18 Computation of Hydrological Data for Design of
Water Projects in Un gauged River Basins
I. Papadakis I and G. A. Schult£
IConsulting Engineer, Werksstr. 15,45527 Hattingen, Gennany
2Ruhr University Bochum, Institute of Hydrology, Water Resources and Environmental
Techniques, 44780 Bochum, Gennany
18.1 Introduction
Socio-economical development on regional, national and international basis requires intensive investigations of water resources. Water differs from other resources by the time variability of the amount of water available for use at any
given moment. Non-standard seasonal distribution of hydrometeorological parameters, their fluctuations from region to region and from basin to basin make the
planning of water projects difficult.
Purposes to be served by water management projects may include: water supply,
flood control, irrigation and drainage, hydropower, industrial use, water pollution
monitoring, environmental protection, ground water etc. More than 1,5 billion
people are living today on the Earth without any access to drinking-water and
about 10 million deaths per year are registered as caused by waterborne diseases,
flood disasters and famines following long drought periods. Furthermore, since the
human population grows rapidly, there is extreme increase in water demand, making efficient management of the available water resources essential for human life.
Planning of water projects requires knowledge of the quantity of water available
at any given time unit. This can only be determined on the basis of adequate sets of
hydrometeorological data for the area under consideration. It is well appreciated,
that sets of hydrometeorogical data which extend back far enough to include typical long-term fluctuations is a prerequisite for the successful planning and design
of any water project. The minimum period of collecting records for reliable analysis is considered to be 20 to 30 years. If such data sets do not exist, or are not
sufficiently long, or not accurate enough, the proposed water project may be either
under-designed with accompanying risk of failure and consequent damage or may
be over-designed which will render them uneconomic. For example, the estimated
mean annual flow based on measured flow data observed in a short-term period,
may be significantly different from that of flow data records over a long period of
observation. The deviation may be positive or negative, depending on the cycle of
the hydrometeorological phenomena to which the observed records belong (wet
period, dry period, transition period). In the case of a multipurpose reservoir the
negative deviation in the estimated mean annual flow would result in a smaller
storage capacity than actually required. A smaller irrigated area and less hydroelectric-power production than expected would be the consequence. In the case of
G. A. Schultz et al. (eds.), Remote Sensing in Hydrology and Water Management
© Springer-Verlag Berlin Heidelberg 2000
Water Projects in Un gauged River Basins
I. Papadakis I and G. A. Schult£
IConsulting Engineer, Werksstr. 15,45527 Hattingen, Gennany
2Ruhr University Bochum, Institute of Hydrology, Water Resources and Environmental
Techniques, 44780 Bochum, Gennany
18.1 Introduction
Socio-economical development on regional, national and international basis requires intensive investigations of water resources. Water differs from other resources by the time variability of the amount of water available for use at any
given moment. Non-standard seasonal distribution of hydrometeorological parameters, their fluctuations from region to region and from basin to basin make the
planning of water projects difficult.
Purposes to be served by water management projects may include: water supply,
flood control, irrigation and drainage, hydropower, industrial use, water pollution
monitoring, environmental protection, ground water etc. More than 1,5 billion
people are living today on the Earth without any access to drinking-water and
about 10 million deaths per year are registered as caused by waterborne diseases,
flood disasters and famines following long drought periods. Furthermore, since the
human population grows rapidly, there is extreme increase in water demand, making efficient management of the available water resources essential for human life.
Planning of water projects requires knowledge of the quantity of water available
at any given time unit. This can only be determined on the basis of adequate sets of
hydrometeorological data for the area under consideration. It is well appreciated,
that sets of hydrometeorogical data which extend back far enough to include typical long-term fluctuations is a prerequisite for the successful planning and design
of any water project. The minimum period of collecting records for reliable analysis is considered to be 20 to 30 years. If such data sets do not exist, or are not
sufficiently long, or not accurate enough, the proposed water project may be either
under-designed with accompanying risk of failure and consequent damage or may
be over-designed which will render them uneconomic. For example, the estimated
mean annual flow based on measured flow data observed in a short-term period,
may be significantly different from that of flow data records over a long period of
observation. The deviation may be positive or negative, depending on the cycle of
the hydrometeorological phenomena to which the observed records belong (wet
period, dry period, transition period). In the case of a multipurpose reservoir the
negative deviation in the estimated mean annual flow would result in a smaller
storage capacity than actually required. A smaller irrigated area and less hydroelectric-power production than expected would be the consequence. In the case of
G. A. Schultz et al. (eds.), Remote Sensing in Hydrology and Water Management
© Springer-Verlag Berlin Heidelberg 2000