Time filter

Source Type

Diodato N.,Met European Research Observatory | Knight J.,University of Witwatersrand | Bellocchi G.,Met European Research Observatory | Bellocchi G.,French National Institute for Agricultural Research
Global and Planetary Change | Year: 2013

Multivariate geostatistical modeling can be used to generate spatial patterns of hydro-climate data over ungauged regions, but these models may be unsuitable when the hydro-climatological data available over large and remote areas are sparse and show different scales of resolution. In these cases, reduced complexity modeling can be better used in order to increase understanding of hydrological extremes at spatial scales and over time periods not covered by rainfall records. In this study we present and evaluate the African Rainfall Erosivity Subregional Empirical Downscaling (ARESED) model which has been developed based on hydro-climatological and geotopographic data from 46 stations across Africa with very varied climates and elevations. We spatially downscale the 85th percentile of monthly precipitation, based on several decades of data, from 50. km to 10. km grid squares in order to predict values of rainfall erosivity across Africa. This yields inputs comparable to values based on the standard Revised Universal Soil Loss Equation (RUSLE). The 46 African stations were chosen for model development because they are also sites for which there are RUSLE-based erosivity values. Once parameterized to capture mean rainfall erosivity over several decades, the ARESED model was run as a validation tool, comparing the output with actual erosivity data. On a continental scale and over decadal time scales, the ARESED model captures most of the important processes within the hydro-climatological system. Its reduced complexity structure also makes it suitable for application to regional management and environmental planning. © 2012 Elsevier B.V..

Diodato N.,Met European Research Observatory | Bellocchi G.,Met European Research Observatory | Bellocchi G.,French National Institute for Agricultural Research
Global and Planetary Change | Year: 2012

This paper presents and assesses the Decadal Rainfall Erosive Multiscale Model (DREMM), in which extreme precipitation data (95th percentile) are used to estimate decadal-scale rainfall-runoff erosivity values compatible with the Universal Soil Loss Equation and its revision - (R)USLE. The test area was a large region including central Europe and Mediterranean countries, in which 111 decades from 88 weather stations (ranging from about 3 to 1680. m above sea level) with rain and (R)USLE rainfall-runoff erosivity data were available. The construction of the model is simplified to a location-explicit term and to the understanding that the most erosive rainfalls are those recorded during the summertime and the beginning of autumn (May-October). These precipitation events are suitable for use in spatial and temporal climate variability studies on decadal time-scales. Once parameterized to capture decadal rainfall-runoff erosivity variability over central Europe and the Mediterranean, the DREMM was run to produce spatial patterns of rainfall-runoff erosivity in Germany and Bulgaria, compared to maps from the (R)USLE approach for 1961-1990. Implications for rainfall-runoff erosivity modelling were discussed concluding that a limited number of parameters may be sufficient to represent decadal rainfall-runoff erosivity for the central European and Mediterranean region. A transferable approach is recommended by employing the DREMM to assess the spatial impact of rainfall extremes. Its use to characterize the long-term dynamics of rainfall-runoff erosivity may also be of value in climate investigation. © 2012 Elsevier B.V..

Diodato N.,Met European Research Observatory | Gericke A.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Bellocchi G.,Met European Research Observatory | Bellocchi G.,French National Institute for Agricultural Research
Catena | Year: 2012

Pulsing storms and prolonged rainfall events have been associated to floods, soil erosion and nutrient fluxes in many European river catchments. This motivated us to develop a parsimonious approach to model the climate forcing on sediment yields in a mountainous Austrian-German river catchment. The hydro-climatologic forcing was interpreted by the novel RAMSES (RAinfall Model for SEdiment yield Simulation) approach to estimate the annual sediment yields. We used annual data on suspended-solid yields at the gauge Füssen, monitored from 1924 to 2003, and monthly rainfall data. The dataset was split into the period 1924-1969 for calibration and the period 1970-2003 for validation. The quality of sediment yield data was critically examined, and a few outlying years were identified and removed from further analyses. These outliers revealed that our model underestimates exceptionally high sediment yields in years of severe flood events. For all other years, the RAMSES performed well against the calibration set, with a correlation coefficient (. r) equal to 0.83 and a Nash-Sutcliffe Index (. NSI) of 0.69. The lower performance in the validation period (. r=. 0.61, . NSI=. 0.36) has to be partly attributed to discontinuities in the monitoring strategy. For the calibration dataset, monthly precipitations proved nonetheless to be better predictors for annual sediment yields than annual values. These first results lay the foundation for reconstructing intra- to inter-decadal variability of sediment yields in river catchments where detailed precipitation records are not available as well as for the reconstruction of historical sediment yields. © 2012 Elsevier B.V.

Diodato N.,Met European Research Observatory | Brocca L.,CNR Research Institute for Geo-hydrological Protection | Bellocchi G.,Met European Research Observatory | Bellocchi G.,French National Institute for Agricultural Research | And 2 more authors.
Hydrological Processes | Year: 2014

Complexity-reduction modelling can be useful for increasing the understanding of how the climate affects basin soil moisture response upon historical times not covered by detailed hydrological data. For this purpose, here is presented and assessed an empirical regression-based model, the European Soil Moisture Empirical Downscaling (ESMED), in which different climatic variables, easily available on the web, are addressed for simplifying the inherent complexity in the long-time studies. To accommodate this simplification, the Palmer Drought Severity Index, the precipitation, the elevation and the geographical location were used as input data in the ESMED model for predicting annual soil moisture budget. The test area was a large region including central Europe and Mediterranean countries, and the spatial resolution was initially set at 50km. ESMED model calibration was made according to the soil moisture values retrieved from the Terrestrial Water Budget Data archive by selecting randomly 285 grid points (out of 2606). Once parameterized, ESMED model was performed at validation stage both spatially and temporally. The spatial validation was made for the grid points not selected in the calibration stage while the comparison with the soil moisture outputs of the Global Land Data Assimilation System-NOAH10 simulations upon the period 1950-2010 was carried out for the temporal validation. Moreover, ESMED results were found to be in good agreement with a root-zone soil moisture product obtained from active and passive microwave sensors from various satellite missions. ESMED model was thus found to be reliable for both the temporal and spatial validations and, hence, it might represent a useful tool to characterize the long-term dynamics of soil moisture-weather interaction. © 2013 John Wiley & Sons, Ltd.

Borrelli P.,European Commission - Joint Research Center Ispra | Diodato N.,Met European Research Observatory | Panagos P.,European Commission - Joint Research Center Ispra
International Journal of Digital Earth | Year: 2016

Soil erosion by water is a serious threat for the Mediterranean region. Raindrop impacts and consequent runoff generation are the main driving forces of this geomorphic process of soil degradation. The potential ability for rainfall to cause soil loss is expressed as rainfall erosivity, a key parameter required by most soil loss prediction models. In Italy, rainfall erosivity measurements are limited to few locations, preventing researchers from effectively assessing the geography and magnitude of soil loss across the country. The objectives of this study were to investigate the spatio-temporal distribution of rainfall erosivity in Italy and to develop a national-scale grid-based map of rainfall erosivity. Thus, annual rainfall erosivity values were measured and subsequently interpolated using a geostatistical approach. Time series of pluviographic records (10-years) with high temporal resolution (mostly 30-min) for 386 meteorological stations were analysed. Regression-kriging was used to interpolate rainfall erosivity values of the meteorological stations to an Italian rainfall erosivity map (500-m). A set of 23 environmental covariates was tested, of which seven covariates were selected based on a stepwise approach (mostly significant at the 0.01 level). The interpolation method showed a good performance for both the cross-validation data set ((Formula presented.) = 0.777) and the fitting data set (R2 = 0.779). © 2016 The Author(s). Published by Taylor & Francis.

PubMed | University of Aarhus, University of Natural Resources and Life Sciences, Vienna, CSIC - Aula Dei Experimental Station, European Commission - Joint Research Center Ispra and 13 more.
Type: | Journal: The Science of the total environment | Year: 2016

Rainfall erosivity as a dynamic factor of soil loss by water erosion is modelled intra-annually for the first time at European scale. The development of Rainfall Erosivity Database at European Scale (REDES) and its 2015 update with the extension to monthly component allowed to develop monthly and seasonal R-factor maps and assess rainfall erosivity both spatially and temporally. During winter months, significant rainfall erosivity is present only in part of the Mediterranean countries. A sudden increase of erosivity occurs in major part of European Union (except Mediterranean basin, western part of Britain and Ireland) in May and the highest values are registered during summer months. Starting from September, R-factor has a decreasing trend. The mean rainfall erosivity in summer is almost 4 times higher (315MJmmha

Diodato N.,Met European Research Observatory | Fiorillo F.,University of Sannio
Water and Environment Journal | Year: 2013

Climate variability induces considerable interannual fluctuations in spring discharge, especially in mountain areas, where groundwater is recharged mainly by rain and snow melt. This study presents the discharge climatological model (DISCLIM), which was developed to test a complexity-reduced approach to perform historical reconstruction in the lack of physical assumptions. The Mount Cervialto aquifer (Southern Italy) is the test site, where a powerful karst spring is monitored since the 1920s and is very sensitive to climatic conditions. DISCLIM incorporates seasonal precipitation and climate indicators only. Despite its simplicity, DISCLIM has been able to well estimate the yearly fluctuations of discharge hydrological, explaining about 90% of the interannual variability at the calibration stage, and more than 80% at validation stage. This means that DISCLIM can be easily used for estimating the discharge in historical times, when no all the hydrological balance data are available for the purpose. © 2012 CIWEM.

Diodato N.,Met European Research Observatory | Diodato N.,University of Sannio | Guerriero L.,University of Sannio | Fiorillo F.,University of Sannio | And 4 more authors.
Water Resources Management | Year: 2014

Current precipitation and past climate variability induce considerable intermonthly fluctuations in spring discharges. This study presents the DISHMET model (Discharge Hydro-Climatological Model) developed to perform historical spring reconstructions in the lack of physical assumptions. We analyzed discharge data of the Caraventa spring, located on the southern side of Mount La Montagna in Southern Italy, which has been monitored since the 1996s. The La Montagna aquifer is tectonically and litologically complex and deformed bedding controls the groundwater flow. Due to this aspect a parsimonious model should be more suitable than a complex model in spring discharge estimation. Thus, the DISHMET model incorporates monthly and annual precipitation only. The model is able to estimate sufficiently well the monthly fluctuations of groundwater discharge. DISHMET can be easily used to assess historical discharge, even when hydrological data is discontinuously available. The magnitude of this discharge is linked to the frequency and type of weather patterns transiting over the central Mediterranean area during the autumn and winter seasons. It is mainly related to the local precipitation that recharges the Mt. La Montagna aquifer. An analysis of antecedent rainfall and spring discharge reveal moderate to strong relationships. © 2014 Springer Science+Business Media Dordrecht.

Enzi S.,Kleio ass. | Bertolin C.,CNR Institute of atmospheric Sciences and Climate | Diodato N.,Met European Research Observatory
Holocene | Year: 2014

Snow events are not a rare episode in Mediterranean area, especially in northern and hilly areas of Italy. However, snowfall occurring quasi-simultaneously in the whole peninsula is extraordinary. This study collects, reconstructs, and analyzes the extraordinary snowfall episodes that occurred simultaneously in the whole Italian peninsula since 1709. This is the longest snowfall time series in the central Mediterranean area. The data, obtained by several documentary sources (from ancient archival to online databases), have been analyzed using different statistical tests, in order to explore normality, homogeneity, and stationarity. The results are characterized by a time-series stationarity with a quasi 60- and 100-year-dominant oscillation. No clear trend in the snowfall episode records is found. The 60-year cycle roughly matches with global-scale oscillations linked to natural forces, such as the Atlantic Multidecadal Oscillation and the winter North Atlantic Oscillation. Particular attention was directed to analyze the impact of snowfall on pre-industrial society, underlining the differences among northern and central regions, where snow was a more usual phenomenon, and its impact was mainly on transports of supplies or exceptionally on buildings, and southern regions, where it had a stronger impact also on orchards and cattle. © The Author(s) 2014.

Diodato N.,Met European Research Observatory | Bellocchi G.,Met European Research Observatory
Earth Interactions | Year: 2010

Earth ecosystems are not static, and they respond to environmental changes, particularly climatic and anthropogenic. Precipitation varying in its extremeness, with shifts to greater or lesser intensity of individual storms and/or to change in the length and frequency of wet and dry periods, can adversely affect both urban and rural ecosystems. Here, the authors review longterm precipitation records of the central Mediterranean area and employ a Web geographical information system (GIS)-based analytical approach to compare current rainfall impact with historical data on different spatial and temporal scales. Autumn (September-November) was recognized as the most hazardous season that marks the evidence of a changing climate, with a shift toward more intense rainfalls in recent times. In the first decade of the third millennium, areas of peninsular and insular Italy have been especially affected by extreme rains. A focus was put on the island of Sicily, where extraordinary rain events occurred in September 2009, discussed in the context of upcoming trends and climate histories. An improved knowledge and understanding of the scale at which changes on extremes occur is essential for dealing with the forthcoming challenges regarding soil and water conservation practices. The characteristics of changes in natural rainfall, its role on terrestrial ecosystems, and its effect on surface water erosion dynamics are discussed. It is argued that understanding these issues are major priorities for future research to promote a better understanding of the Earth interaction with water resources and related hydrological issues.

Loading Met European Research Observatory collaborators
Loading Met European Research Observatory collaborators