Browsing by Author "Paul, Rupak Kumar"

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Open Access
Change Detection in Hydrological Time Series Data
(R K Books, 2022) Paul, Rupak Kumar; Ismile, MD; Siddiqui, Azizur Rahman; Miah, Chhahir Ali
Scientists are accustomed to use statistical tools and techniques to detect change in hydrological time series, but these available techniques are not the panacea for resolving such issues since the concerned techniques provide expressions of probability and not certainty. For instance, the change in annual discharge has been detected for long term dataset but this change might not be due to alteration of any one or more components like land use land cover, or climate or change in agri-technology - of the system in basin scale, rather it happened due to change in methodology of concerned data generation or shifting of gauge station etc...
Open Access
Determining Seasonal Pattern in Stream Water Quality: A Case Study of River Mahananda at Siliguri, West Bengal, India
(Sardar patel Institute of Economic and Social Research, 2022) Paul, Rupak Kumar
The objective of the present study is to recognize the seasonal pattern in water quality status of the stretch of river Mahananda at Siliguri Municipal Corporation of West Bengal. Monthly observations on 21 water quality parameters for the period between January, 20 IO and May, 2022 were used for resolving the present problem. The whole database was generated by West Bengal Pollution Control Board following the guideline of Central Pollution Control Board, Govt. of India. The Hierarchical Cluster Analysis was applied to determine the seasonality while Spearman's Rank correlation was used for determining the association of water quality parameters with seasonal and monthly normal rainfall total in view to capture the role of rainfall in controlling such seasonality. The result demonstrates that the temporal change in water quality status forms three specific hydrogeochemical seasons, January to May, June to August, and September to December which are governed by local rainfall pattern. Further observed that geogenic parameters e.g., Turbidity, TFS, TSS etc. completely follow seasonality of rainfall but this straight forward relation is not found for anthropogenic contaminants. Many anthropogenic parameters (e.g., Na+, EC, TA etc.) show significant negative relationship with rainfall while many of them (e.g., BOD, DO, etc.) do show any pattern at all. Since rainfall cannot fully explain the whole complexity, the role of other factors like discharge associated with hydrogeochemical seasons, needs to be evaluated in this context.
Open Access
Diurnal Asymmetry in Temporal Response of Surface Air Temperature at Siliguri, West Bengal, India
(New Archaeological & Genological Society, 2022-11) Paul, Rupak Kumar
The objective of present study is to explore the diurnal asymmetry in temporal response of surface air temperature in Siliguri Municipal Corporation (SMC). Three groups of parameters namely seasonal and annual mean maximum temperature, seasonal and annual mean minimum temperature, and mean seasonal and mean annual temperature were computed based on daily maximum and daily minimum gridded temperature data available for the period between 1950 and 2020 at grid resolution of 1 °xl 0 from the official India Meteorological Department (IMD) Pune website. Three grid points are found to be located around SMC and the input data available from them were interpolated to get the spatial average value for SMC. The trend analysis was done using Modified Mann-Kendall test for autocorrelated time series, otherwise Mann-Kendall test was applied. The Buishand test was applied to detect the change point for normally distributed series and otherwise it was done by Pettitt's test. The result shows that although the annual mean temperature is significantly (p<0.05) increasing at the rate 0.004°C per year for the whole study period, there is a diurnal asymmetry in the temperature response. The rise in daytime temperatures is more pronounced during monsoon and post-monsoon seasons than in other seasons, but the rise in nighttime temperatures began in post- l 980s and prior to that it had just opposite trend. Siliguri, here, is considered as the locational reference point in space 1.e., present study did not intend to explore the spatial variation across urban and rural areas and hence the cu1Tent findings are applicable over a wide area in and around SMC, irrespective of rural urban effect differences.