Abstract:
Rainfall simulator is an essential tool to simulate natural rainfall accurately and precisely. A
reliable, accurate and portable small scale rainfall simulator is required for runoff, infiltration,
sediment generation and erosion studies. And this has been used extensively to gather runoff,
infiltration and erosion data in both laboratory and field experiments. This study was conducted
to determine rainfall intensity, rainfall drop sizes and erosivity. An existing rainfall simulator
was modified to be easily assembled, transported and maintained as well as to create a variety of
rainfall regimes. Performance evaluation of the modified rainfall simulator was carried out with
10 trials to determine the intensity of rainfall, drop sizes and erosivity. Correlations were drawn
out between the data of the simulated rainfall and that of the natural rainfall data. The results
show that rainfall amount, intensity and kinetic energy are the main variables that influence
rainfall erosivity index at 99% confidence level. The erosivity index of both simulated rainfall
and natural rainfall are 36395.40JM-2mmhr-1 and 34792.51JM-2mmhr-1, respectively. The
results of regression analysis of the simulated and natural rainfall show the influence of intensity
and amount of rainfall on erosivity index. The linear regression models of simulated and natural
rainfall show strong influence to varying degrees of (R2-values) which are 0.949, 0.190, 0.949
and 0.955, respectively. It was concluded that the modified rainfall simulator is suitable to
simulate and reproduce natural rainfall characteristics such as rain drop size, intensity, kinetic
energy and erosivity. The modified rainfall simulator is a portable type which can be easily
assembled, maintained, transported and it can also be used in both laboratory and field
experiments for irrigation, infiltration, runoff, sediment and erosion control studies. The
estimated cost of modification was ?44,520.00. |
