37
Apart from that, sediments serve as natural fertiliser for occasionally fl ooded arable
lands along the rivers. This missing nutrient input has to be compensated by artifi cial
fertilisers. As important humic matter is missing as well, deterioration of the soil quality
and its water storage capacity is frequently the consequence. The changes in the groundwater levels around the reservoirs are likely to act as a trigger of soil salinisation.
As can be seen from the description of these potentially adverse effects, largescale water storage facilities also impact on the secondary ways of usage. Along
rivers, technical measures and the water withdrawal of upstream resources have
implications on the users situated downstream.
Another major criticism against the establishment of dams refers to the fact that
during the construction of large reservoirs, considerable amounts of fertile lands are
fl ooded and inhabitants are displaced. Particularly the rights of indigenous populations have been violated in this way, with the compensation measures frequently
remaining unsatisfactory (Robinson 2003 ).
In addition, the proliferation of water-borne diseases like malaria and bilharzia is
a problem linked to the construction of large dams and reservoirs, which may pose
substantial risks to human health (World Commission on Dams 2000 ).
3.2.2 Water Distribution
The stage that usually follows the storage and collection of water is its distribution to
the end users via channels and water pipes. Such transport and distribution systems
contribute to improving negative water balances. This is the case not only in dry
regions but also in areas exhibiting a humid climate, e.g. when the required water quality cannot be achieved for the amounts needed in densely populated areas. An example
is Lake Constance, which supplies a large quantity of the drinking water demand for
the federal state of Baden-Wuerttemberg in South Germany. The geographical disconnection of water abstraction and water use over long distances may lead to a detachment of the responsibility for the protection of water resources from the users of the
source. The compensation of those regions which provide the service is in many cases
not suffi cient and not based on objective fi gures and can thus lead to tensions between
the provisioning (rural) areas and the consuming (urban) centres. For dams and reservoirs, this circumstance has been examined by the World Commission on Dams, stating that those who receive the (economic and social) benefi ts of water distribution
infrastructure (such as urban dwellers, farmers and industries) are typically not the
same groups that bear the social costs (World Commission on Dams 2000 ).
Transport of water always implies a certain loss due to leakages and evaporation,
especially in open channels. This problem can be studied in a very pronounced way
when assessing the water supply of megacities in developing and emerging countries,
where about one third of the delivered water volume can be lost via leaky water pipes
(Niemczynowicz 1996 ). Unless natural slopes can be used, the transport over large
distances may require considerable amounts of energy – a crucial factor for the determination of the provision costs. This is particularly relevant for the effectiveness of large
irrigation systems (this aspect will be dealt with in detail in Part III of this volume).
3 Major Water Engineering Projects: Defi nitions, Framework Conditions, Systemic…
Apart from that, sediments serve as natural fertiliser for occasionally fl ooded arable
lands along the rivers. This missing nutrient input has to be compensated by artifi cial
fertilisers. As important humic matter is missing as well, deterioration of the soil quality
and its water storage capacity is frequently the consequence. The changes in the groundwater levels around the reservoirs are likely to act as a trigger of soil salinisation.
As can be seen from the description of these potentially adverse effects, largescale water storage facilities also impact on the secondary ways of usage. Along
rivers, technical measures and the water withdrawal of upstream resources have
implications on the users situated downstream.
Another major criticism against the establishment of dams refers to the fact that
during the construction of large reservoirs, considerable amounts of fertile lands are
fl ooded and inhabitants are displaced. Particularly the rights of indigenous populations have been violated in this way, with the compensation measures frequently
remaining unsatisfactory (Robinson 2003 ).
In addition, the proliferation of water-borne diseases like malaria and bilharzia is
a problem linked to the construction of large dams and reservoirs, which may pose
substantial risks to human health (World Commission on Dams 2000 ).
3.2.2 Water Distribution
The stage that usually follows the storage and collection of water is its distribution to
the end users via channels and water pipes. Such transport and distribution systems
contribute to improving negative water balances. This is the case not only in dry
regions but also in areas exhibiting a humid climate, e.g. when the required water quality cannot be achieved for the amounts needed in densely populated areas. An example
is Lake Constance, which supplies a large quantity of the drinking water demand for
the federal state of Baden-Wuerttemberg in South Germany. The geographical disconnection of water abstraction and water use over long distances may lead to a detachment of the responsibility for the protection of water resources from the users of the
source. The compensation of those regions which provide the service is in many cases
not suffi cient and not based on objective fi gures and can thus lead to tensions between
the provisioning (rural) areas and the consuming (urban) centres. For dams and reservoirs, this circumstance has been examined by the World Commission on Dams, stating that those who receive the (economic and social) benefi ts of water distribution
infrastructure (such as urban dwellers, farmers and industries) are typically not the
same groups that bear the social costs (World Commission on Dams 2000 ).
Transport of water always implies a certain loss due to leakages and evaporation,
especially in open channels. This problem can be studied in a very pronounced way
when assessing the water supply of megacities in developing and emerging countries,
where about one third of the delivered water volume can be lost via leaky water pipes
(Niemczynowicz 1996 ). Unless natural slopes can be used, the transport over large
distances may require considerable amounts of energy – a crucial factor for the determination of the provision costs. This is particularly relevant for the effectiveness of large
irrigation systems (this aspect will be dealt with in detail in Part III of this volume).
3 Major Water Engineering Projects: Defi nitions, Framework Conditions, Systemic…