The influence of the input data on unsaturated hydraulic soil parameters and on unsteady seepage results for earth fill dams

Abstract

Calculation of seepage on small earth fill dams inevitably involves modelling flow through unsaturated zones. The parameters that influence the flow through unsaturated environments are important for the rain water that seeps through the unsaturated slopes, or when we refer to unsteady flow with rapid variations of water level. Obtaining these parameters involves pricey and time consuming laboratory measurements. Different stages of calculations require different precision of seepage modelling. These parameters can be estimated using existing databases obtained over time, the results are influenced by the quality and quantity of input data available at the moment. The unsaturated hydraulic parameters can be predicted from previously estimated soil hydraulic parameters (the forward problem), from observed retention data and quantifying the hydraulic properties by simultaneous analysis of a limited number of soil water retention data points. The present paper shows differences in seepage calculations using different parameters obtained for three different input data.