Ontwikkeling van hulpmiddels vir die bestuur en beplanning van 'n stedelike vloedvlakte: 'n GIS toepassing

English: The occurrence of floods early in 2000 shows that flood damage research for better assessmentand mitigation measures of the impact of floods is always necessary. Floods were always and will always be a problem in South Africa. Floods caused damages of R150million in one day at Ladysmith (Beeld. 28/02/1996). Losseswere not only financial. but social losseswere experienced as well. "The death toll from days of driving rain and resulting floods soared above 50 yesterday and left thousands of people homeless..." (BusinessDay.16/02/1996). To limit the impact of future floods. the planning and management of flood plains is very important. Recently. the approach of disaster management has changed from reactive to proactive. The problem in South Africa is that the necessary communication systems and institutional framework does not exist. Furthermore. government institutions do not have the necessary knowledge and tools to execute disaster management effectively. The aim of this study (Chapter 1).was to develop systemsand tools that can address the above-mentioned problems and to test the developed tools in a study area. As discussed in Chapter 2. the study area along the Swartkops and Chatty Riversin the Eastern Cape was a suitable area because of the diversity of land uses. A complete survey was done. In the case of the Swartkops River the land uses include industrial. commercial and residential. Along the Chatty Riverthe land usesare mainly residential.In Chapter 3 a system for the management of South African flood plains was developed. To do this. flood policies of other countries were studied. Elements of the flood plain management systemare: • a flood plain management committee e flood studies • flood plain management studies.and • flood plain management plans In Chapter 4 the development of a computer model for the calculation of potential flood damage was discussed. Another application of the model is the evaluation of possible flood damage mitigation options for financial effectivity thereof. To develop this model it was necessary to study models that were developed internationally. The three models of two international institutionsthat were studied were developed by the USArmy Corps of Engineersand the Australian National University. The inputs of TEWA(a computer model for the calculation of Tangible Economic flood Water damages Assessment)that were developed from these models, include flood damage functions, land use data, hydrological and geographic data. The model was tested in Chapter 5, by executing the activities of the flood plain management systemand using the model to calculate the potential flood damage and evaluating the mitigation options. Options that were evaluated were derived from discussionswith role-playersin Uitenhage and Despatch. Flood damage was calculated for the different land usesand combined to get the total flood damage. Damage to the residential sector of Uitenhage, Despatch and Sowetoon- Sea were calculated first. Afterward, damage to the commercial sector of Uitenhage and Despatch and industrialdamage to Uitenhage was calculated. Two options, namely the building of a flood levee and flood proofing were evaluated in Uitenhage and Despatch. Theresultsindicated that flood proofing was the best option for industriesin Uitenhage and a levee will have the most benefits for Despatch. It must be remembered that some assumptionshave been made and that can limit the use of the results.Thestudy has achieved itsgoal to develop a flood plain management systemthat can be used in South Africa to mitigate the impact of floods