Environmental Engineering Reference
In-Depth Information
Table 3.1
Comparative case history and morphometry of two lakes
Sl. no.
Details
Pocharam Lake
Wyra Lake
1.
Construction year
1922
1929
2.
Location
18° 18
′
N and 77° 57
′
E
17° 15
′
N and 80° 25
′
E
3.
Catchment area
16.835 km
2
19.166 km
2
4.
Depth (depending on the season/
fl uctuation in rain fall)
5-6 ft
5-6 ft
5.
Constructed on
Alair River
Godavari River
6.
Usage
Irrigation, domestic and
forestry exploitation
Irrigation and domestic
Venkateswarlu (
1969
), Munawar (
1970
), Venu
(
1981
), Ratna Rao (
1984
), Jaya Devi (
1985
),
Chandrasekhar (
1996
,
2006
), Chandrasekhar and
Nageswara Rao (
2006
), Patil and Panda (
2003
),
Malathi et al. (
2003
) Anitha et al. (
2005
) and
Siddiiqi and Khan (
2002
). In an aquatic ecosys-
tem, water quality infl uences its biotic compo-
nents and it controls diversity, biomass and
spatial distribution of the latter in time and space.
The physico-chemical parameters exert their
infl uence both individually and collectively, and
their interaction produces abiotic environment
which conditions the origin, development and
fi nally succession of biotic communities. Further,
biotic communities, in turn, continuously go on
in a dynamic ecosystem.
The present study was undertaken to have a
comparative account of physico-chemical and
biological conditions of two Deccan wetlands,
viz. Pocharam Lake and Wyra Lake, in Andhra
Pradesh which differed signifi cantly in their lim-
nological aspects and trophy (nutrient status) with
emphasis on the structure and composition of
zooplankton particularly Rotifera and Cladocera.
March 2007, summer; and August 2007, mon-
soon). In order to cover the whole topography of
the water bodies, seven surrounding villages
located at the bank of Pocharam Lake and nine at
Wyra were selected for the surveys. Physical
parameters and titrimetric parameters were anal-
ysed in the fi eld laboratories, and water samples
were brought to head quarters by collecting in
PVC bottles of one litre capacity and given to a
private laboratory for the analysis of nutrients and
light metals. Plankton samples were collected by
diving the plankton net (No. 25) on the sublittoral
regions of the lake waters and preserved in 4 %
formaldehyde solution, and the identifi cation of
rotifer and cladoceran fauna was done with the
aid of standard literature on these two groups.
Results and Discussion
Limnological investigations were restricted to
the three major seasonal surveys, i.e. November
(winter), March (summer) and July/August
(monsoon) on both lakes. The ranges and
mean station-wise/overall values of different
physico-chemical parameters of seven stations
of Pocharam Lake and nine of Wyra Lake were
given in a table during the three major seasons
(winter, summer and monsoon) of the study periods
2003-2004 and 2006-2007, respectively.
The pH values during the study periods varied
between 7.24 and 9.16 with mean value of 8.0 on
Pocharam Lake and 7.0-8.7 with mean value of
7.57 on Wyra Lake indicating the general alkaline
tendency of waters. The higher pH values may be
attributed to the carbonates/bicarbonates and
higher photosynthetic activities. The lower pH
Description of the Lakes
The comparative
morphometry of these two lakes is given based
on the data gathered from different sources
(Table
3.1
).
Methods
The studies on Pocharam Lake had been carried
out during three different seasons (November
2003, winter; March 2004, summer; and July
2004, monsoon) of 2003-2004 and on Wyra
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