Observations for
Minimum Precipitation for a Return Period of years mm

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Minimum Expected Rainfall Amounts

This map shows the expected minimum yearly rainfall for different return periods for Peru.

In menu>variable you can select the return period: 5, 10, 15, 25, 50, 75 or 100 years. In menu>region you can select a region.

The different return periods indicate the recurrence of an extreme event. For example if the map indicates for a return period of 5 years an expected minimum yearly rainfall of 100 mm this indicates that at this point a yearly rainfall of 100 mm is expected every 5 years.

The method used is a frequency analysis of historical events. Historical precipitation data are used to fit a probabilistic distribution. This distribution is used to identify the frequency with which we may expect rainfall events with a certain magnitude.

The Drought Atlas is provided by the Water Centre for Arid Zones in Latin America and the Caribbean (CAZALAC).

Logo CAZALAC

References

Nunez, J.H., K. Verbist, J. Wallis, M. Schaeffer, L. Morales, and W.M. Cornelis. 2011. Regional frequency analysis for mapping drought events in north-central Chile. J. Hydrol. 405 352-366.

Which method is used to estimate the minimum expected rainfall?

The method used is a frequency analysis of historical events. Historical precipitation data are used to fit a probabilistic distribution. This distribution is used to identify the frequency with which we may expect rainfall events with a certain magnitude.

The method applied takes in consideration the low availability of data, data are grouped in regions with similar climatology. This allows the use of more robust statistics.

To be able to alleviate the effect of extreme events the method is based on L-moments instead of normal moments. In this way extreme events do not affect the selection of the probabilistic distribution. This method is chosen because it is more suitable for the region which is characterized by inter annual variability and short data series.

Here you can find more detailed information on the method.

Dataset Documentation

Data
Drought Atlas of Latin America and the Caribbean Dataset
Data Source
CAZALAC Center, Drought Atlas
Analysis
Regional Frequency Analysis using L-Moments

Helpdesk

Contact mwar_lac@unesco.org with any technical questions or problems with this Map Room.

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