270
Discussion
station, C 3 , was measured and the mean concentration of the pollutant in the effluent quantity (from
the river into the aquifer per unit length along the river, c 0 , was calculated). If we were to plot c 0 vs
C3, with the decrease in flow discharge between the two stations, we would obtain a very uneven
"topographical" map. As the authors mention, this may be due to sampling errors. It may also be due
to imperfect understanding of the actual natural process. In the event, the internal storage coefficient
was calculated on the basis of the field data, and its value was estimated at 2.5 x 10
5 .
This paper is a pioneering effort in the direction of comprehensive management of water quality
utilizing both surface and subsurface resources. Although considerable further research seems to be
indicated, the model developed can be used especially in water quality management practices using
low-flow augmentation policies (Jaworski et al, 1970).
The phenomenon reported in this paper was observed also elsewhere (Dor et al, 1972). Sewage
from Jerusalem discharged into the Soreq creek (which runs dry most of the year) has shown remarkable decrease in pollutant concent-rations and a comparable increase in dissolved oxygen over a
distance of approximately 50 km. The figures mentioned were for BOD from 500 to 17 mg/1 (a drop
by a factor of 29), and for DO from 0-20% to 100%-200% of saturation concentration.
REFERENCES:
DOR, I., SCHECHTER, H. and SHUVAL, H. (1972): Natural Purification of Jerusalem Sewage
Discharged into the Soreq Creek, Presented at the Third Scientific Meeting of the Israel Ecological
Society, Tel-Aviv (Hebrew).
JAWORSKI, N.A., WEBER, W.J. Jrn., and DEININGER R.A. (1970): Optimal Reservoir Releases for
Water Quality Control, /. of the Sanitary Engineering Division, Proc. ASCE, 96 (SA3), pp.727-742.
Reply
In narrow river basins with dense populations as we have in Japan, it will not be suitable to follow
the popular pollution control. Nevertheless in Japan, a new and peculiar idea is not quickly accepted.
The present study is just the proposal of a new concept for our rivers in a rather closed environmental system. Therefore, we should find out the regulation factors for pollution control in the
interior of the river system.
Attention is called to the evaluation of the two dimensional plot of Table 1 in the discussion. Many
engineers seem to give an intuitive judgement that there is a linear relationship between flow decrease
and the decrease in chloride ions load, as it is mentioned 'clear trend' by Dr. Buras. But, it is not
necessary to determine a unique relationship at this stage. The phenomena can be observed to follow
the assumed relationship but cannot be so regulated.
We need the auxiliary capacity in the river system to store the result of regulation. The internal
storage capacity is possibly an example of this capacity.
Hermann H. Hahn, West Germany.
If the chemical, physical and biological reactions could be described satisfactorily how will it be
possible to link effect from reactions in surface waters and "stored waters"? It seems more promising
to include the important reactions in the environs of the river in those reactions in surface waters
which we monitor by the use of the "global coefficients".
Reply
It is easy to describe the chemical, physical and biological reactions in a microscopic sense. Even if
these reactions are introduced into the mass balance equation 2, the solution of integrated form cannot
be obtained without the boundary conditions for the surface and subsurface flow system.
Therefore, enlargement of the range of integration with respect to time and space should be
performed in parallel with the inclusion of several important reactions and the management system
procedure proposed.
In the first step of no reaction as described in this paper, the quality of stored water will be
dependent on surface flow. If the reactions are described with use of the internal storage coefficient in
the further step, the quality of surface water will be predicted accurately as a function of stored water
in conceptual river environs including the municipal area, bottom slude and subsurface area.
Discussion
station, C 3 , was measured and the mean concentration of the pollutant in the effluent quantity (from
the river into the aquifer per unit length along the river, c 0 , was calculated). If we were to plot c 0 vs
C3, with the decrease in flow discharge between the two stations, we would obtain a very uneven
"topographical" map. As the authors mention, this may be due to sampling errors. It may also be due
to imperfect understanding of the actual natural process. In the event, the internal storage coefficient
was calculated on the basis of the field data, and its value was estimated at 2.5 x 10
5 .
This paper is a pioneering effort in the direction of comprehensive management of water quality
utilizing both surface and subsurface resources. Although considerable further research seems to be
indicated, the model developed can be used especially in water quality management practices using
low-flow augmentation policies (Jaworski et al, 1970).
The phenomenon reported in this paper was observed also elsewhere (Dor et al, 1972). Sewage
from Jerusalem discharged into the Soreq creek (which runs dry most of the year) has shown remarkable decrease in pollutant concent-rations and a comparable increase in dissolved oxygen over a
distance of approximately 50 km. The figures mentioned were for BOD from 500 to 17 mg/1 (a drop
by a factor of 29), and for DO from 0-20% to 100%-200% of saturation concentration.
REFERENCES:
DOR, I., SCHECHTER, H. and SHUVAL, H. (1972): Natural Purification of Jerusalem Sewage
Discharged into the Soreq Creek, Presented at the Third Scientific Meeting of the Israel Ecological
Society, Tel-Aviv (Hebrew).
JAWORSKI, N.A., WEBER, W.J. Jrn., and DEININGER R.A. (1970): Optimal Reservoir Releases for
Water Quality Control, /. of the Sanitary Engineering Division, Proc. ASCE, 96 (SA3), pp.727-742.
Reply
In narrow river basins with dense populations as we have in Japan, it will not be suitable to follow
the popular pollution control. Nevertheless in Japan, a new and peculiar idea is not quickly accepted.
The present study is just the proposal of a new concept for our rivers in a rather closed environmental system. Therefore, we should find out the regulation factors for pollution control in the
interior of the river system.
Attention is called to the evaluation of the two dimensional plot of Table 1 in the discussion. Many
engineers seem to give an intuitive judgement that there is a linear relationship between flow decrease
and the decrease in chloride ions load, as it is mentioned 'clear trend' by Dr. Buras. But, it is not
necessary to determine a unique relationship at this stage. The phenomena can be observed to follow
the assumed relationship but cannot be so regulated.
We need the auxiliary capacity in the river system to store the result of regulation. The internal
storage capacity is possibly an example of this capacity.
Hermann H. Hahn, West Germany.
If the chemical, physical and biological reactions could be described satisfactorily how will it be
possible to link effect from reactions in surface waters and "stored waters"? It seems more promising
to include the important reactions in the environs of the river in those reactions in surface waters
which we monitor by the use of the "global coefficients".
Reply
It is easy to describe the chemical, physical and biological reactions in a microscopic sense. Even if
these reactions are introduced into the mass balance equation 2, the solution of integrated form cannot
be obtained without the boundary conditions for the surface and subsurface flow system.
Therefore, enlargement of the range of integration with respect to time and space should be
performed in parallel with the inclusion of several important reactions and the management system
procedure proposed.
In the first step of no reaction as described in this paper, the quality of stored water will be
dependent on surface flow. If the reactions are described with use of the internal storage coefficient in
the further step, the quality of surface water will be predicted accurately as a function of stored water
in conceptual river environs including the municipal area, bottom slude and subsurface area.