Rainfall changes and rainfall erosivity increase in the Algarve (Portugal)
There is evidence that, between hydrological years 1931/2 and 1990/1, rainfall changed in the Algarve. There was an annual rainfall increase (+9%) and a (7%) increase in rainfall during the rainy period (October to February). Both trends were
statistically confirmed by parametric and nonparamertric procedures. Rainfall erosivity and land degradation are related to rainfall regime. The Algarve's rainfall erosivity increase (+17%) was more pronounced than annual and seasonal rainfall changes.
Rainfall characteristics, rainfall reliability and the definition of drought : Baringo District, Kenya
Differing assessments of drought and reliable rainfall by upland cultivators and lowland pastoralists, were compared with the rainfall records of the Baringo District, Kenya. - (AJC)
Three aspects of Sudan rainfall information availability are discussed in the light of recent developments : historical archived data, automatic, near real-time rainfall monitoring, and both seasonal and decadal rainfall forecasting. The measurement
and monitoring of rainfall are not ends in themseves and it is important that such information is used in the climate management process.
Spatial and temporal rainfall variability over South Africa, 1963 to 1981
The suggestion that the 1970s would be characterised by above-normal rainfall is examined and found to be valid. Spatial and temporal rainfall variations within this period and the preceding dry period are discussed, and the relationship between
the magnitude of rainfall deviations and spatial coverage of rainfall is considered. (AJC).
On the basis of normal monthly rainfall, seasonal rainfall was evaluated and the State delineated into different zones. The principal meteorological factors have also been identified. - (PLK)
Effects of the movement of rainfall area on flood runoff
Runoff analysis using the radar raingage and the verification of runoff model are made in the Kanna River basin (center of Japan). Based on this verification, runoff estimates using the rainfall model are performed and the relationship between
the movement of rainfall area and flood runoff is discussed. - (SGA)
Mean data from 200 stations in South Africa have been used to determine month-by-month rainfall changes. From this the progress of both the Summer and Winter rainfall seasons is traced. (W. A. Nieman).
Relationships of non rainfall events and total rainfall to maize yields at selected climatological stations in Zambia
Daily rainfall amounts were classified into dry or wet events to arrive at sequences of dry and wet spells at six rainfall stations in Zambia over a 19-year period from 1980 to 1998. In the resulting patterns, the total number of non-rain events per
month were found to have predictive potential of maize yields than rainfall totals. - (AJC)
Correlation between rainfall and dust occurrence at Mildura, Australia : the difference between local and source area rainfalls
The AA. use dust records at Mildura, Australia along with observed wind directions during dust storms and events and both local and regional source area rainfall for the period 1960-1989 to test the adequacy of using local rainfall and to show
the improvement that could be achieved by using regional rainfall in the likely dust source area.
Estimation of rainfall erosivity using 5- to 60-minute fixed-interval rainfall data from China
The aim of this study was to assess the accuracy of the 30-min rainfall erosivity index (EI30) estimations based on 5-, 10-, 15-, 30-, and 60-min time-resolution rainfall data as compared to EI30 estimations from breakpoint rainfall information. 456
Uncertainty in modelling the detachment of soil by rainfall
Rainfall simulation in geomorphology
England ; Model ; Modelling ; Precipitation ; Rainfall simulation ; Reliability ; Research technique ; Soil erosion ; Splash ; United Kingdom
The AA. show that rainfall kinetic energy (and hence soil detachment) does not bear a simple relationship to intensity. For low-intensity rainfall, observed variations in drop-size distributions indicate that soil detachment, at a given rainfall
intensity, may vary by about a factor of two. Comparable estimates of variation in soil detachment at high rainfall intensity are not possible because of a dearth of observational data on variation in drop-size distributions in high-intensity rainfall
. Variation in drop-size distributions in natural rainfall may, therefore, account for a significant component of differences between observed soil detachment and that predicted by models of soil erosion.
Diurnal variations of rainfall events by synoptic type in Natal
Climatological records of hourly rainfall at recording stations in Natal describe the diurnal variation of rainfall events derived from a number of different rainfall-producting systems. These are then identified. - (AJC)
Discussion of the results of experiments using simulated rainfall. It is shown that, because film thickness increases, the direct impact of rainfall on sediment transport decreases with slope length.
Characterization of rainfall generated by dripper-type rainfall simulator using piezoelectric transducers and its impact on splash soil erosion
Honshu ; Japan ; Methodology ; Rainfall simulation ; Soil erosion ; Splash ; Water erosion
In this paper, the effect of rainfall characteristics produced by a dripper-type rainfall simulator on splash soil erosion (Ds) has been investigated. The simulated rainfall kinetic energy (KE) and drop size distribution (DSD) were measured using
piezoelectric transducers. The soil splash was evaluated under various simulated rainfall intensities using the splash-cup method. The simulated rainfall intensity (I) and kinetic energy relationship (I–KE) was found to be different from natural rainfall
. The simulated rainfall intensity and splash soil erosion relationship (I–Ds) also followed this same trend. Results and discussion. Accordingly, to improve the soil splash estimation of simulated rainfall under various rainfall intensities the I–KE
characterization relationship for rainfall simulators has to be taken into account.
A rainfall intensity-duration threshold for landslides in a humid-tropical environment, Puerto Rico
The leading cause of landslides in Puerto Rico is intense and/or prolonged rainfall. A rainfall threshold for rainfall-triggered landsliding is delimited by 256 storms that occurred between 1959 and 1991 in the central mountains. A comparison
of the Puerto Rico threshold with rainfall data from other humid-tropical regions suggests that the threshold developed for Puerto Rico may be applicable to other similar environments throughout the world.
Pattern of rainfall distribution in the Central Pacific coast of Mexico
The Central Pacific coast of Mexico can be classified into four zones, each showing different rainfall patterns. As a result of tropical cyclone influence in the Pacific coast, the level of rainfall probability differs between zones. Such influence
is revealed in the total annual rainfall, in the seasonality and in the monthly rainfall pattern.
Simulation of a serie of daily areal mean rainfalls for a basin using rainfall observations at a reference station located outside the basin
A mathematical model is built which enables daily estimates to be made of the areal mean rainfalls for a basin using rainfall observations at a reference station of the same climature (succession of meteorological phenomena related to the types