Comparison of methods to estimate saturated hydraulic conductivity in texas soils with grass

One of the primary objectives for irrigation and drainage engineers, soil physicists, and hydrologists is to develop effective methods to estimate soil saturated hydraulic conductivity on the basis of readily available soil survey data. Although a few models have been derived from large ranges of soil texture data and successfully applied to many kinds of hydrologic analysis of agricultural lands and watershed for many years, there are few efforts to specifically investigate these models in soils with healthy grass growing. A field study was conducted to investigate and compare the performance of three readily applied models, including the Campbell model, Smettem and Bristow model, and Saxton et al. model, in Texas soils with established grass from September 2009 to May 2010. The results showed that two-parameter models, Campbell and Saxton et al. models, had better performance than the one-parameter model, Smettem and Bristow model. All three models need to be calibrated with local knowledge and data for improved accuracy if they are applied in Texas grassed soils, or even some new methods or models need to be developed with acceptable accuracy and the same simplicity level as these investigated models.