consistently since 1969. The slope of the trend line considering the linear equation is
0.018 (Fig. 2.2d), which means the daily maximum temperature is increasing at a
rate of 0.005% per decade. For the period 1969–2005, the annual temperature has
risen by 1.3
C and has been increasing constantly at 0.001% per decade as seen
from the slope of the best fit line of 0.0358. These facts are evidence for the changes
in climate and certainly explain the current scenarios of global warming and the
occurrence of natural calamities (floods and droughts).
Rainfall Trends
Indian Meteorological Department (IMD) 0.25
0
 0.25
0 gridded data for a period of
1969 to 2016 is an input for generating annual mean rainfall over the entire Bhima
sub-basin. Figure 2.3a, b illustrates annual mean rainfall and maximum daily rainfall
observed during 1969–2016, respectively. The M-K trend test tau value (Fig. 2.3c)
explains the trend for the annual rainfall series of the IMD gridded data over the
basin. The tau value of the M-K test is quite similar and as good as the correlation
coefficient, with its value ranging from À1 to +1. A positive (+) tau value shows the
increasing trend of the series of data (rainfall in this case) and its counterpart, a
negative (À) tau value, represents a decreasing trend. Figure 2.3d illustrates the
average annual rainfall over the basin (with tau value).
Fig. 2.3 (a) Annual mean rainfall (mm); (b) maximum daily rainfall (mm); (c) M-K trend test tau
values; (d) annual rainfall plot. Linear best fit indicated by dotted line
24
N. S. Patil and R. S. Laddimath
0.018 (Fig. 2.2d), which means the daily maximum temperature is increasing at a
rate of 0.005% per decade. For the period 1969–2005, the annual temperature has
risen by 1.3
C and has been increasing constantly at 0.001% per decade as seen
from the slope of the best fit line of 0.0358. These facts are evidence for the changes
in climate and certainly explain the current scenarios of global warming and the
occurrence of natural calamities (floods and droughts).
Rainfall Trends
Indian Meteorological Department (IMD) 0.25
0
 0.25
0 gridded data for a period of
1969 to 2016 is an input for generating annual mean rainfall over the entire Bhima
sub-basin. Figure 2.3a, b illustrates annual mean rainfall and maximum daily rainfall
observed during 1969–2016, respectively. The M-K trend test tau value (Fig. 2.3c)
explains the trend for the annual rainfall series of the IMD gridded data over the
basin. The tau value of the M-K test is quite similar and as good as the correlation
coefficient, with its value ranging from À1 to +1. A positive (+) tau value shows the
increasing trend of the series of data (rainfall in this case) and its counterpart, a
negative (À) tau value, represents a decreasing trend. Figure 2.3d illustrates the
average annual rainfall over the basin (with tau value).
Fig. 2.3 (a) Annual mean rainfall (mm); (b) maximum daily rainfall (mm); (c) M-K trend test tau
values; (d) annual rainfall plot. Linear best fit indicated by dotted line
24
N. S. Patil and R. S. Laddimath