Performance of permeability equations and surface permeability ‎study on Yazd floodwater spreading areas

The main objective of water spreading projects is recharging aquifersþ.þ In this study, changes of soil surface permeability in Yazd water spreading projects, including Sirizi in Bafgh, Herat ýand Miankouh in Mehriz were investigated. Using a double ring, 12 Permeability tests (in first ýand fourth strips and three tests for each strip) were performed. Using measured data the ýperformance of permeability equations such as Kostiakov, Kostiakov-Lewis, Horton, SCS, ýand Philip were compared in estimating cumulative infiltration and infiltration rate in the ýstudy areas. Results showed that average permeability for Bafgh, Herat and Mehriz water ýspreading projects were about 1.06, 1.52 and 2.94 cmhr-1, respectively. The best equation for ýestimating cumulative infiltration in Bafgh was the Horton equation with RMSE and Nash ýSutcliffe coefficients of 0.097 and 0.992, respectively, while in Herat and Mehriz the best ýequation was the Kostiakov-Lewis equation with Nash-Sutcliffe coefficient and RMSE of ý0.385, 0.994, 0.081 and 0.991 respectively.