Use of a microcomputer catchment modelling program designed for stormwater management studies is descriptionbed. The program is a kinematic type model, ie hydrodynamics are based on uniform flow conditions and continuity in conduits. The advantages of modular over finite elements and finite difference models are discussed. The modules in the program include catchments with infiltration, aquifers, conduits with circular, regular or compound cross-sections and storage reservoirs. The modular nature of the program enables alternative combinations of hydrological modules to be assembled ranging from large catchments to urban drainage systems. The program is therefore of use not only for a variety of catchment configurations but also for management studies, ie alternative detention or diversion systems to reduce peak flows and increase catchment recharge. The kinematic equations limit the hydraulic capability, ie backwater computations are not possible, but the resulting equations are suitable for rapid analysis on microcomputers. Routing is achieved by outlet control, but care is necessary to avoid numerical diffusion. An example application demonstrates the versatility in comparing alternative stormwater management strategies in an urban catchment in Sandton. Detention storage and road layout appear to have more influence than disconnected Impervious areas, dual drainage or floodplain storage.
Various attempts have been made in South Africa to establish geotechnical and other related data banks. Such data banks are extremely useful in the planning and design of tunnels. This paper summarized the current position regarding these data banks and illustrated their applicability to tunnelling. The authors concluded with this threefold plea: that the cities of Pretoria, Cape Town, Durban, Port Elizabeth and East London establish urban geotechnical data banks; that the fullest support be given to the SANCOT/CSIR tunnel data project; and that funds and manpower be made available to Geological Survey to enable them to put their geotechnical records on a computerized data base.