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2. Environmental impacts and protective measures
2.1 Overview
2.2 Quantitative overuse of water resources and threats to their
quality
2.2.1 General
2.2.2 Quantitative overuse of resources
2.2.2.1 Groundwater
2.2.2.2 Surface water
2.2.3 Qualitative aspects of overuse and storage
2.2.4 Qualitative aspects of non-piped distribution
2.2.4.1 Close to the distribution point
2.2.4.2 In the remainder of the watershed
2.3 Increase in demand
resulting from positive feedback
2.4 Overuse resulting from a good water supply
3. Notes on the analysis and evaluation of environmental impacts
4. Interaction with other sectors
5. Summary assessment of environmental relevance
The term "rural water supply" covers all the measures taken to satisfy the demand for water in predominantly rural regions.
Rural regions of this kind may be typified by
- nomadic ways of life,
- peasant ways of life,
- peri-urban ways of life. 1)
1) This does not include plantations and large-scale agricultural undertakings.
Rural water supply embraces the supply of drinking and household water to the rural population plus supply of the water required for purposes such as garden watering. However, though this constitutes an environmental problem in its own right, rural water supply also includes the watering of livestock plus the supply of water for livestock watering, because in rural areas it is virtually impossible in practice to draw any clear distinction between drinking water for humans and drinking water for livestock.
The supply of water for general agricultural purposes does not come within the scope of rural water supply; in particular, rural water supply does not cover systems for the irrigation of fields or rural hydraulic engineering works. In contrast to urban water supply systems, there is no piped distribution in the majority of rural water supply systems. Exceptions to this rule are the supply pipes and the (generally quite short) runs of pipe that in deprived areas form the rudimentary networks supplying public stand-pipe systems in spread-out villages.
Water demand must, inevitably, adjust itself to the supply that is present and usable. Where it is simply a matter of supplying the rural population, demand is generally between 15 and 30 l per person per day (l/p/d) and sometimes even less, and it seldom rises to levels of more than 60 l/p/d (only where there are house and yard connections). To cover the demand for water for livestock, an additional 15 l/d will be needed for each small animal unit and around 75 l/d for each large animal unit.
Depending on the nature of the abstraction, rural water supply can be divided into the following types:
- water supply from groundwater
- water supply from surface water based on
Ÿ use of surface waters and
Ÿ use of water furnished by precipitation.
To meet demand, use is often made of all three resources simultaneously, where seasonal water availability permits.
Unlike public, urban, water supply where use is made of a (large) central abstraction system and reservoirs and a connected distribution system, what is typical of rural water supply is so-called "de-centralised" water supply systems where the beneficiaries often assist in constructing the system under self-help projects and later on become responsible for operating it.
Relatively small groups of consumers ranging from a single family to village communities or nomadic herding communities obtain their water supplies from small, often scattered and sometimes widely separated individual abstraction systems with no distribution system, water carrying traditionally being the domain of women and girls in rural areas.
What is typical of de-centralised groundwater abstraction is dug or drilled wells or spring tappings. The lifting units in the systems are generally small, to match the number of consumers, the water resource and the generally limited constructional resources and their capacity is of the order of 1 m3/h in the case of village wells and up to 5 m3/h in the case of wells on pasture land.
Lifting is generally carried out by traditional means operated either by hand or by draught animals, though use may also be made of mechanical lifting aids such as hand-operated or motor-driven (generally diesel) pumps, bucket chains, etc. Artesian wells, in which the water is confined and rises to the surface without the need for lifting, are rare. In some cases water is lifted into community tanks, which are closed tanks of 2 - 6 m3 capacity fitted with a tap.
The characteristic feature of abstraction from surface waters is small impoundment works (normally earth dams). The hallmark of precipitation water use is cisterns (ranging from buckets through water barrels up to closed tanks made of concrete, sheet steel or plastic) and the associated intercepting and collecting surfaces (roofs, sealed upland slopes, etc.).
The predominant method of conveying water between the point of abstraction and the point of consumption is still transport in portable containers or by donkey, generally a job done by women and girls. Supply pipes are rare and generally very short. Transport considerations mean that drinking troughs for livestock are generally sited immediately adjacent to the abstraction or collecting point.
An important part in rural water supply projects is played by local measures to regulate the supply, particularly when the amount of water available is restricted. Such measures include for example restrictions on the daily periods of withdrawal and pumping and on the volumes lifted, and measures to control consumption such as suitable pricing.
2. Environmental impacts and protective measures
2.1 Overview
Environmental impacts from rural water supply projects are possible and they are due primarily to the qualitative and quantitative exploitation which occur as a result of:
(a) the abstraction of water (overuse of the resource),
(b) the lifting, storage and distribution of the water, and
(c) the actual allocation made (requirements and mode of use).
As well as the above, there are also possible secondary and tertiary impacts on the environment in the event of
(d) increased demand due to positive feedback,
(e) overtaxing of the resources due to a good water supply for a short period, accompanied by overgrazing and gnawing of the vegetation and changes in accustomed modes of use.
Environmental protection measures will therefore be qualitatively and quantitatively orientated and hence will be chiefly concerned with strategies for preventing overuse of the water and threats to its hygiene. This means not simply measures that are technically feasible (e.g. limited well development geared to the technology available), but above all complementary efforts to produce organised self-help, in the form of instructional and hygiene campaigns, with women playing a crucial role in these not just in the planning but above all in the implementation.
2.2 Quantitative overuse of water resources and threats to their quality
2.2.1 General
Water resources may be adversely affected not just quantitatively, i.e. in respect of their volume and temporal/spatial availability, but also qualitatively in respect of their quality and hence their fitness for use, which may occur due to pollutants, bacteria etc. The impacts on them exerted by rural water supply operations may affect them in the same way.
In cases where precipitation is collected, overuse is ruled out by the natural
limit on the amount of water collected (which is often small anyway), whereas in cases where supplies are abstracted from surface waters, threats may arise to the water resources, particularly in respect of quality.
Where the most serious adverse impacts are possible, however, is where supplies are abstracted from groundwater. In this case there may be permanent, irreversible deleterious effects on the resource both in quantitative and qualitative terms. Fossil groundwater is a non-renewable resource and as such it should, if at all possible, not be exploited in any way.
For groundwater abstraction, the open well is far more of a risk to water hygiene than a pumping system covered at the top.
In many cases, it is likely in rural areas with well-developed structures that, given the relatively small volumes abstracted for rural water supply, the total available resources will have sufficient regenerative capacity to rule out any threat of sustained overuse. However, if there are also other adverse factors operating, then undesirable overtaxing of the resources may very well occur.
2.2.2 Quantitative overuse of resources
2.2.2.1 Groundwater
Groundwater is the most sensitive resource and as such, the determining factor that governs its regenerative capacity is the recharge rate, which often works out to only a fraction of mean annual precipitation. The significance of the recharge rate can be seen from the following example:
- Where groundwater is
recharged at 80 mm/a from precipitation, an average village well
system composed of individual wells, with a system output of
around 8,000 m3 (around 10 hours' operation a
day at 0.8 to 2 m3/h), requires a watershed of 10
ha or 0.1 km2.
- However, where the recharge rate is only one tenth of that
quoted above, i.e. where it is only 8 mm/a, the watershed needed
by the well system goes up to 10 times 100 ha, or to 1 km2.
This example demonstrates the extreme sensitivity of the water balance in cases where groundwater recharge rates are lower than 10 mm/a, as they are in many of the arid regions of Africa.
Where the hydrogeological defining conditions are as follows, they can be taken as indicating a possible threat of quantitative overuse of groundwater reserves:
- very low annual precipitation,
- high evaporation rates,
- largely impermeable and/or shallow aquiferous strata and
- a restricted number of perched aquifers.
The above factors are outside human control but there are also other, use-related factors which may lead to overtaxing of groundwater resources:
- excessively close grouping of wells/pumps, due for example to poor co-ordination or ignorance, causing the cones of depression of the wells/pumps to overlap and thus have an adverse effect on their yields,
- uncontrolled rises in the abstraction rates, due for example to enlarged livestock holdings and/or greater use of water for irrigation of agricultural land,
- wasting of water, due for example to excessive running of pumps or modes of operation dictated by overlarge lifting aids (pumps) or ones with a needlessly high output.
An essential prerequisite for preventing overuse is as accurate as possible a knowledge of the parameters governing the geohydrological balance, i.e. the inflow to and outflow from the watershed in which the use is taking place. Often, the basic data may not be available, and it may only be after observation over a number of years that adequate information on the parameters in question can be obtained, a fact that often militates against any early implementation of projects. Hence overuse may equally well be the result of over-hasty planning (or total absence of planning on the grounds that a project is only modest in scope) based on observations made over too short a period.
In countries in temperate latitudes, preserving groundwater resources has traditionally been the primary concern of water-management master plans (see the environmental brief on Water Framework Planning).
In arid regions, the need to preserve human life may sometimes mean that this primary concern has to be ignored and even fossil (non-renewable) groundwater abstracted. However, any sustained overtaxing of such resources must inevitably lead to the exhaustion of reserves and may thus, under certain circumstances, have highly adverse long-term repercussions on the conditions of life themselves.
Problems of a purely mechanical kind, though ones which have major implications for the supply, often occur with hand pumping, for which a wide variety of different systems are employed. Often, the pumps break down for lack of only minor spare parts. The parts then prove to be unavailable or there is no money to procure them or no-one will accept responsibility for procuring them. As a result the well can no longer be used and the population are forced to return to using surface water of unacceptable quality.
It will be clear from the above that the questions of defined responsibilities, of the techniques employed and of what the subsequent water charges need to be in order to ensure uninterrupted operation and proper maintenance are the very ones that have to be covered in a project, and to be covered jointly with the target group with full involvement of, above all, the women who are responsible for fetching water.
2.2.2.2 Surface water
Earth dams of modest height (a few metres) are often built around or across rivers/bodies of water, or at the foot of suitable valleys or gorges in the associated watershed, to store surface water for various purposes (e.g. water supply, irrigation) and make it available for long periods or all the year round (see also the environmental brief Rural Hydraulic Engineering).
There will only be any impacts on the water balance, and particularly on the groundwater conditions, downstream of a small impounding work if the volume of impounded water amounts to a relatively high proportion of the discharge from the river or body of water when not intercepted (i.e. if it brings discharge to a level below the mean low water discharge MLQ). Although this is seldom done, should the entire discharge be impounded then the watercourse will dry up and the water table will be lowered. It is advisable for a study to be carried out in each individual case, and an estimate to be made on the basis of its findings, of whether the volume of water abstracted (less losses attributable to use for example) will affect the ecology and if so how. At the same time, as accurate as possible an appraisal must be made of whether total impoundment is justifiable in the light of the serious impacts on the water balance downstream.
The infiltration of surface water to replenish already overused groundwater resources, with the added aim of cleaning the water as it seeps though the soil, can only be contemplated when the general hydrogeological conditions are suitable and when adequate reserves of surface water are available and it will therefore always be an exception. It makes better sense in cases like this for the water to be filtered above-ground or for a water harvesting system to be installed along the course of the river in the form of an impermeable impoundment wall for collecting water with facilities for withdrawal downstream and a filter structure facing upstream.
2.2.3 Qualitative aspects of overuse and storage
There are environmental impacts that are caused by the incorrect storage of collected rainwater and impounded surface water and by contamination and illicit use of the water as it is being conveyed in open channels. It is particularly in rural regions that the resulting hygienic risks of the transmission of waterborne diseases are high, in that, in them, surface water is generally freely accessible to man and beast, the water concerned is not subject to any sort of quota-fixing, and health risks are, in general, not properly appreciated.
Deterioration of water quality is caused chiefly by suffusion with light and algal and plant growth and by pronounced warming of the generally static water. If there is also a rich supply of nutrients combined with a low rate of exchange of the water, then eutrophication processes may occur in the impounded bodies of water, which are generally shallow.
The health risks (malaria, bilharzia, diarrhetic diseases) posed by stored water of this kind are compounded by the proliferation of insects, by the possibility of human and animal excrement on the banks and shores, and by the discharge of waste water. Another possibility is pollution resulting from the use of pesticides in the watershed where the water is collected. In this connection, care must be taken to ensure strict demarcation of the watershed (as a water protection area) and physical separation of the water supply systems for humans from those for livestock (and, where necessary, filtering of the water abstracted).
Where rainwater is stored in cisterns, health risks arise as a result of deterioration of water quality, which may be caused by long residence of the water in the cistern in some cases, by choice of an unsuitable location (exposed to solar radiation), by lack of regular cleaning, by material-related effects (e.g. corrosion of sheet-metal cisterns), or by entry of dirt and animals (which die and decay in the cisterns) allowed by absence of covers or covers that do not seal tightly. Even chlorination of the water, though it may be employed to kill off bacteria, entails considerable health risks if incorrectly applied.
2.2.4 Qualitative aspects of non-piped distribution
There are typical impacts that are generated at distribution points both where these points are small open or pump-equipped wells and where they belong to systems for abstracting water from surface waters. There are a multiplicity of possible ways in which groundwater in general and the water in a well or body of water can be polluted. The main pollution sources producing individual health risks of infectious diseases that should be mentioned are these:
2.2.4.1 Close to the distribution point (well/water takeoff point)
- leaks from the motor or bucket drive (diesel fuel, lubricant), with open wells being more at risk here than closed wells with pumps,
- entry of pollutants as result of the items used
Ÿ for water withdrawal (dirty lifting buckets and carrying vessels),
Ÿ for the transportation of water by car, truck or beast of burden, where there is a risk of contamination with petrol, diesel fuel and excrement,
Ÿ for cleaning of the person and laundering (detergents, phosphates, faeces)
Ÿ for watering livestock, where there may be dung deposits, cattle mires, and greater insect infestation, and pesticides for pest control.
Ÿ for filling and cleaning equipment for spraying pesticides for pest control.
2.2.4.2 In the remainder of the watershed
- pollution caused by totally different activities not directly related to water abstraction such as agriculture (fertilizers, semi-liquid manure, pesticides), artisanal activities and light industry (oil, diesel fuel and petrol, etc.), and the disposal of waste water and solid waste.
A point which needs to be made in connection with the preservation of groundwater quality is that, desirable though it may be to introduce water protection areas to prevent qualitative impairment of the groundwater by humans and animals, it is difficult to achieve in practice and it is only feasible if the population is enlightened as to the need for it. If however some initial protective measures were taken in the immediate vicinity of a water takeoff point (well, pump, community tank, surface water withdrawal point, spring), this in itself would be a first step on the way to mitigating the above risk and hence to improving the health situation. What will be needed here will be work to instruct the public and increase public awareness and this will need to be concentrated above all on women, who are responsible for fetching water and for domestic hygiene and thus family health.
A start can be made by fencing off water takeoff points such as village wells and making sure that they are allocated to specific uses (human/animal, water fetching/washing and laundering/livestock watering) and are well separated physically for this purpose and that there are safe and reliable facilities for discharging the waste water. As a further step towards procuring clean, workable water takeoff points geared to the different needs that exist, what also needs to be done is to introduce a monitoring and inspection system for maintaining and repairing the points and stopping any environmental damage. In this system women will, once again, have a crucial part to play (as well overseers for example).
Given the growing number of car repair shops and filling stations in many countries, other focusses of attention will need to be the development and installation of petrol and oil separators.
2.3 Increase in demand resulting from positive feedback
The existence of a convenient and efficient water supply system, coupled with a general betterment of conditions in rural areas, may give rise to increases in demand.
This will mean a rise in abstraction, generally uncontrolled and chiefly from groundwater, and this in turn will accentuate the quantitative impacts on the resource concerned. Up to this point, and given the small volumes consumed to meet basic needs (see section 1), the matter of waste water will have been of very little concern, but now evidence will begin to be seen of the adverse consequences it can have on the quality of surface water and groundwater and thus, indirectly, on the health of humans and animals. The first steps that can be taken to combat these consequences are such things as instruction in hygiene and the construction of VIP latrines.2) This is another case where women, the persons responsible for obtaining water and ensuring domestic hygiene, will need to be actively involved at the outset.
2) Ventilated improved pit-latrines
2.4 Overuse resulting from a good water supply
A good water supply in rural areas can lead to an increase in livestock holdings, with all the adverse consequential impacts this may have such as overgrazing and gnawing of the vegetation and compaction of the soil. In the longer term there may also be tertiary impacts, such as changes in the microclimate caused by attacks on vegetation (e.g. gnawing of trees by goats causing changes to the ecologically important micro-climate close to the ground) or water or wind erosion where the all-important top soil is stripped away as a result of overgrazing of the vegetative cover.
Detrimental impacts may also arise from the physical layout and position of the supply points (e.g. wells) when the latter are not geared to the socio-economic needs of the target group. Groups from a nomadic population for example need supply points that lie within a few day's march even when the weather is bad and/or fodder is short. This may not be possible in certain instances, so the average length of stay at a given watering place is extended accordingly and the risk of overuse becomes greater. In the worst case, the nomadic way of life might have to be abandoned in favour of a quasi-sedentary way of life, and this would give rise to impacts whose social and socio-economic consequences would be difficult to foresee.
In such cases, project schemes must be drawn up jointly with the target groups and must allow for existing, often traditional water and grazing rights though at the same time, by making provision for enlightening people and making them aware of the interrelationships that exist (and possibly by means of water pricing too where appropriate), they must also afford resource-saving solutions.
3. Notes on the analysis and evaluation of environmental impacts
A vital prerequisite for both analysing and evaluating environmental impacts from rural water supply is a determination of the usable water supply. Factors that have a crucial bearing on the possible intensity of use in this case are regenerative capacity in the case of groundwater and the watershed and its yield curve with time in the case of surface water.
Particular risks attach to the use of fossil groundwater, for this is non-renewable.
Incorrect estimates of the available water supply are possible particularly in arid and semi-arid regions, where not only may there be marked fluctuations from year to year in the yield but there may also be no appreciable regeneration of the resources for a number of years due to the absence of precipitation. Under these circumstances it is only justifiable to make estimates by reference to average values measured over many years when the groundwater-bearing aquifers are thick and cover large areas.
Where the resources are affected by unfavourable natural conditions, this will restrict the opportunities for providing a decentralised supply, and particularly a decentralised supply to rural centres of population, where the quite heavy concentration of population would mean that a number of wells spaced relatively short distances apart would be needed but where the wells would affect each other's yields. Further restrictions may arise from, for example, pollution of the groundwater by refuse pits and soakaways, washing places, and drinking troughs for livestock.
Surveys of the current situation and the potential changes (in population, per capita consumption, commercial activity, etc.) will be needed, together with an analysis and evaluation of the local impacts of the potential hazards.
One of the most essential prerequisites for analysing and evaluating the environmental impacts of rural water supply is a knowledge of the defining climatic and hydrological conditions (direction and strength of winds, precipitation, evaporation, temperatures, and water levels and water tables), which have to be allowed for at the outset in connection with yield and recharging and the resulting opportunities for use. In many countries the basic data available, in the form of uninterrupted sets of measurements extending over a period of years, may be deficient in that the measurement points may be few in number and, as often happens, outside the project region, and because of this it may be necessary to engage in additional long-term measurement surveys to acquire the above knowledge.
This process, though essential to ensure that planning and implementation have proper scientific backing and that sustained use will be possible, often runs counter to the urgent need for supply systems to be created quickly and may meet with incomprehension on the part of, for example, the people affected.
Also, water supply is a sensitive area, and this being so it will be necessary to call on not just engineering knowledge but sociological and ethnological knowledge too. Important questions relating to matters such as the structure of the society, the official/traditional organisation of villages, water consumption customs, domestic hygiene, the income situation (in relation to charges for water), water and garzing rights, and the role of women all need to be clarified with the people involved, if possible in the early stages.
Generally speaking, what standards (limit values, guidelines and directives) relate to are water quality requirements (including hygienic conditions) on the one hand, and limits for heaviness of use for (subsequent) competing applications. Binding standards for ecological and socio-economic implications and impacts do not exist, and there will therefore be a continuing opportunity for differing interpretations to be placed upon them.
There are, for a basic range of constituents, recommendations of world-wide ambit (see section 6) on drinking water requirements, but though many countries with no pertinent national legislation of their own may already be following these recommendations, there are major problems in checking and ensuring compliance with them in practice.
Standards for the limits on possible heaviness of use (e.g. per capita consumption figures for humans and animals, see also section 1) were, in essence, drawn up simply as rule-of-thumb figures. However, given the multiplicity of factors to be allowed for, it seems doubtful whether they will be capable of general application and for this reason preference should always be given to a funded regional investigation.
By appropriate improvement of public understanding and awareness, an attempt should be made in every project to bring into being demands for environmental protection that are as high as possible within the limits set by socio-economic and cultural factors, with particular importance being attached to the involvement of women in their role as the persons responsible for water supply in rural areas.
4. Interaction with other sectors
Where rural water supply has its closest points of contact is with all sectors that create further demand for water, that have the use of water as one of their direct or indirect objectives, or that affect water quality or restrict the quantity of water available.
The chief sector concerned here is agriculture (see also other broadly agricultural areas3) in that it may involve the use of the same supply of ground and surface water, with the possibility of added impacts generated by adjacent abstractions. There may possibly be interaction too with the following sub-sectors, and such interaction should be checked for its consequences in each individual case:
3) plant production, plant protection, forestry, fisheries and aquaculture, irrigation, livestock farming, and agro-industry.
- Water Framework Planning
- Rural Hydraulic Engineering
- Solid Waste Disposal - Collection, treatment and disposal
- Wastewater Disposal (and rainwater) - Collection, treatment, disposal/discharge
- River and Canal Engineering
- Erosion Control
- Large-scale Hydraulic Engineering
- Spatial and Regional Planning.
Water supply occupies a key position in determining how, and how intensively, an area or region can be developed and it therefore has an impact on all projects and sectors that involve planning to preserve, improve or develop the infrastructure.
5. Summary assessment of environmental relevance
Rural water supply projects are contributory means to ensuring the long-term preservation of human life and the quality of life.
It is perfectly possible for the planning and execution of rural water supply projects to be orientated towards meeting the demands of environmental and resource protection. In broad terms, what needs to be remembered is that only seldom does the individual facility such as a well, pump set or collecting basin/water tank create any major environmental impacts of itself, and that if there is environmental damage it normally does not occur until such facilities become concentrated and overused, particularly in connection with livestock watering.
Handpumps are the most widely used aid for water lifting, and it is particularly where they are employed that care must be taken to see that the equipment selected is robust and easy to maintain and obtain spares for, because if they do fail this will jeopardise the underlying goal any project will have of providing a sustained supply of good quality water and will compel the population to revert to using open watering points with their attendant health risks4).
4) Women have traditionally been responsible for water supply and it is they who will need to be trained not only to operate but also maintain the pumps.
To sum up, the following is a list of criteria that must be met for the better environmental orientation of a project:
(1) The time-dependent total water yield must be studied and long-term hydrological and climatic trends must be examined;
(2) It must be decided what the desired sociographic structure of the rural region is to be and what limits are to be set for its possible development, with due allowance for the structures that tradition and ethnicity have put in place;
(3) Planners must be bound by an overall utilisation scheme that makes a quantitative apportionment of the available supply and lays down priorities among uses;
(4) Technology geared to the utilisation scheme laid down must be developed or applied, with active involvement of target groups at an early stage, steps must be taken to ensure that subsequent operation and maintenance will be possible (charges for water), and the transferability of solutions successfully employed elsewhere must be carefully vetted.
Experience teaches that hierarchical levels of planning are a necessary prerequisite for meeting the above criteria and that it makes good sense for rural water supply projects to be subordinated to rural regional development programmes. It is particularly important to have things structured in this way because the opportunities for control in the sensitive area of water supply (e.g. by restricting abstraction) are very limited and security needs to be built no later than the planning stage.
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