Geography

Permanent URI for this collection

http://41.63.25.24:4000/handle/123456789/78

Browse

Now showing 1 - 20 of 21

Bathymetry of Makoye reservoir and its implications on water security for livestock within the catchment
(Conscientia Beam, 2019-09-01) MUCHANGA, MANOAH; SICHINGABULA, HENRY M.; OBANDO, JOY; CHOMBA, INNOCENT; SIKAZWE, HAPPY; CHISOLA, MOSES; Muchanga, Manoah
The objectives of the study were to: determine bathymetry of the reservoir; understand seasonal hydrological regimes of the reservoir; determine factors influencing reservoir bathymetry and, examine the implications of the reservoir's bathymetry on livestock water demand and policy decision making. The determined reservoir bathymetries and capacities at low, medium and full levels confirmed drastic changes in water volumes and eventually, a threat to water security for livestock. This unsteady equilibrium in reservoir's bathymetry and water volumes was mainly due to high mean annual siltation rates (>5,000 tyr-1). Using 3D spatial analysts tools in ArcGIS 10.3 and spreadsheet Microsoft Excel to analyze the data based on the study, hypsometric curves showed strong non-linear relationships among water depth and water surface; water depths and water volume, as well as water surface area and water volume. Generally, through inter-seasonal comparisons of reservoir's bathymetries and water volumes between 2015 and 2017, this study illustrates the significance of bathymetric study of small reservoirs as a plinth to provide policy context and guidelines on water resource management for livestock, as a missing component in general studies of bathymetry, which are usually predominated by understanding the physical processes, but with little or no emphasis on their meaning towards addressing societal needs. Hence, a community engaged strategy to addressing upstream sediment-generating activities would help in stabilizing the bathymetry of the reservoir and eventually enhance water security for livestock. Contribution/Originality: This study is one of very few studies which have investigated implications of bathymetric surveying on sustainable water resource management for livestock. The study documents how bathymetric surveying can be used to understand seasonal hydrological regimes and storage capacity loss of small reservoirs so as to prepare for water security.
Bathymetry of the Makoye reservoir and its implications on water security for livestock within the catchment
(International Journal of Geography and Geology, 2019) Sichingabula, Henry
The objectives of the study were to: determine bathymetry of the reservoir; understand seasonal hydrological regimes of the reservoir; determine factors influencing reservoir bathymetry and, examine the implications of the reservoir's bathymetry on livestock water demand and policy decision making. The determined reservoir bathymetries and capacities at low, medium and full levels confirmed drastic changes in water volumes and eventually, a threat to water security for livestock. This unsteady equilibrium in reservoir's bathymetry and water volumes was mainly due to high mean annual siltation rates (>5,000 tyr-1). Using 3D spatial analysts tools in ArcGIS 10.3 and spreadsheet Microsoft Excel to analyze the data based on the study, hypsometric curves showed strong non-linear relationships among water depth and water surface; water depths and water volume, as well as water surface area and water volume. Generally, through inter-seasonal comparisons of reservoir's bathymetries and water volumes between 2015 and 2017, this study illustrates the significance of bathymetric study of small reservoirs as a plinth to provide policy context and guidelines on water resource management for livestock, as a missing component in general studies of bathymetry, which are usually predominated by understanding the physical processes, but with little or no emphasis on their meaning towards addressing societal needs. Hence, a community engaged strategy to addressing upstream sediment-generating activities would help in stabilizing the bathymetry of the reservoir and eventually enhance water security for livestock. Bathymetry Evaporation GIS Hydrological regimes Livestock Monze District-Zambia Reservoir Sedimentation Water.
The catchment sediment budget as a management tool
(Environmental science & p o li c y, 2008) Walling, Des, E.
There is increasing recognition that fine sediment represents an important diffuse source pollutant in surface waters, due to its role in governing the transfer and fate of many substances, including nutrients, heavy metals, pesticides and other organic contaminants, and because of its impacts on aquatic ecology. Catchment management strategies therefore frequently need to include provision for the control of sediment mobilisation and delivery. The sediment budget concept provides a valuable framework for assisting the management and control of diffuse source sediment pollution and associated problems, by identifying the key sources and demonstrating the importance of intermediate stores and the likely impact of upstream mitigation strategies on downstream suspended sediment and sedimentassociated contaminant fluxes. Accordingly, the utility of the sediment budget concept for catchment management is further discussed, by introducing examples from several contrasting river basins. Keywords: Sediment budget Catchment management Sediment sources Sediment stores Sediment yields
Documenting catchment suspended sediment sources: problems, approaches and prospects
(Progress in Physical Geography, 2004) Walling, Des,E.
Establishing catchment suspended sediment sources is fraught with difficulty. Data collection comprises indirect and direct approaches and an overview is provided. The indirect approach uses a range of techniques to measure or evaluate sediment mobilization. Yet, although recent technological advances in surveying, remote sensing and photogrammetry provide improved resolution of temporal and spatial patterns of catchment erosion, these procedures take no account of source–river connectivity and the uncertainties associated with sediment routing. It is therefore only possible to infer the provenance of suspended sediment loads on the exclusive basis of on-site erosion data for different portions of the upstream catchment unless supportive information on sediment delivery is readily available. In contrast, the direct approach attempts to link sediment sources and flux using alternative means and therefore avoids the need for complementary information. Sediment fingerprinting best represents the direct approach to sediment sourcing and there remains substantial scope for exploiting the potential of this technique. The spatial complexity of sediment mobilization and transfer at the catchment scale necessitates a distributed approach to modelling. Recent developments in computer power and programming techniques are proving useful in this respect, but assembling the input and validation data required by distributed models continues to pose problems and it is frequently difficult to apportion the relative contributions from individual sediment sources. General prospects for future developments are discussed. Key words: catchment suspended sediment sources, direct approach, indirect approach, modelling, sediment fingerprinting.
Effects of Sedimentation on small reservoirs in the Mushibemba catchment, Mkushi farm block, Central Zambia
(Journal of Geography and Geology;, 2019) Sichingabula, Henry
Sedimentation is one of the problems that affects the storage capacity of most small reservoirs, and if not addressed on time it may lead to the dams being filled up with sediment. The aim of this study was to assess the effects of sedimentation on the storage capacity losses of Moffat dam and GRZ Weir located in the Mushibemba Catchment of Mkushi Farm Block, Central Zambia. The method used to understand reservoir storage capacity loss was bathymetry survey using the hydrographic survey boat (RC-S2) which consists of an echo sounder and a Differential GPS. Information on the initial storage capacity of the two reservoirs was obtained from the Water Resources Management Authority (WARMA). The analysis of the data revealed that the measured volumes of Moffat dam and GRZ Weir were 1,180,462 m3 and 197,218 m3, respectively. The estimated storage capacity losses for Moffat reservoir was found to be 223,789 m³ and 53,312 m3 for the GRZ Weir. The estimated rates of sedimentation loss were found to be 13,986.81 m3 yr-1 (Moffat reservoir), with a lifespan of 84 years, and 1,480.89 m3 yr-1 (GRZ Weir) with a lifespan of 133 years. The source of the accumulated sediment was mainly attributed to originate from the cleared commercial agricultural land which predominantly consists of clayey to loamy soils. This also accounted for the high turbidity of the reservoir water. This situation therefore calls for periodic dredging of the deposited sediment to increase reservoir storage capacity. Keywords: Bathymetry survey, Reservoir storage capacity, Sedimentation, Suspended sediment
Evaluating ceres-maize model using planting dates and nitrogen fertilizer in Zambia
(Journal of Agricultural Science, 2015-02-15) Sichingabula, Henry
A field experiment was conducted during the 2013/2014 season to evaluate the performance of CERES-maize model in simulating the effect of date of planting, nitrogen fertilizer and root-zone soil water profile on growth and yield of maize (Zea mays L.) at the Field Research Station of the School of Agricultural Sciences, University of Zambia, Zambia (15o23.6859′S, 28o20.226′E; 1,261 m.a.s.l). The experimental design was a split plot with three replicates, three planting dates (November 24, December 8, and December 22) assigned to main plots and two nitrogen fertilizer rates (112 and 168 kg N ha-1) assigned to sub-plot. Phenological stages and aboveground biomass were used for model evaluation and these were observed at vegetative and reproductive stages. Soil water profiles were monitored using the Diviner 2000 Probe. Planting date significantly affected grain and biomass yield at P < 0.05. The coefficients of variation for grain and biomass yield were below 12% and considered efficient. The Generalized Likelihood Uncertainty Estimation (GLUE) programme was used to estimate the genetic coefficients for the CERES-maize model. The model’s prediction of plant emergence (±1 days), time to anthesis (≥ −3 ≤ ±1 days) and maturity (≥ −4 ≤ 6 days) was good. Simulation of biomass (RMSE=1135 kg/ha, d=0.96, EF=0.86) was reasonably accurate while leaf area index (d = 0.54, EF = −0.65) was simulated with less accuracy due to poor d-stat and forecasting efficiency. The model’s simulation of grain yield was fair (NRMSE = 21.4%) while soil root water availability demonstrated that substantial potential yield may have been lost due to water stress. The results showed that the model can be used to accurately determine optimum planting date, biomass yield and nitrogen fertilizer rates with reasonable accuracy. Keywords: biomass, calibration, CERES-maize, fertilizer application rate, GLUE, tops weight
Impacts on freshwater macrophytes produced by small invertebrate herbivores: afrotropical and neotropical wetlands compared
(Hydrobiologia, 2020) Sichingabula, Henry
We compare invertebrate herbivory upon 13 macrophyte species in freshwater wetland systems located in two global ecozones, the Afrotropics and Neotropics, in the context of biotic and environmental factors influencing these wetlands. The two ecozones are climatically similar regions, with similar water chemistry, but experience contrasting grazing and disturbance pressures from large mammalian herbivores. Our results for macrophytes show that small invertebrates removed significantly more lamina biomass per leaf in Neotropical macrophytes (6.55%) than Afrotropical ones (4.99%). Overall, the results indicate that underestimation of up to 15.6% of leaf biomass may occur if plant tissue removal by invertebrate herbivores is not included in estimates of plant biomass. Regarding the contrasting grazing and disturbance pressures from large herbivores influencing these wetlands, seven mammal species (especially the Black Lechwe antelope, Kobus leche) were observed impacting macrophytes in the Afrotropical wetlands, while in the Neotropics, only much smaller rodents, capybara, (Hydrochoerus hydrochaeris) were sporadically observed. We discuss the relevance of results for invertebrate herbivory in the context of both the methodological approach and the importance of large mammalian herbivores as biotic factors additionally impacting macrophyte populations in these subtropical to tropical wetlands. Keywords Herbivorous mammals , Freshwater ecosystems , Grazing damage , Tropics
Learning for climate change adptation among selected communities of Lusaka Province in Zambia
(AJOL, 2017-09-03) Muchanga, Manoah
This research was aimed at surveying perceptions of climate change and educational themes that would be contextually relevant for climate change adaptation. It locates within the United Nations’ Educational, Scientific and Cultural Organization’s (UNESCO’s) Balaclava recommendations on Climate Change Education for Sustainable Development (2013). Uncertainty as to how residents of selected households understood the causes and effects of climate change as well as the content structure of learning for climate change adaptation constituted the problem. Using social constructivism, hermeneutics, survey design, semi- structured interviews and constant comparative analysis, the article shows that the challenges of climate change are comprehended in diverse ways. It also shows that drawing knowledge from diverse sources or cross-disciplines can evoke behavioural and social change that is critical in order to nurture best thinking and practices regarding adaptation.
Niche-breadth of freshwater macrophytes occurring in tropical Southern African rivers predicts species global latitudinal range
(Elsevier, 2016) Sichingabula, Henry
The study tested the hypothesis that measurement, using multivariate Principal Components Analysis (PCA), of the niche-breadth of river macrophyte species in southern tropical Africa, may predict their larger-scale biogeographical range. Two measures of niche-breadth were calculated for 44 riverine macrophyte species, from 20 families commonly occurring in Zambia, using an approach based on PCA ordination with 16 bio-physico-chemical input variables. These included altitude, stream order, stream flow, pH, conductivity and soluble reactive phosphate concentration (SRP). In the absence of additional chemical water quality data for Zambian rivers, invertebrate-based measures of general water quality were also used. These were benthic macroinvertebrate Average Score per Taxon (ASPT), and individual abundance of nine macroinvertebrate families with differing water quality tolerance, indicated by their Sensitivity Weightings within the Zambian Invertebrate Scoring System (ZISS). Macrophyte large-scale latitudinal range was derived from world geopositional records held by online databases, and additional records held by the authors. The two niche-breadth metrics divided the species into narrow-niche and intermediate/broad-niche categories, showing significant variation (from one or both of correlation and ANOVA test outcomes) in altitude, stream flow, conductivity, SRP, pH and ASPT, but not stream order. Macrophyte alpha-diversity (as a measure of number of individual niches co-existing per habitat) showed no significant relationship with individual species niche-breadth. Narrow-niche species included a higher proportion of Afrotropical endemics than did species with broader niche size. There were significant predictive relationships between macrophyte niche-breadth and latitudinal range of the target species at global and Afrotropical scales, but not for the Neotropics Keywords: Africa Aquatic plants Benthic macroinvertebrates Freshwater ecology Latitudinal distribution Niche analysis Rivers.
Occurence , severity and magnitude of hydrological drought in Zambia :impacts and implications
(1999) Sichingabula, Henry
Persistent occurrence of drought under increasing water supply demands for municipalities and agriculture, and under increased threat of global warming, requires increased understanding of drought characteristics and sustainable use of water resources. Using the theory of runs, several hydroiogical drought parameters of frequency of occurrence, run length, magnitude and run intensity, were investigated for the Kafue and Zambezi rivers. Objectives were to (a) determine magnitude-frequency characteristics of hydroiogical droughts; (b) determine some drought run parameters and frequency of their occurrence; and (c) propose a new approach for increasing Zambia's utilization of its water resources without jeopardizing international relations with neighbouring countries. Better understanding of droughts and assessment of Zambia's present and future water requirements will enable planners and decision makers to bring increased economic benefits to citizens. Zambia's drought and water scarcity problems are outlined and linked to some proposed regional water projects designed to divert water from the Zambezi River system. One possible solution to problems of drought and dwindling water levels on Kafue River is proposed.
Problems of sedimentation in small dams in Zambia
(Human Impact on Erosion and Sedimentation, 1997) Sichingabula, Henry
An inventory of small dams in Zambia and the results of a preliminary analysis of sediment loads for rivers and reservoirs are reported. A regression approach was used to determine relationships between drainage area and sediment load for 21 rivers based on available sediment concentration and discharge data. The resulting regression equation was applied to the drainage areas of 66 small dams located in Southern Province and rates of sediment input to the reservoirs were computed. By assuming 95% trap efficiency for sediment by the dams, the expected useful life of the reservoirs was also calculated. Calculated annual rates of sedimentation in small dams were found to range from 2 to 183 m3 year1 with a mean of 24.6 m3 year1. The estimates of reservoir useful life ranged from 200 tp 5100 years with a mean of 7314 years. Anthropogenic factors contributing to sediment generation and sedimentation in. reservoirs, community participation in dam construction and rehabilitation efforts together with conservation measures embarked on in the country are discussed. Qualitatively, it is concluded that sedimentation in the dams of Southern Province is serious. This calls for detailed quantitative research to assess the problem and to find ways of minimizing adverse impacts of soil erosion on environment and society.
Rainfall variability, drought and implications of its impacts on Zambia, 1886-1996
(1998) Sichingabula, Henry
The theory of runs was used in the investigation of frequency of occurrence, duration, magnitude and severity of drought in 46 districts of Zambia, 1886-1996. The 30-year "normal" rainfall was used as the threshold for drought occurrence with most analyses restricted to the 1921-1970 period. Analysis revealed that rainfall variability, indicated by increasing 11-year coefficients of variation (CVs) for selected stations and decreasing rainfall trends observed in southern Zambia after 1975, was not extraordinary as similar conditions were experienced before the turn of 19th century. What was new, however, is that the decreasing rainfall after 1975 seems to be related to the accelerated global warming associated withanthropogenic activities. Implications of impacts of drought were assessed from scenarios of drought occurrence under the threat of rising global warming. Various drought adaptation measures are discussed. It is concluded that, in Zambia drought is a chronic phenomenon which requires pre-planned measures for minimizing its impacts.
Reflexive debate on use of philosophy in scienctific research
(ARC, 2020-06-01) Muchanga, Manoah
How should philosophy be used in scientific research? is the question addressed in this paper. The aim of this desktop research was to critically contribute to the already ongoing debate around the use of philosophy in scientific research and to propose a user friendly framework on how to integrate philosophical decisions with methodological decisions. This paper argues that the content and length of a research does not make it scientific, but its philosophical foundation and related methodologies. It also shows that use of philosophy in research is not merely a recitation, repetition and dumping of borrowed words, but a reasoned and careful re-contextualization of philosophical assumptions to apply them to one’s own research thesis. There is also no such a thing as epistemological and ontological monovalence because there are many ways of creating and understanding reality and, moreover, which paradigmatic framework is ‘better’ partly depends on the research question(s) one seeks to answer. Only if we understood each philosophy and its assumptions, would we be in a better position to challenge them and, reflexively think differently.
A review of coupled hydrologic-hydraulic models for floodplain assessments in africa: opportunities and challenges for floodplainwetland management
(Multidisciplinary Digital Publishing Institute(Hydrology), 2021) Sichingabula, Henry
Floodplain wetlands are a fundamental part of the African continent’s ecosystem and serve as habitat for fish and wildlife species, biodiversity, and micro-organisms that support life. It is generally recognised that wetlands are and remain fragile ecosystems that should be subject to sustainable conservation and management through the use of sustainable tools. In this paper, we propose a synthesis of the state of art concerning coupled hydrologic and hydraulic models for floodplains assessments in Africa. Case studies reviewed in this paper have pointed out the potential of applying coupled hydrologic and hydraulic models and the opportunities present to be used in Africa especially for data scarce and large basin for floodplain assessments through the use of available open access models, coupling frameworks and remotely sensed datasets. To our knowledge this is the first case study review of this kind on this topic. A Hydrological model coupled with Hydraulic Model of the floodplain provides improvements in floodplain model simulations and hence better information for floodplain management. Consequently, this would lead to improved decision-making and planning of adaption and mitigation measures for sound floodplain wetland management plans and programmes especially with the advent of climate change and variability. Keywords: coupledmodelling; hydrologicmodels; hydraulicmodels; floodplain; wetlandmanagement
Sedimentation and its effects on selected small dams east of Lusaka, Zambia
(Academic star publishing company, 2015) Sichingabula, Henry
In Zambia, the need to conserve water resources has resulted in the construction of small dams. However, small dams are adversely impacted by sedimentation. The aim of this study was to assess the water storage capacity loss for the selected small dams east of Lusaka Zambia. These included Lwiimba, Silverest, Morester and Katondwe dam. Data was collected by bathymetric survey for each small dam using hydrographic boat with echo sounding. The initial storage capacity data were collected from the dam owners and through interviews with key informants on the effects of sedimentation on dam uses and on the existence of sediment control measures. Results of the study revealed that the measured reservoir storage capacities in year 2015 for Lwiimba, Silverest, Morester and Katondwe dams were 101,051.43 m3, 379,480.00 m3, 14,724.88 m3 and 10,714.88 m3, respectively. The estimated rates of sedimentation for Silverest was 14,595.40 m3yr-1; Lwiimba (2,200.99 3yr-1); Katondwe (283.92 m3yr-1), and Morester (251.01 m3yr-1). These rates of sedimentation has led to reservoir capacity storage losses of 99,044.57 m3; 379,480.5 m3; 13,805.68 m3 and 9,937.12 m3 for Lwiimba, Silverest, Morester and Katondwe, respectively, with the general consequences of reservoir drying especially in the dry season. Natural vegetation is the main sediment control measure used in the catchments. It is concluded that the studied small dams East of Lusaka are seriously affected by sedimentation. This calls for periodic dredging of deposited sediment in order to increase reservoir storage capacity for sustainable use of the water resource in small dams’ impoundments. Key words: sedimentation, bathymetric survey, small dam, reservoir capacity, erosion
Special study on sediment discharge and Its consequences (SedSS)
(United Nations Development Programme/Global Environment Facility (UNDP/GEF), 1999) Sichingabula, Henry
Lake Tanganyika is among Zambia's important fisheries which require protection from adverse impacts. Sedimentation is one of the threats to Lake Tanganyika's biodiversity. This is because deposition of sediment clogs streams and reduces their capacities. Pollution by sediment is also one of the major factors causing deterioration in quality of streams and lakes. The sediment deposited into streams, lakes and reservoirs destroys the habitat for fish and other species. In aquatic environments, sediment impairs the dissolved oxygen balance and obscures the light needed for aquatic growth, both of which are detrimental to aquatic life forms. Additionally, heavier sediment particles blanket fish spawning areas and cover food supplies for many species. Pesticides and nutrients origination from agricultural lands are carried off the land by sediment in surface runoff and add to the pollution of downstream waters. For example, phosphates are adsorbed by soil colloids and move into streams and lakes through erosion of soil particles on which it is adsorbed. Nitrogen fertilisers together with phosphorus are the major cause of eutrophication in lakes and rivers which is detrimental to aquatic species. Therefore, the prevention of soil erosion by good conservation practices are the most efficient means of controlling pollution from agricultural lands. The physical characteristics of Lake Tanganyika basin are to a large extent controlled by the geology which is dominated by meta-quartzites of Precambrian ages. These rocks with the high rainfall regime experienced in the area have given rise to the high leached sandveldt soils which characterise the plateau area. These features of the physical environment in the lake Tanganyika basin are discussed in detail. This report documents the activities of the Zambia Special Sediment Study undertaken in almost a period of one year. Methods of data collection an errors inherent in methods used are also discussed. The determination of volumes of discharge and sediment deposited in the lake employed on various statistical models in the development of rating curves. The models selected were tested for accuracy before they were applied to monitored water level data. The study found that mean flow discharges on rivers draining into Lake Tanganyika ranged from 1.426 m3 s-1 on Izi River to 98.563 m3 s-1 on Lufubu River. The lowest and maximum discharges ranged from 0.183 m3 s-1 on Lucheche River to 346.68 m3 s-1 per day on Lufubu River. Similarly, quantities of clastic suspended sediment deposited by the five rivers into the lake between September, 1998 and May, 1999 were found to range from 0.082 tonnes on Kalambo River to 1,539.634 tonnes per day on Lufubu River. The mean values of sediment deposited into Lake Tanganyika were found to range from 1.248 tonnes on Izi River to 208.603 tonnes per day on Lufubu River. Magnitude frequency analysis was used in the determination of the flow ranges which transport the most load in a single year. The effective discharge on the studied rivers was variable ranging from 0.78 m3 s-1 on Izi River to 258 m3 s-1 on the Lufubu River. The durations of these class-based effective discharges were found to range from 2.1% corresponding to the highest discharge, to 54.5% of the time on Izi River where the lowest event transported the most load. The sediment-discharge regimes for rivers in southern Lake Tanganyika basin were characterised by a uniform histogram having a well defined mode and a relatively frequent effective discharge. This was exemplified by Lucheche River. In cases where the regime in which the lower level flows were the effective discharge this was exemplified by Lunzua River
Suspended sediment transport characteristics of upper Kaleya river,Southern Zambia
(2000) Sichingabula, Henry Walling, D.E. Collins, A.L. Leeks, Graham G.L.
Soil erosion has many negative impacts on agriculture and other land related activities and so there is an urgent need to find ways of controlling it. In a bid to increase the understanding of soil erosion and sediment transport processes in Zambia, a project, which was funded by the UK Department for International Development, was conducted in the Upper Kaleya River catchment, southern Zambia, between 1997 and 2000. Being primarily concerned with sediment budgeting, this project necessarily involved the collection of discharge and suspended sediment load data for estimating sediment yields from the study river. This paper reports the suspended sediment transport characteristics of Upper Kaleya River during the study period. Analysis of the data collected at the study catchment outlet, at Roadbridge, revealed that discharge ranged from zero, during some dry season months, to 3.65 m3 s-1, with a daily mean discharge of 0.406 m3 s-1. The corresponding suspended sediment loads ranged from zero to 253.9 tonnes, with a mean of 3.15 tonnes per day. Magnitude-frequency analysis revealed that the flow responsible for transporting most of the suspended sediment load was 1.44 m3 s-1. This discharge represented 1.5 % of the time. During the study period, the total cumulative discharge was estimated at 34.8 million m3, whilst the total suspended sediment load was estimated at 3,130 tonnes. It is concluded that, though the Upper Kaleya River catchment is small, measured discharge and suspended sediment fluxes are reasonably high. Ways of controlling soil loss and of improving water resource protection should therefore be encouraged among the local farmers. There is also an urgent need to conduct this type of research in larger catchments in Zambia and in southern Africa region in order that national and regional sediment-related control measures can be designed and implemented. KEY WORDS: Catchment, effective discharge, magnitude-frequency analysis, river discharge, soil erosion, suspended sediment load.
Understanding controls on biotic assemblages and ecological status in Zambian rivers for the development of sustainable monitoring protocols
(Geophysical Research Abstracts, 2014) Sichingabula, Henry
The water resources of Zambia are likely to experience increasing multiple pressures in the future as a result of very high predicted population growth, industrial development, land use change, and potentially, altered regional rainfall patterns. It is well known that rivers in tropical regions typically have a rich biodiversity, controlled in part by inter-annual variability in climate and discharge, and in part by local catchment conditions. However, till recently little country-wide work had had been carried out on the biota of Zambian rivers, and little was therefore known about the ecological status, or degree of catchment alteration of many of the rivers.To underpin sustainable water management, protocols have been developed to assess the ecological status of Zambian rivers.
Understanding sediment process in the Magoye reservoir of Southrn Province Zambia
(ARIPD, 2017-06-01) Muchanga, Manoah
Reservoir sedimentation is one of the problems facing managers of small reservoirs (with ≤5m height of embankment). The main methods used to understand sedimentation process in the Makoye reservoir included sediment coring, onsite measurements using Sedimeter SM3A, use of Elevation Change Method (EMC), laboratory analysis of sediment core, 3D Spatial Analyst Tools (3DSATs) in ArcGIS 10.3 as well as mathematical models. The reservoir had been silting at a significant rate of 3,112.97 m3 yr-1 leading to average accumulation of 87,163 m3 of sediment, which had eventually reduced the reservoir's storage capacity by 53.5%. The EMC methods also revealed that Makoye reservoir tapped 79,749.38 m3 of sediment giving rise to the between method average sediment volume of 83,456.26 m3. Reservoir's useful life was found to be 24 years. Results from Sedimeter SM3A showed that a total depth of 0.688cm of sediment had accumulated during a period of 309 hours in the 2015/2016 rainy season as compared to 1.56 cm in the 2016/2017 rainy season. The long term average depth of sediment was found to be 2.4 cm. It was concluded that sedimentation in the Makoye Reservoir is a serious problem which may lead to complete loss of reservoir storage capacity.
Using unsupported lead-210 measurements to investigate soil erosion and sediment delivery in a small Zambian catchment
(Elsevier, 2002) Sichingabula, Henry; Walling, D.E.; Collins, A.L.
Traditional techniques used to assemble information on rates of erosion and soil redistribution possess many important limitations. As a result, the use of environmental radionuclides, and more particularly 137Cs measurements, has attracted increasing attention in recent years as a means of obtaining spatially distributed information on rates of erosion and deposition. The application of the 137Cs approach is, however, hampered in some areas of the world where 137Cs inventories are low and the low concentrations of 137Cs found in soils and sediments cause problems for laboratory analysis. These problems will increase as time progresses due to the radioactive decay of the existing inventory, most of which was deposited as fallout ca. 40 years ago. This contribution explores the potential for using another fallout radionuclide, namely unsupported 210Pb, as an alternative to 137Cs, in the small (63 km2) Upper Kaleya catchment in southern Zambia where 137Cs inventories are already very low. The approach employed with unsupported 210Pb is similar to that used for 137Cs, although the essentially constant fallout of unsupported 210Pb through time means that the resulting estimates of erosion and soil redistribution rates reflect a longer period of time (ca. 100 years rather than ca. 40 years). The estimates of erosion and deposition rates derived from the unsupported 210Pb measurements are used to construct typical sediment budgets for the three main land-use types in the Upper Kaleya catchment, namely, commercial cultivation, communal cultivation and bush grazing. The results obtained from the unsupported 210Pb are compared with equivalent results based on 137Cs measurements provided by a previous investigation undertaken in the study catchment. The two sets of results are highly consistent. The study reported confirms the viability of using unsupported 210Pb as an alternative to 137Cs in this environment and demonstrates that conjunctive use of both radionuclides can provide additional information on the erosional history of a study area.

Browse

Browsing Geography by Title

Results Per Page

Sort Options