Potential impacts of climate and environmental change on the stored water of Lake Victoria Basin and economic implications

Abstract

[1] The changing climatic patterns and increasing human population within the Lake Victoria Basin (LVB), together with overexploitation of water for economic activities call for assessment of water management for the entire basin. This study focused on the analysis of a combination of available in situ climate data, Gravity Recovery And Climate Experiment (GRACE), Tropical Rainfall Measuring Mission (TRMM) observations, and high resolution Regional Climate simulations during recent decade(s) to assess the water storage changes within LVB that may be linked to recent climatic variability/changes and anomalies. We employed trend analysis, principal component analysis (PCA), and temporal/spatial correlations to explore the associations and covariability among LVB stored water, rainfall variability, and large-scale forcings associated with El-Niño/Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). Potential economic impacts of human and climate-induced changes in LVB stored water are also explored. Overall, observed in situ rainfall from lake-shore stations showed a modest increasing trend during the recent decades. The dominant patterns of rainfall data from the TRMM satellite estimates suggest that the spatial and temporal distribution of precipitation have not changed much during the period of 1998-2012 over the basin consistent with in situ observations. However, GRACEderived water storage changes over LVB indicate an average decline of 38.2 mm/yr for [2003][2004][2005][2006], likely due to the extension of the Owen Fall/Nalubale dam, and an increase of 4.5 mm/yr over 2007-2013, likely due to two massive rainfalls in 2006-2007 and 2010-2011. The temporal correlations between rainfall and ENSO/IOD indices during the study period, based on TRMM and model simulations, suggest significant influence of large-scale forcing on LVB rainfall, and thus stored water. The contributions of ENSO and IOD on the amplitude of TRMM-rainfall and GRACE-derived water storage changes, for the period of [2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013], are estimated to be 2.5 cm and 1.5 cm, respectively.

Recent changes in terrestrial water storage in the Upper Nile Basin: an evaluation of commonly used gridded GRACE products

“…4), with two distinct rainy seasons driven by the movement of the Intertropical Convergence Zone (ITCZ) (Awange et al, 2013). Long rains (March-May) and short rains (September-November) account for approximately 40 and 25 % of annual rainfall respectively (Basalirwa, 1995;Indeje et al, 2000).…”

Improving Quantitative Rainfall Prediction Using Ensemble Analogues in the Tropics: Case study of Uganda

“…March-May and September-November). The March-May (MAM) seasonal rainfall over Uganda is generally influenced by the Inter-Tropical Convergence Zone [2,8]; the monsoon winds of East Africa [32,33]; the Indian ocean dipole [2,7]; the humid Congo airmass [6]; the tropical cyclones, semi-permanent subtropical anticyclones and easterly waves [7,8]; the complex topography [33], vegetation and inland water bodies which modulate local rainfall [8,34]. The Inter-Tropical Convergence Zone migrates north and southwards over the equator two times a year, which brings two rainfall seasons in the region i.e.…”

“…Over Eastern Africa, the rainfall distribution and quantity is influenced by many factors such as the Inter-Tropical Convergence Zone, El Niño/La Niña episodes, Indian Ocean Dipole and extra-tropical weather systems [7,8]. The spatial and temporal variability of rainfall makes its quantitative prediction a challenge [8,9].…”

Long-Term Water Storage Changes of Lake Volta from GRACE and Satellite Altimetry and Connections with Regional Climate

“…GRACE estimates have been used to study long-term TWS changes at both global and regional scales [9][10][11][12][13][14]. For example, Humphrey et al [12] investigated the relative importance of linear trend and nonlinear interannual variability in long-term TWS changes throughout the world.…”