.
Installation
Substantial masonry foundations are preferable for most troughs, for they provide support, anchorage and alignment. All stock troughs should be anchored sufficiently to prevent livestock from moving them or tipping them over.
Drinking space
In order to avoid crowding, sufficient drinking space should be provided at troughs to water without undue delay the full number of livestock that come to drink at any one time. About 0.7 to 1.0 m of drinking space should be provided for each cow and only 0.3 to 0.4 m to each sheep or goat. When the water source is a dug well from which water is drawn by hand or with animals, the number and distribution of the troughs around the well should be in relation to the maximum expected discharge of the well. Modern dug wells in pastoral area are usually equipped with six circular troughs one metre diameter made of concrete and distributed around the well.
Height
Cattle troughs range from 0.5 to 0.7 m in height, the lower height being preferable for calves and other young livestock.
Ordinarily, sheep troughs should not be more than 0.3m high.
Width
Troughs with a top width of 0.7 m or more can be used from both sides if properly located. Wide troughs should be provided with suitable guardrails to prevent livestock from stepping or being crowded into the trough.
c. Storage tank
Adequate storage facilities are particularly needed when discharge is smaller or greater than the requirement during watering times. The usual conditions of low discharge requiring storage will be wells equipped with pumps operated by windmills, and low yielding springs and free flowing wells. When wells are operated by motor driven pumps and the discharge is much higher than the daily average water demand for watering livestock, storage is needed to avoid wasting of water.
The capacity required for the storage tank will depend largely on the flow available from the water supply, the number of livestock and the dependability of the pumping unit; where windmill power is used for pumping, it is desirable to provide sufficient storage for about one week because calm periods may prevent windmill operation for several days at a time.
If storage requirements are relatively small, combination storage and drinking tanks are usually the most satisfactory and cheapest.
If greater storage is required, wooden, steel or concrete tanks are commonly used.
For very large storage capacity, an excavated earth reservoir may be the cheapest solution.
3.4.1 Rainfall and rangeland resources
3.4.2 Stocking rate and carrying capacity
3.4.3 Overgrazing problems
The forage production from the rangelands will be examined here only in those aspects which affect the water supply design (distribution and quantity) aiming at an even utilization of the forage available.
The biomass annually produced by the rangelands depends mainly on the absolute availability of the growth limiting factors and is therefore strongly influenced by both the quantity of precipitation and the quality of the soils. In the Sahel countries, for the same value of annual rainfall, the actual response of the rangelands in terms of forage production shows a great variability according to the quality of the soil and the availability of nitrogen and phosphorus. There is evidence that soils with higher rainfall tend to be lower in nitrogen and phosphorus. While weight of forage is higher in wetter conditions the nutrient value of the forage may actually be lower. It is therefore impossible to give a simple and general relationship between rainfall and forage production. However various authors have given tentative representations of the variations of the dry matter production of rangelands as a function of rainfall.
Figure 1 shows an estimation of relationship between mean annual rainfall and dry matter production in Somalia. The wide range of precipitation taken into account for representing the variations of productivity Indicates the great uncertainty prevailing in this field.
For the preparation of the 2nd phase of a Livestock Development Project in Mali, J.J. Boudet, rangeland specialist consultant for FAO, developed an exhaustive picture of the variations of the dry matter production of rangelands in relation to annual rainfall and its variability. Figures 2 and 3 graphically summarize the data included in FAO's report.
While Figures I through 3 can provide a rough estimate of rangeland productivity, it is preferable Co have actual assessments by pasture specialists for the particular area of concern. Such specialists may use actual testing of pasture but often are forced to assess by eye using their experience.
Productivity of grazing lands can be improved by controlled grazing, sowing to increase groundcover, introduction of legumes to increase fertility, control of brush, water conservation, reduction of wind erosion, removal of weeds and application of fertilizers. However, many of these methods are too expensive for some extensive grazing areas.
Carrying capacity is commonly expressed as number of animal units per hectare when speaking of intensive ranching or dairy operations, but when referring to extensive nomadic grazing carrying capacity is usually hectares per animal unit. The carrying or grazing capacity of a rangeland is defined in the following paragraphs as the amount of grazing land which should be made available to a Tropical Livestock Unit so that it can be maintained without deterioration of the natural resources of the area over the long term. Other definitions include the necessity of efficient production (milk or meat) but it is believed that under arid and semi-arid area conditions, the main purpose of grazing over a large part of the year is the maintenance of the livestock.
Stocking rate is defined as the amount of grazing land actually available to a Tropical Livestock Unit. The correct stocking rate should always be less than the carrying capacity.
Fig. 2: Relationship between dry matter production and annual rainfall in Sahel environment (Data derived from Table 3 Annex 5 of Livestock Development Project, 2nd phase, Mali, Cooperative Programme FAO/World Bank)
Fig. 3: Relationship between carrying capacity and annual rainfall in Sahel conditions (Data derived from Table 3 Annex 5 of Livestock Development Project, 2nd phase, Mali, Cooperative Programme FAO/World Bank)
Fig. 4: Rainfall probability under Sahelian conditions (Data derived from Cocheme and Franquin 1967)
The carrying capacity or ability of an area to feed stock is primarily a function of the dry matter production of the considered rangeland. It is therefore related to rainfall as well as to the soil quality.
Figure 3 shows the relationship between carrying capacity and annual rainfall for Mali. For each value of rainfall the carrying capacity may vary from a maximum corresponding to bad quality soil and low nutrient content to a minimum corresponding to ideal soil conditions. It should be noted that the lower the annual rainfall, the wider the range between the maximum and the minimum carrying capacity. This is normal since the dry matter production of rangelands tends towards zero for small values of rainfall and bad soil conditions.
In assessing the carrying capacity of rangelands from data on dry matter production, several factors are taken into account including the slow deterioration of forage quality over the dry season (decrease of protein content) and the increasing risk of forage destruction as time goes on.
The purpose of these remarks is to emphasize the uncertainty which prevails on the actual determination of the carrying capacity of rangelands and the difficulty of giving a simple relationship between the most commonly available data - the rainfall - and the grazing capacity of an area.
Attention should also be drawn to the variability of rainfall over a given area from year to year. The simple knowledge of the average annual rainfall is not sufficient to predict the range of variations of the carrying capacity of an area. Figure 4 shows the probable occurrences of rainfall under Sahelian conditions.
As an example, an area receiving an average annual rainfall of 300 mm may receive only 200 mm in one year out of five and as much as 400 mm in one year out of five. This also means, according to Figure 3, that an area with 300 mm average rainfall may have NO carrying capacity at all one year in ten on all the medium Co bad quality soils.
A much simpler table (Table 7) presents grazing capacity with the generally accepted assumption that 50 percent of the forage production is utilized.
Table 7: GRAZING CAPACITY
|
Mean annual rainfall mm |
DM production t/km2 |
Grazing capacity ha/TSU |
|
1000 |
150 |
5 |
|
750 |
100 |
10 |
|
500 |
50 |
15 |
|
250 |
25 |
30 |
In a Sahelian rangeland, the seeds produced by the grasses (graminaceae) reach their maturity and fall onto the soil at the end of the rainy season. The seeds are then buried by the trampling of the livestock and thus protected during the dry season. They can germinate 8-9 months later when the rain comes back again. The conservation of the rangeland depends therefore directly on the seeding process and more precisely on the quantity of seed produced which requires a normal development of the plants.
When the vegetative cycle is disturbed by overgrazing, the plants react by accelerating their rhythm of development which affects the quality of the seeding process. Repeating this phenomenon during several consecutive years may lead to the disappearance of certain species, to the benefit of other species usually less palatable for livestock and sometimes not eaten at all by the animals. This modification of the vegetation may therefore result in an important decrease of the grazing capacity of the rangeland as a consequence of overgrazing during the vegetative period of the grass.
When stocking rate is excessive during the dry season, the vegetation may also temporarily disappear but this will generally not affect the germinating capacity of the seed buried into the soil and the range should resume after the next rainy season approximately at the same level as before for the same amount of rainfall.
The provision of water for animals under extensive grazing or nomadic systems is one element of the man, animal, environment situation. The relations are basically simple but are fraught with variations, exceptions, special conditions which make generalizations unsatisfactory. This means that each area or region needs to be studied in an integrated manner so that physical additions, such as watering points, will have a positive rather than negative effect on the people concerned and on the region. The brief outline of this chapter, however, at least provides a starting point for those who are faced with estimating water requirements.
Chapter 4 attempts to show how the information in this chapter or from other sources may be further used for selection of type of water supply.
