Hydrology

Permanent URI for this collection

https://hdl.handle.net/10530/367

Browse

Now showing 1 - 19 of 19

A geohydrological assessment of the behaviour and response of the Zululand coastal plain to both environmental influences and human activity
(1991) Rawlins, Brian Kenneth; Kelbe, B.
The Zululand coastal plain on the eastern seaboard of South Africa contains large quantities of readily available fresh water. Lake St Lucia, located within the plain, is a wetland habitat internationally recognised for- its environmental importance. Yet over the past few decades extensive forest developments have taken place within the lake catchment. The considerably higher transpiration rate of the fast growing trees planted there over those of grassland environments they replaced is well established. The effects on the hydrological balance of the lake and its environs of the greater water loss resulting from this land use modification has however been the subject of much speculation. This study analyses the hydrological regime of the eastern shores plain over the 17 years from 1973 to 1990. During this period both wet and dry climatic conditions were experienced, and in 1981 a plantation covering 1100 ha was established. In order to clarify the magnitude and variability of hydrological parameters under natural and under altered conditions, comparisons were made between wet and dry periods, and between grasslands and forested areas. The extent to which plantations have modified the hydrological balance could thus be determined and placed in regional perspective. The study began with reviews of the physiography of the eastern shores catchment area and of the existing data base (chapter 2). Following a substantial upgrading of the hydrometric network (chapter 3), specific data collection took place. The components of the hydrological cycle were then assessed in order to identify differences in hydrological response both to climatic variability and to land use. The results of these assessments are presented as individual sections on meteorology (chapter 4), surface hydrology (chapter 5), and geohydrology (chapter 6). It is the conclusion of the study that in this sub-tropical environment, with shallow depths to groundwater, commercial forests are responsible for an additional consumptive use of water of between 150 and 175 mm/year. In the regional perspective of the water balance of Lake St Lucia, the total forested area of 25 000 ha will thus be seen to lower average inflow to the lake by between 10% and 12%. During extreme dry periods this figure increases to approximately 30%. Although they are greatest during dry climatic cycles, the effects of such a reduction in water yield are at all times significant. In the first place, the water balance of the lake is seriously affected. In the second, with.a reduction in its fresh water input, the salinity balance of the lake cannot but be influenced. In the third, changes in this salinity balance will have a direct impact on the flora and fauna of the lake and its environs. It is to be hoped that following the proposed future removal of the plantations from the eastern shores, the situation will improve. However, the remaining 20 000 ha under commercial forestry on the western shores will continue to have a significant effect upon the hydrology of Lake St Lucia.
Geohydrological studies of the Western Shores of lake St Lucia
(1998) Nomquphu, Vaward wandile; Kelbe, B.E
Lake St Lucia is a sensitive estuarine system of international importance which is threatened with over-development within its catchment area by afforestation, overgrazing, proposed dredge mining on the eastern shores and other exploitations. These disturbances and proposed developments have invoked considerable public concern for the sustainability of the Lake St Lucia system. This study looks at the contribution of the groundwater from the western shores area to the lake system in order to evaluate its importance to sustaining the ecology of the system. Under severe drought conditions, the lake experiences considerable lowering of water levels which are accompanied by high rises in salinity levels because of the low freshwater recharge. While the western shores catchment of Lake St Lucia has a number of rivers that contribute freshwater to regulate the salinity of St Lucia, most of these rivers are non-perennial and have been exploited by developments within their catchments. In this study the aquifer system of the southern portion of the western shores area of Lake St Lucia is delineated with the specific intention of defining the coastal geohydrology of the western shores in order to determine its contribution to the water balance of Lake St Lucia. The geological succession of the Zululand coastal plain is described using geophysical information and borehole data which have been compared with field observations and findings in adjacent areas. The general stratigraphic succession, constructed from a number of electrical resistivity soundings and a few boreholes drilled around the western shores area of Lake St Lucia, is described as the first step in defining a conceptual model of the present system for numerical simulation studies. The resistivity soundings have shown that the permeable succession is restricted to post-Cretaceous sediments. The low permeable Cretaceous siltstones, the Lebombo volcanics and the Karoo sediments were all selected to coincide with the base of the numerical model. The overlying, semi-permeable to permeable, upward-fining calcareous and clayey sands of Pleistocene age, known as the Port Durnford Formation, were generally designated as the second layer (LAYER 2) of the model. The electrical resistivity soundings reveal that, on the western shores, the Port Durnford Formation has a thickness of 0 to 30 metres. Overlying the Port Durnford Formation is a relatively thin cover of unconsolidated aeolian, alluvial and estuarine sands of Holocene age which were generally selected as the top layer (LAYER 1) of the model. The upper surface of these coversands coincide with the surface topography, and they range in thickness from 0 to 8 metres and play a major role in the hydraulics of the shallow coastal aquifer. A three-dimensional finite difference model (INTERSAT), was developed from the conceptual geological model. This model was used to determine piezometric surfaces and subsurface flow into Lake St Lucia. Geohydrological and other hydrological parameters assigned to the model were estimated from existing literature and published reports because there were no observation data available. The model parameters for effective rainfall and evapotranspiration were derived from consideration of landuse features to account for surface-groundwater interactions. After the steady state condition had been achieved, the model was validated by comparing the simulated piezometric surfaces (heads) and simulated stream recharge against the observed water table elevations and estimated outflow from rivers, respectively. The simulation results have shown that the groundwater contribution from the western shores to the lake is approximately 40x106m3/year. This component of the water budget may be sufficient to have a buffering effect on the salinity of the lake along the edges of the shores if it is released in times of surface flow droughts. To quantitatively evaluate the groundwater contribution from this area and other sections of the lake system, the presently existing network of electrical resistivity surveys needs to be supplemented with the boreholes or observation wells that should be scattered over the area. From these records a good groundwater database could be built. It is recommended that simulation studies should be extended to the northern shores in order to evaluate its contribution to the water budget of Lake St Lucia.
A geohydrological study of the Richards Bay area
(1999) Germishuyse, Talita; Kelbe, B.E.
Numerical methods such as groundwater models can play a vital rplein understanding the dynamics of an aquifer provided that the input data is accurate and sufficient to represent the environmental system adequately. The groundwater flow mode! used in this project requires specific information about geological features, hydraulic properties as well as recharge and evapotranspiration. All the available information has been collected and interpreted to use.in the model. There is a need to develop conceptual models of the region for theicnplementation of the numerical methods. The regional geology is well described in the literature, but observations on a local scale do not always conform to the?regional stratigraphy. Consequently, many assumptions have been made in the construction of three conceptual models, namely a single layer model, a multi-layer model with homogeneous hydrological properties and a heterogeneous multi-layer model. MODFLOW (McDonald and Harbaugh, 1983), a quasi three dimensional, finite difference, groundwater flow model, was used to determine the regional groundwater flow patterns in the Richards Bay area. A summary of the theory and parameterization process used in the model is presented. Considerable detail is offered for the conceptual modelling of specific processes not incorporated in the finite difference scheme of the numerical model. These include recharge and evapotranspiration. The model domain and parameters that were used in the model as-well as the calibrations are described. For Hie general flow pattern for the region, the groundwater divides for each catchment were determined and are presented in relation to the diverse land use sectors. The project identified the different land use sectors within the principle catchment areas of the main water resources of the region. In particular, it provided a demarcation of which parts of the Richards Bay Industrial sectors could influence the water quality of the various water bodies of the region.
An information base for a decision support system for management of the Mhlathuze River
(2000) Snyman, Nina-Marie; Kelbe, B.
Effective integrated catchment management is dependant on suitable information describing the physical, social and economic conditions in the catchment. It also depends on knowledge of the processes controlling the environmental systems in the catchment. This thesis describes the development of an information base (IB) for a computer-based decision support system (DSS) to support the effective management of the Mhlathuze River system. The IB has been developed to contain most of the available data, which are analysed and processed by models, for utilization by catchment managers. The DSS and accompanying IB was developed during the formulation and implementation of the new Water Act (1998) in South Africa. It attempts to support the implementation of this Water Act, which stipulates the integrated management of water resources on a catchment basis. The database was designed to contain all hydrologically relevant data and information on the Mhlathuze River catchment. Extensive data collection has identified information on rainfall, evaporation, flow measurements, the soil type map of the area, 1:50 000 topographical maps and 1:500 000 maps, 1991 census data, lithology and groundwater, national, regional and local boundaries, pollution and water quality monitoring points, water consumption and details of water users, etc. The database is still growing with the identification and collection of more data and the creation of additional information about the Mhlathuze River catchment from various models. A structure was developed in the IB to give access to the megabytes of information on the database in a structured manner. The operating environment of Arcview 3 (running on Windows 95) was used to develop a user - database interaction system. The Windows concept of interactive icons was used to customise the user interface by incorporating buttons and tools to the IB. Scripts, written in Avenue, were attached to these buttons and tools, to add to the functionality of the IB. A Digital Elevation Model (DEM) was developed from 100-metre elevation contours which originated from 1:500 000 maps. These were supplemented by digitized contours from the 1:50000 maps. The DEM has a horizontal resolution of 125 metre by 125 metre per cell, and covers the whole extent of the Mhlathuze River catchment, stretching 120 km in the east-west direction, and 60 km in the north-south direction. A land use model for the catchment was developed from satellite imagery (7 bands from the Landsat TM satellite). Two different techniques, involving supervised and unsupervised classification methods were applied to identify the land cover classes. The supervised classification method used the maximum likelihood technique, while the unsupervised classification method applied a cluster analysis technique of classification. For the hydrological run-off modelling of the Mhlathuze River system, the HYdrological Modelling System (HYMAS), utilising the Variable Time Interval (VTT) model, was chosen to simulate short duration hydrological events in a distributed manner. The model was used in an Instream Flow Requirements (IFR) study to identify the ecological reserve of the river. Information derived from the DEM and land use model were used during the hydrological simulations. Output from the simulations was compared to the few observed flow measurements which are available for the catchment.
Spatial modelling of the contributions from surface and subsurface water to river flow in catchments
(2007) Snyman, Nina-Marié; Kelbe, B.E.
The groundwater and surface water resources were historically modelled separately because of laws of the governing bodies. Movement towards equity and sustainable development demands the integration of groundwater and surface water in decision making and modelling of these water resources. This research attempts to simulate the contributions in river runoff from surface and groundwater resources, by conceptualizing the flow pathways of the different resources present in a river's catchment. It utilizes the spatial information of the catchment, along with the observed flow hydrograph characteristics, to create a model of the flow components in the river runoff sequence. The model conceptualizes the observed flow hydrograph from a rainfall event as a combination of flow from three different pathways. Excess rainfall (the part of measured rain that causes the storm hydrograph) is separated into the surface runoff; the throughflow (through the unsaturated soil structures and macropores); as well as baseflow (through the deeper saturated soil structures of the catchment): All of these components contribute to the measured flow at the catchment outlet. Analysis of observed flow hydrographs (i.e., the separation of the observed flow into different flow components); indicates constant recession rates for each flow component present in the hydrograph. Information derived from observed flow hydrograph analysis includes the recession rate of each flow component, the percentage of water that is allocated to each flow component for a particular storm event, and the times to peak and recede. This information is used along with the spatial information of the catchment, to derive a simulated flow hydrograph for a rainfall event, for each flow path. The Digital Elevation Model (DEM) of the catchment and geological features are used to determine the pathways and distances that water travels to the outlet. Flow velocities, along these pathways, are influenced by the slopes and the roughness of the medium over/through which the water travels. The flow velocities are estimated from adaptations of recognized hill slope and channels flow velocity equations. The channel geometry, that determines the flow rate through each catchment segment in the DEM, is derived from the contributing area and scaled by the total catchment size. Cumulative flow times along each pathway are used to derive a flow response function for each flow component. These response functions are unique to each catchment and represent the equivalent of a unit hydrograph for each flow component. These response functions are scaled and superimposed to simulate the observed storm hydrograph of a rain event. Storm events are divided into four scenarios representing a combination of high and low intensity rainfall events, as well as events of long and short duration. The model is applied to a rainfall series of five months in the Ntuze research catchments, during which various rain storm types occurred. Model parameters are applied to the much larger Goedertrouw Dam catchment to evaluate the transferability of the model.
The Impact of Flooding Characteristics on Cotton Cultivation in Lower Kano Plain in Nyando District, Western Kenya
(2010) Ocholla, Peter Omondi; Kelbe, B.; Rawlins, B.
Flooding continues to be a common environmental hazard in both developed and developing countries. Kenya has not been spared by the destruction that is usually associated with floods. Crops, settlement and infrastructure are usually impaired wherever flooding occur. The severity of damage as a result of floods has been documented to have had a relationship with the flood magnitude, flood frequency and occupation of the flood prone floodplains of large rivers. In the Lower Kano Plains of Western Kenya, damage to crops by floods is exacerbated by occupation of the lower reaches of the Nyando River. This study sets out to assess the impact of flooding characteristics of the Nyando River on cotton cultivation in the Lower Kano Plains. In particular, the study examined the characteristics of the Nyando River Basin with the aim of describing how the river morphometry could have influenced flooding in the Lower Kano Plains. Also investigated, is the change in the flood magnitude and frequency with time and space, and finally, what anecdotal data (perception of cotton farmers) are available to support the assessment of flooding on cotton cultivation. The study deployed both quantitative and qualitative research methods in examining the variability of rainfall and flow and the consequent impacts of flooding on cotton cultivation. Households living downstream in Lower Kano Plains were the target social unit of analysis. Multi-stage sampling technique was used to sample the respondents whom were interviewed through the use of a self administered questionnaire schedule. Descriptive and inferential statistical techniques were used in data analysis. Relevant probability models were used to analyze the flood magnitude and flood frequency. Generally, the findings related to the research question have shown that flooding in the Lower Kano Plains has inhibited cotton cultivation and lower crop acreage. Furthermore, output has significantly declined for the period when spate has either denied farmers the ability for early planting or destroyed cotton already in the fields. The inter-seasonal and intra-seasonal variability of rainfall and flow show their first peaks are dominant in April and May, while October and November present the second cycle. There is however, a shift in the cycles towards August and September, making the annual flow cycle highly variable in terms of decisions for crop growing. These peaks interfere with the cotton growing calendar, and results in delays in planting or destruction of cotton already planted. The results from the spectral analysis revealed a strong annual and biannual cycle of both rainfall and flow, and an oscillating 4 months cycle that exhibited climate instability. A strong seasonal signal was evidenced between 6 and 12 month period that correspond with the flooding peaks. Similarly, wavelet results demonstrated a strong 12 month spectrum of both rainfall and floods with a large frequency of oscillation in the later period of the 31-year time series. The high power band of 2 to 5 years for both the raw and filtered rainfall and flow time series revealed a Quasi Biennial Oscillation (QBO) and a shift in the rainfall and flow cycle. The findings of the correlation also revealed that (r2 = 0.278) rainfall in catchment explains 27.8% of high flow. The rest (72.2%) is attributed to other factors such as anthropogenic or hydro geologic characteristics of the study area. The study area was revealed to be prone to between 3 and 7 years flood return frequency with an average magnitude of 400 m3/sec. Further results showed that out of the 31 years of continuous time series flow the Nyando River recorded 18 years of bankful flow (200 to 387.6 m3/sec). The high frequency of bankful flow illustrates that Nyando River has limited channel capacity and is therefore vulnerable to flooding downstream. The 1 year return frequency characterizes the Lower Kano Plains to crop damage by annual spates, and thus, demands a shift in the cropping pattern and or change of crop variety to those ones that withstand poor drainage. Other factors that have exacerbated the decline in cotton production include poor price of lint, competition from synthetic fibres and rising cost of cotton production. Because of poor remuneration from cotton production, farmers are shifting to the growing of other crops such as rice and sugarcane that are less affected by flooding conditions. The two latter crops are said to be highly viable, cost effective and reliable. The problem of cotton cultivation in the study area is therefore due to variability of hydrologic conditions and economic factors. There is a need for a sound flood mitigation policy as well as the adoption of appropriate agronomic practices that would enhance cotton cultivation and improve output in the flood prone areas for it to be profitable in the present economic climate.
Developing a low-cost ceramic micro-porous water filter for removal of microorganisms that cause common diseases
(University of Zululand, 2012) Simonis, Jean Jacques; Kelbe, B.E.; Revaprasadu, N.; Basson, A.K.
Africa is one of the most water-scarce continents on earth and the lack of potable water is responsible for the death of approximately 4 900 children every day. Water can be effectively decontaminated by using a household ceramic water filter. The local production of low-cost water filters suitable for the removal of suspended material and pathogenic bacteria from water sources, especially in rural areas, provides a promising solution to the problem and is therefore important to pursue. The traditional slip casting process was used develop a micro-porous ceramic water filter. The method was found to be more suitable than either extrusion or die casting for manufacturing a locally suitable, low cost ceramic water filter. Slip casting, requiring limited expensive equipment, usage of locally available raw materials, labour and expertise makes this the only promising method for manufacturing ceramic filters in a rural, non-technical setting. Using milled lithium alumino-silicate had the main advantages of thermal shock resistance and dimensional stability because of the material’s zero thermal expansion at firing temperatures. Milling tests based on the Andreasen packing model were used for obtaining the best particle packing for the raw material recipe. The material also provides dilatant rheology matching the rheology of the organic carbon poreformer. The candle- type filter required less raw material compared to the other low cost filter such as the pot- type filter from (PfP). The particle size of the pore-former provided us with small pores around 3 microns after firing for the elimination of bacteria from drinking water. These pores were much smaller and more effective when compared with Potters for Peace (PfP’s) pore size of 16-25 micron. The zero thermal expansion (adopted ZTE product name) helped to prevent damage (cracking) to the product during heating and gave accurate control of the ultimate filter size after sintering. The large apparent porosity results of between 67-73 per cent for the finished product provide a specific surface area of 7 m2 g-1 and a high flow rate which explains the filtration efficiency of the filter. The 32 minute retention time of water further helps with the filtration effectiveness. Bacteriological testing exceeded all expectations. The product was tested using water contaminated with high concentrations of selected bacterial cultures as well as with water from local polluted streams. -i v - The product complies with the WHO (2011) recommendation requirement for household water treatment (HWT) technologies of a LRV ≥ 4 (log reduction value). With correct cleaning and basic maintenance, this filter can effectively provide clean drinking water for rural families affected by polluted surface water sources. This product can immediately be useful to families placed in situations where polluted drinking water causes distress. The filter could provide a low-cost solution for the millions of people without access to potable water in Africa. Furthermore, such a project provides opportunities for local financing and innovation. The method of slip casting for the manufacture of porous ceramic used in this study has been showed to work very successfully. The filter requires fewer raw materials, energy for the shaping- and firing- process, finishing, storage space, it is small, compact, and more effective against bacterial load and has a flow rate 3-4 times faster than any other low cost manufactured filter. The low unit manufacturing cost, places Outbac in a strong position, to also compete on a price-only-basis with other low cost, ceramic filter producers in the world.
The evaluation of existing household water treatment system using World Health Organisation recommendations.
(University of Zululand, 2014) Selepe, T.N.; Simonis, J.J.; Basson, A.K.
Household water treatment technology coupled with nanotechnology research have been developed and managed to treat water at household level. This technology will help address United Nation Millennium Goals (UNMG) 2015 of access to safe drinking water within South African Development Countries (SADC). University of Zululand (UNIZULU) Hydrology Department has developed a low cost household treatment system (HWTS) using a traditional slip-cast process of inorganic and organic compounds mixed together and fired at high temperature to produce pores. The filter has shown high strength, high chemical resistance, and thermal stability and proved very durable when subjected to harsh operational conditions. When the filter properties were compared to other low cost HWTS, it shows increased porosity of 69%, pore sizes of 0.3- 4µm and flow rate of 1-2L/h. The HWTS was initially impregnated with metal oxides such as silver oxide (AgO), copper oxide (CuO), zinc oxide (ZnO) and iron oxide (FeO) using capillary suction dried in kiln to improve viral removal. The impacts of these metal oxides were tested on selected bacteria, protozoa and bacteriophages. The selected bacteria show log reduction value (LRV) of 5, protozoa LRV of >6 and bacteriophages LRV 2.8 for AgO and CuO showing LRV of 4. Field testing was repeatedly performed over a period of one month. Cleaning of HWTS was only done at the end of testing. The results were as follows: somatic phages were reduced by 99.999% while Fspecific phages showed a reduction of 99.999%. This concludes that UNIZULU locally developed HWTS has met WHO performance standards and can be utilised to uplift the impact of safe drinking facing the SADC.
Characterization of the hydrostratigraphic units of the Sodwana area using the electrical resistivity method
(University of Zululand, 2015) Nweze, Augustine; Simonis, J.J.; Kelbe, B.
This study was aimed at defining the geological facies of the Sodwana area. It formed part of a bigger project designed to investigate the linkages between the hydrological and ecological drivers of the Mgobolezeni Catchment, Sodwana. Monitoring boreholes were drilled by the Department of Water Affairs (DWA) at several locations in the study area for the purpose of monitoring groundwater changes in the Catchment. There was a need to interpolate the geology and groundwater conditions between the monitoring boreholes. This research provided the geological conditions between the monitoring boreholes using the electrical resistivity geophysical method. The Geotron (G41) resistivity meter was used to conduct the survey. Vertical electrical sounding (VES) were conducted initially in close proximity to DWS monitoring boreholes for calibration purposes. The VES data were plotted and interpreted using IPI2win computer software. Hydrostratigraphic models were developed for all VES locations in close proximity to monitoring boreholes. These models were used for interpolation of the geology between the boreholes. A total of 20 VES were conducting in the study area. 16 VES results showed 5-layer models while 4 VES results showed 4-layer models. The top layer showed very high resistivity values (> 2000Ωm) and was interpreted as dry sand (Kwambonambi Formation). The second layer showed a resistivity range of 200Ωm – 2000Ωm. In some locations, the second layer showed a resistivity range of 120Ωm - 200Ωm and was interpreted as the shallow aquifer in the Kwambonambi Formation. The third layer showed a resistivity range of 50Ωm - 120Ωm and was interpreted as the low transmissivity Kosi Bay/Isipingo Formations. The fourth layer had a resistivity range of 10Ωm - 50Ωm and was interpreted as the deeper aquifer unit of the Uloa Formation. The basement Cretaceous rock formed the fifth layer that showed a clear increase and higher resistivity values than that of the overlying fourth layer. Transmissivity values observed from the pumping tests conducted on the calibration boreholes were combined with VES results to define the transmissivity of the inferred deeper aquifer in between boreholes. The thicknesses of the geoelectric layers obtained from VES results showed a good relationship with corresponding geologic units in borehole logs. The varying apparent resistivity values and lithological information enabled the demarcation of the geoelectric units into hydrostratigraphic units. VES results also showed that the surface of the Cretaceous unit is deeper in the eastern side of the study area than in the western side, showing that the Cretaceous unit dips towards the east. The modelled transmissivity also showed a good statistical relationship (R2 = 0.99) v with the observed transmissivity. Therefore the VES method used for this study successfully achieved the aim of this study.
Production of bioflocculant from marine bacteria and its application in the treatment of coal wash plant fines
(University of Zululand, 2015) Dafel, Jade; Simonis, J.J.; Basson, A.K.
A total of 33 water and sediment samples were randomly selected from the marine environment on the North Coast of KwaZulu-Natal (KZN), South Africa. Strains were isolated and screened for their potential to secrete bioflocculants and tested for flocculating activity with a kaolin suspension. The strains that produced bioflocculants with a high yield of flocculating activity (above 60%) were selected for optimisation and further flocculating tests using coal mine slurry. One strain with good flocculating abilities for both a kaolin suspension and coal mine slurry (74% and 76% respectively) was analysed using its 16S rDNA nucleotide sequence and was identified as Bacillus cereus. The bioflocculant bacterium was optimal when glucose (40g/l) and urea, as the carbon and nitrogen sources, a pH of 4 and Ca2+ as the cation were utilized. The exceptional flocculating performance of Bacillus cereus demonstrated good potential for replacing the chemical flocculants that are currently used in flocculating coal mine slurry generated at Tendele Coal Mine (TCM) located in KZN.
Assessment of groundwater quality in a part of Mhlathuze catchment of Empangeni and Richards Bay, KwaZulu-Natal, South Africa
(University of Zululand, 2018) Sithole, Bongani
The study area comprises of a part of Mhlathuze catchment of Empangeni and Richards bay, KwaZulu Natal. This study has revealed the significance of hydrogeochemical studies in understanding the groundwater quality for drinking and irrigation purposes. The study also identified the hydrogeochemical processes and the probable source of toxic metals in the groundwater. About 40 and 33 groundwater samples were collected in the year 2015 and 2016 respectively and they were analysed. The groundwater ranges from acidic to alkaline in nature. The parameters of drinking water quality such as pH, EC, Na, K, Ca, Mg, Cl, HCO3 and SO4 exceeds the permissible limits of WHO standard. The USSL salinity classification revealed that the groundwater samples of the study area are unsuitable for irrigation as high salinity and high alkalinity hazards are observed. The hydrogeochemistry of the major ions in the groundwater are in the order of dominance of Na > K > Ca > Mg and Cl > HCO3 > SO4 in 2015 and Na > Ca> Mg >K and Cl > SO4 > HCO3 in the year 2016. Ca-Mg-Na, Cl-SO4-HCO3, Ca-Mg-Cl, and Na-Cl are the dominant hydrochemical facies. The hydrogeochemical processes that have strong influence on groundwater quality are the rock water interaction, ion exchange, and reverse ion exchange, carbonate and silicate weathering processes and evaporation. PI values specified that the quality of groundwater is good for irrigation purposes. The abundance of metals exhibited the sequence in increasing order as follows: Mn < Si < Fe < B < Cu < Zn < Pb < Al < Li < Co < Ni < Cd < Cr and Si < B < Zn < Ag < Li < Pb < Mn < Al < Cr < Fe < Cd < Co. The water quality analysis clearly revealed that the toxic heavy metals such as Mn, Fe, Pb, Al, Ni, Cd and Cr exceeded the permissible limit of WHO and USEPA drinking water standard. Spatial variation of heavy metals also revealed that the overall part of the study area are extremely hazardous and polluted by landfill site, industrial effluents, mining and associated activities, fertilizers and anthropogenic sources in and around the study area. Consumption of groundwater by the public may cause severe health issues. Generally, the study concludes that the high level of contamination is contemporary in the Empangeni and Richard Bay area. The study also suggests that utilising this baseline informations, reconciliation strategies should be formulated to improve and protect the groundwater quality in the study region. .
Determination of irrigation water quality of surface and groundwater in Luvuvhu catchment in Limpopo, South Africa
(University of Zululand, 2018) Nethononda, Vhonani G.
Rapid economic expansion and intensive irrigation activities constitute significant threat to groundwater depletion. This study emphasized on the surface water quality and groundwater quality for irrigation purpose by adopting multivariate statistical methods and the hydrochemical processes and on the probable groundwater contamination in the Luvuvhu catchment Limpopo province. Groundwater samples were collected from 41 wells during 2015 and 2016; and seven samples were collected from Luvuvhu River. The physical parameters pH, EC, TDS, temperature and ORP were measured in the field. Major ion Ca2+, Mg2+, Na+, K+, Cl-, HCO3- and nitrate were analyzed. The pH values indicate that groundwater is acidic in nature during 2015 and 2016. TDS values indicate that groundwater is fresh in nature. The dominant sequence of cations is presented as Ca2+ > Mg2+ >Na+>K+ while that of anions as HCO3- > Cl- > SO42_ in the year 2015 and 2016. The Piper and Chadha plots show that the dominant water types are Ca2+-Mg2+-HCO3- and Ca2+–Mg2+–Cl-. Gibbs plot reveals that the chemistry of water was influenced by rock-water interaction. Bivariate plots indicate the dissolution of carbonate and silicate minerals, reverse ion exchange and anthropogenic activities influenced the water chemistry in the study area. Groundwater was saturated and oversaturated with respect to calcite and dolomite and undersaturated with gypsum and halite. High nitrate concentration resulted from agricultural and farming activities and leakage of sewage system. Temporal groundwater fluctuations indicates that recharge processes decrease the concentration of ions in groundwater by mixing of infiltrated fresh water with groundwater. Factor analysis revealed that the two main factors of 80.68% and 79.95% of total variance for both years. These factors indicate the impact of irrigation return flows, human disposals and usage of K+ and NO3- fertilizers. Electrical conductivity, pH and the concentration of Na+, Ca2+, Mg2+, K+, Cl- exceeded the drinking water quality standards prescribed by the DWAF on few samples. DWQI classification results show that 1% and 2% of samples indicate excellent, 49% and 49% specify good, 27% and 29% shows poor, 7% and 10% of very poor, 16% and 10% of unsuitable during 2015 and 2016, respectively. Sodium percentage, residual sodium carbonate and permeability index reveals that surface water and groundwater is suitable for irrigation. USSL diagram suggests that surface water and groundwater is suitable for irrigation with low alkali hazards which represents excellent water quality for irrigation purpose. This study results revealed the divergent methods are significant for the combined evaluation of the natural processes and groundwater contamination. It contributes a technological basis for the strategic future development where broad organization will be useful for public. However, the study suggest for intensive monitoring to detect the anthropogenic and other contamination elements in the groundwater and surface water to produce quality yield.
Groundwater geochemical characteristics and its suitability for drinking and irrigation in Ventersdrop, North West Province, South Africa
(University of Zululand, 2019) Mubva, Khuliso Virginia; Elumalai, V.
Groundwater is major source of freshwater in regions devoid of surface water resources. The dependence on groundwater is increasing worldwide. South Africa is no exception. Groundwater resource has been identified as the main and reliable water resource for human consumption and agricultural practice in the Ventersdorp area, South Africa. Assessment of groundwater quality is necessary for safe usage for drinking and for irrigation purposes so as to boost the socio-economic wellbeing of the region. One such study was taken in Ventersdorp area, Schoonspruit Catchment, South Africa. The groundwater samples were collected from forty boreholes in 2015 as well as seventy boreholes in 2017 and was analysed for major ions and nitrate. The physical and chemical parameters of groundwater namely EC, pH, TDS, Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-and NO3- during 2015 and 2017 were analysed. The concentration of major ions chemistry in groundwater was within the permissible limits of South African National Guidelines and World Health Organisation and for drinking use. The overall pH values for both sample periods represent slightly acidic to alkaline in the study area. Based on DWAF (1996) approved limit of drinking (EC <450), 45% of groundwater samples in 2015 and 13% samples in 2017 exceeded the limit in the study area. The classification of groundwater based on total hardness (TH) in the study area shows that majority of groundwater samples fall within the hard water category and the major groundwater types were Ca–HCO3 and Ca-SO4. The affluence of the major ions in the groundwater of the study area was found to be in the order of Ca>Na>Mg>K and HCO3>Cl> SO4>NO3. Several correlation diagrams between the major ion and other plots like the Gibbs, Chadha, Piper, Durov’s were prepared to ascertain the sources of ions in the study area. Gibbs plots have revealed that groundwater in the study area for both year 2015 and 2017 is of rock water interaction dominance. Similar inferences were obtained from Chadha plot. High correlation between calcium and bicarbonate, chloride with sodium, nitrate and sulphate and nitrate and potassium. Further, in order to ascertain the irrigation water quality, Kelly’s ratio, Sodium percent, residual sodium carbonate, sodium absorption ratio and permeability index were calculated for the groundwater samples in the study area. The IWQI as well as DWQI was calculated to get a snap shot of the region and it confirmed that most of groundwater samples in the study region fall between the range of suitable for both drinking and irrigation purposes in 2015 and 2017. The impact of heavy metal pollution index (HPI) in groundwater was ascertained. The coefficient variation of Zn was found to be higher than that vii of Cu, Cr, Cd, Ni and Pb in groundwater of the study area. The results suggest that Zn concentration has a high probability of being influence by human activities. Apart from this groundwater quality, rainfall data and groundwater level data from 1974 to 2014 was collected from National Department of Water and Sanitation of South Africa. The analysis of the data revealed that shallow aquifers are easily affected by local climate changes while deep aquifers are dependent only on regional changes. Thus, shallow aquifers are more vulnerable to climate variability. The recharge of shallow aquifer is brief as compared to recharge of deep aquifer. In the study area, shallow wells are more likely to be affected by irrigation flow compared to deep wells and inferred from high correlation between Ca and HCO3. Cl was correlated with K and Na. NO3 and Cl are highly correlated. Variables correlating with Cl, SO4 and NO3 are partly derived from agricultural activities. Nitrate concentration in the study area shows strong positive relationship with five major ion and EC for last three decades from 1994 to 2014. In general, the quality of groundwater is suitable for both drinking and irrigation needs. This study helped to comprehend the present state of groundwater chemical composition in Ventersdorp and to assess its fitness for irrigation and drinking uses.
The variance in the water quality of the lower orange river
(University of Zululand, 2019) Sekwaila, Kwena Khutjo; Simonis, J.J.; Rawlins, B.K.
The monitoring and assessment of rivers is important for measuring the status of river ecosystems, water quality and water demand, and can provide early warning for management intervention with regard to water quality and quantity. This can be quite a daunting undertaking for rivers that cross national boundaries such as the Orange River. Concepts such as Integrated Water Resource Management were introduced to enhance the sustainable use and management of such water resources. In addition, transboundary bodies such as the Orange-Senqu River Commission were established between member states in the Southern African region to provide a platform for coordinated water resource management of the river. The DWS has various water quality monitoring programmes throughout the country. The National Chemical Monitoring Programme is the longest running of the national monitoring programmes. While the National Microbiological Monitoring Programme provides data for determining the potential health risks to people related with the potential utilization of pathogenically polluted water resources. This study identified and evaluated the effectiveness of sampling locations by analysing water quality trends from monitoring points in the Lower Orange River located in the Northern Cape. Historical data from the Department of Water and Sanitation‟s Water Management System and National Integrated Water Information System were utilised to illustrate changes in the water quality temporally and spatially. The legislative requirement of water quality in South Africa, according to the South African Water Quality Guidelines, was applied to the data sets. The current water quality network of the Lower Orange is under-utilised. The various sites are not monitored on a consistent basis. A large number of sites have been left inactive and not monitored. Creating a situation where the latest data may not be available for management decisions. The general trend of the river water quality indicates a general increase in the Total Alkalinity in the river. This potentially is the results of years of runoff from irrigation practices into the river. The river also displays high levels of phosphate, nitrate and magnesium at some monitoring points. iv There are large gaps in data, and thus limited information, in terms of water quality of the Lower Orange River. Studies conducted by organisations such as the ORASECOM also indicate a lack of information with regard to Persistent Organic Pollutants, heavy metals and radio nuclides. These potential major pollutants are currently not being given priority compared to other parameters.. Water management authorities and institutions require research that supplies a constant flow of information in order to adequately respond to water quality changes in the river. This study identified gaps between the monitoring and management of the Lower Orange River. In addition, it provides potential mitigation measures that could help ensure the gaps are closed and water quality data is converted into information that can enhance understanding of the water quality in the Lower Orange River. Policy formulation for water quality management in the arid Northern Cape can be made much easier with this information.
The hydrochemical characterization of the Mgobezeleni catchment in Sodwana Bay
(University of Zululand, 2019) Mkhwanazi, Millicent N.; Simonis, J.J.; Bate, G.
The Maputaland region comprises one of the world's most remarkable areas of biodiversity and aquatic systems. It also has the largest primary aquifers in South Africa, constituting 25% of all coastal plain aquifers found in the country. The increasing number of rural households’ development along the Maputaland coastal plain pose significant eutrophication risks on the hydrological system, owing to the use of informal sewage management facilities. To understand the anthropogenic impacts on the hydrological system the Mgobezeleni catchment was selected in this study as it represents a microcosm of the Maputaland region. The Mgobezeleni Estuary is connected to the two lakes (Lake Mgobezeleni and Lake Shazibe), and large swamp forest, and mouth is affected by tidal influence. The hydrological system in the catchment is directly controlled by the groundwater system. The overlying paleo-dune sands are permeable permitting high percolation of the annual rainfall. The catchment is dominated by three aquifers namely, the uppermost KwaMbonambi Formation, Kosi Bay Formation and Uloa Formation. The water table is dynamic, affecting the dimension of the unsaturated zones, the hydraulic gradient and the groundwater flow in the aquifers. The groundwater recharge only becomes visible as base flow in surface water resources after several years. Contaminants that have accumulated over decades are therefore still present in the aquifers, being restricted mainly in the upper KwaMbonambi Formation. Therefore, leaching of nutrients from the informal sanitation systems pose adverse impacts on the groundwater chemistry, which in turn can result in eutrophication of surface water resources. The growth in population in the Mgobezeleni catchment has therefore increased the nutrient load in the groundwater system due to the presence of confining layer that restricts nutrients to the shallow aquifer. Nutrients are relatively elevated in groundwater close to highly populated areas such as Mbazwana. Moreover, the discharge of groundwater as a base flow component in surface water resources (lakes, estuary and wetland) causes the eutrophication (growth of dense macrophytes and microalgae, including toxic cyanobacteria species) due to high nutrient composition. The dense macrophytes species together with the cultivated peat, are decomposing to produce high levels of dissolved OM with humic substances (humic acid and fulvic acid) causing the blackwater in the surface water resources and also increasing the population of microalgal species. The water in the catchment is generally characterized by a sodium-chloride ions signature with relatively low Ca, Mg, K, and SO4 concentrations. It is generally high in Al, Fe and Mn concentrations. vi The high levels of nutrients and planktonic algae in hydrological system threaten the ecological system in the Mgobezeleni catchment. The presence of the bacteria Microcystic aeruginosa can affect the domestic and wildlife including the water supply to Ezemvelo KZN Wildlife’s residential areas. In addition, the cultivation of peat in the Mgobezeleni catchment causes the peat to decompose, thus also increases the N and P concentrations and OM content in the wetlands which are also influencing the water quality in the lakes and estuary.
Simulation of catchment runoff, erosion and sediment transport using a transient numerical model for Mlalazi catchment
(University of Zululand, 2019) Rasifudi, Khathutshelo Joshua; Simonis, J.; Rawlins, B.K.
Catchments and estuaries are fragile systems that are prone to serious degradation from many different anthropogenic impacts. Much research has been conducted on developing an understanding of the fluvial processes in river catchments and in estuary dynamics. Many of the anthropogenic impacts on estuarine systems are generally derived from subjective expert opinion in South Africa. The Mlalazi Estuary is one of the best conserved estuaries in KZN. As a result of the changing state of the marine and fluvial conditions there is a possibility that such changes may trigger management interventions. There is therefore a need to derive reliable flows from the Mlalazi Catchment as it is a driver of sediment deposition and erosion processes which may impact on the opening or closing of the Mlalazi Estuary. The latest Reserve Determination study for Mlalazi Estuary was based on rapid assessment with low confidence (<40%) in simulated monthly streamflow. The study illustrated a need for further detailed assessment of catchment hydrology using appropriate and calibrated models. In an ungauged catchment where there is limited observed data, numerical models are useful tools to derive best estimates of flow, erosion and sediment transport. In this study the HEC-HMS hydrological model was developed, calibrated, validated and applied for simulation of runoff, erosion and sediment transport from the Mlalazi Catchment into the estuary. Calibration and validation was done at delineated sub-catchments with observed flow records. An event based calibration approach and a continuous approach were used in the development of the model. For the event model the initial and constant loss method was used for simulating rainfall loss from the catchment surface, while the Soil Moisture Accounting (SMA) Model was employed for the continuous simulations. The event calibration was based on two selected extreme storm events, namely the Domoina (31 Jan 1984) and Imboa (17 Feb 1984) cyclonic events; and the validation was done on two storm events in February 1985 and September 1987. The calibration and validation for continuous simulations of flows were from 1977-1986 and 1986-1999 respectively. The Nash-Sutcliffe Efficiency (NSE) and overall Root Mean Square Error (RMSE) were used to evaluate the model performance. The continuous flows for the catchment were then simulated from 1950 to 2017 incorporating erosion and sediment transport. The erosion was simulated using the Modified Universal Soil Loss Equation (MUSLE), and the Ackers-White method was chosen for sediment transport potential. The erosion and sediment transport models SIMULATION OF CATCHMENT RUNOFF, EROSION AND SEDIMENT TRANSPORT USING A TRANSIENT NUMERICAL MODEL FOR MLALAZI CATCHMENT v were not calibrated due to limitations of observed data, but parameter values were estimated from other studies available in literature for this region. The simulated sediment yield from the catchment was evaluated by comparison to sediments yield found by other studies in this region. It was concluded that a physically based, numerical simulation model provides a pragmatic method for the derivation of reliable hydrodynamic data and information in catchments with limited observed data like the Mlalazi Catchment. Furthermore, this study allowed a smooth linkage with the study of the Mlalazi Estuary that employed the HEC-RAS model.
The flow and sediment of the Mlalazi estuary in Kwazulu-Natal, South Africa
(University of Zululand, 2021) Mmako, Lesiba Vincent
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 from monitoring sites established in 2015 by the Hydrological Research Unit of the University of Zululand. The hydraulic model gave satisfactory performance statistics for high flood events during calibration and validation periods. The model overestimated the Q2yr stage and velocity event in the upper estuary channel and underestimated the stage and velocity in the lower estuary channel. The simulated velocity and Hjulström-Sundborg diagram were used to analyse the fluvial sediments distribution in the estuary channel and floodplains. The inundation maps of different storm sizes revealed that erosion occurs mainly in the active estuary channel and deposition of alluvial sediment takes place on the floodplains. The study concluded that a physically based, numerical flow model is best method for providing reliable estimates for hydrodynamic data and information in estuaries with limited observed data like the Mlalazi Estuary. The study will also provide essential flow information needed to set up the Mlalazi Mouth Model, which will help to determine the ‘flow reserve’ of the Mlalazi Estuary.
Assessment of coastal aquifer contamination using geochemical and health risk assessment in Maputaland formations, South Africa
(University of Zululand, 2021) Mthembu, Philisiwe Promise
The Maputaland coastal plain of KwaZulu-Natal is among the popular tourist areas in South Africa. Groundwater is the foremostsource for drinking and irrigation abstracted from the unconsolidated aquifers where the infiltration rate is very high. This could possibly increase the risk of aquifer contamination.The main objectives of this study is to evaluate the hydrogeochemical processes, identify the intended sources of groundwater contamination, and understanding the extent of trace metal contamination and health risk assessment. In this study, 53 and 42 groundwater samples were collected from bore wells during 2018 and 2019 and were analysed for major ions, minor ions, nutrients and trace metals. Na-Cl water type was dominant in groundwater followed by Ca-HCO3. Cross plots revealed that ion exchange, reverseion exchange, silicate weathering, seawater mixing, and anthropogenic inputs from agricultural activities govern the groundwater chemistry. GIS methods were adopted to produce spatial distribution maps of major ions through which locations of groundwater contamination and the intensity of hydrogeochemical processes were identified. The water quality index (WQI) varied from 18.9 to 157.1 with an average value of 45.55. Majority of the samples are classified as good, 22 % as poor, 2 % as very poor and 7% under unsuitable category, which are spatially distributed towards the southern and western parts of the study area. Mean concentration of trace metals were in the order: Zn>Li>Al>Fe>Mn>Cu>Pb>As>Co>Cd in 2018 , Fe>Zn>Mn>Sr>B>Pb>Cu>Co>Cr>Cd>Ag>Al>Ni in 2019. Most of the trace metals were found to be within the WHO standards for drinking water except for Cd, Zn, Pb, Mn, Al and Fe. Health risk assessment of trace elements via ingestion and dermal absorption pathways was carried out. Hazard quotient through dermal absorption (HQdermal) and hazard index (HI) for Co and Mn were above 1 in adults, children and infants. HQ derma land HI for Cd was greater than 1 in children and infants. HQ derma land HI for As and Pb were greater than 1 in infants. This implies that these metals pose serious adverse risk on local people and infants are more vulnerable to health risk than children and adults. The heavy metal pollution index shows that the groundwater samples vary from low to high pollution class and 21% of the samples exceed the critical limit of 100 implying that they are highly polluted with respect to heavy metals and are unfit for human consumption. The heavy metal evaluation index and degree of contamination reveal that all the groundwater samples have low pollution with regards to heavy metals and are suitable for human consumption. Moreover, the results of ecological risk assessment reveal that the studied heavy metals pose low ecological risk. Based on the pollution index of groundwater, majority of the samples fall in the insignificant pollution zone. The synthetic pollution index reveal that 2%, 74% and 24% of the samples are suitable, slightly and moderately polluted respectively with heavy metals. Similarly, the overall index of pollution reveal that majority of the samples are excellent and suitable for drinking purpose. Multivariate statistical analysis were adopted to evaluate sources of heavy metals in groundwater. Correlation matrix and principal component analysis reveal that weathering of aquifer matrix and anthropogenic activities are accountable for the release of heavy metals into groundwater. Furthermore, R-mode and Q-mode cluster analysis revealed two clusters. All the clusters from R-mode and Q-mode cluster analysis are linked to mixed sources including weathering and anthropogenic activities. This study provides the baseline data on hydro geochemistry that can be utilised further in future studies. It is recommended that contaminated groundwater in this region be treated before utilisation in order to maintain the sustainability of public health and recommends for further extended studies.
Identification of potential groundwater recharge zones: a case study of KwaZulu-Natal, South Africa
(University of Zululand, 2022) Ponnusamy, Dennisha
Urbanization has accelerated the changes in the uMhlathuze watershed in Kwazulu-Natal resulting in a deterioration in the quantity and stability of water resources, hence calling upon the development of groundwater resources. This study combined the use of GIS and remote sensing to demarcate groundwater potential recharge zones in the uMhlathuze catchment and Maputaland region using various pertinent parameters. The AHP approach and Catastrophe theory were used to determine acceptable zones by assigning weights to the 10parametersand their sub-criteriafor the uMhlathuze catchment, whilst the potential groundwater zones of the Maputaland coastal plain of Kwazulu-Natal is identified by comparing the Analytic hierarchy process (AHP) –Multi-criteria decision-making (MCDM) technique and Boolean logical approach. The map of groundwater potential zones for Maputaland was prepared by assimilating the 8 thematic layers, i.e., geology, geomorphology, lineament density, soils, slope, rainfall, and land use. Each thematic layer were assigned with subjective relative weights under AHP-MCDM technique and Boolean logic and were overlaid in a GIS platform to identify the groundwater potential zones. The groundwater potential zones were delineated under two different GIS techniques to obtain confident results. Weights of thematic layers were allocated using AHP normalized eigen vector methodology and weighted linear combination method was employed to find the groundwater potential index. Whereas in a Boolean approach, AND operator was applied in order to integrate thematic layers to delineate the groundwater potential zones. The AHP and the emerging Catastrophe theory was applied to the drainage density, geology, morphology, lineament density, soil type, rainfall, land use/land cover, transmissivity and aspect parameters and their sub-criteria for the uMhlathuze catchment and then integrated in a GIS environment. The Catastrophe theory consisted of firstly standardization of the parameters and sub-criteria, followed by the normalization of values using the complementary principle according to the model type and mathematical function encompassed by the model. Once they were normalized the highest mean value of the parameters were assigned the highest factor weight, whilst the lowest mean value was assigned the lowest factor weight. The delineated groundwater potential maps using AHP-Boolean-MCDM technique for Maputaland indicates that 6.0% (310.5 km2) from total area falls under very good; 67% (3467 km2) good; 25% (1294 km2) poor and 2% (103.5 km2) under very poor, whereas in Boolean 6logic about 70 % of the area (i.e.,3623 km2) constitutes good and 30 % (1552 km2) of the areas constitutes poor groundwater potential zone and the for the uMhlathuze catchment it was discovered that, 22.92% and 26.38% of the catchment is encompassed by 'Low' groundwater potential recharge zones, 0.37% and 0.08% by 'Very low' groundwater potential recharge zones, 9.42% and 10.26% by 'Good' groundwater potential recharge zones, 66.87%and 63.19% by 'Moderate', and 0.42%and 0.09% by 'Very good', for the AHP and Catastrophe theory respectively. Further, the obtained results in Maputaland indicate that the geology, geomorphology, land use and slope played a vital role in groundwater recharge. This pioneer study in Maputaland coastal plain explores the baseline data of the potential groundwater zones. Furthermore, in the uMhlathuze catchment, it was deduced that due to the hard rock complexion of the catchment, this attribute significantly limited presence of ‘Good’ and ‘Very good’ zones. The resultant groundwater recharge potential recharge zones maps were validated against TDS and nitrate concentrations, and groundwater level data of boreholes in the study area. It was revealed that the lowest and highest TDS, nitrate, and groundwater levels overlap with the ‘Good and Very good’ and ‘Low and Very low’ groundwater potential recharge zones respectively. The results emanating from this study can be used in further understanding of the available groundwater resources and can be helpful in future to find suitable groundwater exploration sites in the area. It was inferred that the convergence and use of GIS and remote sensing for delineating groundwater potential recharge zones are effective and may be utilized for groundwater planning and governance.

Browse

Browsing Hydrology by Issue Date

Results Per Page

Sort Options