Importance of moisture determination in studies of infiltration and surface runoff for long periods

Abstract

The determination of the natural soil moisture is essential to solve problems related to irrigation water requirements, environmental considerations, and determination of surplus water. For the determination of runoff one can adopt models that consider exclusively the infiltration as a loss or one could use computational models of infiltration to model the infiltrated water. Models based on the infiltration calculation consider well the interaction between infiltration - runoff processes and provide additional information on the phenomenon of infiltration which establishes the existing conditions of moisture in the soil before the occurrence of a new event (simulation for long periods). These models require solving Richards’s equation and for this purpose it is necessary to determine the relation between the soil moisture - suction and hydraulic conductivity - suction which require the determination of the hydraulic properties that can be obtained by measuring the water content by moisture profiles. The aim of this study was the verification of these moisture curves in loessic soils in the south of the city of Cordoba, Argentina. To do this, measurements were done and compared with results of infiltration models based on the determined hydraulic functions. The measurements were done using three probes installed at different depths. The results showed that the values obtained with NETRAIN adequately represent the behavior of wetting and drying conditions of the studied soil.The determination of these curves provided a basis for future studies that include the advancement of agricultural chemicals in the soil and its potential capacity to pollute groundwater, fundamental issue to define environmental management policies.