Appraising trends and forecasting of hydroclimatic variables in the north and northeast regions of Bangladesh

Appraising trend and forecasting of seasonal and annual rainfall, temperature, river water discharge, and groundwater level are crucial for local water resource practices and designing agricultural crop production. However, the spatiotemporal trends of these hydroclimatic variables remain uncertain under the changing climate at the regional scale. Therefore, we analyzed hydroclimatic variable trends in the north and northeast regions of Bangladesh for 38 years (1980-2017) using a set of parametric and non-parametric techniques and forecasted by the Autoregressive Integrated Moving Average (ARIMA) model. Based on detrended fluctuation analysis, long-range associations of the hydroclimatic variables suggested that these variables will retain their current trend line in the forthcoming period. Annual temperature and river water discharge exhibited an increasing linear trend of 0.014 degrees C and 0.61 m(3) s(-1) per year, while annual rainfall demonstrated a declining linear trend of - 0.87 mm and resultant in an annual water level decrease of - 0.03 m per year. Seasonal maximum trends were observed for rainfall in the winter (- 2.25 mm), the temperature in monsoon (0.03 degrees C) and water discharge in post-monsoon (10.7 m(3) s(-1)), and water level in post-monsoon (- 0.54 m) per year. The ARIMA model forecasted that the temperature would be increased by 0.14 degrees C/decade and water discharge will be 8.75 m(3) s(-1)/decade, while rainfall and water level will be decreased by 90 mm/decade and 1.24 m/decade respectively for the period 2018-2027. The results found from this research can be a guideline for regional water practices and planning cropping systems in the region.

Automated summary

The study analyzed the trends of hydroclimatic variables in the north and northeast regions of Bangladesh for 38 years and forecasted the changes for the next decade. Findings suggest that annual temperature and river water discharge are increasing, while annual rainfall is decreasing. Seasonal maximum trends were observed in different seasons.