Spatial Assessment of Soil Erosion Risk Using RUSLE and GIS in Upland Agricultural Barangays of Candelaria, Quezon, Philippines

Whilmer Agdan Mendoza

This study integrated Geographic Information System (GIS) and the Revised Universal Soil Loss Equation (RUSLE) model, A= R • K • LS • C • P, to assess soil loss and propose soil conservation strategies in Candelaria, Quezon, Philippines, addressing increasing erosion evidenced by collapsing hillsides, sedimentation, and soil displacement from construction. The RUSLE model, with adjustments in the P factor derived from local farmer interviews, was used to estimate annual soil loss using QGIS 3.43. Initially, the estimated annual soil loss was 2,210.87 tons/year for Bgy. Masalukot IV and 1,398.51 tons/year for Bgy. Masalukot V. After adjusting the P values, the total annual soil loss decreased to 1,375.49 tons/year and 878.47 tons/year for Bgy. Bgys. Masalukot IV and V, respectively, representing reductions of 37.79% and 36.96%. Slope and soil erodibility significantly impact soil erosion, with steeper slopes and higher K-values leading to increased loss, while perennial crops offer better protection than annuals. Integrating multiple conservation practices, especially a combination of six, proves most effective in reducing soil loss. Recommended conservation practices show that terracing is highly effective on steep slopes, while contouring works well on gentler terrain, emphasizing the need for site-specific and integrated soil conservation strategies.