22
Discussion
discharged cooling water with the water in a steam occurs quickly in streams of medium size, if the
amount of cooling water is not too far from the run-off of the river, even if the velocity of the current
is rather low. For example in the Neckar River we found complete mixing achieved 2 km below a
thermal discharge entering from one side at a temperature 6.5°C higher than in the river water, and the
vertical temperature differences were only about 1°C after 1 km distance.
6 Larger streams may show
delayed lateral mixing over very long distances, but vertical mixing occurs generally quickly. In such
cases the one-dimensional model may be extended to a two-dimensional one, assuming different
"parallel streams" flowing in the river bed, which join gradually according to the particular conditions
of turbulent lateral dispersion. There was no need to do this for the Hochrhein calculations, because
we could expect total mixing to occur.
No problem arises in extending our calculations to multiple discharge conditions. In fact the
Hochrhein model has recently been extended to cover the ranges of the River Rhine between Lake
Constance and the German-Dutch border, forecasting the effects of multiple thermal discharges to be
expected in the future.
2 I admit that the one-dimensional model may not be correct for all locations
on the River Rhine for reasons of incomplete lateral mixing. The water temperatures could actually be
somewhat lower than those calculated. But regarding harmful effects by heating the water of the
Rhine, in our calculations we are on the "right side" with our predictions.
I agree that model studies should include an approach to predict the probability of occurrence of
different water temperatures during given periods of time or seasons. This can be done by regarding
the weather situations as a set of defined singularities. The model calculations can be made for each
weather singularity, possible alternatives of river run-off and initial water temperatures could be taken
into account. If the frequency distribution of occurrence of special meteorological singularities is
known, we are able therefrom to derive the expectation for the occurrence of certain water temperatures. In our example this approach was similar, but restricted to average monthly weather conditions. These are artificial weather conditions, derived from monthly averages of hourly values of
global radiation, temperatures and humidity of the air at an observation station in the Hochrhein River
Valley.
Surely it would be best to take the meteorological data for model computations from stations
located at the river bank, and temperatures and water vapor content of the air, and wind from over the
water surface at standardized distance. No observational system of this kind exists at the present time,
but we are just starting installations of this kind along the River Rhine.
We expect further elucidation and verification or correction of the equations used in our computations from the test installations at the Neckar River, which I have already mentioned.
R.J. Davis, Israel
Has the temperature rise due to biotic metabolism been considered?
What are the effects of temperature variations due to either exothermic or endothermic chemical
reactions caused by oxidation or reduction of either organic or inorganic substances?
What are the effects of terrestrial temperatures?
Data obtained during the course of an investigation of the pollution problem of Lake Kinneret
(The sea of Galilee) during 1953-1964 showed that there was an increase in the lake water temperature
while there had been a decrease in the ambient atmospheric temperature over the same period. It
appears that an increase in temperatures occurred in association with ambient temperatures. I found
that the ambient yearly temperature fluctuation, over a period of 20 years (1952-1972), showed a
ratio of rise to fall of 7 to 5; that is a rise over 7 months and a fall over 5 months. I would welcome
the authors' comments on this point.
Additional Literature:
5. SCHMITZ, W.: Grundlagen der Untersuchung der Temperaturverhältnisse in den Fliessgewässern.
Berichte der Limnologischen Flußstation Freudenthal 6, 29-50, 1954.
6. GLASER, H., PETRIKAT, K., SCHMITZ, W., und FLINSPACH, D.: Studie über die thermische
Belastbarkeit der fliessenden Oberflachengewässer. Innenministerium Baden-Württemberg,
Stuttgart 1969.
Discussion
discharged cooling water with the water in a steam occurs quickly in streams of medium size, if the
amount of cooling water is not too far from the run-off of the river, even if the velocity of the current
is rather low. For example in the Neckar River we found complete mixing achieved 2 km below a
thermal discharge entering from one side at a temperature 6.5°C higher than in the river water, and the
vertical temperature differences were only about 1°C after 1 km distance.
6 Larger streams may show
delayed lateral mixing over very long distances, but vertical mixing occurs generally quickly. In such
cases the one-dimensional model may be extended to a two-dimensional one, assuming different
"parallel streams" flowing in the river bed, which join gradually according to the particular conditions
of turbulent lateral dispersion. There was no need to do this for the Hochrhein calculations, because
we could expect total mixing to occur.
No problem arises in extending our calculations to multiple discharge conditions. In fact the
Hochrhein model has recently been extended to cover the ranges of the River Rhine between Lake
Constance and the German-Dutch border, forecasting the effects of multiple thermal discharges to be
expected in the future.
2 I admit that the one-dimensional model may not be correct for all locations
on the River Rhine for reasons of incomplete lateral mixing. The water temperatures could actually be
somewhat lower than those calculated. But regarding harmful effects by heating the water of the
Rhine, in our calculations we are on the "right side" with our predictions.
I agree that model studies should include an approach to predict the probability of occurrence of
different water temperatures during given periods of time or seasons. This can be done by regarding
the weather situations as a set of defined singularities. The model calculations can be made for each
weather singularity, possible alternatives of river run-off and initial water temperatures could be taken
into account. If the frequency distribution of occurrence of special meteorological singularities is
known, we are able therefrom to derive the expectation for the occurrence of certain water temperatures. In our example this approach was similar, but restricted to average monthly weather conditions. These are artificial weather conditions, derived from monthly averages of hourly values of
global radiation, temperatures and humidity of the air at an observation station in the Hochrhein River
Valley.
Surely it would be best to take the meteorological data for model computations from stations
located at the river bank, and temperatures and water vapor content of the air, and wind from over the
water surface at standardized distance. No observational system of this kind exists at the present time,
but we are just starting installations of this kind along the River Rhine.
We expect further elucidation and verification or correction of the equations used in our computations from the test installations at the Neckar River, which I have already mentioned.
R.J. Davis, Israel
Has the temperature rise due to biotic metabolism been considered?
What are the effects of temperature variations due to either exothermic or endothermic chemical
reactions caused by oxidation or reduction of either organic or inorganic substances?
What are the effects of terrestrial temperatures?
Data obtained during the course of an investigation of the pollution problem of Lake Kinneret
(The sea of Galilee) during 1953-1964 showed that there was an increase in the lake water temperature
while there had been a decrease in the ambient atmospheric temperature over the same period. It
appears that an increase in temperatures occurred in association with ambient temperatures. I found
that the ambient yearly temperature fluctuation, over a period of 20 years (1952-1972), showed a
ratio of rise to fall of 7 to 5; that is a rise over 7 months and a fall over 5 months. I would welcome
the authors' comments on this point.
Additional Literature:
5. SCHMITZ, W.: Grundlagen der Untersuchung der Temperaturverhältnisse in den Fliessgewässern.
Berichte der Limnologischen Flußstation Freudenthal 6, 29-50, 1954.
6. GLASER, H., PETRIKAT, K., SCHMITZ, W., und FLINSPACH, D.: Studie über die thermische
Belastbarkeit der fliessenden Oberflachengewässer. Innenministerium Baden-Württemberg,
Stuttgart 1969.