The flow and sediment of the Mlalazi estuary in Kwazulu-Natal, South Africa
type: CreativeWork
description: The catchments and estuaries are fragile systems that are prone to serious degradation from many different anthropogenic impacts (e.g. flow abstraction/diversion, sand mining, soil erosion etc.). In South Africa, many of the anthropogenic impacts on estuarine systems are generally derived from subjective expert opinions that are not supported by hydrodynamic data (Rasifudi, 2019). River flow is one of the main factor that control the dynamics of many estuaries worldwide (Zhou et al., 2014). It is important to understand the water flow depth, direction and velocity in estuaries since they affect and control the erosion, transport and deposition processes of alluvial sediment and nutrients. The Mlalazi Estuary is one of the best conserved estuaries situated along the eastern shoreline of the Kwa-Zulu Natal Province of the Republic of South Africa (RSA). This Estuary is classified as a Temporarily Open/Closed Estuary (TOCE). There is limited observe hydrological data that can be use to improve the decision making process within the Mlalazi Estuary in future. Therefore, a numerical model is useful tool to derive best estimates of flow dynamics and sediment transport. This study investigated the flow dynamics associated with fluvial events within the Mlalazi Estuary resulting from Q2yr, Q10yr, Q20yr, Q50yr and Q100yr flood return periods. The hydraulic modelling software, HEC-RAS (version 5.0) flow model, aided by GIS (HEC-geoRAS), was used to obtain estimates of the flow velocity and water level (depth) within the Mlalazi Estuary and floodplain. Available geometric data (DEM + bathymetry) was used to generate 174 river cross-section profiles at different interval spaces ranging from 60m to 200m along the Mlalazi Estuary. The Mlalazi run-off data simulated from the hydrologic model HEC-HMS (Rasifudi, 2019) was used as an upstream boundary condition. The model was calibrated and validated using the historical data from the 1987 flood survey and continuous water level data…
abstract: The catchments and estuaries are fragile systems that are prone to serious degradation from many different anthropogenic impacts (e.g. flow abstraction/diversion, sand mining, soil erosion etc.). In South Africa, many of the anthropogenic impacts on estuarine systems are generally derived from subjective expert opinions that are not supported by hydrodynamic data (Rasifudi, 2019). River flow is one of the main factor that control the dynamics of many estuaries worldwide (Zhou et al., 2014). It is important to understand the water flow depth, direction and velocity in estuaries since they affect and control the erosion, transport and deposition processes of alluvial sediment and nutrients. The Mlalazi Estuary is one of the best conserved estuaries situated along the eastern shoreline of the Kwa-Zulu Natal Province of the Republic of South Africa (RSA). This Estuary is classified as a Temporarily Open/Closed Estuary (TOCE). There is limited observe hydrological data that can be use to improve the decision making process within the Mlalazi Estuary in future. Therefore, a numerical model is useful tool to derive best estimates of flow dynamics and sediment transport. This study investigated the flow dynamics associated with fluvial events within the Mlalazi Estuary resulting from Q2yr, Q10yr, Q20yr, Q50yr and Q100yr flood return periods. The hydraulic modelling software, HEC-RAS (version 5.0) flow model, aided by GIS (HEC-geoRAS), was used to obtain estimates of the flow velocity and water level (depth) within the Mlalazi Estuary and floodplain. Available geometric data (DEM + bathymetry) was used to generate 174 river cross-section profiles at different interval spaces ranging from 60m to 200m along the Mlalazi Estuary. The Mlalazi run-off data simulated from the hydrologic model HEC-HMS (Rasifudi, 2019) was used as an upstream boundary condition. The model was calibrated and validated using the historical data from the 1987 flood survey and continuous water level data…
author: Mmako, Lesiba Vincent
keywords: Hydrodynamics, Model calibration, Model validation
license: https://devspace.unizulu.ac.za/bitstreams/0c4da5d6-2816-4ea9-84d6-31836853fcdc/download
date published: 2021
date modified: 2026-07-24T06:16:53Z
provider: University of Zululand
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Zululand