The 24th IAHR-APD Congress (24th IAHR-APD Congress)

36 / 2023-12-23 14:12:51

Modeling Infiltration in a Crop Field of Chirgua River Basin, Venezuela

mathematical models,infiltration,crop field,river basin

The objective of this study is to compare estimated infiltration parameters using nine models, four physically based, two semi-empirical and three empirical, using results of 107 infiltration field trials conducted in agricultural soil of Chirgua river basin, Venezuela. Infiltration tests whose data were used in this research were carried out in Chirgua River Basin, during dry and rainy seasons between 2008 and 2009 in three sectors cultivated mainly with potatoes (Solanum tuberosum L.) and corn (Zea mays L.). Infiltration tests were carried out by executing up to 3 measurements at a time, because selected points were not more than 20 meters away from each other. Samples were taken to determine moisture content by weight at the beginning and at the end of test. Each cylinder was placed, driving it into ground up to 10 cm. A point was marked on its upper edge. A small earthen dam 5 to 10 cm deep was made around the cylinder and about 20 cm away from its outer wall; pouring the water into the area between the earthen dam and the cylinder up to a height of 4 – 5 cm. Using a scalemeter, it was placed with zero at the bottom on point that was previously marked on the edge of cylinder. Between 1 and 2 minutes passed from when water was added into cylinder until first reading was taken. After first reading, these were repeated at intervals of 2, 5, 10, 15 and 30 minutes. When the drop in water level in an interval was less than 1 cm, it was moved to a higher interval. The readings were taken until the drop in the water level inside the cylinder was approximately equal in two successive readings with the same time interval. Soils characteristics in the research plots ranged from silty sand to organic silt. Results of regression analysis showed that parameters of models of Mishra-Singh, Kostiakov and Horton explained up to 70% of variability (minimum R²= 0,70). Models that included the time variable in their structure, as Mishra-Singh, Kostiakov and Horton, resulted in satisfactory adjustment of estimated values to those observed. Significance level of Kostiakov and Horton model parameters was higher for the case of different moisture conditions as for the soil types. For the entire data set, results were similar to those obtained for different soil types; the three soil types responded in the same manner against infiltration rate.