Changes and variation in the discharge regime of the Upper Suriname River Basin and its relationship with the tropical Pacific and Atlantic SST anomalies

Long-term changes and variability in river flows in the tropical Upper Suriname River Basin in Suriname (2-6 degrees N, 54-58 degrees W) are analysed, including the relation to sea surface temperatures (SSTs) in the tropical Atlantic and Pacific Ocean. To analyse variability, lag correlation and statistical properties of the data series are used. Long-term changes are analysed using parametric and non-parametric statistical techniques. The analyses are performed for the period 1952-1985. The results show that both river discharge series at Semoisie and Pokigron are non-stationary and have a negative trend. The negative rainfall trend in the centre of Suriname may be responsible for the negative trend in the annual river discharges in the basin. The highest correlation (Pearson's coefficient c) is obtained when the Tropical North Atlantic (TNA) SSTs lags the monthly discharges at Pokigron by 3-4 months (c = 0.7) and when the Tropical South Atlantic (TSA) SSTs lags the discharges by 4 months (c = -0.7). It also follows that the high (low) monthly flows, from April-August (September-March) are associated with increasing (decreasing) SSTs in the TNA and with decreasing (increasing) SSTs in the TSA. The results also reveal that years with low (high) discharges are more related to warmer (colder) SSTs during the year in the TNA region and a southward displacement of the Inter-Tropical Convergence Zone (ITCZ). However, the Pacific El Nino (La Nina) events may also be responsible for low (high) flow years in this basin. Copyright (C) 2007 John Wiley & Sons, Ltd.