Research Article Characteristics of Lake Chad Level Variability and Links to ENSO, Precipitation, and River Discharge Churchill Okonkwo, Belay Demoz, and Sium Gebremariam Beltsville Center for Climate System Observation (BCCSO), Atmospheric Science Program, Howard University, Washington, DC 20059, USA Correspondence should be addressed to Churchill Okonkwo; churchill.okonkwo@bison.howard.edu Received 29 May 2014; Revised 15 September 2014; Accepted 28 September 2014; Published 27 November 2014 Academic Editor: Catherine Ottle Copyright © 2014 Churchill Okonkwo et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. his study used trend, correlation, and wavelet analysis to characterize Lake Chad (LC) level luctuations, river discharge, El Ni˜ no Southern Oscillation (ENSO), and precipitation regimes and their interrelationships. Linear correlation results indicate a negative association between ENSO and LC level, river discharge and precipitation. Trend analysis shows increasing precipitation in the Lake Chad Basin (LCB) but decreasing LC level. he mode of interannual variability in LC level, rainfall, and ENSO analyzed using wavelet analysis is dominated by 3-4-year periods. Results show that variability in ENSO could explain only 31% and 13% of variations in LC level at Kindjeria and precipitation in the northern LCB, respectively. he wavelet transform coherency (WTC) between LC level of the southern pool at Kalom and ENSO is statistically signiicant at the 95% conidence level and phase-locked, implying a cause-and-efect association. hese strong coherencies coincide with the La Ni˜ na years with the exception of 1997-1998 El Ni˜ no events. he WTC shows strong covariance between increasing precipitation and LC level in the northern pool at a 2- to 4-year band and 3- to 4-year band localized from 1996 to 2010. Implications for water resource planning and management are discussed. 1. Introduction he Lake Chad Basin (LCB) (latitude 6 ∘ N–24 ∘ N; longitude 7 ∘ E–24 ∘ E) is part of the Sahel, a semiarid region that is prone to drought [1]. Lake Chad (LC), a closed lake at the center of the LCB, is highly sensitive to hydroclimatic events [2]. he LCB hydroclimatic system is inluenced by many factors including precipitation, river discharge, climate indices, tele- connection, and anthropogenic factors [3]. However, formal treatment of anthropogenic contributions to the shrinking of LC is treated elsewhere [4]. Many studies have shown that precipitation in the Sahel region of Africa is inluenced by oceanic conditions impact on atmospheric circulations especially Atlantic Multidecadal Oscillation AMO [5] and El Ni˜ no Southern Oscillation ENSO [6]. his study will focus on the temporal variability of precipitation as relected in time series of precipitation and river discharge in the LCB and global El Ni˜ no Southern Oscillation (ENSO) events. According to the International Panel on Climate Change (IPCC) Fourth Assessment Report, decreases in the size of lakes can be attributed primarily to human use and declining precipitation [7]. Isiorho et al. [8] reported that precipitation is one critical element that determines the amount of inil- tration for groundwater recharge and runof (river low) to the phreatic aquifers southwest of LC. Also, the Komadugu and Yobe Rivers southwest of LC now low for six months of the year instead of nine [9]. he frequent severe drought in the Sahel region, of which LC is a part, is modulated by high- frequency climate variability in ENSO [6]. he ENSO system, a coupled cycle of atmosphere and ocean [10], has been linked to global climatic anomalies [11]. his phenomenon has received huge attention due to its apparent catastrophic impacts including looding and droughts. Studies on the role of ENSO events and the Paciic index in modulating precipitation in the Sahel region include those by Caminade et al. [6, 12]. El Ni˜ no results in the weaken- ing of West African Monsoon (WAM) low and creates a dry condition across the Sahel region. La Ni˜ na, on the other hand, creates a wet condition through the enhancement of Walker circulation [13]. Hwang et al. [14] studied the link between Hindawi Publishing Corporation e Scientific World Journal Volume 2014, Article ID 145893, 13 pages http://dx.doi.org/10.1155/2014/145893