Application of frequency ratio, statistical index, and weights-of-evidence models and their comparison in landslide susceptibility mapping in Central Nepal Himalaya

The Mugling–Narayanghat road section falls within the Lesser Himalaya and Siwalik zones of Central Nepal Himalaya and is highly deformed by the presence of numerous faults and folds. Over the years, this road section and its surrounding area have experienced repeated landslide activities. For that reason, landslide susceptibility zonation is essential for roadside slope disaster management and for planning further development activities. The main goal of this study was to investigate the application of the frequency ratio (FR), statistical index (SI), and weights-of-evidence (WoE) approaches for landslide susceptibility mapping of this road section and its surrounding area. For this purpose, the input layers of the landslide conditioning factors were prepared in the first stage. A landslide inventory map was prepared using earlier reports, aerial photographs interpretation, and multiple field surveys. A total of 438 landslide locations were detected. Out these, 295 (67 %) landslides were randomly selected as training data for the modeling using FR, SI, and WoE models and the remaining 143 (33 %) were used for the validation purposes. The landslide conditioning factors considered for the study area are slope gradient, slope aspect, plan curvature, altitude, stream power index, topographic wetness index, lithology, land use, distance from faults, distance from rivers, and distance from highway. The results were validated using area under the curve (AUC) analysis. From the analysis, it is seen that the FR model with a success rate of 76.8 % and predictive accuracy of 75.4 % performs better than WoE (success rate, 75.6 %; predictive accuracy, 74.9 %) and SI (success rate, 75.5 %; predictive accuracy, 74.6 %) models. Overall, all the models showed almost similar results. The resultant susceptibility maps can be useful for general land use planning

Iliopsoas abscess: Analysis and perspectives from an endemic region of Eastern Nepal

Abstract Objective: To evaluate the clinical profile and outcome in patients with iliopsoas abscess. Methods: A descriptive study was carried out in B.P. Koirala Institute of Health Science, Dharan, Nepal from February 2005 to March 2006. The medical records of all thirty six patients admitted in surgery ward with diagnosis of iliopsoas abscess during the study period were analyzed. Results: Thirty six patients were included the study. There were 22 (61.1%) males and 14 (38.9%) females with a mean age of 24.33 ±19.19 years. Demographic distribution of the patients revealed the highest number 13 (36.1%) from Sunsari district, eastern part of the country. Right sided unilateral involvement was the most common presentation and only 2 cases had bilateral involvement. In none of our patients the dorsolumbar spine radiograph revealed any involvement of the bone. The most common complaints were pain in lower abdomen and lump in iliac fossa with flexion deformity at hip joint. All the patients underwent open surgical drainage and their outcomes were analyzed in term of cure, morbidity and mortality. Staphylococcus aureus was the most common organism 24 (61.5%) isolated. Twenty two (91.66%) of Staphylococcus aureus samples were sensitive to ciprofloxacin. There was one mortality in the group who died of septicaemia secondary to necrotizing fascitis. Six patients had wound infection, which were cured by regular dressing. Conclusion: On the basis of our experience and review of available relevant literature, we can conclude that a high index of suspicion and awareness of the varying clinical picture are required to diagnose this condition properly. Ultrasonography should still be the preferred imaging modality as it is cheap, safe, cost effective and readily available. Ciprofloxacin should be used as a first line drug. Image guided aspiration may be practical in selected cases having little pus and traditional open drainage should be considered without hesitation