Effects of Vetiver Planting Patterns on Hydrological Variables in Complex Hillslopes: A Laboratory Study

Recognizing the profound impact and importance of hillslope geometry and vegetation cover, and their planting patterns in managing and controlling runoff and soil loss, this research aimed to understand the one-sided and interaction effects of different Vetiver cover planting patterns and different geometry of complex hillslopes (CHSs) on surface runoff, and to compare the results with bare soil conditions. To achieve this, rainfall simulation experiments were utilized with plot sizes of 1 m ×2 m with different shapes of CHSs, along with Vetiver cuttings with square planting (SPP) and Rhombic planting (RPP) patterns. The results demonstrated that among hillslopes with convex profiles, those with divergent and convergent plans exhibited the highest runoff values and soil loss rates, respectively. Across all hillslopes, the RPP reduced the runoff more effectively than the SPP. Furthermore, the hillslopes’ geometry significantly affected the runoff values and soil loss ( p value ⩽ 0.00). The results also showed that the lowest runoff volume amount was observed in the convex-convergent hillslope with the RPP pattern (0.19 L/m 2 ) and the lowest soil loss amount was observed in the straight-parallel hillslope with the RPP pattern (0.37 g/m 2 ).