Estimation of effective infiltration rates in cracked soils

Extract

Infiltration is the most important aspect in the hydraulics of surface irrigation, since the design of irrigation systems depends to a large extent upon the infiltration characteristics of the soil. Many workers have contributed to the theoretical understanding of the infiltration phenomenon (Kirkham & Powers, 1972). However, very little work is available on the evaluation of infiltration into cracked soils. Measurement of infiltration into these soils poses a special problem. Depending on the degree of cracking, a fraction of the water added on the soil surface flows down through cracks and goes to waste. The water flowing through the cracks does not contribute to the moisture storage of the soil profile which may subsequently be used by the crops. Also, infiltration rates measured using ring infiltrometers are erroneous. In order to have an efficient design for an irrigation system, realistic estimates of infiltration characteristics for this type of soil are essential. In the present paper an attempt has been made to estimate the effective infiltration rate into such cracked soils. The procedvire suggested has been tested under limited conditions and found useful under field conditions. However, extensive field testing under various soil conditions is necessary before it can be recommended for general use.