International Rainwater Catchment Systems Conference
Catchment: An Answer to the Water Scarcity of the Next Millennium."
Petrolina, Brazil - July 1999
Section 3: Rainwater Catchment and Droughts
Richard J. Heggen
Department of Civil Engineering
University of New Mexico, USA
Rainwater catchment is an anticipatory response to drought.
Catchment design requires a prudent definition of target drought. Target
drought might be a normal dry season, two rainless weeks, etc. Definition is by
both duration and depth of precipitation. Target draught is often a balance
drawn from past hydrologic history, consequences of rainwater catchment system
failure, social implications and public acceptance. Most of the numerous
drought indices are inappropriate as catchment performance targets. This paper
briefly reviews drought definitions and suggests an analysis for identifying
proper rainwater catchment design criteria.
Analysis must anticipate the variety of meteorological
futures that a catchment might experience. Stochastic analysis improves
understanding of probable catchment behavior and the risks associated with
alternative catchment designs. Drought Duration Depth Frequency analysis allows
the time step for which a system is sized to be matched to the duration of
drought. An example illustrates such assessment.
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