The effect of land use on water infiltration characteristics in some soils of Ardabil and Zanjan Province

Study of soil quality indicators were considered as a useful method in the land use management. Changing the land use affect soil hydrological processes such as water infiltration process. Spatial variation of water infiltration in soil plays a very important role in hydrologic processes. Variability of this process is affected by the inherent and non-inherent characters of the lands. In order to prevent land degradation and soil and water pollution, realizing the respective processes and quantifying their relationships is unavoidable. Infiltration process is one of the most important components of the hydrological cycle. Due to most changes in soil moisture, provide a suitable model for the accurate estimation of infiltration is important. The aim of this study was to evaluate the infiltration characteristics due to land use changes and to determine the best water infiltration model. Therefore, water infiltration into soil was measured in seven area of Zanjan province and one area of Ardabil province at three agricultural, horticultural and bare land uses. Measurement the water infiltration rate in each land use was conducted by double ring method with three replications and at times 0.16, 0.33, 0.5, 0.66, 0.83, 1, 2, 3, 4, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 110, 120, 135, 150, 165, 180, 195, and 210 minute. Also Kostiakov, Kostiakov - Lewis, Horton and Soil Conservation Service of America models was used to estimate soil water infiltration rate. In order to choose a suitable model, RMSE (root mean square error) and R2 (determination coefficient) criteria were determined for each model. Cumulative infiltration and final infiltration rate were determined for each land use. The results showed that in all three users, all models used in this study could cumulative infiltration water in the soil estimated acceptable accuracy and were low RMSE and high R2. Then suggest estimation infiltration using models and interpretation them is the logical for all areas study. Also the results showed that the estimated cumulative infiltration the bare land use by Horton model was maximum R2 (0.999). But in cultivated and horticultural land use by Kostiakov – Lewis model was maximum R2 (0.997) .According to results the cumulative infiltration and final infiltration rate in cultivated and horticultural land use were higher than those of bare lands. This was due to operation of the plant, causing more disturbance of the soil surface layer, thus infiltration soil in the cultivated and horticultural land use is more bare lands (in which was affect human factors less).