Spatiotemporal changes of precipitation and runoff under climate change in the Meghna basin: Implications for future water resource management

Muhammad Masood, Kuniyoshi Takeuchi

Wednesday 1 july 2015

11:15 - 11:30h at North America (level 0)

Themes: (T) Extreme events, natural variability and climate change, (ST) Hydrological extremes: floods and droughts

Parallel session: 9I. Extreme events - Flood Drought

The copious precipitation in the Meghna basin has remarkable consequences for flash floods in the north-eastern region of Bangladesh. In addition, due to climate change more frequent extreme precipitation may also increase the frequency and intensity of flash floods. However, the assessment of climate change impacts by using well-calibrated hydrologic modelling has seldom been conducted in the Meghna basin due to data constraint. This study investigates the spatio-temporal changes of precipitation and runoff under climate change by applying hydrologic model H08 using the super-high-resolution (20-km) MRI-AGCM3.2S through three time-slice experiments; the current (1979–2003), the near-future (2015-2039), and the far-future (2075–2099) periods. The study revealed that the projected maximum increment of mean annual precipitation (runoff) is +23% (+34%) and +31% (+39%) during the near-future and far-future. The projected increment of median value of monthly discharges at basin outlet is significantly high in wet period (May-July), ranging from 38-44% and 25-104% in the near-future and far-future, respectively. Probability plot of annual maxima series of discharges also shows the higher probability of strong annual peak in the future. Moreover, the monsoonal peaks are expected to come about 1~1.5 month earlier, which ultimately lead to higher possibility of earlier flash flood in the future. This anticipated higher increment in peak discharge as well as future shifting of seasonal cycle of river discharge will have significant implications for future water resource management especially for agriculture and flood disaster management.