Adjustment of modified holtan equation for a non calcic brown soil of a semi-arid region

ADJUSTMENT OF MODIFIED HOLTAN EQUATION FOR A NON CALCIC
BROWN SOIL OF A SEMI-ARID REGION

JosepVanglesio of Aguiar1, Paulo Leonel Libardi2, Luis Carlos Uchôa Saunders3
Vital and Pedro da Silva Paz4

ABSTRACT

The study of the infiltration of water in the soil is of great importance for the knowledge of soil water dynamics and for the elaboration of models to monitor the moisture in the soil. The objective of this paper was to study the behavior of infiltration in a soil classified as Non Calcic Brown, at the
Experimental Station of the “Universidade Federal do Cear”, using a modified Holtan equation. The study consisted of determining of the maximum infiltration capacity, constant infiltration capacity and total porosity of the soil. The infiltration rates, as a function of soil moisture data, were also obtained to adjust equation i=if+(io-if)[(Qo-Q)/Qo]a.The following equation has been obtained: i=17,5+(1128,2-17,5)[(0,2437-Q)/0,2437]1,4726 , which may be used to predict the infiltration rate without considering the accumulated infiltration and the depth.

Key words: infiltration, infiltration rate, infiltration equation

INTRODUCTION

Knowledge of water infiltration in soil is very important in irrigation management, the assessment of losses flood study and drainage problems. Several factors influence the rate of water infiltration, can be mentioned
The physical properties of the soil (texture, structure, porosity) initial water content and time of infiltration.
A simple equations to describe the process infiltration, was proposed by Kostiakov (1932) and presents follows:

i = io. t-b (1)

where t is the time elapsed after the beginning of the infiltration, io is velocity at the beginning of the infiltration, ie, t = 0 and b is an constant dependent on the characteristics and initial conditions soil moisture, ranging from 0 to 1. Although its parameters have no physical meaning, are widely accepted in because of their