Time-scale characteristics of Kasai river hydrological regime variability for 1940-1999

TL;DR

This study analyzes the nonstationary variability of the Kasai River's hydrological regime from 1940 to 1999 using wavelet analysis, revealing fluctuating patterns, oscillations, and weak climate connections.

Contribution

It applies wavelet analysis to characterize the multi-scale variability and nonstationarity of the Kasai River hydrology over six decades.

Findings

Strong annual oscillation in rainfall and discharge patterns

Intermittent oscillations at 2-8 and 8-16 year scales

Weak correlation between hydrological variables and climate indices

Abstract

The present study was undertaken with the aim of contributing to the characterization of the nonstationary variability of the hydrological regime of the Kasai River using the wavelet analysis for 1940-1999. The rainfalls and discharge over Kasai Basin have marked fluctuations with a perceptible downward trend and some shift around 1950, 1960, 1970, 1983 and 1994. The results show that rainfalls over Kasai basin and the discharge at Ilebo station patterns exhibit a strong annual oscillation and some intermittent oscillations in 2-8 years (1950-1975, 1983-1995) and 8-16 years (1970-1999) time scales. The wavelet coherence analysis reveals a weak possible connection between hydrological variables (rainfalls, discharge) and climate indices relative to sea surface temperature and atmospheric circulation over Atlantic tropical, Indian and Pacific Oceans (coherence less than 0.55).