Soil infiltration of different rainfall intensities and land uses on slopeland of central Taiwan

Soil infiltration was one of important factors in affecting soil and water losses. If soil infiltration on hillslope was large, the rainfall excess would be small. Then surface runoff and soil loss of slopeland would be also small. This study used rainfall simulator under different rainfall intensities to carry out infiltration tests at different land uses of Lienhuachi and Piluchi slopeland in central Taiwan. Based on infiltration data analysis, Philip's estimated equations were better than Horton's estimated equation for most different rainfall intensities and land uses, execept for a few inadaptable cases. The final infiltration rates of respective test plots in decreasing order were as follows: natural coniferous forest of Piluchi, natural coniferous-hardwoods mixture forest of Piluchi, natural hardwoods forest of Lienhuachi, grass land of Lienhuachi, bamboo plantation of Lienhuachi, deforested land of Lienhuachi, orchard of Piluchi, China-fir plantation of Lienhuachi, and bare land of Lienhuachi. The final infiltration rates will increase as rainfall intensities increase. But rainfall reach to larger intensity rates, the final infiltration rates will increase gradually slow, until to maximum final infiltration rates. Based on final infiltration estiemated equation by macro-porosity, the final infiltration rates will increase as macro-porosity volumes increase.