Statistical Analysis of Recent and Future Rainfall and Temperature Variability in the Mono River Watershed (Benin, Togo)

Author : Lawin Agnidé Emmanuel ; Nina Rholan Hounguè; Chabi Angelbert Biaou; Djigbo Félicien Badou, .


This paper assessed the current and mid-century trends in rainfall and temperature over the
Mono River watershed. It considered observation data for the period 1981–2010 and projection data
from the regional climate model (RCM), REMO, for the period 2018–2050 under emission scenarios
RCP4.5 and RCP8.5. Rainfall data were interpolated using ordinary kriging. Mann-Kendall, Pettitt
and Standardized Normal Homogeneity (SNH) tests were used for trends and break-points detection.
Rainfall interannual variability analysis was based on standardized precipitation index (SPI), whereas
anomalies indices were considered for temperature. Results revealed that on an annual scale and
all over the watershed, temperature and rainfall showed an increasing trend during the observation
period. By 2050, both scenarios projected an increase in temperature compared to the baseline period
1981–2010, whereas annual rainfall will be characterized by high variabilities. Rainfall seasonal cycle
is expected to change in the watershed: In the south, the second rainfall peak, which usually occurs in
September, will be extended to October with a higher value. In the central and northern parts, rainfall
regime is projected to be characterized by late onsets, a peak in September and lower precipitation
until June and higher thereafter. The highest increase and decrease in monthly precipitation are
expected in the northern part of the watershed. Therefore, identifying relevant adaptation strategies
is recommended.
Keywords: Mono River watershed; trend analysis; climate


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