Effective rainfall estimation

Abstract A method for estimating the rainfall effective in generating runoff is presented which is based on the infiltration process. With the use of the known equations which describe the ponding infiltration rate in time, a functional relationship between the cumulative infiltration and the maximum possible infiltration rate is stated. Based on that statement the equation of infiltration rate such as it occurs during a general rainfall is derived and the infiltration envelope curve is defined. The theory is applied to the evaluation of infiltration from rain of constant intensity and the results are compared with the numerical analysis of Smith, offering a good agreement. The method is further used to determine the effective rainfall for a given rain of nonconstant intensity.