نفوذپذيري و تعيين ضرايب معادلات نفوذ با روش هاي استوانه مضاعف ، بارانساز مصنوعي و آبپاش

Infiltrability and Coefficients of Infiltration Equations Using Double Rings, Rainfall Simulator and Raindrop Methods

In order to evaluate infiltration rates, cumulative infiltrations and to determine coefficients of infiltration models (Green-Ampt, Philip, Kostiakov, modified Kostiakov and Horton) using various infiltrometers (flooding and sprinkling), an investigation was carried out at the Agricultural Research Center of East Azarbaidjan (Khosrovshahr) in 1998. The experimental design was factorial with randomized complete blocks and four replications. The first factor was assigned to four different methods of infiltration measurement (rainfall simulator with two intensities of 200, 100 mm/h, double rings and raindrop simulator). The second factor, was two conditions of soil surface (tilled and untilled) and the third factor included 5-minute measuring periods. The results indicated that infiltration rate from double rings in tilled soil was 2-3 times higher than those from the other methods both in tilled an untilled conditions. There was a significant difference at 5% level of probability between the means of cumulative infiltrations of the three methods: the highest figure was occurred in double rings in the tilled soil and under untilled conditions it was less than other two infiltrometers. Means of infiltration rates in all three infiltrometers at the first 5-minute period was about twice more than the other 5-minute intervals. Infiltration rates and cumulative infiltrations of rainfall simulator with 200 mm/h intensity was more than 100 mm/h intensity. Infiltration rates and cumulative infiltration in both intensities were significantly less than raindrop simulator infiltrometer. Among the various infiltration models, Kostiakov model showed best fitness to the experimental data.