Topographic influence on landslides characteristics and implication for risk management in upper Manafwa catchment, Mt Elgon Uganda

Abstract

This study aimed to characterize the topographic effect on landslides attributes and explore the implications on risk management in a tropical mountainous environment. A database was constructed based on landslide inventory from field surveys supplemented by desk research. The topographic parameters were derived from STRM DEM of a 30 m resolution for the study area. The analysis of the data was conducted in Arc GIS 10.5 environment. The relationship between landslides and topographic conditioning factors was analysed using the Frequency Ratio model. Results revealed that most landslides were distributed within the altitudinal range of 1500 to 1800 m a.s.l. on moderately steep slopes (15 o-20o) in concave curvatures (hollows). Shallow slides mainly debris flows and debris slides were predominant. Most slope failures were initiated on mid to upper slope positions in either new or old scars. Some runout depositions of large slides ended in streams thus undermining water quality. The findings on topographic parameters have implications and yet landslide risk management by the local population was generally inadequate. Any efforts toward effective landslide risk management should prioritise greening the sensitive topographic hollows and old scars particularly on mid to upper slope positions.

Mapping the susceptibility of persons with disabilities to landslides in a highland landscape of Bushika Sub County, Mount Elgon, Eastern Uganda

“…These ranges are in line with those Bamutaze ( 2019 ) revealed as sites with the highest prevalence of landslides during his study on morphometric conditions underpinning the spatial and temporal dynamics of landslide hazards on the volcanic Mount Elgon, Eastern Uganda. With aspect, PWDs lived on slopes facing S-E and S-W which are highly susceptible to landslides as revealed by Nakileza and Nedala ( 2020 ). Concerning susceptibility to erosion and gulley formation at their places of living, the bulk of the PWDs lived in locations with SPI beyond > 10 with higher erosive power of the flowing water in the streams, thus higher chances of gully formation and consequently becoming susceptible to landslides.…”

“…Terrain parameters selected to determine landslide risk were Hillslope, altitude, stream power, slope angle, curvature, and slope aspect. The choice of these parameters was based on existing literature of studies by Nakileza and Nedala ( 2020 ) and Bamutaze ( 2019 ) that underpin them as most influential in landslide occurrence for Elgon areas. The mid altitudes of 1500 m – 1800 m are classified to be more susceptible to landslides.…”

“…The local slope aspect influences weathering process and landslide occurrences on the hillslopes (Masoumi, Jamali & Khabazi 2014 ; Nohani et al 2019 ). Also, Planula curved hillslopes are highly susceptible to large landslides in Mount Elgon areas (Nakileza & Nedala 2020 ).…”

Artificial intelligence approaches for spatial prediction of landslides in mountainous regions of western India

“…It can be seen that the topographical factors such as slope, TRI, and elevation exerted more influence on landslide occurrences compared to the categorical factors (lithology, soil, and geomorphology) in the study area. Researcher inferred that topographical variables are the most responsible for landslide incidents (Nakileza and Nedala, 2020;Arabameri et al, 2020). This is because of the topographical factors mainly slope angle which plays a key role in slope stability and controls the shear and normal strength on the plane of weakness.…”

Influence of the topographic effect on the seismic response of buried pipelines

“…Topographic irregularities are a type of site effect that can significantly affect the seismic site response and the performance of pipelines. The effect of topography on seismic excitation can result in damage to structures built on slopes and cause avalanches (Athanasopoulos et al 1999;Hancox et al, 2003;Khazai and Sitar 2003;Sepúlveda et al, 2005a, Sepúlveda et al, 2005b and landslides (Nakileza and Nedala 2020). In the recent past, numerous seismic motion records and observed earthquake damage have pointed towards topographic amplification as an important factor affecting damage to structures (Davis and West 1973;Griffiths and Bollinger 1979;Pedersen et al 1994;Hartzell et al 1994;Spudich et al 1996;Chavez-Garcia et al 1996;Le-Brun et al 1999;Caserta et al 2000;Graizer 2009;Massa et al, 2010;Marzorati et al 2011;Buech et al 2010;Meslem et al 2012;Assimari and Jeong, 2013;Hailemikael et al 2016;Khan et al 2020).…”