Landslide Risk Assessment for the Built Environment in Sub-Saharan Africa

Redshaw, Peter; Dijkstra, Tom; Free, Matthew; Jordan, Colm; Morley, Anna; Fraser, Stuart

doi:10.1007/978-3-319-53483-1_2

Cited by 4 publications

(1 citation statement)

References 16 publications

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“…While some studies take the whole polygon defining the landslide boundaries as input, others consider either the centroid, a portion of the highest pixels within the landslide, the source area or construct a seed cell zone around (portions of) the landslide to represent the conditions under which the landslide occurred (e.g. Dai and Lee, 2003;Suzen and Doyuran, 2004;Van den Eeckhaut et al, 2006;Che et al, 2012;Hussin et al, 2016).…”

Section: Landslide Samplingmentioning

confidence: 99%

Field-based landslide susceptibility assessment in a data-scarce environment: the populated areas of the Rwenzori Mountains

Jacobs

Dewitte

Poesen

et al. 2018

Nat. Hazards Earth Syst. Sci.

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Abstract. The inhabited zone of the Ugandan Rwenzori Mountains is affected by landslides, frequently causing loss of life, damage to infrastructure and loss of livelihood. This area of ca. 1230 km2 is characterized by contrasting geomorphologic, climatic and lithological patterns, resulting in different landslide types. In this study, the spatial pattern of landslide susceptibility is investigated based on an extensive field inventory constructed for five representative areas within the region (153 km2) and containing over 450 landslides. To achieve a reliable susceptibility assessment, the effects of (1) using different topographic data sources and spatial resolutions and (2) changing the scale of assessment by comparing local and regional susceptibility models on the susceptibility model performances are investigated using a pixel-based logistic regression approach. Topographic data are extracted from different digital elevation models (DEMs) based on radar interferometry (SRTM and TanDEM-X) and optical stereophotogrammetry (ASTER DEM). Susceptibility models using the radar-based DEMs tend to outperform the ones using the ASTER DEM. The model spatial resolution is varied between 10, 20, 30 and 90 m. The optimal resolution depends on the location of the investigated area within the region but the lowest model resolution (90 m) rarely yields the best model performances while the highest model resolution (10 m) never results in significant increases in performance compared to the 20 m resolution. Models built for the local case studies generally have similar or better performances than the regional model and better reflect site-specific controlling factors. At the regional level the effect of distinguishing landslide types between shallow and deep-seated landslides is investigated. The separation of landslide types allows us to improve model performances for the prediction of deep-seated landslides and to better understand factors influencing the occurrence of shallow landslides such as tangent curvature and total rainfall. Finally, the landslide susceptibility assessment is overlaid with a population density map in order to identify potential landslide risk hotspots, which could direct research and policy action towards reduced landslide risk in this under-researched, landslide-prone region.

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Section: Landslide Samplingmentioning

confidence: 99%

Field-based landslide susceptibility assessment in a data-scarce environment: the populated areas of the Rwenzori Mountains

Jacobs

Dewitte

Poesen

et al. 2018

Nat. Hazards Earth Syst. Sci.

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Slope hazards on the Ethiopian road network

Hearn¹

2018

QJEGH

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Jointed rock masses, adverse lithological sequences, often deeply-weathered soil profiles, seasonal rainfall, stream erosion and seismicity have created conditions favourable to the development of landslides in many parts of Ethiopia. Large, deep-seated landslides occupy many hillsides and some may date from the late Pleistocene–mid Holocene. Others are more recent and their activity is controlled by rainfall and, in some cases, the effects of land use change and road construction and widening schemes. The road network of Ethiopia has been expanding significantly over recent decades and has been impacted in many areas by reactivated ground movements and new, first-time failures. The Ethiopian Roads Authority (ERA) has undertaken a number of initiatives to combat these problems, including a research programme aimed at developing mitigation designs for 118 locations on the federal road network of the country. Engineering geological mapping formed the cornerstone of the geotechnical investigations, together with targeted trial pitting, drilling and geophysical investigations, that allowed remedial options to be scheduled. Nevertheless, geotechnical uncertainty prevailed at several locations, especially where ground investigation was precluded by budget constraints. A pragmatic approach had to be applied to the construction contract documentation that made provision for confirmatory ground investigation prior to design finalization and geotechnical inspection and interpretation during construction.

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The John Mitchell Lecture 2023: road asset, socio-economic and fatality risk from debris flow

Winter

2024

QJEGH

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Fast-moving, rainfall-induced debris flow events are relatively common in the mountainous areas of the UK. The mechanisms of rainfall-induced, fast-moving debris flows are considered as they bridge between slow mass movements and flood phenomena. A series of case studies of debris flow impacts from Scotland and overseas will be described. The assessment of landslide hazards and risks is an essential precursor to landslide risk reduction. This is particularly the case when an authority is responsible for an infrastructure or building portfolio that may be affected by multiple hazards. A framework for risk acceptance is used to set the context, and the use of a semi-quantitative assessment to determine the sites of highest risk is described. These highest risk sites are subject to quantitative risk assessments for road user fatalities as a result of debris flows. A novel approach is taken to assess the socio-economic risks and the use of fragility curves to articulate the vulnerability of road infrastructure, including the newly-developed approach involving systems of assets, is also described. The effects of climate change are considered alongside likely social and/or demographic change. A strategic approach to landslide risk reduction is used to illustrate how a clear focus on the overall goal of risk reduction can be beneficial in developing an effective strategy before homing in on the desired outcomes and the generic approach to achieving those outcomes.

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Landslide Risk Assessment for the Built Environment in Sub-Saharan Africa

Cited by 4 publications

References 16 publications

Field-based landslide susceptibility assessment in a data-scarce environment: the populated areas of the Rwenzori Mountains

Field-based landslide susceptibility assessment in a data-scarce environment: the populated areas of the Rwenzori Mountains

Slope hazards on the Ethiopian road network

The John Mitchell Lecture 2023: road asset, socio-economic and fatality risk from debris flow

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