Research Articles (Disaster Management Training and Education Centre for Africa (DiMTEC))

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Browsing Research Articles (Disaster Management Training and Education Centre for Africa (DiMTEC)) by Author "Belle, Johanes A."

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    Geospatial analysis of shoreline change of ethekwini coastline from 1990 – 2023
    (Elsevier, 2025) Mshelia, Zachariah H.; Amatebelle, Ekang C.; Belle, Johanes A.
    Coastal areas are dynamic environments impacted by both natural and anthropogenic processes. Hence, it is important to continually and accurately monitor these areas for change and develop coastal management strategies. The present study uses the Digital Shoreline Analysis System (DSAS) and satellite imagery to assess the changing dynamics of the Durban coastal stretch of the eThekwini Municipality from 1990 to 2023. Net Shoreline Movement (NSM), End Point Rate (EPR), and Linear Regression Rate (LRR) were calculated in DSAS to analyse the shoreline changes. The analysis revealed significant variations in erosion and accretion across the coastline. The average shoreline movement was 2.49 m in the north and -7.42 m in the south, indicating predominant erosion in the southern regions. Specifically, 53.85 % of transects in the north and 71.9 % in the south were negative distances, highlighting erosion areas. The EPR analysis indicated an average annual change rate of 0.09 m/year for the north and -0.22 m/year for the south, with erosion rates averaging -2.05 m/year in the north and -1.21 m/year in the south between 1990 and 2023. The LRR method corroborated these findings with annual changes of -0.01 and -0.37 m/year, respectively. High erosion rates were concentrated in areas such as Umhlanga Rocks and Beachwood, while engineered structures contributed to accretion in parts of Durban North. Conversely, the southern coastline, particularly around Amanzimtoti and Isipingo, experienced more erosion than accretion due to fewer protective structures. This study highlights the dynamic nature of shoreline changes along the Durban coast. Understanding these trends is essential for effective coastal planning and management and building resilience against the multiple hazards ravaging coastal communities.
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    Optimizing the master recession curve for watershed characterization and drought preparedness in Eastern Cape, South Africa
    (MDPI, 2024) Owolabi, Solomon T.; Belle, Johanes A.
    Regions grappling with water scarcity are compelled to fortify their hydrological analytical protocols for efficacious drought disaster preparedness, considering the escalating influence of climate change on river periodicity and the sustainable management of water resources. Hence, this study presents a novel optimization and standardization approach for master recession curve (MRC) parameterization to improve the existing MRC computation for environmental flow (EF) parameterization. The study framework is based on constructing MRC using the RECESS computational tool. The concept involved normalizing quadratic improvement in the digitally filtered, smoothed, and automatically extracted MRC parameters from 24 long-term winter streamflows (2001–2020) in South Africa. The optimum recession length suitable for MRC computation obtained was ten days based on the significant proportion of the variance in streamflow as a function of flow timing (R2 > 0.935), EF consistency in most watersheds (p-value < 0.00), optimum standard error, and the appreciable years of significant discharge. The study obtained the MRC index, EF threshold, and the probable diminution period of 3.81–73.2, 0.001–20.19 m3/s, and 3.78 to 334 days based on the periods of significant discharge ranging between 4 and 20 years, respectively. The concurrent agreement of rainfall trend and baseflow (p-value < 0.05) with MRC parameters validate their performance as tools for EF conservation. The intra-variation in MRC across the 24 stations alluded to the overriding influence of river aquifer connectivity on watershed viability. The study provides profound insight into perennial and ephemeral rivers’ viability/vulnerability, indispensable for watershed prioritization, policy formulation, early warning systems, and drought preparedness.