A Quality Management Model for River and Underground Flow System
261
the lower area of the river. But it should be remembered that the above practice has less
evaluated with marginal utility. By way of illustration, the following data will be considered. In Fig. 1, NH 4 —N concentrations with flows under 120 m
3 /s increase excessively
over the calculated value with assumed constant loads generated in the Yodo basin.
From our own 5 stations (SI, SII, SIH, SIV and S4 in Fig. 2) an 11 day survey
conducted in winter of 1970 in the Katsura branch of the Yodo showed C x Q values
obtained with Cl significantly lower along the stream, as in Tables 1 and 2. A similar
tendency could be observed for C x Q values obtained with B.O.D. and S.S., but these
water quality indices are not so useful in the present stage of building new management
models.
( m )
Fig.2. Layout of Observation Stations and Test Wells
TABLE 1 Values of Q (m
3 /s)
Dec.17
24
30
31
Jan. 1
2
3
4
5
6
7
SI
19.3
11.8
13.5
11.3
9.0
8.0
20.0
18.5
18.5
17.5
16.0
SII
0.9
0.4
0.6
0.7
0.8
0.7
0.8
0.8
0.9
0.7
0.7
SIII
10.8
9.1
8.4
6.0
3.4
3.2
3.2
3.9
4.2
6.5
6.3
SIV
6.6
6.8
2.5
6.5
3.7
3.7
3.3
2.9
2.9
2.9
2.5
S4
28.2
23.0
20.7
27.4
13.0
11.2
26.5
20.3
22.9
24.3
22.6
Decrease
9.4
5.1
4.3
-2.9
0.5
4.4
0.8
5.8
3.6
3.3
2.9