Potential impacts of climate and environmental change on the stored water of Lake Victoria Basin and economic implications
Western Australian Centre for Geodesy, Institute for Geoscience Research, Curtin University, Perth, WA 6102, Australia; Department of Natural Resources and the Environment, University of Connecticut, Storrs, CT, United States; Graduate School of Global Studies, Doshisha University, Kyoto, Japan; Institute of Geodesy and Geoinformation, Bonn University, Bonn, Germany; IGAD Climate Prediction and Applications Centre, Nairobi, Kenya
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 2003-2006, 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 2003-2013, are estimated to be ∼2.5 cm and ∼1.5 cm, respectively. © 2013. American Geophysical Union. All Rights Reserved.
Climatic variability; Economic implications; Gravity recovery and climate experiments; In-situ observations; Regional climate simulation; Spatial and temporal distribution; Temporal correlations; Tropical rainfall measuring missions; Climatology; Computer simulation; Digital storage; Economics; Geodetic satellites; Lakes; Principal component analysis; Rain gages; Water management; Rain; anthropogenic effect; basin management; climate effect; climate modeling; economic activity; El Nino-Southern Oscillation; environmental change; GRACE; lake water; numerical model; population growth; principal component analysis; rainfall; regional climate; shore (nonmarine); spatial distribution; temporal distribution; TRMM; water storage; water use; East African Lakes; Lake Victoria