Document Type : Research Paper
Authors
1
Soil Conservation and Watershed Management Research Institute
2
Soil Science Department, Faculty Agriculture and Natural Science, Lorestan University, Khoram Abad, Iran.
3
Fars Agricultural and Natural Resources Research and Education Center
4
Water Engineering Department, Faculty of Agriculture, Lorestan University
5
Agronomy and Plant Breeding Department, Faculty of Agriculture, Lorestan University
10.22092/ijsr.2024.364327.736
Abstract
Gully erosion is one of the most important and destructive forms of water erosion, and there are ambiguities regarding its initiation and development. The study aimed to identify the soil properties and other factors affecting gullies of South Nazar Abad in 2021. After the field survey, based on the Google Earth images, gullied area boundary draw, 32 gullies were selected, and their location was recorded with the GPS. A surface soil sample was taken from head cut wall of each gully and general analyses were done. The gullies watershed boundaries and morphological characteristics including area, perimeter, and slope were extracted from the DM obtained from unmanned aerial vehicle (UAV) images. The general characteristics of the soil surface in the watershed of the gullies including canopy, bare soil, and residual percent were determined by 1 m x1 m plot. The gully length, width, and depth were measured and volumes were calculated. Modeling of factors affecting gullies was done using a multivariable linear regression model (step-by-step method) in MINITAB on 70% of observations. The relationship between the volume of gullies with gullies soil properties and watershed characteristics were investigated and a suitable gully development model (soil loss) was introduced. Also, in this research, 30% of the measured samples that were not used in the model construction were used for model validation. Percentage, RMSE, CRM, NSE, CD, MAE and drel statistics were used to determine model efficiency. Principal component analysis showed that EC, Na+, Cl-, K+, Erodibility, Mg++, canopy, bare soil, and SP characteristics had noticeable effect on gullies volume. Based on the results of the research and especially based on the Nash-Shutcliffe efficiency coefficient, no reliable model has been developed. Also, the presented model is valid based on the regression at the five percent significant level and according to the validation coefficients. The model with a correlation coefficient of 0.59 and four factors K+, bulk density, crop residues, and percent bare soil could explain 35% of the changes.Strengthening and restoring crop cover in the area is recommended.
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