Rain Energy Research Articles

Interrill Runoff and Erosion: Effects of Row-sideslope Shape, Rain Energy, and Rain Intensity

The effects of row-sideslope shape, rain energy, and rain intensity on interrill runoff and erosion were studied on two soils in the laboratory. A typical curved row sideslope averaged about 14% less erosion than a row sideslope of uniform steepness. Different energy levels produced by different rainfall-simulator nozzles affected erosion rates approximately in direct proportion to the rain impact energy. The effect of rain intensity (I) on resulting erosion (E) changed with the applied energy level, as evidenced by a decrease for the coefficient a and an increase for the exponent b in E=aIb as energy level decreased. Runoff was affected most by rain intensity, some by rain energy, and little by slope shape. Results from this research also emphasize the importance of applying storms with the characteristics of natural rainfall when conducting erosion experiments.

Rain energy and soil amendments effects on infiltration and erosion of three different soil types

The effect of rain kinetic energy and soil amendments on infiltration and erosion from three Israeli soils was studied using a drip-type simulator. The soil samples were from the top layer (0-250 mm depth) of cultivated fields differing in their texture, specific surface area and lime content. Three kinetic energies of raindrops were obtained by varying heights of fall (h = 0.4, 1-0 and 1.6 m) of 3 mm diameter drops. The soil types studied were Typic Chromoxerert, Typic Rhodoxeralf and Calcic Haploxeralf. Soil amendments were phosphogypsum (PG) and a combined application of an anionic polyacrylamide (PAM) with PG. An increase in the impact energy of the raindrops reduced depth of rain before ponding, final infiltration rate (FIR), cumulative infiltration (i.e. infiltration parameters) and increased soil erosion. The addition of PAM+PG to the soil surface significantly increased the infiltration parameters and reduced erosion compared with the PG and control treatments. The Typic Chromoxerert was the least susceptible of the three soils to sealing, probably because of its high smectitic clay content, high specific surface area and high CaCO3 content which stabilize soil structure. The Typic Rhodoxeralf with the lowest specific surface area was the most susceptible to clay dispersion, and seal formation. Relative to the Typic Chromoxerert and the Typic Rhodoxeralf, the Calcic Haploxeralf was intermediate in its susceptibility to seal formation.

Effects on seal properties of changes in drops energy and water salinity during a continuous rainstorm

The effect of changes in rainfall energy and water salinity, during a continuous simulated rainstorm, on seal properties was tested in a silty loam soil (Calcic Haploxeralfl with medium (9.0) and low (2.5) exchangeable sodium percent (ESP) values. Saline water (EC = 5 -6 dS m-1) and distilled water were rained at two energy levels: high energy with kinetic energy of 22.9 J mm-1 m2, and low energy with kinetic energy of <0.01 J mm-1 m-2. A seal may be fully or partially developed. The seal formed by a distilled water rain of high energy and sufficient duration is fully developed. A seal formed by rain with low energy, or by high-energy rain of short duration, or by saline rainwater of high energy and long duration, is a partially developed seal. A fully developed seal is stable and its permeability responds only to simultaneous changes in electrolyte concentration and rain energy. Conversely, a partially developed seal is not stable and its permeability responds to changes in electrolyte concentration only.