Precipitation Concentration in Bangladesh over Different Temporal Periods

Abstract EN

Precipitation concentration is an important component of climate, and an unbalanced distribution of precipitation can yield excess or scarcity of water resources, which in turn can influence plant growth, flood risk, and water resource use.

The precipitation concentration index (PCI) is a well-known indicator for the measurement of temporal precipitation in a short or long area.

The purpose of this study was to analyze precipitation concentration rates in different regions of Bangladesh using the precipitation concentration index (PCI) and the inverse distance weighting method.

In this study, the rainfall data from 30 meteorological observatory stations across Bangladesh were collected for the period 1980 to 2011.

We defined periods of varying lengths (i.e., annual, supraseasonal, seasonal, and three- and two-month rainfall concentrations) and compared their PCI values.

The results showed that precipitation concentrations were mostly irregular when rainfall was concentrated within two to four months of the year.

Higher PCI values were mainly identified in the eastern region and have strong seasonal influences, whereas lower PCI values were mostly observed in the northern region.

The analyses of periodic variation and precipitation in Bangladesh generally follow through the SW–NE direction due to the summer monsoon, while during the winter monsoon, they follow the N–S direction where JAS and JFM showed higher and lower PCI values.

We observed variations in PCI among different regions using the Kruskal–Wallis test of the mean PCI on a decadal scale (1980–1989, 1990–1999, and 2000–2011).

The result showed that significant changes in the precipitation occurred during the period of 1980–2011.

At a two-month scale, significant changes were identified during transition periods where PCI values were lower from 2000 to 2011 than those in the earlier decades.