Land Use Change in The Knysna River Catchment and Its Impacts on the Geomorphological Characteristics of the Estuary between 1984 and 2019

Taylor, Salwah

Land Use Change in The Knysna River Catchment and Its Impacts on the Geomorphological Characteristics of the Estuary between 1984 and 2019

Master Thesis

2022

Abstract

The Knysna catchment and estuary are recognized in South Africa for their conservation significance as a sanctuary for marine species and biodiversity alike. The economy of the area which is dependent on tourism of the Knysna Estuary and catchment. The services obtained from the ecosystem include integral biodiversity value and is of significant importance for residents and tourists. Land use and land use cover dynamics remain some of the most crucial and obvious changes that has happened in the Knysna Estuary and catchment. Such changes severely affect ecosystems health, catchment areas, estuaries and the degradation of nature reserves. A ‘cloud-based platform for scientific analysis and visualization of geospatial datasets.' (Liu et al., 2020) method namely Google Earth Engine (GEE) is applied utilizing multi-temporal satellite imagery and Sentinel as interpretation to understand land use change over 35 years. A timeseries associated with land use changes and biodiversity loss were considered between the years 1984 and 2019. Additionally, Normalized Difference Vegetation Index (NDVI) and Supervised classification were performed using GEE software and Arc Geographical information systems (GIS) to identify land cover dynamics. The images are classified into three major land use classes, waterbodies, urban areas and vegetation. Vegetation is further classified into various classes namely fynbos, thicket, plantation forestry, salt marsh and agriculture. An accuracy assessment together with ground truthing, were conducted to verify and assess the overall classification accuracy of the results. The results indicated that over the study period urban growth and cultivated land makes up the most common land use category to have impacted the Knysna Estuary. Urban areas have increased significantly in reaction to the rapid increase in population ranging from 2.5% - 2.8% during the years 1984-1992, which reached to 2.9% - 4.1% during the years 1993-2007, and finally augmented to 4.3% to 6.3% during the years 2008-2019. The major reason behind the altering in the land use and geomorphology based on the research of the Knysna Estuary is human activities that have led to key determinantal impacts on surface runoff and land degradation. Overall, the noticeable changes in surface runoff and land degradation are strongly related to land use/land cover changes brought about by human impacts.