Abstract
Abstract. Most of the actual studies and previews of future rainfall patterns, based on past observed records for Mediterranean climate areas, focus on the decline of the rainfall amounts over the years, and also on the increase of the frequency of heavy/intense rainfall events particularly in the winter season. These changes in heavy rainfall events may have severe implications and impacts on soil erosion resulting in increased soil degradation risks. The objective of the present work is to evaluate the spatial distribution of extreme precipitation events in Southern Portugal, using a geostatistical approach to assess the relationships between spatial and temporal extreme rainfall patterns. The used dataset comprises a set of 105 stations' records of daily precipitation within the period 1960–1999. Two indices of extreme precipitation were selected to be computed based on the daily precipitation observation series: one representing the frequency of extremely heavy precipitation events (R30) and another one characterizing flood events (R5D). The space-time patterns of the precipitation indices were evaluated and simulated using a geostatistical approach. Despite no significant temporal trends were detected on the calculated indices series, the space-time decadal patterns are becoming more continuous in the last two decades than the previous ones.
Highlights
In Mediterranean climate regions, precipitation patterns are highly variable concerning time, space, amount and duration of the events
The use of extreme precipitation indices are recommended by the joint working group on climate change detection of the World Meteorological Organization – Commission for Climatology (WMO-CCL), the Research Programme on Climate Variability and Predictability (CLIVAR) (Peterson et al, 2001), and the CLIVAR/GCOS/WMO workshop on indices and indicators for climate extremes (Karl et al, 1999) that has released a list of recommended indices
– spatial variability, as can be seen from the semivariogram ranges, has decreased over time since the 1960s up to the end of the 20th century. This means that extreme phenomena, characterized by the R5D and R30 indices, have become more spatially homogeneous since ; Fig. 6. (I) Average of the equiprobable images of the R5D index for the decades: (a) 1970–79, (b) 1980–89 and (c) 1990–99; (II) R5D index local variability for the decades: (a) 1970–79, (b) 1980–89 and (c) 1990–99
Summary
In Mediterranean climate regions, precipitation patterns are highly variable concerning time, space, amount and duration of the events. The increasing number of heavy precipitation events increases the flood risk (Hidalgo et al, 2003) Issues such as drought and erosive rainfall have been raising concern about the risks of land degradation and desertification (Lazaro et al, 2001). These changes in heavy precipitation events may have severe implications and impacts on soil erosion resulting in increased soil degradation risks. The use of extreme precipitation indices are recommended by the joint working group on climate change detection of the World Meteorological Organization – Commission for Climatology (WMO-CCL), the Research Programme on Climate Variability and Predictability (CLIVAR) (Peterson et al, 2001), and the CLIVAR/GCOS/WMO workshop on indices and indicators for climate extremes (Karl et al, 1999) that has released a list of recommended indices
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
