Using Electrical Resistivity To Model Channel Seepage From Irrigation Canals

There is increased pressure on water managers, as a whole, to improve their water use efficiency. In irrigation areas, a major aspect of water usage is the seepage of water from irrigation<br>canals. In Australia significant amounts of water may be lost from irrigation canals through seepage and evaporation. The methodology applied for this paper uses the measurement of the soil resistivity to aid water managers in the determining the quantity of seepage from irrigation canals. Initially, the resistivity of the irrigation canal bed was measured, followed by soil sampling<br>and analysis. The spatial and resistive variability was established from the resistivity measurements and was inputted into the HYDRUS 2D/3D model according to resistive groupings. The soil<br>analysis resulted in the particle size, bulk density and hydraulic conductivity and these were inputted for the respective soil group into the model. The modelling was conducted over 30 years and the results determined the soil type plays an initial role in the seepage from irrigation canals. However, once the profile becomes saturated it does not matter which soil types are present. The method outlined employs the rapid assessment technique of resistivity to improve the understanding of seepage of irrigation canals.