Haryana Delhi & Chandigarh, East Madhya Pradesh, and West Uttar Pradesh
received more than 20% less rainfall in comparison to the first half (1901–1958).
Winter Rainfall
The trends in winter –rainfall obtained from ITA reveal that most of the subdivisions
(86.1%) experienced decreasing trends during the study period (1901–2015). About
69% of them are statistically significant at 95% confidence level. These decreasing
trends are found in the whole study area except for a few pocket areas of Gangetic
West Bengal, Himachal Pradesh, Konkan & Goa, and Coastal Andhra Pradesh. The
highest decreasing and increasing trend (ITA) was observed in Arunachal Pradesh
(slope ¼ À0.53) and Sub-Himalaya West Bengal and Sikkim (slope + 0.30), respectively. On the other hand, the results of MK/mMK reveal that more than three fourths
(89%) of the subdivisions showed decreasing trends during the study period; out of
this only 39% are statistically significant at 10%, 5%, and 1% significance level.
(Table 7.6 and Fig. 7.6h). Sen’s slope analysis revealed that an average rate of
decrease is À0.154 mm/year over India in the winter season. The spatiotemporal
variation obtained from Sen’s slope is shown in Fig. 7.6g, which depicts homogeneity in decreasing trends in all of central India. However, the highest decreasing
trend is observed in Andaman & Nicobar Island (À0.84 mm/year) and the highest
increasing trend in Himachal Pradesh (+0.30 mm/year). The coefficient of correlation results between the slope of ITA and Sen’s slope (r ¼ 0.728) and slope of ITA
and Z of MK/mMK (r ¼ 0.503) indicate the new robust ITA is reliable in trend
analysis of the hydrometeorological series. Percentage bias of winter rainfall showed
that sub-Himalaya West Bengal and Sikkim (49.09%) have gained the highest
increase in rainfall in the second half (1959–2015) in comparison to the first half
(1901–1958). Similarly, Saurashtra & Kutch (62.22%) have gained the highest
decrease in rainfall in the second half (1959–2015) in comparison to the first half
(1901–1958).
Table 7.4 (continued)
ITD innovative trend detection
*
The trend is significant at 10% significance or 90% confidence level
**
The trend is significant at 5% significance or 95% confidence level
***
The trend is significant at 1% significance or 99% confidence level
The trend was detected by modified Mann-Kendall test based on lag 1 autocorrelation
174
T. Mandal et al.
received more than 20% less rainfall in comparison to the first half (1901–1958).
Winter Rainfall
The trends in winter –rainfall obtained from ITA reveal that most of the subdivisions
(86.1%) experienced decreasing trends during the study period (1901–2015). About
69% of them are statistically significant at 95% confidence level. These decreasing
trends are found in the whole study area except for a few pocket areas of Gangetic
West Bengal, Himachal Pradesh, Konkan & Goa, and Coastal Andhra Pradesh. The
highest decreasing and increasing trend (ITA) was observed in Arunachal Pradesh
(slope ¼ À0.53) and Sub-Himalaya West Bengal and Sikkim (slope + 0.30), respectively. On the other hand, the results of MK/mMK reveal that more than three fourths
(89%) of the subdivisions showed decreasing trends during the study period; out of
this only 39% are statistically significant at 10%, 5%, and 1% significance level.
(Table 7.6 and Fig. 7.6h). Sen’s slope analysis revealed that an average rate of
decrease is À0.154 mm/year over India in the winter season. The spatiotemporal
variation obtained from Sen’s slope is shown in Fig. 7.6g, which depicts homogeneity in decreasing trends in all of central India. However, the highest decreasing
trend is observed in Andaman & Nicobar Island (À0.84 mm/year) and the highest
increasing trend in Himachal Pradesh (+0.30 mm/year). The coefficient of correlation results between the slope of ITA and Sen’s slope (r ¼ 0.728) and slope of ITA
and Z of MK/mMK (r ¼ 0.503) indicate the new robust ITA is reliable in trend
analysis of the hydrometeorological series. Percentage bias of winter rainfall showed
that sub-Himalaya West Bengal and Sikkim (49.09%) have gained the highest
increase in rainfall in the second half (1959–2015) in comparison to the first half
(1901–1958). Similarly, Saurashtra & Kutch (62.22%) have gained the highest
decrease in rainfall in the second half (1959–2015) in comparison to the first half
(1901–1958).
Table 7.4 (continued)
ITD innovative trend detection
*
The trend is significant at 10% significance or 90% confidence level
**
The trend is significant at 5% significance or 95% confidence level
***
The trend is significant at 1% significance or 99% confidence level
The trend was detected by modified Mann-Kendall test based on lag 1 autocorrelation
174
T. Mandal et al.