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The spatiotemporal variability and hydrological characterization of the surface water in the Cuvelai Etosha Basin, Namibia: A flood record (Bachelor Honors thesis)

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Title
Title The spatiotemporal variability and hydrological characterization of the surface water in the Cuvelai Etosha Basin, Namibia: A flood record (Bachelor Honors thesis) ?
Author Tamekeni Pius Nantuua ?
Abstract Identification and estimation of the physio-chemical evolution of surface water forms an important objective towards characterisation of the basin system as a whole. Baseline information of such a scope can ultimately aid in establishment of vital interlinks of surface water to atmospheric and/or ground water systems. The Cuvelai Etosha Basin (CEB) in northern Namibia is an important water system for both human usage and eco-natural systems. The present study mainly examines the temporal and spatial variation of stable isotope of surface water but a few other complementary physio-chemical parameters are also measured. 224 grab surface water samples were collected during the 2017 CEB wet season over four successive sampling campaigns (February, March, April and May). Sampling cites were randomly selected mainly floodplains (Iishana) and local natural occurring surface water ponds across the Cuvelai drainage region on a minimum sampling spacing of 10km. Physio-chemical parameters turbidity, electrical conductivity and pH were measured for on-site using HACH portable meters. Samples were analysed for stable isotopes (²H and 18O) compositions in the University of Namibia (UNAM) laboratory with an off-axis integrated cavity output spectroscope (Los Gatos Research, DLT-100). Results show pH, turbidity and electrical conductivity varied with time depended on the degree and kind of event captured by the campaigns. Stable isotopes composition range between -13.51 to 12.44 ‰ for δ18O and between -100.08 to 50 .92 ‰ for δ2H. An evaporation line for the CEB with an equation of δ2H = 5.91δ18O - 16.7 is presented by samples collected in March to April. The evaporation line slope is adversely influenced to a higher value by the CEB east surface water. Time series results show a relative decrease in the stable isotope composition in March, coinciding with peak rainfall and flood inflows which concludes to an amount and altitude effect. A progressive increase in the stable isotope composition of the CEB surface water from March to April caused mainly by growing evaporation effect with respect to time is evident. The east and west surface water points to sources with comparatively different isotope compositions. Conclusively, the differences are due to the flood inflow which significantly lowers the composition of the west side of the drainage region to more negative values. There is a lack of significant differences in the isotope composition along the north-south transect which translates to a common storm system affecting the basin. The knowledge spatial and temporal variations of the basin hydrological system will contribute to improved water resource management in the area and provide baseline information to various future scientific studies. ?
Dataset
Document Reference Date Type publication ?
Date 2017-12-01 ?
Language English ?
Online Linkage ?
Associated project SASSCAL (Phase 1) ?
Subproject 007 Improving knowledge and understanding of groundwater flow, water quality and quantity variations, improve methodology of groundwater availability study: Cuvelai – Kunene ?
Dataset Classification
Type PDF ?
Category thesis ?
Geographic Location
Study site Cuvelai Etosha ?
Geographic Description Namibia ?
Metadata
Metadata Contact Person Wanke, Heike, Dr ?
Metadata Date Stamp 2018-07-19 ?
Identifier
Internal identifier sdp_doc_documents_6426 (Link)