Modelling amenity landscape plant water use in South Africa

Abstract

South Africa is classified as a semi-arid environment with limited natural water sources. Amenity landscapes provide broad ranging benefits for society. Amenity landscapes account for between 31% - 50% of water supplied for domestic and urban use. To reduce water use and water conservation in amenity landscapes, strategies, regulations and interventions are required. Every landscape is a unique complex system with a large number of variables that differ from each other. The variability can be summarized into management/design, irrigation, climatological, edaphic and plant related aspects. Several amenity landscape water use models have been developed around the world and two in South Africa. This study developed a comprehensive South African hydrozone based plant database and an Amenity Landscape Water Use Model South Africa (ALWUMSA). This will improve hydrozoning of amaneity landscapes and ultimately also improve water conserbvation for these sites. It allows users/owners to determine water use requirements through an extensive data gathering, from aspects such as design, management, microclimate, environmental, edaphic, irrigation and plant related factors. Comparisons of results from ALWUMSA to three test sites, selected existing models and a range of scenarios produced results demonstrating that ALWUMSA consistently projected lower water requirements. The model also allows for site aspects to be changed thus encouraging end users to implement specific water saving intiatives with the amenity landscape to reduce water use. These savings will be translated into both water-use savings as well as financial savings for users of the amenity landscape water use model.