Modelling land use and land cover change in the Western Cape Province

Abstract

The Western Cape Province is currently faced with population growth, declining household sizes, increasing household numbers, high levels of migration, urbanization and escalating development pressures. These factors have consequently triggered changes in land use and land cover (LULC) and incited issues such as urban sprawl, marginalization of the poor, limited public access to resources, land degradation and climate change. Furthermore, the issues surrounding LULC in the Province emanate from past inequities in access to land coupled with unsustainable land use practices. This poses a challenge to the government which strives for a sustainable nation that safeguards democracy by providing basic access to services, managing limited resources and advancing effective and efficient integrated planning whilst maintaining ecosystem functions. Understanding drivers of LULC change and how various factors influence LULC is important in meeting this challenge. Models which integrate and evaluate diverse factors of LULC change can be used to guide planners in making more informed decisions and achieving a balance between urban growth and preservation of the natural environment. The implementation of these models at a regional scale is however very limited in South Africa. LULC change models are valuable if their structures are based on deep knowledge of the system under investigation and if they produce credible results. This study therefore investigates the suitability of LULC change models in simulating LULC changes at a regional scale by quantifying changes in LULC in the Western Cape Province, determining the driving factors of LULC changes and exploring and implementing a regional land use change model. An investigation of changes in LULC was conducted by integration of a desktop study of LULC maps using the 1990 and 2013-2014 South African National LULC datasets; document analysis; and expert opinion in the form of semi-structured interviews with municipality town planners. An adapted Driver-Pressure-State-Impact-Response (DPSIR) Framework was used to analyse and present LULC changes in the study area. A literature review was conducted in shortlisting of models and further evaluations involved analysis of the models using selection criteria which focused on the model’s relevance to the study area, linkage potential to other models or software, transferability, user friendliness, data requirements and cost. The results of this study show that LULC changes in the Western Cape Province are driven by political, economic, technological, demographic, environmental and cultural factors which must be considered in strategies and policies in future planning to avoid detrimental impacts on the environment whilst maintaining socio-economic benefits. These factors were integrated in a hybrid model that was successfully implemented in the study area by combining Dyna-CLUE and Markov concepts. The hybrid model produced probability maps and simulation maps for the years between 1990 and 2014. Validation of the simulated maps was conducted using both visual and statistical analysis and the results indicated that the simulated maps were in good agreement with the validation map. Data availability was observed as the main drawback which influenced both the implementation of other suitable models and the accuracy of simulated maps. This study however contributes to the understanding of driving factors of LULC change and implementation of LULC change models at a regional scale in the South African context. Knowledge derived from this study can be used by planners as a guide to effectively gauge the impacts that planning policies and other driving factors might have on future LULC patterns in the Western Cape Province.