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)
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.
Spatial and temporal variation in two rainfall simulators : implications for spatially explicit rainfall simulation experiments
Rainfall simulation in geomorphology
Comparative study ; England ; Experimentation ; Model ; Monte Carlo analysis ; Rainfall simulation ; Research technique ; Soil erosion ; Spatial variation ; Stochastic model ; United Kingdom ; Water erosion
Rainfall simulators are widely used yet there is little evidence in the literature to show that their spatial and temporal variability has been adequately taken into account. A first aim of this paper is therefore to examine this variability
, and to appraise methodologies by which it may be quantified. A second aim is to evaluate the implications for spatially explicit rainfall simulation experiments.
Empirical catchment-wide rainfall erosivity models for two rivers in the humid tropics of Australia
The concept of rainfall erosivity is extended to the estimation of catchment sediment yield and its variation over time. Five different formulations of rainfall erosivity indices, using annual, monthly and daily rainfall data, are proposed
and tested on two catchments in the humid tropics of Australia. Rainfall erosivity indices, using simple power functions of annual and daily rainfall amounts, were found to be adequate in describing the interannual and seasonal variation of catchment sediment
Rainfall variability in Murang'a District, Kenya : meteorological data and farmers'perception
This study examines meteorological data and farmer's perception of rainfall in the Central Highlands of Kenya. Rainfall data from 5 meteorological stations during the period from 1947 to 1996 were analysed on an annual and a monthly basis. Analysing
in rainfall amounts for the study period. The farmers think rainfall has decreased over the last 40 years.
Post-mining landform evolution modelling : 1. Derivation of sediment transport model and rainfall-runoff model,parameters
Rainfall simulation in geomorphology
This paper reports the results of natural rainfall monitoring and the derivation of sediment transport model and distributed parameter Field-Williams (DISTFW) rainfall-runoff model parameter values for an unvegetated, unripped waste rock dump (WRD
Drip-screen rainfall simulators for hydro- and pedo- geomorphological research : the Coventry experience
Rainfall simulation in geomorphology
Cultivated land ; England ; Erodibility ; Experimentation ; Land use ; Rainfall simulation ; Rill wash ; Slope ; Slope gradient ; Soil erosion ; Soil properties ; United Kingdom ; Urban area ; Water erosion
This paper describes the development of a laboratory-based drip-screen rainfall simulator at Coventry University and presents 7 case studies demonstrating its application. Experiments include an evaluation of the water balance of both agricultural
This paper analyses the hydrological processes of flood events in three Mediterranean ephemeral streams, taking into account the peculiarities of the rainfall and morphology patterns of the study area. Daily and other detailed information (every 5
min) has been used to study rainfall-runoff relationships, spatial and temporal rainfall variability and flash flood characteristics.
Runoff and soil erosion under rainfall simulation of andisols from the Ecuadorian Páramo : effect of tillage and burning
Ecuador ; Grassland ; High mountain ; Human impact ; Land use ; Rainfall simulation ; Rill wash ; Soil erosion ; Soil properties ; Soil water ; Volcanic soil
of land use (burning and tillage) on soil hydrodynamic properties, rainfall simulation was conducted at 2 different sites (Pichincha near Quito and El Angel). Water repellency combined with the low bulk density of soil aggregates explain the intensity
Relationship between raindrop erosion and runoff erosion under simulated rainfall in the Sudano-Sahel : consequences for the spread of nematodes by runoff
Rainfall simulation in geomorphology
Agricultural practice ; Carrying capacity ; Cultivated land ; Microrelief ; Rainfall simulation ; Rill wash ; Senegal ; Slope gradient ; Soil erosion ; Spatial distribution ; Splash ; Suspended load ; Water erosion
This paper presents a rainfall simulation experiment carried out on three 50 m2 plots in the Senegalese groundnut belt. The results indicate that the carrying capacity of the runoff at the scale of 10 m2, on gentle slopes ploughed perpendicular
Analysis of 20th century rainfall and streamflow to characterize drought and water resources in Puerto Rico
The aim of this paper is to characterize recent droughts of Puerto Rico in terms of rainfall accumulation, streamflow in rivers feeding the principal reservoirs, and public supply reservoir levels. These droughts are compared to the droughts
Characteristics of sediment deposits formed by intense rainfall events in small catchments in the Belgian Loam Belt
This paper discusses the results of 2 detailed field surveys, carried out after extreme rainfall events in springtime. The objectives are 1) to investigate to what extent the sediment delivery ratio of a catchment scale is controlled by the spatial
This paper provides a review of the nature and variability of the climate and hydrology in the source region of the Blue Nile, the central Ethiopian Highlands. Annual rainfall over the basin decreases from the south-west to the north-east
, with about 70 per cent occurring between June and September. Rainfall over the basin showed a marked decrease between the mid-1960s and the late 1980s, and dry years show a degree of association with low values of the Southern Oscillation Index (SOI)
Cultivated surface ; Model ; Rainfall simulation ; Rill wash ; Road ; Sediment transport ; Soil erosion ; Thailand ; Tropical zone
Rainfall simulation was used to examine runoff generation and sediment transport on roads, paths and 3 types of agricultural fields in Pang Khum Experimental Watershed (PKEW), in mountainous northern Thailand. Because interception of subsurface flow
size. Runoff rate, flow velocity and sediment delivery were measured in the field under different slopes and plot sizes for both natural and simulated rainfall. Rain-impacted flow conditions were also compared to flow conditions only.
The primary objectives of this initial study were to prepare sediment budgets for rill networks developed on a natural soil under simulated rainfall in a laboratory flume (University of Toronto, Scarborough), and identify the effect of confluences
Arid area ; Badland ; Erodibility ; Granada ; Infiltration ; Mass movement ; Rainfall simulation ; Slope ; Soil erosion ; Soil properties ; Spain ; Water erosion
Rainfall simulation experiments were used to find a relationship between soil moisture change and sediment concentration behaviour. This relationship appeared to be able to show, in its role as indicator, differences between materials affected
was studied by means of 19 hydropedological stations. Soil and piezometric conditions were studied on these stations for 3 annual cycles (1989-1992) during which rainfall conditions were representative of the mean rainfall conditions for that hillside
elements. Water discharge, rainfall intensity and sediment size are held constant, and stone size, stone cover and slope are varied. Slope is varied as a means of altering flow intensity without changing discharge.