Landslides Hazard Mapping in Rwanda Using Bivariate Statistical Index Method

Landslides hazard mapping (LHM) is essential in delineating hazard prone areas and optimizing low cost mitigation measures. This study applied the Geographic Information System and statistical index method in LHM in Rwanda. Field surveys identified 336 points that were employed to construct a landslides inventory map. Ten landslides predicting factors were analyzed: normalized difference vegetation index, elevation, slope, aspects, lithology, soil texture, distance to rivers, distance to roads, rainfall, and land use. The factor variables were converted into categorized variables according to the percentile divisions of seed cells. Then, values of each factor’s class weight were calculated and summed to create landslides hazard map. The estimated hazard map was split into five hazard classes (very low, low, moderate, high, and very high). The results indicated that the northern, western, and southern provinces are largely exposed to landslides hazard. The major landslides hazard influencing factors are elevation, slope, rainfall, and poor land management. Overall, this LHM would help policy makers to recognize each area’s hazard extent, key triggering factors, and the required hazard mitigation measures. These measures include planting trees to enhance vegetation cover and reduce the runoff, and construction of buildings on low steep slope areas to reduce people’s hazard exposure; while agroforestry and bench terraces would reduce sediments that take out the exposed soil (erosion) and pollute water quality

Silicene and transition metal based materials: prediction of a two-dimensional piezomagnet

We use first-principles density functional theory based calculations to determine the stability and properties of silicene, a graphene-like structure made from silicon, and explore the possibilities of modifying its structure and properties through incorporation of transition metal ions (M: Ti, Nb, Ta, Cr, Mo and W) in its lattice, forming MSi2. While pure silicene is stable in a distorted honeycomb lattice structure obtained by opposite out-of-plane displacements of the two Si sub-lattices, its electronic structure still exhibits linear dispersion with the Dirac conical feature similar to graphene. We show that incorporation of transition metal ions in its lattice results in a rich set of properties with a clear dependence on the structural changes, and that CrSi2 forms a two-dimensional magnet exhibiting a strong piezomagnetic coupling