316
P. Khanna . P. Ram Babu . S.K. Gadkari
Table 17.1. Physico-chemical characteristics of creek waters durings pre-commissioning and postcommissioning phases of Dallanu Thermal Power Station (October 1991 and October 1996)
Sam- Parameters
piing pH
Salinity
Suspended
Chlorides
DO
P04
point
(ppt)
solids (mgll)
(mgll)
(mg/l)
(mg/l)
1991 1996 1991 1996 1991 1996 1991 1996 1991 1996 1991 1996
1
8.4
n.s.
36.7
n.s.
270
n.s.
20400
n.s. 5.4
n.s.
0.02
n.s.
2
8.1
n.s.
37.1
n.s.
236
n.s.
20580
n.s. 5.5
n.s.
0.02
n.s.
3
8.4
7.3
37.1
2.7
194
20
20580 1500 5.3
6.4
0.03
<0.01
4
8.4
n.s.
37.5
n.s.
310
n.s.
20800
n.s. 5.3
n.s.
0.06
n.s.
n.s.
7.6
n.s.
2.4
n.s. 10
n.s. 1300 n.s.
6.0
n.s.
<0.01
6
8.3
7.6
36.0
2.0
320
30
20010 1100 5.3
6.2
0.09
<0.01
7
n.s.
7.5
n.s.
3.6
n.s. 40
n.s.2oo0 n.s.
6.4
n.s.
<0.01
n.s.: not sampled. Remarkable decrease in salinity, suspended solids and chlorides is noticed in 1996
in comparison-to 1991. Reduction in phosphate concentration and pH have adverse effects on
phytoplankton, affecting the food chain.
17.2.2
Changes in Aquatic Ecosystem
The following changes during 1991-96 have effected the aquatic ecosystem in Dahanu creek:
• Remarkable decrease in salinity, suspended solids and chlorides (Table 17.1);
• Reduction in phosphate concentration and pH levels have adverse effects on biomass
of phytoplankton, affecting the food chain;
• Diversity index, indicative of ecological health, has decreased (Table 17.2);
• Number of fish and prawn varieties has decreased;
• The instabilitY of inverted ecological pyramid has become critical due to relatively
large decrement of biomass in lower levels and meobenthos (Fig. 17.2).
In addition, the decrease in crown density of forest resources, displacement of tribal
population, salinity intrusion into ground water along the coast and sea water intrusion
into coastal villages are important consequences of anthropogenic activity in this region.
17.3
Conclusions and Recommendations
The judiciary requested the Institute to examine issues related to:
• Conformity of regional plan in respect of Dahanu area, formulated by the Government of Maharashtra, with the notification (20th June 1991) declaring Dahanu Taluka
as an ecologically sensitive area; and notification (19th February 1991) declaring
coastal stretches as coastal regulation zone (CRZ) and regulating activities in the
CRZ; both under the Environmental (Protection) Act, 1986;
• Environmental viability of the regional plan;
• Delineation of suggestions to protect and preserve ecology in Dahanu region;
P. Khanna . P. Ram Babu . S.K. Gadkari
Table 17.1. Physico-chemical characteristics of creek waters durings pre-commissioning and postcommissioning phases of Dallanu Thermal Power Station (October 1991 and October 1996)
Sam- Parameters
piing pH
Salinity
Suspended
Chlorides
DO
P04
point
(ppt)
solids (mgll)
(mgll)
(mg/l)
(mg/l)
1991 1996 1991 1996 1991 1996 1991 1996 1991 1996 1991 1996
1
8.4
n.s.
36.7
n.s.
270
n.s.
20400
n.s. 5.4
n.s.
0.02
n.s.
2
8.1
n.s.
37.1
n.s.
236
n.s.
20580
n.s. 5.5
n.s.
0.02
n.s.
3
8.4
7.3
37.1
2.7
194
20
20580 1500 5.3
6.4
0.03
<0.01
4
8.4
n.s.
37.5
n.s.
310
n.s.
20800
n.s. 5.3
n.s.
0.06
n.s.
n.s.
7.6
n.s.
2.4
n.s. 10
n.s. 1300 n.s.
6.0
n.s.
<0.01
6
8.3
7.6
36.0
2.0
320
30
20010 1100 5.3
6.2
0.09
<0.01
7
n.s.
7.5
n.s.
3.6
n.s. 40
n.s.2oo0 n.s.
6.4
n.s.
<0.01
n.s.: not sampled. Remarkable decrease in salinity, suspended solids and chlorides is noticed in 1996
in comparison-to 1991. Reduction in phosphate concentration and pH have adverse effects on
phytoplankton, affecting the food chain.
17.2.2
Changes in Aquatic Ecosystem
The following changes during 1991-96 have effected the aquatic ecosystem in Dahanu creek:
• Remarkable decrease in salinity, suspended solids and chlorides (Table 17.1);
• Reduction in phosphate concentration and pH levels have adverse effects on biomass
of phytoplankton, affecting the food chain;
• Diversity index, indicative of ecological health, has decreased (Table 17.2);
• Number of fish and prawn varieties has decreased;
• The instabilitY of inverted ecological pyramid has become critical due to relatively
large decrement of biomass in lower levels and meobenthos (Fig. 17.2).
In addition, the decrease in crown density of forest resources, displacement of tribal
population, salinity intrusion into ground water along the coast and sea water intrusion
into coastal villages are important consequences of anthropogenic activity in this region.
17.3
Conclusions and Recommendations
The judiciary requested the Institute to examine issues related to:
• Conformity of regional plan in respect of Dahanu area, formulated by the Government of Maharashtra, with the notification (20th June 1991) declaring Dahanu Taluka
as an ecologically sensitive area; and notification (19th February 1991) declaring
coastal stretches as coastal regulation zone (CRZ) and regulating activities in the
CRZ; both under the Environmental (Protection) Act, 1986;
• Environmental viability of the regional plan;
• Delineation of suggestions to protect and preserve ecology in Dahanu region;