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Comprehensive water resources studies on the Ara Valley area
16
River Pollution
improvement is so insignificant that this factor may be considered as compensated for quality deteriorating constituents which cannot yet be taken into account. 5. D E T E R M I N A T I O N O F T H E M I N I M U M S T R E A M F L O W T O B E M A I N T A I N E D B Y 1980 I N T H E R I V E R B E D I N T H E R E A C H D O W N S T R E A M FROM THE TISZA RIVER BARRAGE NO. II If the primary purpose of creating a reservoir is to have a specific river reach downstream improved by dilution, it follows that any discharge from the reservoir is conditioned by the quality of the water present in the said river reach and also by quality changes occurring there. Should the reservoir have another prime function, e.g. irrigation, then the problems of water quality are mainly those pertinent to the question of the minimum stream flow in the river bed. In this case two conflicting requirements have to be satisfied: From the viewpoint of national economy it is important that the greatest possible quantity of water should go for irrigation, while it is equally important to have the greatest possible quantity of water available for dilution purposes in the river downstream of the barrage. TABLE 2. MINIMUMFLOWS
TO BE DISCHARGED FROM THE
TISZARESERVOIR
NO. II W I T H AND W I T H O U T
REGARD TO SEWAGE UTILIZATION FOR IRRIGATION
Required f l o w Months
( m a s e c - 1)
downstream from: The city Szolnok The river Harmas K6r6s
Without regard to sewage irrigation June July August September
78 86 96 98
74 81 93 96
With regard to sewage irrigation
47 50 54 55
39 45 53 53
June July August September
From the results obtained, the selection of the minimum flow to be discharged from the reservoir may be considered so that the oxygen demand in the river should not exceed the required limit, e.g. 10 mg/l. According to Chapter 4, the quality of the water discharged from the reservoir was assumed to be identical to that of the incoming water. Calculations based on the proportion of stream flow in the main river and its tributaries according to Chapter 2 were carried out. In the reaches between the estuaries the decomposition rate of the organic matter has been assumed accordingly to be the same as in 1960. The final results of the computations are given in TABIm 2. In this way from the stream flow and the water quality in a given river it is considered possible to determine the minium stream flow necessary to maintain the water quality in other watercourses and river systems.
Comprehensive water resources studies on the Ara Valley area. AKINORI SUGIKI, T o k y o , Japan 1. I N T R O D U C T I O N In 1964 a new water conservation scheme was undertaken for the Neya river basin, the first of its kind in Japan.
River Pollution
17
Although modern sewerage construction was started in the 1890s in Japan only 11 per cent of total urban area is sewered and no more than 7.2 per cent of the urban population is served with m o d e m sewage treatment. Urbanization has been rapid. By 1965, 47 million persons, about 41 per cent of the total population in Japan were living in urban areas, and it is estimated that 93 million, or nearly 80 per cent of the total population, will live in urban areas by 1985. Industrial production is expected then to be 7-8 times greater than that in 1965. Though sewage systems have been designed as local facilities up to now, it would be impossible to maintain water quality, unless water pollution control projects are designed on a larger scale. The purpose of this paper is to present a method for applying system design criteria for these area water pollution control schemes and to show how this accords with an optimum water conservation programme. The area of the Ara Valley is chosen for the case study. 2. G E N E R A L
DESCRIPTION
OF THE
ARA
VALLEY
AREA
The catchment area of this valley is 3000 km 2 and the basin length along the major channel from the sea is 180 km (see Fla. 1).
~1
%%q,, ~, 0 KO'/)os/,/~
&\
.A oo
-°"N~
1
SAITAMA "~', CENTRAL DISTRI~ CT
~A ~miya ~ ,
t /~bkyo Works
Urawa
I t
o Warabi .
(
-
,,
"-
~SINGASHI / ODAI ~_. I I I L ..... -.z . . . . J*' I ' ~"MIKAWASHIMA
N
OCHIAI .....
5
io
',..,
I I / xI ~KASAI
/
I
~ "~ SHIBAURA
"",.~ ,o ....
-h--. USE \
~,5 k,,,
FIG. 1. Catchment area of the Ara Valley.
'
,,! /
TSKYO BAY
18
River Pollution
The population dwelling in this area in 1965 was 4 million in the Tokyo Metropolitan District and 2.82 million in Saltama Prefecture. The gross amounts of industrial production was estimated to be 4100 billion yen in Tokyo and 669 billion yen in Saltama. 3. E S T I M A T I O N
OF THE
POLLUTION
LOAD
TO THE
ARA
RIVER
A n estimate of the pollution load from industry is made as follows. First, the estimated gross amount of industrial production is distributed to 20 classified industry groups according to trends from 1955 to 1965. Second, the load from each group is obtained by multiplying the distributed amount by the respective group pollution load per unit amount which is shown in TABLE 2. The summation of 20 groups loads yields the gross load from industry. The pollution load from domestic sewage is estimated as the product of population and BOD per capita per day.
TABLE 1. POLLUTION LOAD OF INDUSTRIAL WASTES
Industry groups
Food Processing Textile and Dyeing Mill Clothier Saw-mill Furniture and Effects Pulp and Paper Mill Printing Chemical Energy Rubber Tannery Ceramics Steel Nonferrous Metal Metal Machines Electronics Carriers Precision Machines Others
Class
A B A B C B B B A B B A B A B A B B B B B B B B B B
Waste water mS/million yen per day
Water quality
Employees
BOD
Under 30 persons
Above 30 persons
mg/1
0.38 2.32 1.90 0.30 0.93 0.04 0.07 0.19 5.34 0.05 0.07 2.73 2.83 0.09 0.53 0.66 0.11 0.52 0.88 0.56 0.24 0.10 0.11 0.06 0-14 0.48
0.96 3.06 4.13 0.54 1.97 0.06 0.09 0.30 16.19 0.14 0.16 4.79 3.21 0.71 0.84 0.91 0.10 1.29 2.05 0.98 0.42 0.21 0.26 0.22 0.23 0.79
859 12 256 12 18 12 12 12 427 12 12 139 12 21 12 525 12 12 12 12 12 12 12 12 12 12
A = Heavily polluting waste; B = non-polluting waste; C = Medium pollutingwaste. The estimated present and future gross BOD loads which will flow into this basin are shown in TABLE 3. Thus, the future pollution load will increase 7 or 8 times more than the present, unless pollution is controlled.
River Pollution 4. E S T I M A T I O N
OF THE
WATER
19
CONSUMPTION
IN
1985
Even ff the water consumption per unit of industrial production m o u n t does not change in the future, the gross water demand including domestic and industrial uses is estimated to amount to 48 million tons/day. TABLE 2. BOD LOAO rN DOMESTIC WASTE (g/capita per day)
Night-soil Other waste (kitchen waste, etc.) Total
1965
1985
13 22 35
13 52 65
TABLE 3. POLLUTION LOAD IN 1965 AND IN 1985 DISCHARGE TO ARA RIVER (1) BOD load in 1965 (tons per day)
Domestic
Industrial
Total
63.4
138'9
202.3
(2) BOD load in 1985 (tons per day)
In sewage system D Upper stream from Akigase Down Stream from Akigase Total
2.35
Other
Total
I
D
I
D
I
Subtotal
160.23
21.94
180.19
24.29
340.42
364.71
19.29 266.29 41.23 446.48 487-71
38-50 62.79
1124.7 1445.15 1507.94
1143-23 1507.94
19.21 838.44 21.56 998.67 1020.23
D = Domestic waste; I = industrial waste. 5. P L A N N I N G
REGULATION
The water resources in this area will be destroyed unless action is taken to control pollution and to avoid a serious water shortage. To prevent these estimated trends, some regulation of new factory construction will be required for certain groups of industry. The principles and the regulations of industrial development are proposed in this study as follows: (1) Industrial output should not be dictated by any regulations. (2) Construction of factories for food, pulp, paper and chemical industries should be forbidden. (3) Construction of factories for refinery, and ceramic industries is limited to coastal zones. (4) Factories for the clothing industry, saw-mill and printing are encouraged. The restrictions described above may reduce the pollution load to 60 per cent of that estimated without improving conditions and the water consumption to 50 per cent.
20
River Pollution 6. R E S E A R C H E S
NEEDED
(1) The pollution load and water consumption resulting from industrial activities should be more precisely investigated. This would provide a better forcast for the future. (2) Improved techniques of system design for water pollution control schemes should be more economical and effective tools for water conservation.
The prediction of the distribution of dissolved oxygen in rivers. M. OWENS a n d G. KNOWLES, S t e v e n a g e , E n g l a n d The basic processes governing the change in oxygen content between two stations in a river can be represented by the following expression (neglecting longitudinal mixing which is considered in detail later): Q = F(C2-C1) = Pa+Pv--RM--RB-Re+D, where Q is the rate of change of oxygen content per unit surface area of reach (g/m 2 per hr), F t b e flow (m3/hr), S the surface area of the reach (m2), and C1 and £72 the concentrations of oxygen (mg/1) at stations 1 and 2 at times tl and t2 where t2 - tt is the retention period of the reach. PB and PB are the photosynthetic oxygen production by attached plants and phytoplankton respectively (g/m 2 per hr) RM, RB and Re the oxygen consumption of bottom deposits, attached plants, and suspended organisms (g/m 2 per hr); and D the oxygen contributed by diffusion through the water surface. Attempts have been made at the Water Pollution Research Laboratory, Stevenage, England to isolate and to determine the magnitude of these processes and also the influence of environmental factors upon their rates. As a result of this work it is possible to describe the influence of environmental conditions upon these component processes by a series of empirical relations. These are: (i) PB = a l I b:, where at and bx are constants and I is the intensity of solar radiation at the water surface (cal/cm 2 per hr). (ii) Ra = Ma2 (C'~)b2, where a2 and b2 are constants, C in the average oxygen concentration (mg/l) in the reach (that is weight/m2).
C2-[- C I
2-
and M the average biomass of rooted plants present (g dry ,
(iii) RM = a a (C~')ha, where aa and ba are constants. (iv) D = 1"024 r-2o 0.508Uo.67H-O.sS(Cs - C-), where T i s the average temperature of the reach (° C), U the mean velocity (cm/sec), H the mean depth (cm), and Cs the average air-saturation concentration of dissolved oxygen. Given the basic information required to evaluate these expressions, together with such data as the surface area between the upstream and downstream stations, the average depth of the reach, the flow of water, the dissolved-oxygen content of the water as it passes the upstream station, the average biomass of aquatic plants, the water temperature and the intensity of solar radiation, then it is possible to calculate the concentration of oxygen at the downstream station. For an unpolluted stream calculated and observed dissolved-oxygen distributions are compared and shown to be in fairly good agreement. Photosynthetic oxygen production by phytoplankton (Pe) and oxygen consumption by suspended organisms (Pe) were negligible in these studies and were therefore omitted from the calculations. In this simple mathematical model the changes in oxygen content between upstream and downstream stations are related to the mean retention time between the two stations. This is determined by measuring the times of transit of a "flow-tracer" between the stations, the difference in time between the centres of gravity of the observed concentration-time curves at each station being used. Calculations have been made to determine mixing corrections from the distribution of these flow tracers. A method is described by which longitudinal mixing coefficients were obtained from the tracer data by a finite-difference procedure carried out using a digital computer. Some confirmation of the accuracy of the simulation was afforded by the agreement of retention times with those obtained by the centres-ofgravity method mentioned above. Values of longitudinal mixing coefficients derived by this procedure
River Pollution
improvement is so insignificant that this factor may be considered as compensated for quality deteriorating constituents which cannot yet be taken into account. 5. D E T E R M I N A T I O N O F T H E M I N I M U M S T R E A M F L O W T O B E M A I N T A I N E D B Y 1980 I N T H E R I V E R B E D I N T H E R E A C H D O W N S T R E A M FROM THE TISZA RIVER BARRAGE NO. II If the primary purpose of creating a reservoir is to have a specific river reach downstream improved by dilution, it follows that any discharge from the reservoir is conditioned by the quality of the water present in the said river reach and also by quality changes occurring there. Should the reservoir have another prime function, e.g. irrigation, then the problems of water quality are mainly those pertinent to the question of the minimum stream flow in the river bed. In this case two conflicting requirements have to be satisfied: From the viewpoint of national economy it is important that the greatest possible quantity of water should go for irrigation, while it is equally important to have the greatest possible quantity of water available for dilution purposes in the river downstream of the barrage. TABLE 2. MINIMUMFLOWS
TO BE DISCHARGED FROM THE
TISZARESERVOIR
NO. II W I T H AND W I T H O U T
REGARD TO SEWAGE UTILIZATION FOR IRRIGATION
Required f l o w Months
( m a s e c - 1)
downstream from: The city Szolnok The river Harmas K6r6s
Without regard to sewage irrigation June July August September
78 86 96 98
74 81 93 96
With regard to sewage irrigation
47 50 54 55
39 45 53 53
June July August September
From the results obtained, the selection of the minimum flow to be discharged from the reservoir may be considered so that the oxygen demand in the river should not exceed the required limit, e.g. 10 mg/l. According to Chapter 4, the quality of the water discharged from the reservoir was assumed to be identical to that of the incoming water. Calculations based on the proportion of stream flow in the main river and its tributaries according to Chapter 2 were carried out. In the reaches between the estuaries the decomposition rate of the organic matter has been assumed accordingly to be the same as in 1960. The final results of the computations are given in TABIm 2. In this way from the stream flow and the water quality in a given river it is considered possible to determine the minium stream flow necessary to maintain the water quality in other watercourses and river systems.
Comprehensive water resources studies on the Ara Valley area. AKINORI SUGIKI, T o k y o , Japan 1. I N T R O D U C T I O N In 1964 a new water conservation scheme was undertaken for the Neya river basin, the first of its kind in Japan.
River Pollution
17
Although modern sewerage construction was started in the 1890s in Japan only 11 per cent of total urban area is sewered and no more than 7.2 per cent of the urban population is served with m o d e m sewage treatment. Urbanization has been rapid. By 1965, 47 million persons, about 41 per cent of the total population in Japan were living in urban areas, and it is estimated that 93 million, or nearly 80 per cent of the total population, will live in urban areas by 1985. Industrial production is expected then to be 7-8 times greater than that in 1965. Though sewage systems have been designed as local facilities up to now, it would be impossible to maintain water quality, unless water pollution control projects are designed on a larger scale. The purpose of this paper is to present a method for applying system design criteria for these area water pollution control schemes and to show how this accords with an optimum water conservation programme. The area of the Ara Valley is chosen for the case study. 2. G E N E R A L
DESCRIPTION
OF THE
ARA
VALLEY
AREA
The catchment area of this valley is 3000 km 2 and the basin length along the major channel from the sea is 180 km (see Fla. 1).
~1
%%q,, ~, 0 KO'/)os/,/~
&\
.A oo
-°"N~
1
SAITAMA "~', CENTRAL DISTRI~ CT
~A ~miya ~ ,
t /~bkyo Works
Urawa
I t
o Warabi .
(
-
,,
"-
~SINGASHI / ODAI ~_. I I I L ..... -.z . . . . J*' I ' ~"MIKAWASHIMA
N
OCHIAI .....
5
io
',..,
I I / xI ~KASAI
/
I
~ "~ SHIBAURA
"",.~ ,o ....
-h--. USE \
~,5 k,,,
FIG. 1. Catchment area of the Ara Valley.
'
,,! /
TSKYO BAY
18
River Pollution
The population dwelling in this area in 1965 was 4 million in the Tokyo Metropolitan District and 2.82 million in Saltama Prefecture. The gross amounts of industrial production was estimated to be 4100 billion yen in Tokyo and 669 billion yen in Saltama. 3. E S T I M A T I O N
OF THE
POLLUTION
LOAD
TO THE
ARA
RIVER
A n estimate of the pollution load from industry is made as follows. First, the estimated gross amount of industrial production is distributed to 20 classified industry groups according to trends from 1955 to 1965. Second, the load from each group is obtained by multiplying the distributed amount by the respective group pollution load per unit amount which is shown in TABLE 2. The summation of 20 groups loads yields the gross load from industry. The pollution load from domestic sewage is estimated as the product of population and BOD per capita per day.
TABLE 1. POLLUTION LOAD OF INDUSTRIAL WASTES
Industry groups
Food Processing Textile and Dyeing Mill Clothier Saw-mill Furniture and Effects Pulp and Paper Mill Printing Chemical Energy Rubber Tannery Ceramics Steel Nonferrous Metal Metal Machines Electronics Carriers Precision Machines Others
Class
A B A B C B B B A B B A B A B A B B B B B B B B B B
Waste water mS/million yen per day
Water quality
Employees
BOD
Under 30 persons
Above 30 persons
mg/1
0.38 2.32 1.90 0.30 0.93 0.04 0.07 0.19 5.34 0.05 0.07 2.73 2.83 0.09 0.53 0.66 0.11 0.52 0.88 0.56 0.24 0.10 0.11 0.06 0-14 0.48
0.96 3.06 4.13 0.54 1.97 0.06 0.09 0.30 16.19 0.14 0.16 4.79 3.21 0.71 0.84 0.91 0.10 1.29 2.05 0.98 0.42 0.21 0.26 0.22 0.23 0.79
859 12 256 12 18 12 12 12 427 12 12 139 12 21 12 525 12 12 12 12 12 12 12 12 12 12
A = Heavily polluting waste; B = non-polluting waste; C = Medium pollutingwaste. The estimated present and future gross BOD loads which will flow into this basin are shown in TABLE 3. Thus, the future pollution load will increase 7 or 8 times more than the present, unless pollution is controlled.
River Pollution 4. E S T I M A T I O N
OF THE
WATER
19
CONSUMPTION
IN
1985
Even ff the water consumption per unit of industrial production m o u n t does not change in the future, the gross water demand including domestic and industrial uses is estimated to amount to 48 million tons/day. TABLE 2. BOD LOAO rN DOMESTIC WASTE (g/capita per day)
Night-soil Other waste (kitchen waste, etc.) Total
1965
1985
13 22 35
13 52 65
TABLE 3. POLLUTION LOAD IN 1965 AND IN 1985 DISCHARGE TO ARA RIVER (1) BOD load in 1965 (tons per day)
Domestic
Industrial
Total
63.4
138'9
202.3
(2) BOD load in 1985 (tons per day)
In sewage system D Upper stream from Akigase Down Stream from Akigase Total
2.35
Other
Total
I
D
I
D
I
Subtotal
160.23
21.94
180.19
24.29
340.42
364.71
19.29 266.29 41.23 446.48 487-71
38-50 62.79
1124.7 1445.15 1507.94
1143-23 1507.94
19.21 838.44 21.56 998.67 1020.23
D = Domestic waste; I = industrial waste. 5. P L A N N I N G
REGULATION
The water resources in this area will be destroyed unless action is taken to control pollution and to avoid a serious water shortage. To prevent these estimated trends, some regulation of new factory construction will be required for certain groups of industry. The principles and the regulations of industrial development are proposed in this study as follows: (1) Industrial output should not be dictated by any regulations. (2) Construction of factories for food, pulp, paper and chemical industries should be forbidden. (3) Construction of factories for refinery, and ceramic industries is limited to coastal zones. (4) Factories for the clothing industry, saw-mill and printing are encouraged. The restrictions described above may reduce the pollution load to 60 per cent of that estimated without improving conditions and the water consumption to 50 per cent.
20
River Pollution 6. R E S E A R C H E S
NEEDED
(1) The pollution load and water consumption resulting from industrial activities should be more precisely investigated. This would provide a better forcast for the future. (2) Improved techniques of system design for water pollution control schemes should be more economical and effective tools for water conservation.
The prediction of the distribution of dissolved oxygen in rivers. M. OWENS a n d G. KNOWLES, S t e v e n a g e , E n g l a n d The basic processes governing the change in oxygen content between two stations in a river can be represented by the following expression (neglecting longitudinal mixing which is considered in detail later): Q = F(C2-C1) = Pa+Pv--RM--RB-Re+D, where Q is the rate of change of oxygen content per unit surface area of reach (g/m 2 per hr), F t b e flow (m3/hr), S the surface area of the reach (m2), and C1 and £72 the concentrations of oxygen (mg/1) at stations 1 and 2 at times tl and t2 where t2 - tt is the retention period of the reach. PB and PB are the photosynthetic oxygen production by attached plants and phytoplankton respectively (g/m 2 per hr) RM, RB and Re the oxygen consumption of bottom deposits, attached plants, and suspended organisms (g/m 2 per hr); and D the oxygen contributed by diffusion through the water surface. Attempts have been made at the Water Pollution Research Laboratory, Stevenage, England to isolate and to determine the magnitude of these processes and also the influence of environmental factors upon their rates. As a result of this work it is possible to describe the influence of environmental conditions upon these component processes by a series of empirical relations. These are: (i) PB = a l I b:, where at and bx are constants and I is the intensity of solar radiation at the water surface (cal/cm 2 per hr). (ii) Ra = Ma2 (C'~)b2, where a2 and b2 are constants, C in the average oxygen concentration (mg/l) in the reach (that is weight/m2).
C2-[- C I
2-
and M the average biomass of rooted plants present (g dry ,
(iii) RM = a a (C~')ha, where aa and ba are constants. (iv) D = 1"024 r-2o 0.508Uo.67H-O.sS(Cs - C-), where T i s the average temperature of the reach (° C), U the mean velocity (cm/sec), H the mean depth (cm), and Cs the average air-saturation concentration of dissolved oxygen. Given the basic information required to evaluate these expressions, together with such data as the surface area between the upstream and downstream stations, the average depth of the reach, the flow of water, the dissolved-oxygen content of the water as it passes the upstream station, the average biomass of aquatic plants, the water temperature and the intensity of solar radiation, then it is possible to calculate the concentration of oxygen at the downstream station. For an unpolluted stream calculated and observed dissolved-oxygen distributions are compared and shown to be in fairly good agreement. Photosynthetic oxygen production by phytoplankton (Pe) and oxygen consumption by suspended organisms (Pe) were negligible in these studies and were therefore omitted from the calculations. In this simple mathematical model the changes in oxygen content between upstream and downstream stations are related to the mean retention time between the two stations. This is determined by measuring the times of transit of a "flow-tracer" between the stations, the difference in time between the centres of gravity of the observed concentration-time curves at each station being used. Calculations have been made to determine mixing corrections from the distribution of these flow tracers. A method is described by which longitudinal mixing coefficients were obtained from the tracer data by a finite-difference procedure carried out using a digital computer. Some confirmation of the accuracy of the simulation was afforded by the agreement of retention times with those obtained by the centres-ofgravity method mentioned above. Values of longitudinal mixing coefficients derived by this procedure