A linear run-on method for soil infiltrability measurement

Abstract

A new method was advanced to measure the soil infiltrability with linear run-on water flow on hill-slope and the experimental procedures were outlined for the purposes. Algorithms for estimating infiltrability with the experimental data were also formulated. An experimental system was developed, including a Mariotte Bottle for water supply, a special outlet unit for linearly distribution of water flow at soil surface and a scaled flume. A digital camera was used to record the wetted area on the soil surface as a function of time. Mathematic models were derived to compute the soil infiltrability-time function from the recorded wetted soil surface advancement. Laboratory demonstrational experiments using a sandy loamy soil were conducted at a flow rate of 4.4 l/hr and a slope of 5o with air-dry soil and 3 replicates. The experimental results showed that both the advances in wetted areas and the infiltrability as functions of time were very well fitted with exponential functions, with determination coefficients (R2) greater than 0.99. The dynamics of the infiltration curve very well conceptually presents the infiltrability of a soil. Very little water is needed to make one measurement. Comparison of the cumulative infiltrated water with the total supplied water indicated that the relative estimation error was 6.1% demonstrating the accuracy of the method. The results validate the rationale of this newly suggested method, the computational models as well as the experimental procedures. This method is convenient for faster field determination of soil infiltrability with much less water required than conventional methods.