Freiburger Schriften zur Hydrologie
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Band/volume 21: EISELE M. & LEIBUNDGUT Ch. (2006):
Hydrologische Güte - ein Beitrag zur erweiterten Bewertung von
Flusseinzugsgebieten im Gewässerschutz
The assessment procedure "Hydrological Quality" enables the
assessment of human impacts on the hydrological system of river basins.
Substantial parts of the methodology have been developed in a project,
funded by the state of Baden-Württemberg (research program BW-PLUS)
and completed in 2001. The aim of a subsequent project, also funded by
BW-PLUS, was the development of a procedure, which is operationally applicable
at regional scales and state wide. To demonstrate its applicability, the
procedure was applied to the state of Baden-Württemberg. As part
of the procedure a software system for operational application (AHQ-IHF)
was developed on the basis of test applications.
In the assessment part catchment properties the potential human
impact on the hydrological system is quantified based on spatial data
which are commonly available. As an aggregation of the different assessment
parameters the "index of human impact" is calculated. In the
part stream flow dynamics anthropogenic alterations of the annual
variations of different stream flow variables are identified and assessed.
To describe the temporal variability of stream flow the Indicators of
Hydrological Alteration (IHA) are chosen. They describe different aspects
of the hydrological regime and can be linked to specific ecological functions.
The human impact is investigated using measured or modeled time series
of daily stream flow. Alterations in the annual time series of the different
stream flow variables are quantified using the Range of Variability Approach
(RVA). Nutrient emissions (nitrogen and phosphorus) in the river basins
and the water quality of rivers (concerning nitrogen and phosphate) are
subject of the optional assessment part nutrient budget and water quality.
Nutrient balance models (e.g. MONERIS) are used for quantification of
the emissions. The assessment of water quality is based mainly on time
series of water quality samples.
The software system AHQ-IHF (Assessment of Hydrological Quality) enables
an operational application of most of the calculations involved in the
methodology. Within the system differ-ent projects (e.g. a set or subset
of catchments) as well as different project versions (e.g. dif-ferent
datasets or calculation settings) can be managed. For defined lists of
investigation areas (e.g. catchments) or gauging stations spatial data
(point-, linear and areal data) as well as time series can be imported,
processed and assessed. Import and export of data, calculation and classification
steps are activated through a graphical user interface. Data are managed
in a database (MS-Access) using a specific data model.
As a result of the application of the procedure assessment data for catchment
properties as well as for nutrient emissions and water quality
are available for the entire state of Baden-Württemberg. An assessment
of alterations in stream flow dynamics was carried out for 79 gauging
stations. In addition a map of resulting flow alterations in the river
system was pro-duced, combining the results of the gauging station based
investigations with results from the morphological survey. This map (status:
09/2005) is provided in the appendix of this report. It will also be published
in the 3rd delivery of the "Water and Soil Atlas Baden-Württemberg"
Applying the procedure in Baden-Württemberg anthropogenic impacts
on water balance and nutrient budgets could be shown mainly in the Neckar
basin, the Rhine valley and in parts of the Danube basin. Anthropogenic
impacts on stream flow dynamics are only small or moder-ate in most rivers
of Baden-Württemberg. More severe impacts in some rivers can be ascribed
to the effect of dams or discharge abstractions.
With the completion of the subsequent project in 2004 an operational assessment
procedure is now available. The advanced procedure was developed as a
tool for water recource planning at the survey scale. It can be used for
assessing the anthropogenic impacts on hydrology and water quality of
river basins in addition to the regular biological and morphological assess-ment
of rivers. The proposed assessment of impacts on the variability of stream
flow focuses on an aspect of river ecology widely ignored so far which
is an important factor for aquatic habitats.
Volume 18 of the paper series "Freiburger Schriften zur Hydrologie"
focused mainly on the methodology for the assessment of nutrient budget
and water quality as well as on the results from the application of
the procedure in different test catchments. The final document presented
now as volume 21 in the same series contains the revised methodology of
all three parts of the methodology (with a special focus on the part stream
flow dynamics) as well as the results which were obtained in the subsequent