Time filter

Source Type

Moutahir H.,University of Alicante | Bellot P.,University of Barcelona | Monjo R.,Climate Research Foundation FIC Madrid Spain | Bellot J.,University of Alicante | And 2 more authors.
Hydrological Processes | Year: 2016

Groundwater resources are typically the main fresh water source in arid and semi-arid regions. Natural recharge of aquifers is mainly based on precipitation; however, only heavy precipitation events (HPEs) are expected to produce appreciable aquifer recharge in these environments. In this work, we used daily precipitation and monthly water level time series from different locations over a Mediterranean region of Southeastern Spain to identify the critical threshold value to define HPEs that lead to appreciable aquifer recharge in this region. Wavelet and trend analyses were used to study the changes in the temporal distribution of the chosen HPEs (≥20mmday-1) over the observed period 1953-2012 and its projected evolution by using 18 downscaled climate projections over the projected period 2040-2099. The used precipitation time series were grouped in 10 clusters according to similarities between them assessed by using Pearson correlations. Results showed that the critical HPE threshold for the study area is 20mmday-1. Wavelet analysis showed that observed significant seasonal and annual peaks in global wavelet spectrum in the first sub-period (1953-1982) are no longer significant in the second sub-period (1983-2012) in the major part of the ten clusters. This change is because of the reduction of the mean HPEs number, which showed a negative trend over the observed period in nine clusters and was significant in five of them. However, the mean size of HPEs showed a positive trend in six clusters. A similar tendency of change is expected over the projected period. The expected reduction of the mean HPEs number is two times higher under the high climate scenario (RCP8.5) than under the moderate scenario (RCP4.5). The mean size of these events is expected to increase under the two scenarios. The groundwater availability will be affected by the reduction of HPE number which will increase the length of no aquifer recharge periods (NARP) accentuating the groundwater drought in the region. © 2016 John Wiley & Sons, Ltd.

Monjo R.,Climate Research Foundation FIC Madrid Spain | Gaitan E.,Climate Research Foundation FIC Madrid Spain | Portoles J.,Climate Research Foundation FIC Madrid Spain | Ribalaygua J.,Climate Research Foundation FIC Madrid Spain | Torres L.,Climate Research Foundation FIC Madrid Spain
International Journal of Climatology | Year: 2015

The Mediterranean coast of Spain often experiences intense rainfall, sometimes reaching remarkable amounts of more than 400 mm in one day. The aim of this work is to study possible changes of extreme precipitation in Spain for this century, simulated from several Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models. Eighteen climate projections (nine models under RCP4.5 and nine RCP8.5 scenarios) were downscaled using a two-step analogue/regression statistical method. We have selected 144 rain gauges as the rainiest of a network by using a threshold of 250 mm in one day for a return period of 100 years. Observed time-series have been extended using the ERA40 reanalysis and have subsequently been used to correct the climate projections according to a parametric quantile-quantile method. Five theoretical distributions (Gamma, Weibull, Classical Gumbel, Reversed Gumbel and Log-logistic) have been used to fit the empirical cumulative functions (entire curves, not only the upper tail) and to estimate the expected precipitation according to several return periods: 10, 20, 50 and 100 years. Results in the projected changes for 2051-2100 compared to 1951-2000 are similar (in terms of sign and value) for the four return periods. The analysed climate projections show that changes in extreme rainfall patterns will be generally less than the natural variability. However, possible changes are detected in some regions: decreases are expected in a few kilometres inland, but with a possible increase in the coastline of southern Valencia and northern Alicante, where the most extreme rainfall was recorded. These results should be interpreted with caution because of the limited number of climate projections; anyway, this work shows that the developed methodology is useful for studying extreme rainfall under several climate scenarios. © 2015 Royal Meteorological Society.

Loading Climate Research Foundation FIC Madrid Spain collaborators
Loading Climate Research Foundation FIC Madrid Spain collaborators