Geography Reference
In-Depth Information
Table 11.2. Inventory of discharge data used for the analysis
Period of
discharge record
or precipitation
(TRMM)
Percentage
deviation of P
from long-term
mean
Mean annual P in Krishna
Basin during period of
discharge record (mm)
Catchment
area (km
2
)
River
Station
Ghataprabha (A)
Bagalkot
8 610
1976
-
95
844
0.8
Bhima
Takli
33 916
1970
-
96
839
0.2
1975
-
97
Malaprabha
Huvanur
11 400
855
2.1
1973
-
5, 1979
-
96
Krishna
Kurundwad
15 190
848
1.3
1988
-
95
Tungabhadra
Oolenur
32 813
872
4.2
Sina
Wadakal
12 092
1970
-
96
839
0.2
Krishna
Huvinhedgi
55 150
1976
-
93
846
1.0
Bhima
Gulbarga
69 863
1970
-
86
821
−
1.9
Musi
Dameracherla
11 501
1968
-
80
835
−
0.3
Palleru (B)
Palleru Bridge
2 928
1988
-
99
870
4.0
Munneru
Keesara
10 294
1988
-
95
872
4.2
Halia
Halia
3 243
1988
-
95
872
4.2
Kagna
Jeewangi
1 920
1988
-
95
872
4.2
Wyra
Madhira
1850
1988
-
99
870
4.0
Vedvathi
T Ramapuram 23 500
1971
-
75
804
−
3.9
TRMM precipitation
—
—
1998
-
2009
833
−
0.5
Long-term mean precipitation
—
—
1968
-
2009
837
0.0
Mean annual precipitation in the Krishna Basin is calculated from subdivision rainfall reported by the Indian Institute of Tropical Meteorology
(IITM).
Top five catchments drain the Western Ghats (black circles in
Figure 11.3
), remaining catchments drain the Deccan Pleateau and
Eastern Ghats.
(A) and (B) indicate the catchments selected for further analysis, which are indicated by A and B in
Figure 11.3
.
(2) A spatially distributed but temporally lumped model
predicted E/P by dividing each catchment into differ-
ent precipitation zones (500 mm increments). Annual
E/P was then estimated for each zone from the annual
E
p
/P and the fitted Budyko curve for the Deccan
Plateau. This model accounted for spatial variability
in E
p
/P and E/P, but not for temporal variability.
the data often did not overlap with the available discharge
data. Therefore, long-term average P, Q and E
p
were used
to establish a Budyko curve. The average monthly and
annual precipitation from 1998 to 2009 was calculated
from high-resolution (4 km) TRMM 2B31 data. E was
calculated as annual P minus the average annual discharge
(Q). Potential evaporation (E
p
) was calculated using the
Penman
Monteith equation, using solar radiation from the
surface radiation budget and interpolated climate param-
eters from 26 meteorological stations in the basin (see
Biggs et al.,
2007
for details). The period of record of the
TRMM precipitation did not overlap with the periods of
record of most of the discharge stations (
Table 11.2
). It was
assumed that both the rainfall and runoff records included
enough years of data to represent the long-term climatic
mean. In order to confirm that precipitation during each
period of discharge record was representative of the long-
term average, the precipitation in the Krishna Basin from
the Indian Institute of Tropical Meteorology (IITM) was
used to quantify precipitation over the period of each
discharge record and of the period of TRMM precipitation
data (
Table 11.2
). The percentage deviation of precipita-
tion over each period of record from the long-term mean
precipitation maximum gives an indication of how
-
Data availability
Data on long-term mean discharge (Q) was available for 15
stream gauges in the basin, each covering a different range
of years from 1968 to 1996 (
Table 11.2
). Basin sizes
ranged from 1850 km
2
to 69 863 km
2
. For nested basins,
the discharge and drainage area of upstream gauges were
subtracted from the observed discharge of downstream
gauges, and P and E
p
were calculated on the subcatchment.
Estimates of naturalised runoff were available for some but
not all of the catchments, so the observed long-term mean
discharge was used.
High-resolution precipitation data were necessary to
compute a climatic-mean precipitation in each catchment.
Sufficient rain gauge data were not available for all catch-
ments, particularly to capture the higher precipitation
depths in the Western Ghats. For rain gauges with data,
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