GIS Application for Comprehensive Spatial Soil Erosion Analysis with MUSLE Model in Sandakan Town Area, Sabah, Malaysia

Abstract

Soil erosion is one of the principal causes of soil degradation in Sandakan, Sabah, Malaysia. The natural phenomenon of erosion is now accelerated by human activities that alter the natural mechanisms. This acceleration is caused by destruction of plant cover, the growing of wrong cultivations, unsuitable farming techniques etc., all of which may be prevented with correct management and land planning. Soil erosion has been identified as one of the important environmental issues and therefore, detail assessment on prediction of soil loss and its impacts has been carried out using the application of the Modified Soil Loss Equation (MUSLE) and Geographical Information System (GIS). ARC-INFO was used for the storage of the data layer on each factor controlling soil erosion. Identification of potential high-risk erosion areas was made using a thematic data layering approach to analyze risk areas. The quantitative soil loss (t ha-1 yr-1) ranges estimates by MUSLE model by a spatial information analisis approach (GIS) were computed: (a) Very High risk (>150 tons/ha/year); (b) High risk (100-150 tons/ha/year); (c) Moderate risk (50-100 tons/ha/year); (d) Low risk (10-50 tons/ha/year); and (e) Very low risk (<10 tons/ha/year). About 46.33% of the area was classified as very low, 43.50% as low, 5.23% as moderate, 4.49% as high and 0% as very high. Soil erosion hazard has been identified and found to be significant in areas with slope above 36.96o. All findings showed that integration of GIS can be used for spatial analysis in a large scale. Production of A total value maps can be applied to particular development planning areas especially for housing and agriculture developments.

Experimental Identification on Thresholds for Early Warning of Rainfall-induced Failure on Fractured Slopes after Giant Earthquake

“…The process of artificial rainfall tests and rainfall parameters are shown in Figure 6 and the record of rainfall intensity of major deformations were between 29.4 mm and 54.2 mm/h and the average rainfall intensity was 48.1 mm/h (Zong-ji et al 2013). Additionally, the water content was up to 0.2 at the failure point of the slope which can be defined as the threshold value of the failure of the slope (Roslee et al 2017). Major deformation was observed and the slope failed progressively from the bottom with scarp angle of 40 to 50° which indicated the envelope of the gradient of the slope failure.…”

“…There is a lot of ways in mitigation and prevention of rainfall-induced mountain hazards including landslides and debris flows . Mechanical counter measures such as retaining walls and ground anchors have been widely used to prevent slope failures (Roslee et al 2017;Tian et al 2010;Towhata et al 2011), However, they are expensive and it is not realistic to apply mechanical measures to every potentially risk slope and geohazard site because in Wenchuan earthquake region, mountain hazards existed everywhere with an innumerable number and most of them occured at extremely large scales. Therefore, careful real-time monitoring and pre-warning of mountain hazards FIGURE 2.…”

“…By the formula above, an envelope threshold curve for the early warning of Taziping landslide may give a guidance and approximate time for evacuation and preparation for potential landside by comparing monitoring rainfall intensities and its duration (Hayat et al 2017;Lindang et al 2017;Roslee et al 2017). Early warning can be applied by comparing the I-A and I-D with real-time monitoring rainfall data.…”

“…An artificial rainfall test was conducted on a weathered andesitic deposit in order to observe its critical threshold value and correlation with pre-failure behaviours (Roslee et al 2017). The experimental site is located on Taziping landslide slope in Dujiangyan County, which is located in the middle part of Sichuan Province (Figure 2).…”

Failure Characteristic and Fracture Evolution Law of Overburden of Thick Coal in Fully Mechanized Sub-level Caving Mining

“…The paper certain coal mine as the experimental face, by using the equipment which is sealed two ends by capsules in borehole, affused measurable water between the two capsules and borehole televiewer system, ground penetrating radar, microseismic monitoring system in underground coal mine, the height of water flowing fractured zone of fully-mechanized top caving are monitored, a numerical simulation experiment on the failure process was conducted, a similarity simulation experiment on the cracks evolution was conducted, at the same time, empirical formula of traditional was modified Roslee et al (2017).…”