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Dr.-Ing. (Dr. Engineer)
Dipl.-Ing. (Engineer)
Dam authority of Saxony
GERMANY
The Free State of Saxony belongs to the states of the Federal Republic of Germany,
which are characterized by a far-going strong industrialization. The first smaller
dams and pond systems originate from the 15. Century, due to water requirements
of the mining industry in the Ore-Mountains (Erzgebirge). The history of modern
dam construction in Central Europe began with the industrial revolution at the
end of the 19. Century.
In particular by the initiative of Professor Intze, dams became a remarkable
instrument of water-resources management and man overcame the awe of such "dangerous"
hydraulic structures. Today many Intze dams (masonry dams) still witness this
epoch in Saxony. Owing to the good geomorphology for the construction of dams
-low mountain ranges in the south and gradually dropping terrain to the low
country in the north- dam construction in Saxony continues until nowadays. Due
to special regional features, Saxonian dams are particularly used for the supply
of drinking- water and flood protection and less for the production of electricity.
As a result of the profound structural changes in industry and agriculture since
the breaching of the Wall in 1990, dams especially established for industrial
and irrigation water use are no longer needed. Touristical issues, as well as
nature and landscape protection issues become the focus of attention at these
systems today. The de-velopment of dam construction and dam operation in Saxony
in connection with the acceptance of these structures by society led to the
fact that dams have be-come an indispensable element of the landscape in our
country.
This report does not deal with the Saxonian tailings dams.
Saxony belongs to the states within the Federal Republic of Germany with most
existing dam structures. According to the Saxonian dam register [1], there are
120 storage structures, which meet the national water-legal criteria -building
height > 5 m and storage capacity > 100,000 m³ or additional "adopted"
systems- (see fig. 1).
Among them are six big opencast mining remainder lakes with large water volumes
without dam structures, which will be excluded from the following reflections.
Consequently there remain 114 dam structures. This corresponds to a "dam
density" of 1 dam/160 km². The ICOLD register [2] contains 43 of them.
Fig. 2 illustrates the temporal emergence of the stock of dams in Saxony from
the 15. Century until today. Particularly many installations were built in the
years up to World War I, during the time after the world economic crisis up
to World War II, during the recovery years after World War II and in the period
be-tween 1965 and 1985, when an intensification of a non-resource considerate
ag-riculture and water consumption-intensive industrial development took place
in this country.
Fig. 3 shows the classification of the Saxonian storage installations according
to their barrage structures. One notices that the proportion of fill dams related
to all barrage structures (outer circle in fig. 3) is "about average" with
77%. Yet there is a relatively high proportion of massive dams (44%) amongst
the large storage installations (ICOLD register, inner circle in fig. 3).
Massive dams were built exclusively as gravity dams, whereby some of them may
be assigned to as arch gravity dams. It is also characteristic that more than
half of the gravity dams are masonry dams (i.e. older design). Almost all Saxonian
dams built between 1890 and 1930 possess masonry dam structures made of quarrystone.
They are characterized by special requirements of adjust-ment to the current
"generally recognized rules of technique" and decisively de-termine the rehabilitation
events of today. The building of a series of concrete dams between 1960 and
1985 can be defined as the result of a perfected build-ing technology in former
East Germany.
Most of the fill dams are dams with an inner soil core (impervious core or inclined
impervious zone). Five rockfill dams have an asphaltic concrete facing, two
dams possess a concrete core wall and only one large dam is sealed with a synthetic
membrane. Some small and old dams were constructed as homogeneous earthfill
dams.
Fig. 4 and 5 supply an overview of the Saxonian dams and their scale of size.
Fig. 4
Division of 114 Saxonian reservoirs related to storage
Vue d'ensemble de la taille du réservoir utilisable de tous les 114 barrages
saxons
Fig. 5
Division of 114 Saxonian dams related to height of dams
Hauteur des édifications de retenue de tous les 114 barrages saxons
According to international standards the stock is thus dominated by small storage
structures. Nevertheless there are still some structures of remarkable size,
of which the Eibenstock reservoir (built in 1984) being the largest shall exemplary
be mentioned (see fig. 6).
Fig. 6
Drinking water dam Eibenstock
Barrage d'eau potable d'Eibenstock
It has a total storage capacity of approx. 82 hm³. Its concrete gravity
dam has a height of approx. 66 m above foundation respectively 57 m above valley
elevation [3]. In all other respects the geomorphologic conditions in the Saxonian
mountain regions, the dense population in the valleys and the demands for exploitation
of the reservoirs determine the order of magnitude of the Saxonian barrage structures.
In particular the two last-named aspects determine that many storage structures
lie at the upper course of the rivers and streams and thus only dispose of small
and humanly relatively little influenced catchment areas.
The 114 classified Saxonian storage structures offer a usable reservoir ca-pacity
IN of altogether approx. 620 hm³. The total of all reservoir surfaces (at full
reservoir level) amounts to approx. 105 km². This is only 0,6% of Saxonys total
area (18412 km²). On the other hand 35% of the total surface of Saxony are catchment
areas for reservoirs. This high percentage results from the very few dams along
the lower courses of the rivers (see chapter 4.2) and which however only have
a small extension ratio compared to the average yearly flow supply and thus
only play a subordinated role within the water management of a river basin but
causing sedimentation problems.
It remains to be mentioned in this chapter that the major part of the Saxo-nian
storage structures (72%) are presently in national property due to a water-legal
regulation and are maintained and operated by the State dam authority of Saxony
- including all drinking-water reservoirs and all supraregional flood-control
basins. The remaining storage structures are in the property of municipalities
-especially smaller installations of merely local concern- or in the property
of pri-vate companies - as for example all storage structures, which primarily
serve for hydroelectric power production.
The main utilizations of Saxonian water storage structures are:
- flood protection by means of providing flood plains
- storage of water for
- low-water discharge enhancement for the lower courses of the rivers
- supply of industrial water
- supply of irrigation water
- the production of hydroelectric power.
Tourism respectively recreation are the most substantial side effects of storage
structures utilizations. Many structures besides also serve to nature and landscape
protection purposes.
Fig. 7 shows the characterization of the Saxonian storage structures ac-cording
to their predominant types of utilization. Related to all storage structures
(outer circle in fig. 7), most of the structures serve to industrial water supply.
The vast number of small irrigation reservoirs for the agriculture (which strived
for im-port independence) in the former GDR is determining for this. Reservoirs
which supply drinking-water are in second place and flood-control basins are
in third place. Only few storage structures were established predominantly for
hydroe-lectric power production or recreational issues. The impression of the
utilization form of the Saxonian storage structures mentioned above changes
as soon as only the large structures (ICOLD register, inner circle in fig. 3)
are considered. By far the majority (47%) serves to supply potable water. Structures
for industrial water supply and flood protection are more or less equal with
portions of 23% re-spectively 21%. Only 9% of the structures are hydroelectric
power plants.
In addition to this it is necessary to mention that there are many multi-functional
storage structures among the aforementioned. Many drinking-water and industrial
water reservoirs besides serve to flood protection and hydropower production,
although often only with small installed capacity in order to cover the needs
of the structure itself. Therefore approx. 50% of all, respectively 65% of the
ICOLD storage structures serve to flood protection and approx. 15% of all, respectively
33% of the ICOLD storage structures are used for hydropower generation.
The storage capacities specified in fig. 8 are at disposal in order to satisfy
the different utilizations. For explanation purposes one needs to point out
that the flood storage within the reservoir is assigned to function for the
regular flood protection of the lower courses of the river, whereas the flood
surcharge above spillway level particularly serves for security reasons for
the structure itself. Active storage of the reservoir provides the actual water
supply. Inactive storage below active storage may basically not be considered
in terms of water management. Increasing demands for better water quality in
storage structures though require assessing this indispensable buffer storage
too, in order to guarantee good water quality (utilization-dependent or due
to ecological desires).
In the field of the drinking-water supply, the Saxonian storage structures
nowadays fundamentally contribute to a functioning infrastructure. The installations
of the 26 drinking-water reservoirs -together with their 10 pre-regulating reservoirs-
altogether constantly provide 5500 l/s (170 millions m³/a) of raw water to water
purification and distribution plants. Reservoir operation is carried out in
a way that supply failure is practically impossible also during extreme dry
periods.
The Southern parts of Saxony need to be supplied with surface respec-tively reservoir
water, due to geohydrologic conditions (no productive ground-water supply, predominantly
near surface water sources only). At present a population of almost 2 million
inhabitants (approx. 40% of the Saxonian popula-tion) are supplied with drinking
water from reservoirs (see fig. 9). Whereas some areas supplied with reservoir
water may also fall back on to other sources (e.g. the city of Dresden), there
are also supply areas which are exclusively de-pendent on reservoir water (e.g.
city of Chemnitz).
In Saxony the supply of reservoir water commenced with the completion of the second
oldest German masonry dam, the Einsiedel dam, already in 1894. The demand for
water rose rapidly with the increase of the urban population and hasty industrial
development. The construction of new dams followed inevitably. The need for provision
of surplus storage capacity for public drinking-water sup-ply continues -only
interrupted by the long-term effects of the two World Wars- to a few years ago.
Fig. 10 illustrates this development.
Apart from the increase of water supply capacities, former "supply islands" developed
to regional supply networks over the decades. Compound systems of reservoirs developed
in the field of raw water as well as supraregional remote water connecting systems
in the field of drinking water. Today all subsystems to-gether form two efficient
spacious remote water compound systems in Southern Saxony. They will be linked
in the near future by a gap-closing pipeline. Arising from this is a compound
system of 11 drinking-water reservoirs.
Fig. 11 schematically shows the aforementioned remote water compound system.
The output of the individual dams of this system varies between fewer than 100
l/s and 1600 l/s. The new remote water compound system permits a network operation
with following substantial advantages:
- Problem-free balance of regional and supraregional supply and/or require-ment
fluctuations.
- Possibilities to control critical situations like technical disasters and
in particular also adverse effects to water quality in the field of raw water.
- Possibilities to compensate rehabilitation-determined partial or complete
failure of technical components within the system, such as dams, purification
plants, pumping plants or pipelines.
- High degree of supply concerning quantity of water and water quality
Although the use of surface respectively reservoir water is to be described
as sensitive, the production of reservoir water by means of dams proves to be
economical. On the one hand reservoir water can still be processed to potable
water with relatively simple technologies. On the other hand raw water usually
can be transmitted to the water companies by means of natural slope or with
small pressures. The water companies themselves are mostly situated in a geodetic
altitude, which permits a forwarding of the drinking water without any or with
only small energy and thus cost.
In Saxony the national operator succeeds in financing the operation and maintenance
of all drinking-water dams with cost-covering prices for the supplied raw water.
A payment is demanded from 8 contractually bound customers (water supply companies),
whose height depends on the amount of water which is held out for every specific
company. As a result of the dams being owned by a single authority, a uniform
specific price applies to all dams and customers.
The constantly decreasing water demand in Saxony is a current problem since
1990. Decreasing population, rising water prices, breakdown of industry in addition
to the reduction of water losses in pipelines and finally counter produc-tive
water savings propaganda contributed to the fact that drinking-water demand
decreased by almost 50%. In connection to this, the extent of utilization of
all Saxonian drinking-water reservoirs has sunk from 100% to about 70%. Certainly
this does not change the indispensability of almost all Saxonian drinking-water
reservoirs. However this puts a considerable strain on the economic situation
and gives to think about use modification alterations or shutdowns of smaller
dams, especially when regarding the remote water compound system mentioned above.
Finally the infrastructural side effects of the existing drinking-water reser-voirs
are to be pointed out in this section. They can be explained by the water protection
zones proven to guarantee water quality in the reservoirs. They put a heavy
strain on population, industry, agriculture and forestry in the catchment ar-eas
because of prohibitions and complications, e.g. great demands on waste water
disposal and road construction, transport limitations for water-endangering
materials, prohibition to use certain herbicides and pesticides as well as fertilizer
etc.. High national subsidies for waste water investments and damage compen-sations
to agriculture and forestry however absorb the negative effects. The re-munerationless
social binding obligation of property is additionally effective. The many restrictions
in drinking-water protection zones nevertheless lead to positive effects, such
as an environmental infrastructure, agriculture and forestry.
High population densities and enormous property assets developed throughout
the centuries, despite the knowledge about the latent dangers within the original
flood plains and natural retention areas of streams and rivers. Thus flood protection
demands constantly increased in these areas of Saxony, too.
The streams and rivers of the Ore-Mountains are considered to be particu-larly
flood-endangered because very often weather conditions develop, which lead to
extreme rainfall in summer. Precipitation of more than 150 mm in just a few hours
and runoff factors of more than 10 m³/s * km² have been registered several times,
causing devastating floods (1897, 1927, 1954, 1957, 1958, 1995, 1999). The demand
for flood protection by means of flood retention in the catch-ment area, especially
after harm-bringing flood events, led to construction of flood-control basins.
The diagram in fig. 10 illustrates the creation of flood storage capacity in reservoirs
on a time-dependent basis. Besides 18 storage structures established exclusively
for flood protection purposes, further 39 multi-purpose storage structures contribute
to flood protection. As shown in fig. 8, a total of 114 hm³ flood storage and
further 60 hm³ of flood surcharge capacity are available today. This amounts to
almost 28% of the total storage capacity of all Saxonian storage structures after
all.
The flood protection effects, which can be obtained with all individual stor-age
structures for the lower courses of the rivers, are very different. They depend
primarily on the absolute amount of retention capacity in the storage structures,
but however are decisively limited by the size of the catchment area (flood arising
area). In smaller catchment areas (< ~50 km²) floods with a statistical return
in-terval of 50 to 100 years are fairly easy to restrain, whereas in larger catchment
areas this can be merely attained with very large efforts. Fig. 12 illustrates
this fact. It shows, to which extent flood retention is carried out in the catchment
areas of Saxonian storage structures. Apart from this actual flood retention ability,
the obtainable flood protection is considerably dependent upon the performance
of the lower courses. The main targets of flood protection -according to German
standards- generally are, to protect high-quality built-up areas against floods
with statistical return intervals of 100 years and remaining cultivated areas
and su-praregional transportation installations against floods with statistical
return inter-vals of 50 years. The smaller damage potential becomes in the flood
areas, the less worthy conservation becomes.
In order to guarantee sufficient flood protection, systems of flood-control
structures were established in some river basins of Saxony. The structures in
the area of Gottleuba, Weißeritz and Müglitz (14 storage structures in the Eastern
Ore-Mountains, 1 in planning stage), in the area of Pleiße (8 storage structures
south of Leipzig) and in the area of Hoyerswerdaer Schwarzwasser (4 storage
structures in the mountain areas of Lausitz) are to be mentioned.
A large number of cities and municipalities is protected effectively against
floods with the Saxonian dams and flood-control basins. In particular the large
city of Leipzig and the state capital of Dresden participate from them, whereby
the large dams in the upper courses of Elbe, Eger and Moldau in the Czech Re-public
are important for the latter, too. Pirna, Freital, Riesa, Hoyerswerda and Aue
in Saxony as well as Elsterberg and Greiz in Thuringia are further protected
larger cities.
Since their existence, dams and flood-control basins in Saxony have con-tributed
verifiably towards flood protection. For example it was possible to hold back
approx. 10 million m³ once and over 22 million m³ water another time during
two large summer floods in 1995. Large damages were prevented in each case.
The multi-purpose reservoir Eibenstock merely held back more than 5 million
m³ and was able to reduce the discharge peak from 150 m³/s to 20 m³/s. Dams
and flood-control basins remain indispensable for an effective flood protection,
even if modern flood protection concepts today particularly place on the reactivation
of natural flood plains, renaturalization of rivers and unsealing of built up
surface. A balanced mix of all possible flood protection measures can only be
the practical solution.
A total of 60 Saxonian water storage structures (14 of them are ICOLD structures)
are intended for industrial water supply and for this purpose hold a total of
236 hm³ storage capacity (see fig. 8). The secured constant discharge from these
storage structures amounts to almost 10 m³/s (315 million m³/a)
water. The industrial water supply serves for the different purposes already mentioned
in chapter 3.1.
Low-water discharge enhancement in the lower courses of rivers can be necessary
for quantitative and qualitative seizure of water intakes from these rivers
and/or to guarantee water-ecological demands in dry periods. Both procedures
are practised with some larger Saxonian multi-purpose reservoirs, by means of
controlling their water discharges depending on the discharges at certain reference
flow gauging stations in the lower courses of the rivers.
Low-water discharge enhancement is carried out at the following rivers in Saxony:
Weiße Elster, Zwickauer Mulde, Pleiße, Flöha, Große Röder, Spree and Schwarzer
Schöps. Due to closure of many production plants at these rivers, the former
use-oriented low-water discharge enhancement shifts more towards an ecologically
oriented discharge control.
Today mainly fish hatcheries, fishing industry and small hydroelectric power
plants benefit from low-water discharge enhancement. Low-water discharge en-hancement
will however be important throughout the next years for the Spree (Bautzen dam)
and its tributary Schwarzer Schöps (Quitzdorf dam) when filling the old collieries
in the Niederlausitzer open-cast mining district and for recreation of a balanced,
self-adjusting water management from the Spree area to Berlin.
As already mentioned before, far-reaching restructurings in industry and agriculture
since the reunification of Germany led to closure of many businesses on the
one hand but also to technological renewals on the other. Drastic decreases
in demand for industrial and irrigation water are the consequence of these processes
in Saxony. Industrial water supply from the state reservoirs decreased from
60 million m³ in 1991 to 14 million m³ in 1998. This shows that many Saxonian
storage structures have lost their industrial water supply function partly or
completely today. This is a large nuisance for the authorities or companies
who maintain these storage structures, because the expenditures are financially
hardly covered by the receipts. This is particularly serious with a whole set
of monofunctional systems, where lacking surplus functions at present do not
justify further dam operation. The owners often intend to sell the dams in these
cases and in general there are chances that maintenance and dam operation are
gradually reduced to a safetyendangering degree. Even the State itself is no
exception from this.
Since nature and population have practically taken possession of these more
or less no longer necessary storage structures over the years and because these
systems have also become natural sanctuaries and recreational centres, the expensive
decommissioning or removal of these storage structures with complete or partial
demolition of the constructions and latter renaturalization does not seem to
be a suitable solution of the problem (see chapter 4.2).
Worth considering are cases, where the circumstances justify a new utiliza-tion
for purposes like ecologically oriented low-water discharge enhancement or flood
protection. Since these are sovereign duties according to local laws, it re-quires
the willingness of the community to finance these duties. Experience has shown
that delayed action with such decisions makes it substantially more diffi-cult
and sometimes politically impossible to reactivate reservoir management (raising
and lowering of the reservoir level), because population and nature are accustomed
to the constantly filled reservoir and reservoir falls in particular are disadvantageous
for them.
Contrary to many other countries, the production of hydroelectric power is
not the focal point of dam operation in Saxony. Only 6 registered storage structures
were exclusively established for this purpose [1]. However 5 of these hydroelectric
power plants belonging to private companies are worth mentioning because of
their special features:
- Kriebstein dam at the Zschopau river was put into operation in 1930 with
an installed capacity of approx. 5 MW as run-of-river power station. Kriebstein
dam is one of the oldest cast concrete dams.
- The pumped-storage plant Niederwartha with upper and lower basin near the
city of Dresden achieved a power output of 80 MW after construction in 1929/30
and 120 MW after renovation in 1960. After inauguration it was the largest
power station of its kind at that time.
- The pumped-storage plant Markersbach went into operation with a power output
of 1050 MW in 1979. Even today it is still the largest hydro-power plant in
Eastern Germany. The difference in altitude of the upper and lower basin is
approx. 285 meters.
Electric power is currently being produced by hydro power plants at 13 Saxonian
multipurpose storage structures [1]. Both river and industrial water discharges
are energetically used. In total the capacity installed at these storage structures
only amounts to 5,2 MW with an average yearly production of 20 GWh. The
produced electricity primarily serves to cover the domestic requirements of
the storage structures and only secondly to external power supply.
Except for the pumped-storage plants which produce peaktime electricity, the
hydroelectric power plants in Saxony are almost negligibly important for power
supply. For private operators the generation of hydroelectric power is in-teresting
though, particularly due to legal obligations to take delivery of the pro-duced
power at excessive prices.
Storage structures are a substantial interference in nature and landscape as
well as in settlement, economical and infrastructural structures of the area
concerned. This was obviously exactly the same at the time, when the Saxonian
storage structures were established.
The interruption of the river continuum system and thus the disturbance of a
(to a large extent) naturally grown ecosystem surely was the most substantial
interference in the ecological system.
In many cases roads, supply lines (power, gas, water, telephone), farms and
mills and in some cases even railway lines and also cemeteries had to be transferred.
Settlements and industrial plants were usually also affected with large storage
structures, so that substitutional housebuilding was necessary and industrial
estates needed to be created. Whereas the demolition area was nor-mally equal
to the reservoir area, the demolition area usually needed to be ex-tended to
the so-called "drinking-water protection area I" with drinking-water res-ervoirs.
According to rough estimations, altogether about 3500 people had to be resettled
(an average of about 30 people per storage structure) in the past be-cause of
storage structure constructions in Saxony (114 dams). About 600 people were
affected by the resettlement in the most unfavourable case (drinking-water reservoir
Lichtenberg).
In this connection one needs to explain that democracy did not really exist
at the times when the Saxonian storage structures were licensed and licensing
procedures under pubic law did not allow public participation and contradiction
possibilities up to legal action. Therefore construction of storage structures
was relatively simple at that time. However there were many economic problems,
which are not to be dealt with in this connection.
On the basis of the existence of Saxonian storage structures, the question now
is to be answered, how their "relation" to the environment developed in the
course of the time?
It is to be stated at first that the substitutional investments including the
resettlements in direct connection to the establishment of the storage structures
led to no long-term effects of social relevance, which naturally does not exclude
certain difficulties in isolated cases. At this point the reader shall again
be reminded of the former political circumstances already mentioned before.
In the long run these direct consequences were however assumed by the people
involved.
The hazard potential emerging from the storage structures is no object of public
discussion in Saxony so far. However there has been no failure of a dam or a
flood-control basin yet. Beyond that people probably acknowledge that eve-rything
has been done (planning, construction) and is being done (operation, maintenance,
monitoring) for the safety of the dams. The authors are aware of this.
Specific consequential problems result in the case of drinking-water reser-voirs
from the (lawfully assessed) drinking-water protection areas. The total area
of the drinking-water protection areas for all Saxonian drinking-water reservoirs
amounts to approximately 645 km². This is 3,4% of the complete surface of Saxony.
The protection areas are usually divided into three different zones, to which
different regulations and restrictions apply (see also chapter 3.2). In protection
zone I (water intake zone) practically all actions are forbidden, which might
be a potential danger to the water condition. Thus the water surfaces and reser-voir
banks of all Saxonian drinking-water reservoirs are a taboo with recreation
(swimming, windsurfing, boat rides). Years after the assessment of drinking-water
protection areas, the restrictions still lead to arguments with the affected
people. Political pressure is often produced, in order to loosen these restrictions.
Considering the increasing demands on reservoir water quality by the water supply
businesses, preventive drinking-water protection according to the multi-barrier
principle may however not be given up.
Apart from the unpopular effects of drinking-water protection areas, they in-evitably
also cause positive synergetic effects regarding the general objective to achieve
and protect good water quality in the reservoirs and to limit human influ-ences
in the catchment areas to a permissible degree. At this point there is a congruence
with interests of nature and landscape protection.
With reference to the interruption of the river continuum systems it is a rela-tively
favourable fact that the most of Saxonian storage structures lie at the upper
courses of the rivers. The percentage distribution of the expansions of the
catchment areas may illustrate this. Approx. 60% of all Saxonian reservoirs
pos-ses catchment areas <25 km²; related to 100 km² the share is almost 80%.
Less than 1% of all reservoirs have an own catchment area >1000 km². Therefore
the interrupted rivers can further naturally develop downstream of the dam on
the major part of their original courses thanks to the position of the dams
at their up-per courses in many cases (if other man made disturbances don't
prevent it). The storage structures can often considered to be a "new spring"
of the river supported by the compulsory water outlet of the dam.
Regarding the interferences in the ecosystem with the construction of stor-age
structures and the subsequent "counterreactions" or better "adjustments" of
nature, one can basically observe that new ecological systems have developed
at the reservoirs within just a few years, which are typical for still waters
and in detail are determined by the respective local conditions (climate, altitude,
basin morphology, water quality, storage management etc..). In very many cases
con-ditions have thereby adjusted, which -according to current nature conservation
laws- are to be classified as "worth protecting". It is very important to know
that reservoirs thereby determine or at least enrich the character of landscapes.
On closer examination approx. 70% of the 114 Saxonian storage structures are
summarily connected with protection areas according to nature conservation laws.
Just looking at the 43 large ICOLD structures even almost 90% are con-nected!
64 reservoirs are situated in 35 landscape protection areas. The as-sessment
of almost half of the landscape protection areas goes back to the ex-istence
of the reservoirs. Nature reserves are located at 14 reservoirs, among them
3 flora-fauna-habitat-areas (FFH guideline 92/43/EWG) and 3 Special Pro-tected
Areas (SPA guideline 79/409/EWG). 16 reservoirs are situated in the na-ture
park Erzgebirge/Vogtland and 2 in the planned nature park Dübener Heide. Moreover
several so-called "nature-area-monuments" and protected biotopes are to be found
at a number of storage structures. Fig. 13 tries to visualize these facts.
The Saxonian nature conservation law stipulates that all actions are forbidden,
which could spoil the character of the protection areas [5]. Landscape and nature
benefits are thereby included. From that point of view Saxonian storage structures
are often certified to be successfully and inseparably integrated into Saxonian
man-made landscape. The good integration of storage structures into their natural
environment is furthermore substantiated by the fact that increasing demands
are made on water quantity and water quality management of reservoirs according
to conservational interests. It even occurs that competitive interests of nature
conservation clash with each other. Wherever possible one seeks for solutions
that satisfy all demands for utilization of storage structures. The causal and
remaining functions of water management may thereby however not fall by the
wayside.
A quite different aspect is that a set of storage structures considerably in-fluenced
both the technical and the cultural development of Saxony. Thus almost 20 old
storage structures are listed today and are furthermore defined as cultural
monuments. In particular some old masonry dams belong to them as well as the
so-called "Revierwasserlaufanstalt Freiberg", an ancient system of artificial
ponds, ditches and tunnels which supplied the ore mining industry with industrial
water.
At the end of this chapter the importance of the Saxonian storage struc-tures
for recreation and tourism is to be briefly examined. Despite from just a few
acidic reservoirs in the upper Ore-Mountains, all reservoirs are used for fishing
and therefore are popular fishing waters. That also applies to a limited amount
of drinking-water reservoirs. An active water sports utilization is another
side effect at many reservoirs. Ten very popular reservoirs for tourists received
the official status of a "EU swimming lake". This means that the reservoirs
have been reg-istered with the European Union and have to meet the water quality
standards of the EU. But swimming, windsurfing and boating is popular at other
reservoirs, too. Pleasure steamers operate on two reservoirs. As already mentioned
in chapter 3.4.3, touristic utilizations have meanwhile become the main utilizations
at some reservoirs. Finally the recreation value, which definitely is available
at drinking-water reservoirs, is to be mentioned. Because of their location
in an in-teresting countryside, they meet the requirements for a so-called "gentle
tour-ism".
When summarizing the role of Saxonian storage structures in terms of land conservation,
one must state that they are no disturbing elements in nature or landscape,
despite the interferences certainly connected with their construction. On the
contrary: the environment is obviously able to integrate storage structures
into itself far better than often claimed. Nevertheless storage structures should
not necessarily be built to a larger extent than absolute necessary. From today's
point of view the one or the other smaller storage structure was built too much
in the past in Saxony, due to the former political and economic circumstances.
However that does not alter the fact that the Saxonian storage structures have
become a constituent part of the Saxonian landscape.
- Talsperren, Wasserspeicher und Rückhaltebecken im Freistaat Sachsen;
Sächsisches Landesamt für Umwelt und Geologie, Materialien zur Wasserwirtschaft
1997
- World Register of Dams; International Commission on Large Dams (ICOLD),
Paris 1998
- Sieber, H. U., Talsperren in Sachsen; Herausgeber: Landestalsperrenverwaltung
des Freistaates Sachsen, 1992
- Hochwasserschutz in Sachsen: Materialien zur Wasserwirtschaft 2/1996; Freistaat
Sachsen, Staatsministerium für Umwelt und Landesentwicklung,
Juli 1996
- Schutzgebiete in Sachsen; Materialien zu Naturschutz und Landschafts
pflege 1996; Sächsischen Landesamt für Umwelt und Geologie,
Dezember 1996
© The owners of the copyright of the included maps are "Sächsisches Landesamt
für Umwelt und Geologie" and "Landestalsperrenverwaltung des Freistaates Sachsen".
Copies are allowed with permission of these authorities only.
Construction and operation of dams have a long tradition in Saxony and reaches
back to the 15. Century. The construction of 114 dams and reservoirs (H>
5 m and V>100,000 m³) in Saxony is connected to the constantly rising demand
of water since the beginning of the industrial revolution at the end of the
19. Century until the 80's of this Century. 43 of these dams are filed
in the ICOLD register. Today substantial infrastructure functions are fulfilled
with storage structures in Saxony, for the benefit of the population and in
conformity with long-term environment conservation targets.
The existing reservoirs in Saxony are assigned to:
- provide raw water for the drinking-water supply of almost 2 million inhabitants
in Saxony (about 40% of the population)
- provide flood-control storage capacity
of 114 hm³ (flood storage) and approx. 60 hm³ (flood surcharge) in flood-control
basins and multi-functional reser-voirs in order to protect the lower courses
of the river
- supply industrial water for different purposes, as for example
low-water dis-charge enhancement in the lower courses during dry periods and
the provi-sion of water for industry and agriculture
- produce hydro power
- provide utilizations for tourism (the multi-purpose reservoirs above all)
- protect water quality and conserve nature by assigning drinking-water protection
areas at drinking-water reservoirs as well as protecting further banks and water
surfaces in landscape protection and conservation areas.
Some of the old dams in Saxony are cultural monuments and therefore listed as
well as protected.
In summary it may be said that the Saxonian storage structures have be-come indispensable
elements of infrastructure and constituents of the Saxonian landscape. However
re-organizations as well as decommissioning or removal of storage structures are
being discussed in some cases, due to drastically decreasing demands for water
in all supply areas since the reunification of Germany.
La construction et l'exploitation de barrages ont, dans la République
de Saxe, une longue tradition qui remonte au 15ème siècle. La
construction de 114 barrages (Hauteur >5 m et capacité >100.000 m³)
en Saxe est liée au besoin croissant en eau depuis le début de
la révolution industrielle, de la fin du 19ème siècle jusqu'aux
années 80 du 20ème siècle. 43 de ces barrages sont enregistrés
dans le registre CIGB. Aujourd'hui, les barrages saxons remplissent des tâches
essentielles d'infrastructure au profit de la population et en harmonie avec
les objectifs durables de protection de l'environnement.
Les barrages sont utilisés en Saxe pour les tâches suivantes:
- Mise à disposition d'eau brute pour l'alimentation publique en eau
potable de près de 2 millions d'habitants en Saxe, ce qui représente
environ 40% de la population.
- Fourniture de 114 hm³ de volume ordinaire et env. 60 hm³ de volume extraordinaire
de protection contre les crues dans des réservoirs de protection contre
les crues et barrages à usage multifonctionnel au service de la protection
contre les crues des populations en aval.
- Mise à la disposition d'eau non potable pour différentes utilisations,
comme l'élévation du niveau des basses eaux dans les cours inférieurs
dans les périodes de sécheresse et la fourniture d'eau à
l'industrie et à l'agriculture.
- Production d'énergie électrique tirée de la force hydraulique.
- Utilisation touristique surtout des barrages d'eau industrielle.
- Mise en oeuvre de tâches de protection des eaux et de la nature par
l'identification des régions de protection d'eau potable avec les barrages
d'eau potable ainsi que la protection d'autres surfaces de berge et d'eau
dans des régions de protection de l'environnement et de la nature.
Quelques-uns des barrages saxons sont classés monuments historiques.
En résumé, on peut constater que les barrages saxons sont
devenus des éléments indispensables de l'infrastructure et un
élément à part entière du paysage de la Saxe. D'autre
part, dans quelques cas, la restructuration voir la mise hors service des barrages
est à l'ordre du jour en raison des besoins en eau qui ont considérablement
diminués dans toutes les zones d'alimentation depuis la réunification
allemande.
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