NRU :: Browsing by Author "Nseka, Denis"

Browsing by Author "Nseka, Denis"

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Analysis of topographic parameters underpinning landslide occurrence in Kigezi highlands of southwestern Uganda
(Natural Hazards, 2019) Nseka, Denis; Kakembo, Vincent; Bamutaze, Yazidhi; Mugagga, Frank
An assessment of the influence of topography on landslide occurrence in the Kigezi highlands of southwestern Uganda was conducted. Whereas the frequency and magnitude of landslides in these highlands are on the increase, the topographic attributes underpinning landslide occurrence are not well understood. Sixty-five landslide scars were surveyed and mapped to produce landslide distribution maps. Specific topographic parameters, namely slope gradient, profile curvature, topographic wetness index (TWI), stream power index (SPI), and topographic position index (TPI), were assessed on landslide slope sites. The attributes were parameterized in the field and GIS environment using a 10-m DEM. Landslides were noted to concentrate along narrow topographic hollows, as opposed to broad concave slopes in the landscape. The occurrence is dominant in slope zones where slope gradient, profile curvature, TWI, TPI, and SPI are 25°–35°, 0.1–5, 8–18, − 1–1, and > 10, respectively. It was established that profile curvature and slope gradient are the most and least significant topographic parameters in landslide occurrence (R2 = 0.802, p value = 0.088 and R2 = 0.5665, p value = 0.057), respectively. An understanding of these topographic underpinnings would serve to identify and predict potential landslide zones within the landscape and enhance landslide hazard mitigation.
The damage caused by landslides in socio-economic spheres within the Kigezi highlands of South Western Uganda
(Environmental & Socio-economic Studies, 2021) Nseka, Denis; Mugagga, Frank; Opedes, Hosea; Ayesiga, Patience; Wasswa, Hannington; Mugume, Isaac; Nimusiima, Alex; Nalwanga, Faridah
An assessment of the socio-economic implications of landslide occurrence in the Kigezi highlands of South Western Uganda was conducted. Landslide occurrence is on the increase and threatens community livelihoods in these highlands. Detailed field investigations were undertaken with the help of local communities between June 2018 and May 2020 to identify and map recent and visible landslide scars in Rukiga uplands of Kigezi highlands. In the course of field inventories, 85 visible landslide scars were identified and mapped using handheld GPS receivers to produce a landslide distribution map for the study area. A socio-economic analysis was conducted to establish the effects of landslide damage on people’s livelihoods as well as their existing coping and adaptation mechanisms. The assessment was administered through field observations and surveying, focus group discussions, key informants and household interviews as well as the use of Local Government Environmental Reports. The study established an increase in the spatial-temporal distribution of landslides over the Kigezi highlands in the past 40 years. The landslides have resulted in a reduction in the quality of land, loss of lives, destruction of transport infrastructures, settlements, farmlands, crops and other socio-economic infrastructures. Therefore, it is important to look for reliable and sustainable measures to prevent landslide hazards. Total landscape reforestation with deep-rooted trees can possibly reduce the landslide risk. It is also important to undertake policy implementation for preparedness and mitigation plans against landslides in this region and in the country at large. Proper soil and water conservation measures could help in enhancing soil strength against landslide hazards.
The Fragility of Agricultural Landscapes and Resilience of Communities to Landslide Occurrence in the Tropical Humid Environments of Kigezi Highlands in South Western Uganda
(Springer, Cham., 2019) Nseka, Denis; Bamutaze, Yazidhi; Mugagga, Frank; Nakileza, Bob
This chapter examines the influence of agricultural land uses on the occurrence of landslides in the humid tropical environments of Kigezi highlands in South Western Uganda. Analysis of the agricultural land use practices is a prerequisite to understanding landscape fragility and community resilience to landslide hazards. An analysis of agricultural land use patterns was undertaken through interpretation of Sentinel 2A images for 2016. The imagery data was acquired from the European Space Agency (ESA) Sentinels Scientific Data Hub. Field surveys and investigations were also carried out to establish and map the spatial distribution of landslide hazards. Six agricultural land use categories were identified, namely, annuals, perennials, grazing, fallow, wood lots and agroforestry. Considering the agricultural land use patterns, annual crops are the dominant agricultural land use type spanning 69% of the total area followed; by perennials (13%). Grazing land and fallows covered 11% and 5%, respectively. The study revealed that annual crop land is the most affected agricultural land use category. Out of the 65 landslide scars mapped, 31% occurred on annual crop areas. Wood lot areas experienced the least landslide occurrence (4%). A close spatial distribution of agricultural land use practices and landslide occurrence is discernible. It is recommended that a comprehensive tree planting campaign be carried out in areas prone to landslides since it was inferred that wood lots suffered least from landslides. It is also recommended that farmers be encouraged to restore and manage terrace bunds which could help to check on water velocity and consequently increase on slope stability.
Landslide susceptibility mapping using weights of evidence model on the slopes of Mount Elgon, eastern Uganda
(East African Journal of Environment and Natural Resources, 2022) Mande, Manasseh; Nseka, Denis; Mugagga, Frank
Generally, landslide susceptibility mapping is an important step in mitigating their impacts. There is, however, particular dearth of information on the application of GIS-based bivariate methods particularly the weights of evidence model in mapping landslide susceptibility on the slopes of Mount Elgon in eastern Uganda. This study, therefore, evaluated the susceptibility of Bukalasi milli-watershed to landslides, as an early warning strategy for the major landslide hotspot in Uganda. A landslide inventory for the study area was prepared, and the weights of influence of selected landslide-conditioning factors were calculated to present their relative importance in landslide susceptibility. Eight conditioning factors were considered in this study namely; land use, lithology, rainfall, elevation, slope aspect, slope angle, plan curvature and profile curvature. Following the results of the Agterberg-Cheng conditional independence test (probability = 62.5%), the hypothesis of conditional independence among these factors was accepted. Validation using the ROC indicated satisfactory performance of the model considering the model prediction rate (Area under the Curve = 0.882) and success rate (Area under the Curve = 0.912). The final landslide susceptibility map highlights high susceptibility in the southern and western parts of the study area. It further shows that whereas Bukibumbi, Bundesi and Suume parishes are the most prone parishes, Shibanga Parish is relatively the least prone to landslides disasters. Thus, such highly susceptible areas should be prioritised during intervention programmes, especially relocation of the residents at risk. Since the absence of forests has been indicated to exacerbate susceptibility to landslides, deforestation should have severe penalties, and extensive tree-planting should instead be encouraged. Other human activities like farming on fragile slopes, which would further destabilise the slopes should particularly be discouraged.
Vulnerability of smallholder sorghum farmers to climate variability in a heterogeneous landscape of south-western Uganda
(Journal of Disaster Risk Studies, 2020) Mugagga, Frank; Nakanjakko, Noeline; Nakileza, Bob; Nseka, Denis
Smallholder farmers in sub-Saharan Africa are at a greater risk to the impacts of climate variability. We therefore sought to assess vulnerability of smallholder sorghum farmers to climate variability in Kigezi highlands of south-western Uganda. A vulnerability index that integrates selected socio-economic and biophysical variables was obtained through key informant interviews and household surveys, from 230 conveniently sampled sorghum farming households within three sub-counties differentiated by altitude. Rainfall data were obtained from Uganda National Meteorological Authority. Quantitative data were analysed using Statistical Package for Social Sciences (version 23) and STATA software to generate inferential and descriptive statistics, notably frequencies, percentages and chi-square tests, to establish relationship between variables. Content analysis was used to generate themes emerging from the qualitative data. The overall vulnerability index results indicate Kashambya as the most vulnerable (6.9), followed by Bubare (1.8), while Kamwezi was the least vulnerable (–0.2). This study recommends targeted extension services such as access to customised weather information and better agronomic practices to reduce smallholder sorghum farmers’ vulnerability.

Browsing by Author "Nseka, Denis"

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