Droughts are natural but temporary imbalances of water
availability, consisting of a persistent lower-than-average
precipitation, of uncertain frequency, duration and
severity, of unpredictable or difficult to predict occurrence,
resulting in diminished water resources availability
and impacts on natural and man-made ecosystems.
To successfully cope with drought there is a need to
understand the characteristics and consequences of related
phenomena; however, differences in the perception
of drought lead to difficulties in adopting risk management.
The effectiveness of drought risk management depends
upon drought monitoring, drought prediction and
warning capabilities, and means to provide information
to users, as well as on related awareness of populations.
For drought monitoring and warning, drought indices
are useful. The SPI has been extensively used in Portugal
and stochastic methods have been developed for prediction
of drought class transitions to be used for early
warning. For agricultural purposes, the PDSI was modified
and successfully referred to the rainfed olive crop,
thus originating the MedPDSI. Its evaluation against the
SPI and PDSI shows the appropriateness of this index.
Relative to information systems, a variety of approaches
were used to support deficit irrigation. However, its
economic feasibility is questionable and more studies
are required to assess ways to improve irrigation under
droughtinfo:eu-repo/semantics/publishedVersio
