Search results for "rainfall"
showing 10 items of 233 documents
Physically based modeling of rainfall-triggered landslides: a case study in the Luquillo forest, Puerto Rico
2013
This paper presents the development of a rainfall-triggered landslide module within an existing physically based spatially distributed ecohydrologic model. The model, tRIBS-VEGGIE (Triangulated Irregular Networks-based Real-time Integrated Basin Simulator and Vegetation Generator for Interactive Evolution), is capable of a sophisticated description of many hydrological processes; in particular, the soil moisture dynamics are resolved at a temporal and spatial resolution required to examine the triggering mechanisms of rainfall-induced landslides. The validity of the tRIBS-VEGGIE model to a tropical environment is shown with an evaluation of its performance against direct observations made w…
Compared regimes of NDVI and Rainfall in semi-arid regions of Africa
2006
International audience; Bi-monthly normalized difference vegetation index (NDVI) at an 8km spatial resolution from the advanced very high resolution radiometers (AVHRR) was used from 1981 to 1995 to analyse the vegetation response to rainfall supply in semi-arid regions of Africa. Within the 200-600 mm annual rainfall belt, for which the apparent NDVI response to rainfall was the strongest, three regions were selected which exhibited different patterns in their NDVI regimes and/or relationships with rainfall. The regions, located in western, southern and eastern Africa, were split into coherent sub-regions in terms of mean regime of photosynthetic activity through a cluster analysis. Overal…
Relationship Between Extreme Rainfall and Surface Temperature in Sicily (Italy)
2018
The study of the relationship between extreme rainfall events and surface temperature represents an important issue in hydrology and meteorology and it could be of capital importance for evaluating the effect of global warming on future precipitation. Various approaches have been tested across different parts of the world, and, in many cases, it has been observed an intensification of precipitation with increasing temperature consistently with the thermodynamic Clausius-Clapeyron relation (CC-rate of 6-7% °C-1), according to which a warmer atmosphere is capable of holding more moisture. Nevertheless, in different locations, the scaling rate between temperature and extreme precipitation has …
Assessment of soil particle erodibility and sediment trapping using check dams in small semi-arid catchments
2017
Check dams can be used as a source of information for studies on sediment characteristics and soil particle erodibility. In this study, sediment yield and grain size distribution (GSD) were measured in twenty small catchments draining into a rock check dam in NW Iran for different runoffs during 2010–2011. Significant correlations were found between sediment yield and slope steepness, vegetation cover and soil erodibility factor (K) of the catchments. The erodibility of soil particles was determined using the comparison of GSD between sediment and original soil. Clay was the most erodible soil particle which showed 2.05 times more percentage in sediment than the original soil. The erodibili…
REGIONAL FREQUENCY ANALYSIS FOR EXTREME RAINFALL IN SICILY
2008
AN INTEGRATED SYSTEM FOR THE ANALYSIS OF RAINFALL-TRIGGERED LANDSLIDES
2011
La presente ricerca mira a fornire un sistema integrato per l'analisi delle frane attivate da precipitazioni, sviluppando due diverse metodologie: un'analisi statica per l'individuazione delle zone maggiormente propense a produrre scivolamenti (susceptibility mapping) su scala spaziale regionale, ed un'analisi dinamica per la prevision del dove e quando un evento franoso potrebbe veri carsi, ad una scala spaziale di maggior dettaglio . L'analisi statica comporta lo sviluppo di modelli statistici in grado di stimare la probabilità di eventi franosi, sulla base della correlazione tra fattori predisponenti le frane e gli eventi storici. L'esito dell'analisi è la derivazione di una mappa suscet…
Diagnosis and predictability of intraseasonal characteristics of wet and dry spells over equatorial east Africa
2010
Most of Eastern Africa has arid and semi-arid climate with high space-time variability in rainfall. The droughts are very common in this region, and often persist for several years, preceded or followed by extreme floods. Most of the livelihoods and socio-economic activities however remain rain-dependent leading to severe negative impacts during the periods of occurrence of climate extremes. It has been noted that one extreme event was capable of reversing national economic growth made over a period of several years. Thus no sustainable development can be attained in eastern Africa without effective mainstreaming of climate information in the development policies, plans and programmes. Many…
The influence of ENSO on winter rainfall in South Africa
2011
Whereas the impact of ENSO on the African summer rainfall regions is largely documented and still regularly investigated, little is known about its impact on the winter rainfall regions located at the southwestern and northwestern tips of Africa. Yet, these regions are densely inhabited and are net exporters of high-quality agricultural products. Here we analyze the relationship between El Nino Southern Oscillation (ENSO) and South Africa austral winter rainfall using a 682 raingauges daily rainfall database documenting the period 1950–1999. The May, June and July (MJJ) seasonal rainfall amount shows a positive correlation with the Nino3.4 index that becomes significant since the so-called …
Estimating rainfall erosivity by aggregated drop size distributions
2016
Rainfall erosivity is defined as the potential of the rain to cause erosion, and it can be represented by rainfall kinetic power. At first in this paper, the raindrop size distributions (DSD) measured by an optical disdrometer located at Palermo in the period June 2006–March 2014 and aggregated for intensity classes, are presented. Then an analysis of raindrop size characteristics is carried out, and the reliability of Ulbrich's distribution, using both the maximum likelihood and momentum estimate parameter methods, is tested. The raindrop size measurements are used to determine the experimental rainfall kinetic power values, which are compared with the ones calculated by a theoretically de…