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Luxon Nhamo published an article in May 2018.
Top co-authors See all
25 shared publications
Albert T. Modi
12 shared publications
12 shared publications
12 shared publications
Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale 2351, NSW, Australia
10 shared publications
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(2015 - 2018)
(2015 - 2018)
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Article 0 Reads 0 Citations Improving the Accuracy of Remotely Sensed Irrigated Areas Using Post-Classification Enhancement Through UAV Capability Published: 05 May 2018
Remote Sensing, doi: 10.3390/rs10050712
Although advances in remote sensing have enhanced mapping and monitoring of irrigated areas, producing accurate cropping information through satellite image classification remains elusive due to the complexity of landscapes, changes in reflectance of different land-covers, the remote sensing data selected, and image processing methods used, among others. This study extracted agricultural fields in the former homelands of Venda and Gazankulu in Limpopo Province, South Africa. Landsat 8 imageries for 2015 were used, applying the maximum likelihood supervised classifier to delineate the agricultural fields. The normalized difference vegetation index (NDVI) applied on Landsat imageries on the mapped fields during the dry season (July to August) was used to identify irrigated areas, because years of satellite data analysis suggest that healthy crop conditions during dry seasons are only possible with irrigation. Ground truth points totaling 137 were collected during fieldwork for pre-processing and accuracy assessment. An accuracy of 96% was achieved on the mapped agricultural fields, yet the irrigated area map produced an initial accuracy of only 71%. This study explains and improves the 29% error margin from the irrigated areas. Accuracy was enhanced through post-classification correction (PCC) using 74 post-classification points randomly selected from the 2015 irrigated area map. High resolution aerial photographs of the 74 sample fields were acquired by an unmanned aerial vehicle (UAV) to give a clearer picture of the irrigated fields. The analysis shows that mapped irrigated fields that presented anomalies included abandoned croplands that had green invasive alien species or abandoned fruit plantations that had high NDVI values. The PCC analysis improved irrigated area mapping accuracy from 71% to 95%.
Article 0 Reads 0 Citations The Water-Energy-Food Nexus: Climate Risks and Opportunities in Southern Africa Published: 27 April 2018
Water, doi: 10.3390/w10050567
The discourse on the need for water, energy, and food security has dominated the development agenda of southern African countries, centred on improving livelihoods, building resilience, and regional integration. About 60% of the population in the Southern African Development Community (SADC) live in rural areas relying mainly on rainfed agriculture, lacking access to clean water and energy, yet the region is endowed with vast natural resources. The water-energy-food (WEF) nexus is a conceptual framework that presents opportunities for greater resource coordination, management, and policy convergence across sectors. This is particularly relevant in the SADC region as resources are transboundary and supports efforts linked to regional integration and inclusive socio-economic development and security. We conducted an appraisal of WEF-related policies and institutions in SADC and identified linkages among them. The present ‘silo’ approach in resource management and allocation, often conducted at the national level, contributes to the region’s failure to meet its development targets, exacerbating its vulnerabilities. The lack of coordination of WEF nexus synergies and trade-offs in planning often threatens the sustainability of development initiatives. We highlighted the importance of the WEF nexus to sustainably address the sectoral coordination of resources through harmonised institutions and policies, as well as setting targets and indicators to direct and monitor nexus developments. We illustrate the significance of the nexus in promoting inclusive development and transforming vulnerable communities into resilient societies. The study recommends a set of integrated assessment models to monitor and evaluate the implementation of WEF nexus targets. Going forward, we propose the adoption of a regional WEF nexus framework.
Article 2 Reads 0 Citations Living with floods – Household perception and satellite observations in the Barotse floodplain, Zambia Published: 01 August 2017
Physics and Chemistry of the Earth, Parts A/B/C, doi: 10.1016/j.pce.2016.10.011
Highlights•Cycles and impacts of the historical floods in the Barotse floodplain were assessed.•Remote sensing and residents’ perceptions were combined to improve results.•The flood patterns are changing and more difficult to predict and adapt.•Modern technology with indigenous knowledge improve the acceptance and reliability. AbstractThe Barotse Floodplain, a designated Ramsar site, is home to thousands of indigenous people along with an extensive wetland ecosystem and food production system. Increasingly it is also a popular tourist destination with its annual Kuomboka festival which celebrates the relocation of the king and the Lozi people to higher ground before the onset of the flood season. This paper presents an integrated approach which cross validates and combines the floodplain residents’ perceptions about recent floods with information on flood inundation levels derived from satellite observations. Local residents’ surveys were conducted to assess farmers’ perception on the flooding patterns and the impact on their livelihoods. Further, a series of flood inundation maps from 1989 to 2014 generated from remotely sensed Landsat imagery were used to assess the recent patterns of floods. Results show that the floodplain has a population of 33 thousand living in 10849 small permeant or temporary buildings with a total cropland area of 4976 ha. The floodplain hydrology and flooding patterns have changed, confirmed by both surveys and satellite image analysis, due to catchment development and changing climate. The average annual inundated areas have increased from about 316 thousand ha in 1989-1998 to 488 thousand ha in 2005-2014. As a result the inundated cropland and houses increased from 9% and 6% in 1989 to 73% and 47% in 2014, respectively. The timing of the floods has also changed with both delaying and early onset happening more frequently. These changes cause increasing difficulties in flood forecast and preparation using indigenous knowledge, therefore creating greater damages to crops, livestock, and houses. Current floodplain management system is inadequate and new interventions are needed to help manage the floods at a systematic manner.
Article 1 Read 1 Citation Improving Water Sustainability and Food Security through Increased Crop Water Productivity in Malawi Published: 21 September 2016
Water, doi: 10.3390/w8090411
Agriculture accounts for most of the renewable freshwater resource withdrawals in Malawi, yet food insecurity and water scarcity remain as major challenges. Despite Malawi’s vast water resources, climate change, coupled with increasing population and urbanisation are contributing to increasing water scarcity. Improving crop water productivity has been identified as a possible solution to water and food insecurity, by producing more food with less water, that is, to produce “more crop per drop”. This study evaluated crop water productivity from 2000 to 2013 by assessing crop evapotranspiration, crop production and agricultural gross domestic product (Ag GDP) contribution for Malawi. Improvements in crop water productivity were evidenced through improved crop production and productivity. These improvements were supported by increased irrigated area, along with improved agronomic practices. Crop water productivity increased by 33% overall from 2000 to 2013, resulting in an increase in maize production from 1.2 million metric tons to 3.6 million metric tons, translating to an average food surplus of 1.1 million metric tons. These developments have contributed to sustainable improved food and nutrition security in Malawi, which also avails more water for ecosystem functions and other competing economic sectors.
Article 1 Read 0 Citations An assessment of the impact of climate change on plant species richness through an analysis of the Normalised Difference... Published: 13 September 2016
South African Journal of Geomatics, doi: 10.4314/sajg.v5i2.11
This study assesses the effects of climate change on vegetative species diversity exploring the usefulness of the Normalised Difference Water Index (NDWI) in predicting spatio-temporal diversity variations. The relationship between species richness and climatic variables of rainfall and temperature is explored based on species data collected from the field over a 3 year period and climate data collected from four local weather stations. Relationship between NDWI and species diversity indices is examined to confirm the usefulness of Remote Sensing in predicting vegetative diversity. The resultant predictive model was used to estimate changes in species richness over a 27 year period (1987-2014). The species diversity data was then regressed with climatic data for the same period. The results show a significant (P<0.05) correlation between species diversity and the two climatic variables. The results also indicate that there is a significant positive (P=0.0001; α=0.05; R2=0.565) relationship between species richness and NDWI. This implies that the NDWI is essential when assessing changes in species diversity over time. The Mann Kendall test revealed a decrease, though not statistically significant, in the rainfall received within the catchment over the period and significant variability. The minimum and maximum temperatures over the period were significantly increasing. These changes in climate variables were matched with a decrease in species richness. Some species tend to be succumbing to the environmental changes influenced by climate change resulting in their changes in phenology, abundance and distribution.
Article 2 Reads 2 Citations Malaria and large dams in sub-Saharan Africa: future impacts in a changing climate Published: 05 September 2016
Malaria Journal, doi: 10.1186/s12936-016-1498-9
Background Sub-Saharan Africa (SSA) has embarked on a new era of dam building to improve food security and promote economic development. Nonetheless, the future impacts of dams on malaria transmission are poorly understood and seldom investigated in the context of climate and demographic change. Methods The distribution of malaria in the vicinity of 1268 existing dams in SSA was mapped under the Intergovernmental Panel on Climate Change (IPCC) representative concentration pathways (RCP) 2.6 and 8.5. Population projections and malaria incidence estimates were used to compute population at risk of malaria in both RCPs. Assuming no change in socio-economic interventions that may mitigate impacts, the change in malaria stability and malaria burden in the vicinity of the dams was calculated for the two RCPs through to the 2080s. Results were compared against the 2010 baseline. The annual number of malaria cases associated with dams and climate change was determined for each of the RCPs. Results The number of dams located in malarious areas is projected to increase in both RCPs. Population growth will add to the risk of transmission. The population at risk of malaria around existing dams and associated reservoirs, is estimated to increase from 15 million in 2010 to 21–23 million in the 2020s, 25–26 million in the 2050s and 28–29 million in the 2080s, depending on RCP. The number of malaria cases associated with dams in malarious areas is expected to increase from 1.1 million in 2010 to 1.2–1.6 million in the 2020s, 2.1–3.0 million in the 2050s and 2.4–3.0 million in the 2080s depending on RCP. The number of cases will always be higher in RCP 8.5 than RCP 2.6. Conclusion In the absence of changes in other factors that affect transmission (e.g., socio-economic), the impact of dams on malaria in SSA will be significantly exacerbated by climate change and increases in population. Areas without malaria transmission at present, which will transition to regions of unstable transmission, may be worst affected. Modifying conventional water management frameworks to improve malaria control, holds the potential to mitigate some of this increase and should be more actively implemented. Keywords Malaria Dam Reservoir Climate scenario Sub-Saharan Africa