ABSTRACT
Water is one of the most precious natural resources for the survival and advancement of civilization. Depending upon the intensity, a part of the rainfall enters the soil surface and the remaining runs off as an overland flow. An important soil/ecosystem function is to enhance infiltration of precipitation water into the soil with less runoff and erosion. This process is controlled by biological and physical interactions, which create a stable soil structure with enough macropores to rapidly transmit water. Soil that is continually disturbed with tillage and other anthropogenic activities often develops poor structure, leading to surface sealing of pores and crusting, and consequently less infiltration and high runoff. This chapter describes the concept of steady and unsteady state infiltration and different methods of measurement or prediction of infiltration rate and parameters affecting it.
