Exploring forest-water nexus in a changing environment of Kafue river basin, Zambia.
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Date
2025
Authors
Kamamba, Muyaka
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Zambia
Abstract
Water insecurity in Zambia's Kafue River Basin (KRB) is rising due to climate change, land-use change and increased water abstraction. The role of forests in the hydrological cycle, particularly through evapotranspiration (ET) has not been adequately explored. This study addressed this gap. The main objective was to explore the forest-water nexus in the Upper Kafue River Sub-Basin (UKRSB), its implications for sustainable river basin management and Inter-Basin Water Transfer (IBWT) from Luapula River Basin to KRB, Zambia. A systematic literature review using PRISMA
guidelines was conducted through Google Scholar (1970 to 2023). Remote sensing datasets: Actual ET (AET), NDVI, Total Canopy Cover and Tree Density were acquired and processed. In combination with forest inventory procedures. Data was analysed using QGIS for spatial analysis and Microsoft Excel version 2108 for statistical analysis. Twenty-five relevant papers on the forest-water nexus were identified, indicating limited research on this topic. A bibliometric analysis highlighted small co-author clusters with prominent figures like Paletto and Springgay
suggesting limited collaboration. Indirect field observations emphasised the significance of riparian forests and Nymphaeaceae (water lilies) in stabilising riverbanks and reducing stream turbidity respectively. AET in 2022 ranged from 268 mm year־¹ to 1505 mm year־¹, with an annual average of 985 mm year־¹. Correlation between AET and NDVI varies with season, moderate during the dry season (r² = 0.48) and weaker in the wet season (r² = 0.32). Long-term trends (2009 2022) showed a decline in AET with a slope of -12.14, suggesting climatic changes or deforestation. A threshold AET rate of 80 mm month⁻¹ was observed from 2013 to 2022. To offset water loss seasonal variations, an annual requirement of 4.36 billion m³ is needed. The Kalahari Woodland land cover (1177 mm year־¹) had the highest AET rate, whereas Miombo/Chipya (1082 mm year־¹), Parinari (1005 mm year־¹) and Munga (1005 mm year־¹) woodlands showed lower rates. Species-wise, Julbernardia globiflora (1444.6 mm year־¹) exhibited the highest AET rate in the Kalahari Woodland. Pinus kesiya and Eucalyptus grandis plantations also demonstrated elevated AET rates both at 1280 mm year־¹. For these reasons, there is need for considering land cover types and species-specific ET rates in IBWT planning to mitigate water loss. Necessitating integrated river basin and forest management strategies aimed at water conservation in the KRB. Future research should determine tree age effects on ET and employ sap flow meters for species specific ET estimation. Collaboration among forestry and water institutions is necessary to enhance policy and management strategies.
Description
Thesis of Master of Science in Integrated Water Resources Management.