well-distributed network of meteorological stations of the India Meteorological
Department (IMD). In this study, a parametric statistical technique, namely, linear
regression analysis, has been employed to compute the magnitude of trends of
climatic variables. Findings of this study can be summarized through the following
points.
1. Annual mean temperature of the country as a whole is rising at the rate of 0.56
C
per hundred years. Increasing trend of annual mean maximum temperature
(1.02
C/100 years) is significantly higher than that of annual mean minimum
temperature (0.12
C/100 years), although since 1990 the annual mean minimum
temperature is steadily rising at a higher rate than the annual mean maximum
temperature. The maximum rising trend of annual mean temperature is observed
in the post monsoon season (0.77
C/100 years) followed by the winter season
(0.70
C/100 years), pre monsoon season (0.64
C/100 years), and monsoon
season (0.33
C/100 years), respectively.
2. The average annual and monsoon rainfall of the entire country does not show any
significant trend during the time period of 1901–2009, although over this time
period alternating sequences of multi-decadal periods of 30 years with frequent
droughts and floods are observed in the monsoon rainfall pattern of India. In the
post monsoon season a trend of slightly increasing of rainfall is observed over
most of India whereas in the winter season a decreasing trend is noticed.
3. During the time period of 1961–2000 a slight delay in onset and withdrawal of
monsoon activity is observed, and its duration has increased by about a week in
comparison to the normal duration in the past.
Kumar and Jain (2010) have conducted a river basin trend analysis of annual
rainfall and annual rainy days, employing Sen’s method and the Mann–Kendall test
to estimate the magnitude of the trend and to assess its statistical significance.
Findings of this study can be summarized through the following points.
1. Of 22 major river basins in India, 15 river basins have experienced a decreasing
trend of annual rainfall ranging from 0.27 mm/year to 10.16 mm/year during
1951–2004. An increasing trend of annual rainfall ranging between 0.45 mm/year
and 4.93 mm/year is observed in 6 river basins of India, and in the Ganga River
basin no trend is found.
2. Annual rainy days have increased (0.024 days/year to 0.111 days/year) over
4 river basins during 1951–2004 whereas in 15 river basins a decreasing trend
(0.044 days/year to 0.375 days/year) of annual rainy days is observed. In 3 river
basins, no changes in terms of annual rainy days are indicated.
Rathore et al. (2013) outlined state level climate change trends over India during
1951–2010 with respect to temperature and rainfall under the Meteorological Monograph Series of the Indian Meteorological Department (IMD). They examined longterm continuous temperature and rainfall datasets as recorded in 282 and 1451
meteorological stations, respectively. In this study, two nonparametric statistical
techniques, Sen’s method and the Mann–Kendall test were employed to detect
increasing or decreasing trends and to judge the presence of a statistically significant
6 Impact of Climate Change on Groundwater Resource of India: A Geographical. . .
129
Department (IMD). In this study, a parametric statistical technique, namely, linear
regression analysis, has been employed to compute the magnitude of trends of
climatic variables. Findings of this study can be summarized through the following
points.
1. Annual mean temperature of the country as a whole is rising at the rate of 0.56
C
per hundred years. Increasing trend of annual mean maximum temperature
(1.02
C/100 years) is significantly higher than that of annual mean minimum
temperature (0.12
C/100 years), although since 1990 the annual mean minimum
temperature is steadily rising at a higher rate than the annual mean maximum
temperature. The maximum rising trend of annual mean temperature is observed
in the post monsoon season (0.77
C/100 years) followed by the winter season
(0.70
C/100 years), pre monsoon season (0.64
C/100 years), and monsoon
season (0.33
C/100 years), respectively.
2. The average annual and monsoon rainfall of the entire country does not show any
significant trend during the time period of 1901–2009, although over this time
period alternating sequences of multi-decadal periods of 30 years with frequent
droughts and floods are observed in the monsoon rainfall pattern of India. In the
post monsoon season a trend of slightly increasing of rainfall is observed over
most of India whereas in the winter season a decreasing trend is noticed.
3. During the time period of 1961–2000 a slight delay in onset and withdrawal of
monsoon activity is observed, and its duration has increased by about a week in
comparison to the normal duration in the past.
Kumar and Jain (2010) have conducted a river basin trend analysis of annual
rainfall and annual rainy days, employing Sen’s method and the Mann–Kendall test
to estimate the magnitude of the trend and to assess its statistical significance.
Findings of this study can be summarized through the following points.
1. Of 22 major river basins in India, 15 river basins have experienced a decreasing
trend of annual rainfall ranging from 0.27 mm/year to 10.16 mm/year during
1951–2004. An increasing trend of annual rainfall ranging between 0.45 mm/year
and 4.93 mm/year is observed in 6 river basins of India, and in the Ganga River
basin no trend is found.
2. Annual rainy days have increased (0.024 days/year to 0.111 days/year) over
4 river basins during 1951–2004 whereas in 15 river basins a decreasing trend
(0.044 days/year to 0.375 days/year) of annual rainy days is observed. In 3 river
basins, no changes in terms of annual rainy days are indicated.
Rathore et al. (2013) outlined state level climate change trends over India during
1951–2010 with respect to temperature and rainfall under the Meteorological Monograph Series of the Indian Meteorological Department (IMD). They examined longterm continuous temperature and rainfall datasets as recorded in 282 and 1451
meteorological stations, respectively. In this study, two nonparametric statistical
techniques, Sen’s method and the Mann–Kendall test were employed to detect
increasing or decreasing trends and to judge the presence of a statistically significant
6 Impact of Climate Change on Groundwater Resource of India: A Geographical. . .
129