13
Changing Rainfall Patterns and Their
Linkage to Floods
in Bhagirathi-Hooghly Basin, India:
Implications for Water Resource
Management
N. C. Jana, Sujay Bandyopadhyay,
Prasanta Kumar Ghosh, and Ritendu Mukhopadhyay
Abstract
The present study provides a synoptic view of
recent changes in the patterns of rainfall and
their linkages to extreme floods in
Bhagirathi-Hooghly Basin (BHB). The objectives are: (a) to obtain a better understanding
of long-term and short-term trends and variations in rainfall; and (b) to ascertain whether
the extreme floods were coincided with
multi-decade excess monsoon rainfall epochs
at the basin level. To fulfill the above
objectives, we use district-wise long-term
(1901–2000) monthly rainfall data and annual
maximum flood series in BHB. The data are
mostly obtained from Indian Meteorological
Department (IMD), Irrigation and Waterways
Department, Government of West Bengal,
numerous research articles, published and
unpublished reports. The methodology
includes various statistical approaches and
simple techniques, such as the Mann–Kendall
(MK) test with Sen’s slope estimator, Cramer’s t-statistic and linear regression in order
to evaluate the trends and patterns of the
rainfall series. The analyses revealed a
long-term insignificant declining trend of
annual as well as pre-monsoon rainfall,
whereas increasing trend in monsoon and
post-monsoon season over BHB. Rainfall
during winter seasons showed a decreasing
trend. Statistically monsoon rainfall can be
considered as very dependable as the coefficient of variation is 17.31%. However, there is
decreasing monthly rainfall trend in June and
August, whereas increasing trend in July and
September. On the other hand, the shorter
period of recent data showing higher significance may have better practical utility and
correlatable with major floods in the basin.
This changing rainfall trends during monsoon
months is a major concern for the rain-fed
agriculture. The results of this study therefore
would be of immense help to the reservoir
managers and policymakers in planning and
management of water resources of the BHB.
Keywords
Climatic variability Á Rainfall trends Á
Extreme floods Á Monsoon rainfall periods Á
Water resources
N. C. Jana (&) Á P. K. Ghosh Á R. Mukhopadhyay
Department of Geography, The University of
Burdwan, Golapbag, Barddhaman 713 104, West
Bengal, India
e-mail: jana.narayan@gmail.com
S. Bandyopadhyay
Department of Geography, Kazi Nazrul University,
Nazrul Road, Post Office: Kalla (C.H.), Asansol,
West Bengal 713 340, India
e-mail: sujaybandyopadhyayest@gmail.com
R. Mukhopadhyay
Department of Geography, Burdwan Raj College,
Aftab House, Barddhaman 713 104, West Bengal,
India
© Springer Nature Switzerland AG 2021
B. W. Pandey and S. Anand (eds.), Water Science and Sustainability, Sustainable Development Goals Series,
https://doi.org/10.1007/978-3-030-57488-8_13
169
Changing Rainfall Patterns and Their
Linkage to Floods
in Bhagirathi-Hooghly Basin, India:
Implications for Water Resource
Management
N. C. Jana, Sujay Bandyopadhyay,
Prasanta Kumar Ghosh, and Ritendu Mukhopadhyay
Abstract
The present study provides a synoptic view of
recent changes in the patterns of rainfall and
their linkages to extreme floods in
Bhagirathi-Hooghly Basin (BHB). The objectives are: (a) to obtain a better understanding
of long-term and short-term trends and variations in rainfall; and (b) to ascertain whether
the extreme floods were coincided with
multi-decade excess monsoon rainfall epochs
at the basin level. To fulfill the above
objectives, we use district-wise long-term
(1901–2000) monthly rainfall data and annual
maximum flood series in BHB. The data are
mostly obtained from Indian Meteorological
Department (IMD), Irrigation and Waterways
Department, Government of West Bengal,
numerous research articles, published and
unpublished reports. The methodology
includes various statistical approaches and
simple techniques, such as the Mann–Kendall
(MK) test with Sen’s slope estimator, Cramer’s t-statistic and linear regression in order
to evaluate the trends and patterns of the
rainfall series. The analyses revealed a
long-term insignificant declining trend of
annual as well as pre-monsoon rainfall,
whereas increasing trend in monsoon and
post-monsoon season over BHB. Rainfall
during winter seasons showed a decreasing
trend. Statistically monsoon rainfall can be
considered as very dependable as the coefficient of variation is 17.31%. However, there is
decreasing monthly rainfall trend in June and
August, whereas increasing trend in July and
September. On the other hand, the shorter
period of recent data showing higher significance may have better practical utility and
correlatable with major floods in the basin.
This changing rainfall trends during monsoon
months is a major concern for the rain-fed
agriculture. The results of this study therefore
would be of immense help to the reservoir
managers and policymakers in planning and
management of water resources of the BHB.
Keywords
Climatic variability Á Rainfall trends Á
Extreme floods Á Monsoon rainfall periods Á
Water resources
N. C. Jana (&) Á P. K. Ghosh Á R. Mukhopadhyay
Department of Geography, The University of
Burdwan, Golapbag, Barddhaman 713 104, West
Bengal, India
e-mail: jana.narayan@gmail.com
S. Bandyopadhyay
Department of Geography, Kazi Nazrul University,
Nazrul Road, Post Office: Kalla (C.H.), Asansol,
West Bengal 713 340, India
e-mail: sujaybandyopadhyayest@gmail.com
R. Mukhopadhyay
Department of Geography, Burdwan Raj College,
Aftab House, Barddhaman 713 104, West Bengal,
India
© Springer Nature Switzerland AG 2021
B. W. Pandey and S. Anand (eds.), Water Science and Sustainability, Sustainable Development Goals Series,
https://doi.org/10.1007/978-3-030-57488-8_13
169