Geoscience Reference
In-Depth Information
12
Analysis of Trend and Periodicity
in Long-Term Annual Rainfall
Time Series of Nigeria
12.1 Introduction
Understanding trends and variations of current and historical hydroclimatic
variables is pertinent to the future development and sustainable management
of water resources of a particular region. Information regarding
hydroclimatological issues is important within the context of global warming,
water and energy cycles and the increasing demand for water due to population
and economic growth (Sankarasubramanian and Vogel, 2003; Oguntunde et
al., 2006). Changes in the climate system and land cover have been widely
accepted to have important consequences for regional to global water resources
management and conservation. The extent to which human alteration of earth's
environment affects the global hydrologic cycle is still largely unknown
(Szilagyi, 2001). Valuable historical records of hydrologic patterns over
complex drainage basins help to understand anthropogenic and climatic effects
on large-scale terrestrial ecosystems (Vörösmarty and Sahagian, 2000). One
of the very important necessities of research into climate change is to analyze
and detect historical changes in the climatic system (Houghton et al., 1996).
Rainfall is a principal element of the hydrological cycle, hence understanding
its behaviour may be of profound social and economic significance. Detection
of trends and oscillations in the rainfall time series yields important information
for understanding the climate. However, rainfall changes are particularly hard
to gauge, because rainfall is not uniform and varies considerably from place
to place and time to time, even on small scales.
Invited contribution by
Philip G. Oguntunde - Department of Agricultural Engineering,
the Federal University of Technology, Akure, Nigeria and Babatunde
J. Abiodun - Department of Environmental and Geographical Science,
University of Cape Town, South Africa.
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