The effects of rainfall on the stability of soil slopes in Khanh Vinh district, Khanh Hoa province

Abstract

This study presents a procedure for calculating the change of the safety factor for unsaturated slopes of homogenous, residual soils suffering from rainfall infiltration within Khanh Vinh district, Khanh Hòa province. Rainfall is supposed as a main trigger caused failure of the potential sliding slopes. Rainwater into the slope due to infiltration caused an increase in moisture content and negative pore water pressure; a decrease in matric suction and in shear strength on the failure surface. Thus, slopes are reduced stability and can be failed. Soil permeability and rainfall intensity were found to be the primary factors controlling the instability of slopes due to rainfall, while the initial water table location and slope geometry only played a secondary role. A numerical model of analysis coupled seepage-stability used to simulate the seepage and slope stability under conditions of specific environment such as soil permeability, rainfall intensity, water table location and slope geometry in the study area. The relationships between safety factor and rainfall intensity, soil permeability, angle slope, high slope were identified to provide a good indication for the management of landslide hazards under the effects of rainfall.

Diversity of Anopheles mosquitoes in Binh Phuoc and Dak Nong Provinces of Vietnam and their relation to disease

“…pampanai , and nil in Dak Nong Province. These results are in agreement with those reported by Nguyen in 2006 [ 31 ], who conducted a study of lymphatic filariasis in Khanh Hoa Province (located in south-central Vietnam east of Dak Nong and Bonh Phuoc Provinces) and reported that 3.64% of the population suffered from Bancroftian lymphatic filariasis; however, none of 144 An. vagus dissected were infected with W. bancrofti .…”

“…Unlike malaria, filariasis, a neglected disease, is rarely fatal but severe morbidity, including disabilities and adverse economic consequences due to disfigurement of limbs and male genitals (elephantiasis and hydrocele, respectively), occurs in 40% of infected individuals [ 29 , 30 ]. Bancroftian lymphatic filariasis occurs in the southern and central provinces of Vietnam [ 31 , 32 ], but little information is available about the co-infection of the microfilariae and malarial parasites in Anopheles mosquitoes. Even though Vietnam is now in the pre-elimination phase for the control of lymphatic filariasis [ 33 ], it is important to obtain additional information on the prevalence and transmission of this disease to better define its distribution in the country.…”