Water is vital for life. Since the dawn of civilization, much effort has
been made to harness sources of fresh water. Recent years have raised
global awareness of the need for increasing demand of water worldwide,
largely because of growing population, rising standard of living, higher
demand for energy, and greater appreciation for environmental quality.
As an example, the world population has increased threefold in the past
five decades. In order to meet the rising water demand, water resources
are being developed by building large dams, reservoirs, barrages and
weirs across rivers worldwide. The guiding principle for water resources
development has been to ensure adequate supply of water for agriculture,
domestic use (including fine drinking water), waste disposal,
industries, and energy production, with due attention to maintain the
ecosystem functions. This development, however, depends on a holistic,
cooperative and scientific approach. The basic inputs in the assessment
of water resources for a given region are from hydrological data and the
subject of hydrology forms the core in achieving sustainable development
of water resources. Barring a few exceptions, hydrological data for most
river basins are sparse and therefore it is difficult to comprehensively
assess their water resources. The major source of water is rainfall
which occurs as a result of condensation of atmospheric moisture
governed by the science of meteorology.
