| dc.description.abstract | Since the 1970s, West African streams experienced profound modifications
connected to pluviometric deficit, which have influenced on a strong decrease of water
resources. The objective of this study is to analyze trends of precipitation at the six
selected stations in the Senegalese part of Gambia River basin, using graphical and
statistical approach. Methodology is consisted of an analysis of monthly, seasonal and
annual variability of precipitation for the 1971-2010 period, through Non-parametric tests.
Study revealed a strong variability and often a contrasting evolution between various
stations (Kédougou, Simenti, Tambacounda, Kounghel, Nioro and Goudiry). Between the
periods 1971-1990 and 1991-2010, the value U of Mann-Whitney, had changed from 60 to
40 at Tambacounda, 64 to 59 at Kédougou and 63 to 51 at Simenti station, which showed
non-significant trends in annual total precipitation for the studied period. Sen’s estimator
revealed significant descending trends on Kédougou station (9.812 mm/year for the
period 1971-1990 and 0.309 mm/year for the period 1991-2010), and Simenti station too.
On the other hand (in the whole article), on the stations of Tambacounda, Goudiry and
Koungheul, the reduction is noticed for the period 1971-1990 (3.658 mm/year on
Tambacounda), and an increase is noticed in the period 1991-2010 (13.21 mm/year on
Tambacounda). For the station Nioro, on other hand, increase is noted in both periods
(3.801 mm/year and 8.841 mm/year). The assumption is that these significant trends of
precipitation during the last four decades could be attributed to the climate changes.
Key words: rainfall, trend, non-parametric tests, Gambia River, Senegal | en_US |
