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Action influencing the water balance refers to activities which influence the quantity, physical distribution and time-related distribution of rainwater by means of construction measures. Virtually every form of economic activity involves action of this type, which includes in particular

- irrigation and drainage measures
- removal of water from, and discharge of water into, surface waters and groundwater
- changes in the flow conditions in surface waters as a result of development or correction measures etc.
- creation of surface waters such as impounding reservoirs, fishing waters, canals etc.

Depending on geoecological conditions and regional land-use, alterations to the available water supply by means of such measures can have impacts on

- the climatic situation (air temperature, humidity, air movement)
- the quality of the groundwater and surface water (dilution/breakdown/accumulation of pollutants)
- the soil quality and the availability of agricultural and forestry land (groundwater level, soil degradation)
- the living conditions for terrestrial and aquatic fauna and flora and thus also for pathogens.

Standards for allowed, permissible or environmentally sound forms of action influencing the water balance exist only as general guidelines for quantitative water management (e.g. Federal Water Act (Wasserhaushaltsgesetz) and Federal Nature Conservation Act (Bundesnaturschutzgesetz) in Germany). They can also be readily derived in this form from the general goals of environmental policy and have been formulated by bodies such as the FAO and in certain environment treaties. It is stipulated that water resources are to be used in such a way that

- their long-term availability is guaranteed (i.e. they are not subjected to ruthless exploitation) and
- other functions performed by the natural household (see above) are not affected more than is necessary.

Precisely what this means for a specific project in a specific geoecological context can be determined only on a case-to-case basis, with particular consideration of the following aspects:

- precipitation (= primary water supply)

- the factors influencing how the precipitation divides up into evapotranspiration, surface run-off and groundwater afflux (particularly climate, vegetation, soil and geohydrological conditions)

- the requirements to be fulfilled by water resources

The granting of permits for measures requiring approval under water-resources legislation is intended to ensure that the goals referred to above are achieved (although it generally fails to do so). Particular attention must be drawn here to regulations laying down increasingly ecologically-oriented requirements for hydraulic engineering measures and to special (research) projects which aim to promote ecologically oriented hydraulic engineering or related water-resource management.

Standards could conceivably be established for the following:

- maximum permissible quantities of water that may be drawn off or introduced, where appropriate depending on the time of year

- acceptable changes in groundwater level (extreme values and periodic values) in the case of measures directly affecting the groundwater level

- flow rate of receiving waters (extreme values and periodic values) in the event of development measures

- flow velocity and turbulence

With regard to project activities, particular note should be taken of regulations or recommended values applying to the following areas:

a) Agriculture

- irrigation and drainage measures influencing the groundwater level/local water balance

b) Municipal and industrial water supply

- drawing of water from surface waters and groundwater
- discharge of polluted water and cooling water

c) Mining/raw-material recovery

- pumping out

d) Water development, which includes the following activities:

- creation of a body of standing water with a variable water level, in the upper reaches of a river (consequences: increase in water temperature, changes in chemism, water losses as a result of evaporation and seepage)

- creation of a more or less channelised stretch downstream of the impoundment (consequence: prevention of water exchange between groundwater and surface water)

- storage of water during the wet season and thus reduction of high water (and flooding) in the lower reaches and - due to delivery of water during dry seasons - increases in flow (consequences in both cases: changes in water exchange between groundwater and surface water, delayed changes in water losses from evaporation)

- creation of irrigated areas (irrigation systems and large expanses of water) (consequences: loss of available surface water through seepage, evaporation and transpiration, but at the same time also recharging of groundwater through seepage)

- development of surface water to accelerate flow and to prevent high water and flooding (consequences: changes in flow rate, more pronounced high water downstream, lowering of groundwater level etc.)

Action influencing the surface configuration comprises measures which, extending beyond the soil bed, lead to morphological changes in the parent rock (C-horizon) or the lower-lying body of rock, as well as filling or deposition measures which significantly alter an area's natural topography (landscape). Unless industrial and domestic waste is being dumped, such measures always involve a process of redistribution, i.e. material is removed from one site by means of excavation near the surface or underground and then deposited elsewhere, generally by being placed or pumped as fill material. Only the utilisable raw materials are extracted for further processing or direct use (e.g. rock phosphate). Depositing of material removed in this way does not necessarily have to lead to obvious changes in surface configuration. The practice of depositing material in the sea or in caves can also be of major ecological relevance but is not discussed in detail here since it is employed only in specific regions.

Depending on their nature and extent, measures influencing the surface configuration can have a wide variety of serious ecological impacts. They may influence the mesoclimate and microclimate, the available water supply and water quality, soil quality, availability of agricultural and forestry land, and biotope conditions. Extensive measures of this type are generally irreversible and have long-term ecological impacts. In such cases, recultivation measures do not restore the natural ecosystem, but rather create "substitute systems".

In ecological terms, the following are measurable criteria for surface configuration:

- topographic height
- slope
- relief intensity
- degree of shaping
- exposure

For measures below the surface, recourse can be had to the sole criterion used for technical reasons in other circumstances, namely:

- volume of the material excavated/moved.

Measures influencing the surface configuration have no direct effects from the human-ecology viewpoint (unless they involve the dumping of wastes) and give rise to no chemically induced changes in environmental quality. They are thus not covered by any relevant standards, since standards are generally based on toxicological aspects.

In terms of project activities, the following measures are of particular relevance here:

a) Transport

- embankments, cuttings
- channels (shipping)
- technical facilities (bridges, tunnels etc.)

b) Mining/raw-material recovery

- open-cast mining (wet, dry)
- underground mining
- depositing of material removed

c) Water development

- creation of ditch systems
- correction/development of rivers
- development of port facilities
- deepening of waters
- land reclamation measures
- construction of canals
- creation of impounding reservoirs

The ecological significance of such measures depends on

- the depth to which they extend
- the nature and composition of the rock beds exposed
- the size of the area covered
- the opportunities for recultivation (taking all natural environmental conditions together)
- the shortage of areas performing the same ecological function.

The impacts of such measures essentially comprise

- breaking-up of the habitat of flora and fauna
- impairment of the surface layer's effectiveness as a filter and thus hazarding of the groundwater
- climatic changes
- restricting effects on man's living environment and sources of subsistence.

Deposition of excavated material in the form of tips generally leads to major changes in surface configuration, whose ecological consequences depend on

- the height of the tip and the area which it covers
- the compactness of the tip
- the nature and chemical composition of the material
- recultivation measures (grassing etc.)
- erosion protection measures.

Approval procedures in most countries also lay down environmental protection requirements based on specific guidelines or regulations. There are no binding standards in the strict sense for action influencing the surface configuration (unless it directly involves other types of measures as well).

Noise is defined as the harmful environmental impact of sounds which, by virtue of their nature, volume or duration, are likely to give rise to health hazards or other adverse effects. The term "sound emission" refers to the radiation of sound from a sound source or a collection of sound sources (e.g. road, industrial area).

Sound emission does not lend itself to direct measurement. Instead, the noise level measured at a specified distance from the noise source or determined using a specified measuring set-up or calculation method is designated as the emission level. In the case of area-specific representations of immissions, the emission level is used as the basis for further calculation of the sound pressure at the place of immission (see Section 4).

For acoustic assessment of equipment, machines, vehicles or installations, the emission level is determined using a type-specific measuring procedure. This may be done, for example, in the course of licensing procedures in order to check compliance with specific emission standards.

Existing emission standards for technical sound levels are in all cases geared to the state-of-the-art; in other words, it is possible to comply with them for the purpose of any prototype or type approval procedures that may be necessary. They are determined on the basis of recognised engineering practice, taking the cost-benefit ratio into account. It is common practice for regulations first to lay down emission standards, graduated according to power and operating condition, which apply with immediate effect. Following consideration of technical, health-related and financial aspects, more stringent standards are then specified to take effect on a stipulated future date. The final step involves specifying machines which must fulfil tougher noise abatement requirements (see in particular the section on "International Environment Legislation"). There is virtually no monitoring of noise levels during day-to-day operation or use. As a result, actual noise emissions may exceed standards on account of modification, wear or special uses of a machine or piece of equipment.

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