Keywords Hydrometeorological time series · Temporal changes · Graphical trend
analysis · Classical trend analysis · Climate change · India
Introduction
Precipitation, an important component of the global hydrological circle, is significant
in maintaining energy balance between terrestrial and atmospheric ecosystems
(Mandal et al. 2020; Das et al. 2020b; Satishkumar and Rathnam 2020). Variability
in rainfall has considerable influence on agriculture, forest, and water resources, and
therefore the changes in rainfall, temperature, and humidity are important aspects
that indicate climate change (Huang et al. 2020). According to Krishnan et al.
(2016), changes in rainfall and temperature alter the hydrodynamic and thermal
regime of the rivers, stream discharge, surface runoff, and the freshwater ecosystem.
The amount of rainfall is an important part of the water resources of a country with
multidimensional utility and considerable impact on socioeconomic conditions
(Tabari and Talaee 2011). A significant association is observed between rainfall
variability and the occurrence of extreme events such as floods, droughts, and
landslides that make the community more vulnerable and cause huge economic
loss (Roxy et al. 2017). Extreme or low rainfall events affect the availability of
groundwater, soil moisture, runoff, and stream discharge, ultimately affecting the
occurrence of floods and droughts. Furthermore, spatiotemporal changes in precipitation affect the agricultural system: crop type, cropping intensity, productivity, and
the increased risk of crop failure (Farook and Kannan 2016; Guntukula and Goyari
2020; Rahman et al. 2020).
The Indian climate is controlled by monsoon winds: 75–90% of the rainfall in the
Indian subcontinent is determined by the summer monsoon, which contributes about
60% of gross water demand for agriculture (Guhathakurta et al. 2011). Seasonal
variation and geographical distribution of the rainfall in India is highly heterogeneous (Sreelekha and Babu 2019; Sinha et al. 2019; Varikoden et al. 2019). The
Indian summer monsoon rainfall (ISMR) greatly influences the Indian economy
because about 55% of the rural workforce is directly linked with agriculture and 60%
of the net area is in the rainfed zone (Das et al. 2020a). The extension of agriculture
and the rapid increase of population swell the demands for water resources (Islam
and van Amstel 2018; Sarkar and Chouhan 2019, 2020). It is also observed that
many hydrological phenomena are directly associated with extreme rainfall events or
a low rainfall event and that such events are cyclic (Chang et al. 2009). Time series
analysis can capture this periodicity of events and helped to forecast near-future
phenomena (Islam and van Amstel 2018; Khan et al. 2018). For the researcher’s
evaluation of long-term trends in meteorological data are an important aspect of
understanding climate change and its impact on human communities (Nisansala
et al. 2020). Therefore, analyses of rainfall trends, patterns, and their spatial
156
T. Mandal et al.
analysis · Classical trend analysis · Climate change · India
Introduction
Precipitation, an important component of the global hydrological circle, is significant
in maintaining energy balance between terrestrial and atmospheric ecosystems
(Mandal et al. 2020; Das et al. 2020b; Satishkumar and Rathnam 2020). Variability
in rainfall has considerable influence on agriculture, forest, and water resources, and
therefore the changes in rainfall, temperature, and humidity are important aspects
that indicate climate change (Huang et al. 2020). According to Krishnan et al.
(2016), changes in rainfall and temperature alter the hydrodynamic and thermal
regime of the rivers, stream discharge, surface runoff, and the freshwater ecosystem.
The amount of rainfall is an important part of the water resources of a country with
multidimensional utility and considerable impact on socioeconomic conditions
(Tabari and Talaee 2011). A significant association is observed between rainfall
variability and the occurrence of extreme events such as floods, droughts, and
landslides that make the community more vulnerable and cause huge economic
loss (Roxy et al. 2017). Extreme or low rainfall events affect the availability of
groundwater, soil moisture, runoff, and stream discharge, ultimately affecting the
occurrence of floods and droughts. Furthermore, spatiotemporal changes in precipitation affect the agricultural system: crop type, cropping intensity, productivity, and
the increased risk of crop failure (Farook and Kannan 2016; Guntukula and Goyari
2020; Rahman et al. 2020).
The Indian climate is controlled by monsoon winds: 75–90% of the rainfall in the
Indian subcontinent is determined by the summer monsoon, which contributes about
60% of gross water demand for agriculture (Guhathakurta et al. 2011). Seasonal
variation and geographical distribution of the rainfall in India is highly heterogeneous (Sreelekha and Babu 2019; Sinha et al. 2019; Varikoden et al. 2019). The
Indian summer monsoon rainfall (ISMR) greatly influences the Indian economy
because about 55% of the rural workforce is directly linked with agriculture and 60%
of the net area is in the rainfed zone (Das et al. 2020a). The extension of agriculture
and the rapid increase of population swell the demands for water resources (Islam
and van Amstel 2018; Sarkar and Chouhan 2019, 2020). It is also observed that
many hydrological phenomena are directly associated with extreme rainfall events or
a low rainfall event and that such events are cyclic (Chang et al. 2009). Time series
analysis can capture this periodicity of events and helped to forecast near-future
phenomena (Islam and van Amstel 2018; Khan et al. 2018). For the researcher’s
evaluation of long-term trends in meteorological data are an important aspect of
understanding climate change and its impact on human communities (Nisansala
et al. 2020). Therefore, analyses of rainfall trends, patterns, and their spatial
156
T. Mandal et al.