Cationic polymer effects on infiltration rates with a rainfall simulator
Helalia, A.M. | Letey, J.
The cationic polymer "CP-14" was applied to three soils at concentrations of 0, 5, 10, 20, and 50 mg L(1) in synthesized canal water (CW) (0.05 dSm (1)) and well water (WW) (0.7dS m(1)) through a rainfall simulator. This first cycle was followed after drying by two cycles with untreated water. In some cases, a fourth cycle was conducted with the same polymer concentration as the first cycle. The infiltration rate (IR) was measured in each case. With one exception, the IR increased as the polymer concentration increased for all soils and both waters. The IR was higher with WW than with CW in all cases. The IR decreased successively from the first through the third cycle due to dispersion at the soil surface caused by drop impact and chemical effects of the applied water. Although the IR increased during the first cycle with increasing polymer concentration, the highest effects were obtained at 5 and 10 mg L(1) concentrations with diminishing effects at higher concentrations. In most cases, benefits of the higher concentrations were observed during the two cycles when polymers were not added to the water. The IR during the fourth cycle with polymer addition was higher than for the second and third cycle but lower than for the first cycle. The clay concentration in the effluent from CW did not change with polymer addition but the IR changed significantly. In addition, the clay concentration in the effluent from WW was very much lower than for CW. The IR values in the present study were correlated with the results of a flocculation test at 5% significance. Therefore, the flocculation test appears to be a useful, quick technique for determining the relative effectiveness of water quality and polymer addition on IR.
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