CLIMATE CHANGE AND TREND OF RAINFALL IN THE SOUTH-EAST BANGLADESH (original) (raw)

Climate Change and Trend of Rainfall in the South-East Part of Coastal Bangladesh

European Journal of Scientific Research

Rainfall has been widely considered as one of the starting point towards the apprehension of climate change courses. Various studies have indicated due to climate change rainfall pattern in Bangladesh is most likely to change which would have adverse impacts on lives and livelihoods of millions of people. This study investigates temporal variability of precipitation of the south-east coast of Bangladesh over the period of 1949-2011. The Mann-Kendall test and the Sen’s slope estimators have been used to detect rainfall trends and to understand magnitude of changes. We find that after 1990 mean annual rainfall has increased significantly in the south east part of Bangladesh compare to the period between 1949 and 1989. The rate of increase is 10% that is 463 mm/year. However, this pattern of increase in rainfall is not evenly distributed among all the four seasons. Sixty three years (1949-2011) trend analysis shows that rainfall has increased significantly during pre-monsoon season. Th...

Analysis of Rainfall Trends in the South-East Bangladesh

This paper explores annual and seasonal trends of rainfall in the South-East part of coastal Bangladesh over the period between 1980 and 2011. Non-parametric- Mann-Kendall and Sen’s test estimate is applied for detecting and estimating rainfall trends respectively. An assessment of rainfall data indicate amount of annual rainfall in South-East Bangladesh is increasing although this trend is not statistically significant. Seasonal analysis reveals least amount of rainfall occurs in winter and it is getting drier. However, trends analysis indicates the other three seasons, e.g. Pre-Monsoon, Rainy Monsoon and Post Monsoon, are becoming wetter. It is important to note that among all the seasons rainfall in Pre-Monsoon is increasing significantly (significant at p= 0.05 level) and the rate of increase is 8.5 mm/year.

ANALYZING LONG-TERM TRENDS IN MONTHLY AND ANNUAL RAINFALL OVER WESTERN PART OF BANGLADESH

ICCESD 2020 Conference , 2020

Rainfall is the key climatic variable that governs the regional hydrologic cycle and availability of water resources. The climatic variability is referred to the long-term changes in rainfall, temperature, humidity, evaporation, wind speed and other meteorological parameters. In order to identify the change, quantification of environmental change is necessary that will be supportive to make forecast for future. This will result into a better planning and awareness for natural disasters. The objective of the study is to examine the rainfall variability over the western part of Bangladesh. This will give an understanding about trends or changes in rainfall over the studied region. In the current study, trend analysis has been carried out on monthly and annual rainfalls for the selected eleven rainfall stations located within the western part of Bangladesh. The well-known statistical trend analysis techniques including Mann-Kendall test and Sen's slope estimator are used to detect trends at the 5% significance level on time series data of the study area for the time period from 1948 to 2014. These tests are adopted to identify the change in magnitude and direction of existing trend over time. The analysis for trend detection using the Mann-Kendall test and Sen's slope estimator is undertaken in the XLSTAT 2016 platform. Trend detection of rainfall using the adopted techniques over 65 years shows increasing trend in monthly rainfall for four rainfall stations, namely Satkhira, Khulna, Jessore and Ishurdi stations. Three of them are located in the southwest coastal part of the study area. Furthermore, the analysis indicates similar trend in annual rainfall and the increasing trend is evidenced for three rainfall stations, namely Satkhira, Khulna and Ishurdi stations in which two are located in the coastal part. The findings of this analysis would be of interest to water resources managers and policy makers for the effective planning and management of water resources in Bangladesh.

Rainfall Variability and Linear Trend Models on North-West Part of Bangladesh for the Last 40 Years

American Journal of Applied Mathematics, 2016

Rainfall has been extensively considered as one of the initial point towards the apprehension of climate change courses. Bangladesh is recently experiencing climate change impact related to hazards like cyclone, rainfall, flood, draught etc. Climate variable like rainfall is the most important parameter which is linked with agricultural aspects too for this country. Most of the rain occurred during monsoon period in Bangladesh. This study investigates temporal variability of rainfall and liner trend models on the NorthWest part of Bangladesh over the period of 1975-2014 using data from the Bangladesh Meteorological Department. We computed and analyzed the linear trend models by using least square estimation. We estimated mean with standard deviation, cross-correlation and linear trends of annual and monsoon rainfall using MS Excel and SPSS v21. The variability of rainfall between the stations was measured by correlation test. The annual and monsoon rainfall has been found in decreasing trends in recent times. In some areas in the NorthWestern part of the country, the amount of annual and monsoon mean rainfall may be decreased abruptly comparing with average normal rainfall all over the country. The linear trend analysis of rainfall reveals a bit different trend for the last four decades. The observed data and linear trend line shows the decreasing trend of annual rainfall rate is 0.102 mm per year, whereas the decreasing trend of monsoon season rainfall rate is 0.080 mm per year. The time series statistical analysis of this study also provided the information about the correlation coefficients of rainfall among the selected five stations of the SouthWest region. The result of this study would hopefully help the planners and program managers to take necessary actions and to measure disaster management, agricultural production, drought mitigation, flood control etc.

Long-term trends in precipitation indices at eastern districts of Bangladesh

SN Applied Sciences

This study analyzed the trends of extreme daily rainfall indices over three meteorological stations located in the eastern region of Bangladesh from 1960 to 2000. The climate change-related indices included frequency-based indices: number of heavy rainfall days and consecutive dry and wet days, and intensity-based indices: annual wet-day rainfall total, daily and consecutive five-day maximum rainfall, very and extremely wet days and simple daily intensity index. The magnitude of trends in extreme rainfall indices time series was determined using the nonparametric Sen's slope estimator method, and the statistical significance of the trends was analyzed using the Mann-Kendall test. The rainfall trends exhibited regional patterns. Overall, results suggested an increase in annual rainfall over the study area; however, a tendency toward reduction of rainfall in the wet season was observed. Analysis of extreme rainfall indices demonstrated non-significant increase in frequency of heavy rainfall days, decrease in consecutive dry days and increase in consecutive wet days coupled with regional decline in daily and consecutive five-day maximum rainfall in the monsoon.

Spatio-Temporal Variability of Rainfall Over Bangladesh During the Time Period 1969-2003

Spatial and temporal variability of rainfall in Bangladesh has been studied in this paper from thirty-five years of rainfall data recorded at 24 rain gauges distributed over the country. Long-term annual average rainfall, coefficient of variation of annual rainfall, precipitation concentration and aridity indices at each station have been computed and then interpolated using kriging method within a geographic information system to show the temporal and spatial variability of rainfall. Mann-Kendall test has been used to analyze the trend in rainfall data in different recording stations and the Sen's slope method has been used to determine the magnitude of change. A moderate variation in inter-annual rainfall and high variation in Intra-annual rainfall in Bangladesh have been observed. Non-significant positive trend of annual, monsoon and pre-monsoon rainfall, and a negative trend in winter rainfall are found in Bangladesh. Spatial distribution of rainfall trends shows that rainfall is increasing in the coastal zone and northern Bangladesh, and decreasing in the central part of the country. A declining trend of precipitation concentration is also observed in most of the stations. These results may be a first indication of the precipitation response to global warming -a hypothesis which needs to be further investigated by means of climate model projections.

Analysis of Long-term Rainfall Trends in Bangladesh

2021

The study of rainfall trends is critically important for Bangladesh whose food security and economy are dependent on the timely availability of water. Trends in monthly, seasonal, and annual rainfall on the eight divisions as well as all Bangladesh were examined in this study using a monthly data series of 40 years (1981–2020). Most of the divisions showed decreasing trend in monsoon seasonal rainfall but for only three divisions namely Dhaka, Rajshahi and Rangpur were statistically significant except in Chattogram division, whereas rainfall trend showed positive but not significant. On an annual scale, all divisions also showed a decreasing trend with insignificant exceptions in Dhaka and Rajshahi divisions, which showed a statistically significant trend. For all Bangladesh, no significant trend was detected for seasonal rainfall. Annual, pre-monsoon, monsoon and winter rainfall decreased, while post-monsoon rainfall increased at the national scale but was not significant. Only ann...

Rainfall Variation In Bangladesh: Trends, Factors And Effects

Management research and practice, 2013

Bangladesh has always been predominantly an agriculture based country. In early days, agricultural production was fully dependent on rainfall. Over the study period of recent 30 years, trend values of monsoon average rainfall in Chittagong, Dhaka and Rajshahi has risen as a consequence of the increase of the increase in rainfall. On the other hand, the trend value in Sylhet has declined with the decrease in rainfall. This paper has measured the correlation coefficients between rainfall and time for four stations: Chittagong, Dhaka, Rajshahi and Sylhet where correlation coefficient for Dhaka station and Sylhet station is maximum and negative respectively. This study indicates that climate change, global warming, destruction of hills etc. have disastrous effects on rainfall which is hampering not only the agricultural production but also the ecosystem. It is hoped that this research may be of help to the concerned organizations and experts working on this problem.

Rainfall variability and the trends of wet and dry periods in Bangladesh

International Journal of Climatology, 2010

Spatial patterns of annual and seasonal rainfall trends of Bangladesh over the time period 1958–2007 has been assessed using rainfall data recorded at 17 stations distributed over the country. Mann–Kendall trend test and the Sen's slope method are used to detect the significance and the magnitude of rainfall change, respectively. Historical dry and wet months are identified by using standardised precipitation index method and their trends are analysed to assess the possible change in wet and dry events in Bangladesh. The result shows a significant increase in the average annual and pre-monsoon rainfall of Bangladesh. The number of wet months is found to increase and the dry months to decrease in most parts of the country. Seasonal analysis of wet and dry months shows a significant decrease of dry months in monsoon and pre-monsoon. Copyright © 2009 Royal Meteorological Society

Spatio-temporal analysis of climatic variables in the western part of Bangladesh

Environment, Development and Sustainability, 2016

Monitoring and detecting trends of climatic variables like rainfall and temperature are essential for agricultural developments in the context of climate change. The present study has detected trends in annual and cropping seasonal rainfall and temperature data for the period of 1961-2011 using Mann-Kendall (MK) test, Spearman's rho (SR) test and modified Mann-Kendall test that has been applied to the significant lag-1 serial correlated time series data, and slope has been estimated using Sen's Slope estimator for twelve meteorological stations located in the western part of Bangladesh covering about 41 % of the country. Almost 71 % trends explored by MK test in annual rainfall are