3. Notes on the analysis and evaluation of environmental impacts
Contents - Previous - Next
3.1 Interrelated aspects
A General Water Resources Management Plan must take account of all possible effects of water management activities on the environment. It must deal with the present situation in the planning area, which can vary considerably from one country to another.
The water situation may be characterised by the following:
- extremely high or low annual rainfall depending on the region,
- risk of no rain falling for several years,
- very low rates of groundwater regeneration,
- extremely heavy rainfall and flooding,
- low level of consumption and low percentage of population being supplied,
- unreliable supply,
- irrigation accounting for a high percentage of demand,
- extensive re-use of waste water and salt water, inclusion of sea water desalination.
For analysis and assessment of the environmental effects of water management activities it is necessary to consider the entire process chain i.e. the hydrological cycle from the primary stage of rainfall through to the disposal of sewage and waste materials.
A prerequisite for the above is a reliable database which also describes the present environmental situation (inherited problems) of the natural geographical unit in question or of the region. In this way it is possible to establish the scale of the current environmental problem i.e. the changes brought about by past activities, and to estimate the effects of measures planned.
Such databases (e.g. hydrological journals, environmental registers, geological reports) are unavailable in many countries and must first be compiled or replaced with suitable indicators in order to make a reasonable assessment of measures planned. National regulatory bodies and international organisations may be able to provide important information; such information can rarely be transferred directly to the case in hand, partly because individual regulations and parameters should be understood as part of an overall system, which cannot be assumed to exist in all countries. For example, when determining the limits for discharge of pollutants into surface waters, the uses and self-cleaning properties of water-courses must be taken into account.
The framework plan provides a valuable basis for assessing possible alternative forms of development and expansion. Such evaluations must, however, proceed from the same objectives. Attempts to evaluate alternatives on the basis of a single assessment criterion (e.g. cost index, "index of harm") fail to take account of the many different aspects involved.
It is important to reduce the almost infinite number of possible criteria to be included. For example, it is possible to exclude from the outset those projects or development variants which fail to satisfy certain minimum requirements (for example, no housing or industrial developments or removal of groundwater should be permitted in water conservation areas or flood plains).
Environmental impacts should be prioritised in different ways depending on the existing water situation;
- Regions with scarce water resources: Priority given to adequate quantitative provision, water-saving measures.
- Regions with adequate supply: Priority given to health and hygiene, quality assurance.
- Regions with a (temporary) surplus: Priority given to flood prevention.
Generally speaking, problems of water wastage (e.g. irrigation with connate groundwater) demand greater attention.
3.2 Analysis of use and quality of natural water resources
3.2.1 Determination of natural water supply
The natural water supply is determined by processes in the hydrological cycle, essentially by rainfall and factors such as evapotranspiration, overground and underground drainage, seepage, new groundwater formation etc. Considerable influence is brought to bear by controlling variables such as climate, vegetation, topography, soil, geo-hydrological conditions etc., and also anthropogenic influences such as land-use (large area irrigation, areas of habitation with low infiltration and increased runoff).
The supply is mainly determined by
- stocks in overground reservoirs,
- drainage into bodies of surface water,
- underground water stocks including the geological (connate) water stocks which, however, are not renewable and should not, therefore, be regarded as usable stocks where possible,
- new groundwater formation (normally only a small fraction of rainfall, depending mainly on evaporation, surface drainage, infiltration, climate, vegetation, soil type, topography, groundwater level, geo-hydrological conditions).
Drainage, new groundwater formation or other parameters of the hydrological cycle are normally compared with averages over many years, including a description of extreme values (wet years, dry years). For the Water Resources Management Plan these details are vital for orientation, but must also be considered in the context of a chronological and geographical breakdown as there may be extreme seasonal and regional variations. If, for example, the hydrological year consists of a decidedly dry season and a rainy season, but in addition there are substantial fluctuations in rainfall quantity from year to year, long-term average values for surface drainage and groundwater supply should not be used in project planning.
In many countries the database is often inadequate. The measuring stations are too far apart. A Water Resources Management Plan provides information on how the measuring network density may be increased. The necessary data (e.g. water levels and run-offs, detritus and suspended matter in surface waters, groundwater levels, physical, chemical and biological parameters of water quality, hydrometeorological and hydrogeological data) must be observed and evaluated according to applicable international standards (such as WMO, FAO, WHO). These must be published regularly in hydrological journals in the interests of sound planning, otherwise separate measuring campaigns will be necessary, which will be costly yet inadequate in view of their brevity.
3.2.2 Determination of usable water supply
The usable water supply is regarded as that proportion of the natural water supply which can be exploited, taking the following aspects into account:
|- Catchment||Nature and position of body of water or aquifer, geological and geomorphological conditions for well construction, diversion works and reservoirs, available technologies.|
|- Distribution||Periodic and quantitative redistribution (storage), geographical redistribution (transfer).|
|- Economy||Costs of development, extraction, treatment and distribution, wastewater treatment|
|- Chemical/hygienic toxicology||Water quality, risks of
treatment technology, water pollution
control measures for bodies of water, recycling
|Destruction of valuable,
dependent vegetation stocks, drying-up
of water holes and water courses,
karstification of soils, erosion, drying-up
of marshes and swamps
|- Other reasons for water management||e.g. shipping, hydroelectric power
generation, priority of use outside the
Certain minimum requirements (of quantity, area etc.) must be satisfied as a matter of priority in order to allow for ecological considerations.
3.2.3 Determination of water demand
Water demand comprises essentially the following components:
- drinking water for people and animals, trade and industry and - at least in densely populated areas - for fighting fires
- water for industrial use
- irrigation water
- water to maintain a minimum rate of flow and for shipping
- water for hydroelectric power generation
- service water, e.g. cooling water for power stations
Future demand is forecast from an analysis of current demand and changes in demand over past years, a comparison with similar periods in other regions and a knowledge of changes in population, of per capita consumption, which depends in particular on the level of sophistication of household water supplies (well, communal standpipe, house connected to main), the development of trade and industry and irrigation development.
In many countries, irrigation needs account for the majority of demand, while industrial and commercial demand is still relatively modest, but must be expected to grow with increasing industrialisation in many countries.
As far as the drinking water supply is concerned, the basic demand that may be considered adequate and reasonable depends on the consumption habits of the population and climatic and cultural conditions. According to (4), an adequate basic supply can be achieved with 20-40 l/cd. These values increase with rising standards of supply. The following may be assumed as guidelines to reasonable consumption quantities:
up to 40 l/cd with communal standpipes
up to 60 l/cd with outdoor mains connection
up to 120 l/cd with indoor mains connection.
Losses in many distribution systems amount to 50 to 100% of actual consumption and must be taken into consideration when assessing demand.
Future changes in water demand are determined by
- growing population
- agglomeration in densely populated areas
- expansion of food supply and thus of irrigation systems
- development of trade and industry
- rise in per capita consumption
- increased demand for hydroelectric power.
When attempting to forecast future development of water demand there is a risk of estimates proving wrong due to unforeseen changes of a demographic, socio-economic or technical nature. Therefore a General Water Resources Management Plan should be designed so as to be flexible and must be updated at suitable intervals so that specific estimates can be made of alternative forms of development or development scenarios, assessing their effects on ecosystems, natural resources and resource utilisation.
In all demand analyses, possible ways of controlling consumption and of controlling development trends should also be examined (priorities, quotas, tariffs, reliability of supply). In particular, ensuring that tariff revenue fully covers costs is an important means of promoting efficient water use; this also enforces the "polluter pays principle". It may be necessary to defer the development of new water reserves, until all possible ways of saving water or rehabilitating contaminated water have been fully exploited.
3.2.4 Hydrological balance and general planning
Various measures can be derived from a comparison of usable supply and demand in the hydrological balance, taking aspects of nature and resource conservation into account:
· To increase resource utilisation:
- building reservoirs
- tapping groundwater
- increasing rates of delivery
- expanding the distribution system
- desalination of seawater, where applicable
· To improve the quality of treated water:
- improvement of treatment technology
- mixing with less contaminated water from other areas
· To protect the quantity and quality of the resource:
- erosion protection, reforestation
- designation of water conservation areas, restriction of pesticide and fertiliser use
- improvement of sanitation and hygiene education
- building of sewage treatment plants
- restriction of discharge of pollutants into surface waters
- rehabilitation of bodies of water
- preservation of self-cleaning properties of bodies of water by refraining from expansion or through expansion in a way similar to nature
- "conjunctive use" of surface water and groundwater
· To reduce water consumption and promote rational use of water reserves:
- fundamental changes in behaviour through consciousness-raising
- water-saving (elimination of leaks in supply networks, control of consumption with water meters, water and sewage tariffs adequate to cover costs)
- induced recharge of groundwater
- use of rainwater
- separation of service water and drinking water supplies
- multiple use of water in households, trade and industry
- use of water-saving irrigation techniques (tariffs adequate to cover costs)
· To protect soil and vegetation
- rehydration and induced recharge of groundwater
- lowering water table to protect against salination.
Shaping of general economic conditions is vitally important in all the areas mentioned. Many changes can be decisively instigated and controlled through an active subsidy policy (e.g. through start-up financing), through fiscal policy (e.g. higher taxation of undesirable variants) and through the establishment and imposition of tariffs (price policy). The question of feasibility and also the abilities of the affected population should also be considered very carefully. The widely held opinion that water is "free" is false. People must be made conscious of the value of the resource.
3.3 Analysis of effects on ecosystem, natural resources and resource utilisation
Water resources management projects can have a major impact on ecosystems and natural resources, which are either observable directly or only through a number of indirect consequential effects.
normally arise immediately through
- water extraction:
lowering of surface
waters and decline of groundwater table, runoff depletion,
destruction of flora and fauna habitats
- water storage:
raising of water level,
inundation of land
discharge of dangerous
and/or oxygen-depleting substances, discoloration, odour
- water retention:
endangerment of periodically flooded areas (such as swamps, marshes)
Secondary and tertiary effects may also occur through complex interactions, for example due to socio-economic or socio-cultural effects, and may only be observable in the long term. Two examples will serve to illustrate this:
- To assess the major effects which a barrage dam may have on the environment, it is not sufficient merely to examine the feasibility of the project in terms of soil physics, hydraulics and engineering. Information is also needed to allow a realistic assessment of water demand, water supply, sediment transport and deposition in the reservoir, changes in the downstream flow regime and conflicts of use between catchment area, user area and downstream area.
- The construction of deep wells equipped with motor-driven pumps in the savanna of the northern Sahel resulted in previously nomadic livestock farmers becoming partially settled, with a simultaneous increase in livestock numbers. Particularly when certain wells dry up, overgrazing and progressive desertification occurs in the area of facilities which are still productive. Since living conditions are no longer regulated by the available water supply in the upper groundwater levels of the region, the ecological and socio-economic situation suffers accelerated deterioration.
Increased availability of water may also result in salination of soils if unsuitable irrigation techniques are used in arid and semi-arid areas.
3.4 Analysis of effect on health and hygiene
When assessing the water supply in a planning area, attention should be paid to the availability of hygienic and non-toxic water. Not only the quantity but also the quality of the water is important. Furthermore the quality parameters to be considered depend on the use envisaged, and may differ widely depending on whether, for example, drinking water, irrigation water or power-generating water is required.
Water quality can be affected positively through water quality and conservation objectives formulated on the basis of a General Water Resources Management Plan, through wastewater treatment, through restrictions on use of bodies of water, through the designation of groundwater conservation areas and through hygiene education activities carried out in parallel with water supply projects.
In the assessment of the future changes in water consumption it is frequently overlooked, for example, that increased consumption will result in an increased volume of wastewater. Wastewater is often collected in open channels and fed to surface waters, or simply allowed to seep away in the immediate vicinity of the source. This has the effect of polluting the surface water, while the groundwater is subject to the greatest risk. For example, watering of vegetable plantations with wastewater may cause permanent health damage.
Therefore no water supply should be laid on without adequate drainage to alleviate environmental loading. This applies both to the drinking water and to agricultural irrigation water.
Additional efforts to promote organised self-help in the form of education and hygiene campaigns, which women often play a decisive role in planning and implementing, help to avoid over-use and contamination of water.
The rapid development of agricultural production in many countries not only creates steadily growing demand for irrigation water, but also results in greater consumption of artificial fertilisers and pesticides. Uncontrolled use of these chemicals can also lead to pollution of surface waters and groundwater. The use of drainage water for agricultural irrigation - a process that is often repeated several times in succession - may increase the salt content of the water, thereby causing salination problems for downstream users.
Damming of surface water causes solids carried by the incoming water to become deposited in the reservoir. This causes progressive silting and, with the introduction of nutrients, eutrophication of the water. This nutrient-rich shallow-water environment - in conjunction with the climatic conditions prevailing in many countries - causes vectors to flourish, resulting in the spread of water-borne diseases such as malaria, bilharzia or guinea worm.
3.5 Socio-economic and socio-cultural impact
The hydrological balance set out in a General Water Resources Management Plan is an important factor in targeted regional development. It also provides a basis for decisive and far-reaching socio-economic and socio-cultural changes.
The opening-up of new supplies of usable water may lead to an uncontrolled influx of large groups of people from water shortage areas. Besides the risk of over-use of the natural resources, this may also bring people from different groups together; social systems previously functioning as the basis for survival strategies, may become threatened and vulnerable.
The ecological consequences of barrages to protect against flood and to safeguard the supply may affect the livelihoods of fishermen living by the water if the fish population changes. In the storage basin area, agricultural and horticultural land will be lost and normally cannot be replaced, for topographical and pedological reasons. This may have serious socio-economic consequences for the affected population. In the downstream area, this may result in a depleted flow of water with consequent lowering of the water table, or to deterioration of soil quality in the fields along the watercourse, if the land is no longer periodically flooded with nutrient-rich water. This likewise impairs the economic basis of the population.
Improved irrigation facilities for agriculture and horticulture can lead to changes in cultivation practices (artificial fertilisation, monocultures), so that after a brief increase in yield the soil will become progressively depleted, leading in turn to increased fertiliser use. Furthermore it may lead to salination of the soil and serious material contamination of surface waters and groundwater.
A socio-economic analysis should include sex-specific and group-specific investigations showing to what extent women or individual social groups are affected by water resources management activities, as either injured parties or beneficiaries.
Regional and traditional forms of land-use, often unwritten water, soil and grazing rights, ethnic structures, preferential rights of upstream river dwellers etc. are all important and may also be restrictive. It is imperative that a General Water Resources Management Plan take account of these factors.
3.6 Administrative and political framework
A General Water Resources Management Plan requires an administrative and legal framework (water legislation). It must be possible to establish rules and also policy objectives (priority of uses, prohibition of multiple use, allowance for traditional forms of use, international and cross-border rules etc.) for implementation by means of a suitable administration or appropriate organisations.
It is therefore vital to create or strengthen the authority or institution responsible for water resources management. It is essential to establish the necessary decision-making procedures and bodies, to eliminate the fragmentation of powers which is often encountered, to make adequate financial provision and deploy qualified and well-motivated staff. It is crucially important to ensure appropriate involvement of women and other groups in decision-making bodies and procedures.
4. Interaction with other sectors
A General Water Resources Management Plan is absolutely fundamental, not only to the handling of all problems associated with water management. It goes to the heart of overall infrastructural development of the planning area and lays down general conditions for individual plans in the various sectors. It is therefore of overriding importance for planning measures in individual sectors, primarily affecting the following:
- Spatial and Regional Planning
- Planning of Locations for Trade and Industry
- Overall Energy Planning
- Urban Water Supply
- Rural Water Supply
- Wastewater Disposal
- Solid Waste Disposal
- Inland Ports
- Shipping on Inland Waterways
- Ports and Harbours, Harbour Works and Operations
- River and Canal Engineering
- Erosion Control
- Rural Hydraulic Engineering
- Large-Scale Hydraulic Engineering
- Weirs, Hydroelectric Power Stations
- Surface Mining
- Thermal Power Stations
5. Summary assessment of environmental relevance
As a planning tool used at the right time, a General Water Resources Management Plan can contribute significantly to the preservation of natural water resources and help prevent environmental damage by establishing parameters. It enables water resources to be managed in such a way as to protect resources and ensure their long-term sustainability.
A General Water Resources Management Plan lays down the basic parameters, not only from the technical and economic points of view, but also embraces and describes the interactions of the many different factors at work within the water system, as well as taking account of ecological, socio-economic and socio-cultural conditions. A General Water Resources Management Plan points in the direction of possible future development of living conditions and economic circumstances in relation to water. It provides a basis whereby different ways of using water resources may be identified, compared with one another and assessed to see how water resources management projects can be planned and implemented in an environmentally acceptable way.
This planning must take account of possible side-effects and consequences, and the draft plan should include proposals for avoiding adverse effects, monitoring important environmental indicators and possibly implementing compensatory measures. Target groups should be involved from the outset in the development of this draft plan.
(1) Baumann, W. et al., BMZ (Ed.): Öklogische Auswirkungen von Staudammvorhaben, Forschungsberichte des Bundesministeriums für wirtschaftliche Zusammenarbeit, Bd. 60, Munich, 1984.
(2) Biswas, A. K., Qu Geping (Ed.): Environmental Impact Assessment for Developing Countries' Natural Resources and the Environment Series, Volume 19, London, 1987.
(3) BMZ (Ed.): Sektorpapier Wasserversorgung und Sanitärmaßnahmen in Entwicklungsländern.
(4) Buchwald, K., Engelhardt, W. (Ed.): Die Bewertung und Planung der Umwelt, Handbuch für Planung, Gestaltung und Schutz der Umwelt, Munich, 1980.
(5) Deutscher Verband für Wasserwirtschaft und Kulturbau e. V. (DVWK) (Ed.): Ermittlung des nutzbaren Grundwasserdargebotes, DVWK-Schriften, Heft 58/1 und 58/2, 1982.
(6) FAO: Guidelines for watershed management, FAO Conservation Guide, Rome, 1977.
(7) FAO: Keeping the land alive, Soil erosion - its causes and cures, FAO Soils Bulletin No. 50, Rome, 1983.
(8) Gesetz zur Ordnung des Wasserhaushalts (Wasserhaushaltsgesetz, WHG) und Wassergesetze der Länder, 1986.
(9) Goldsmith, E., N. Hildyard: The Social and Environmental Effects of Large Dams, Volume 1, Cornwall, 1984, Volume 2, Cornwall 1986.
(10) Munasinghe, M.: Managing Water Resources to avoid Environmental Degradation, World Bank Environmental Paper No. 41, Washington, 1990.
(11) National Committee of the UNESCO Man and the Biosphere, Programme at the Ministry of Environmental Protection and Water Management of the GDR, Reservoirs as major engineering works in nature, Interactions and after-effects shown at the example of the highlands of the GDR, UNESCO, 1984.
(12) Niemeyer-Lüllwitz, A., Zucchi, H.: Fließgewässerkunde, Ökologie fließender Gewässer unter besonderer Berücksichtingung wasserbaulicher Eingriffe, Verlag Diesterweg, 1985.
(13) OECD (Ed.): Management of water projects, Paris, 1985.
(14) Olbrisch, H.-D. et al.: Wasserwirtschaftliche Meß- und Auswerteverfahren in Trockengebieten, published by the Deutscher Verband für Wasserwirtschaft und Kulturbau (DVWK), DVWK Schriften Nr. 96, 1991.
(15) Richtlinien für die Aufstellung von wasserwirtschaftlichen Rahmenplänen, appearing in the "Gemeinsames Ministerialblatt" (joint ministerial gazette), published by the Bundesminister des Innern (Federal Ministry of the Interior), Nr. 16, Bonn, 29 June 1984.
(16) BMZ (Ed.): Sektorkonzept Wasserwirtschaft, August 1987 (draft).
(17) Tehranien, D.: Die Relevanz der Umweltprobleme für die ökonomische Entwicklung in den Entwicklungsländern, Verlag K. Reim, 1976.
(18) Umweltbundesamt [German Federal Environmental Agency (Ed)]: Handbuch zur ökologischen Planung, Bde. 1 und 2, Erich Schmidt, Berlin, 1981.
(19) UN: Water Resources Planning to meet Long-Term Demand, Guidelines for Developing Countries, Natural Resources/Water Series No. 21, New York, 1988.
(20) UN: Criteria and Approaches to Water Quality Management in Developing Countries, New York, 1990.
(21) UN: Criteria for and Approaches to Water Quality Management in Developing Countries, Natural Resources/Water Series No. 26, New York, 1990.
(22) UNESCO/UNEP (Ed.): The impact of large water projects on the environment, Proceedings of an international symposium 21-31 October 1986, UNESCO Headquarters, Paris.
(23) WHO: Legal Issues in Water Resources Allocation, Wastewater Use and Water Supply Management, Geneva, 1990.
Environmental brief on water planning
* Surface water
* Water quality
* Plant production
* Animal production
* Structural and regional planning
* Planning of locations
* Overall energy planning
* Urban water supply
* Rural water supply
* Wastewater disposal
* Waste disposal
* Ports on inland waterways
* Shipping on inland waterways
* River and canal Engineering
* Erosion control
* Rural hydraulic engineering
* Large-scale hydraulic engineering
* Mining - open cast
* Thermal power stations
Contents - Previous - Next