A VIRTUAL LAB ENVIRONMENT FOR IMPROVING STUDENTS' UNDERSTANDING OF INFILTRATION AND RUNOFF PROCESSES

摘要

Infiltration of water in the soil is a key process in the hydrological cycle and its understanding is paramount for students of any course related to natural resources management. Different equations describing hydrological processes have been proposed. The solutions of these equations can be very complex in function of boundary conditions to which they are subjected. and of the level of detail required in any particular case. Water movement in the soil, for example, can be described by the Richards equation, but its solution requires numerical methods in most of the cases. Therefore, amongst the most used ways of calculating water infiltration are the Green and Ampt method, Horton's equation, Philip's equation and the Curve Number method. In all these equations, different soil parameters intervene that can be measured in the field or estimated from soil properties. The understanding of the physical meaning of these parameters, their relative influence, and of the differences between the abovementioned methods is important for students. Infiltration measurements in the field or lab are time-consuming. We therefore developed a tool that helps the students to calculate infiltration in a step-by-step way, allowing to easily change the input parameter values so as to understand the importance of the different variables. This virtual lab environment was coded in MATLAB and used for the first time during the academic year 2013-2014. In this study, we present the main characteristics of this didactic software tool and present an evaluation of its usefulness by students.