Landslide Mitigation Through NDSI-Based Soil Erodibility Value Prediction on Coffee Land in Wajak Subdistrict, Malang Regency, East Java Dinna Hadi Sholikah (a), Kurniawan Sigit Wicaksono (b), Soemarno (c), Istika Nita (d), Uci Riandayani Damanik (e)), Muhammad Rifqi Al Jauhary (f), Raihan Naufal (g), Aldo Jetco Husada (h), Syifa Salsabila Bratawijaya (i), and Destantri Kridiati (j)
Brawijaya University, Malang City, Indonesia, 65145
Abstract
Wajak Subdistrict has an area of 9,960.70 ha, of which 23.31% has a rather steep slope, as well as a sandy dominant soil texture that has the potential for landslides. However, the land with the potential for landslides is used for the development of coffee planting areas. To prevent a decrease in coffee production, efforts are needed to mitigate the danger of landslides. Landslide estimation using the erodibility method approach Wischmeier and Smith based on Normalized Difference Soil Index from Sentinel 2A imagery. This image is widely used for disaster analysis, especially in assessing plant factors, however, it is still rare to analyze soil factors. The parameters used are soil texture, organic matter, structure, and permeability to determine soil erodibility and NDSI value. The point sampling method use stratified randomized sampling. This study used 33 sample points on coffee fields, of which 26 points were used as models and 7 points for validation. Modeling applications using ArcGIS 10.8, QGIS 3.24, and RStudio, methods of analysis through correlation, linear regression, paired t-tests, and mean absolute percentage error. The results showed that the soil erodibility estimation model is Y=(1.53xNDSI)-0.47, and influenced 82%. The validation test results showed that the model did not differ from the actual condition, and the model feasibility test results showed a good MAPE value (14%). Soil erodibility values of 0.25 to 0.82, the higher soil erodibility value indicate that the soil is sensitive to landslide events. The estimated landslide hazard estimation model is Y=(3.27xNDSI)-2.21 and has a range value of landslides in coffee fields is 1.35 to 4.95.
