CS Holdings partners with local government in disaster management

The Cape Metropolitan Council (CMC) is using high technology solutions to predict potential disaster situations in their water management programme for Strand and adjoining low lying areas, in line with government`s proposals contained in its Green Paper on Disaster Management.

An active partnership between national, provincial and local governments, statutory and voluntary organisations and communities, is needed in order to develop and implement effective disaster-management strategies.

In line with this approach, the CMC has partnered with JSE-listed IT group CS Holdings to design a prediction and control system that will be used to timeously warn residents of coastal town, the Strand, and the entire Lourens River catchment in the Helderberg Administration area, of possible flooding.

According to CS Holdings` project engineer Derwyn Oxley, the system provides the Strand Disaster Monitoring Centre with critical early flood warning and alarm information. Neighbouring Somerset West is part of the early warning system as well.

Consulting engineers Stewart Scott were responsible for implementing the system, which included a new Adroit SCADA (Supervisory Control and Data Acquisition) system to be installed at the disaster monitoring room at Strand fire station. Adroit Systems` SCADA was considered the best choice for this installation due to its frequent use in water monitoring systems.

"The system records rainfall in the region and, through continuous forecasting and monitoring of physical indicators, can alert the monitoring staff at the disaster monitoring room to the potential flood situation. They are then able to rapidly warn the public and residents in low-lying areas downstream of the monitored river points, through a prepared method of early warning. In the past, early warning systems were set up to enable the ongoing detection and monitoring of hazards. They concentrated on physical indicators - of rainfall, crops, flooding, etc. Now that it is accepted that people vary in their vulnerability to the effects of disasters, and that the mapping and tracking of vulnerability is also required. So our system is but one critical facet in the continuum of disaster management by the CMC," explains Oxley.

The town of Strand, with some 50 000 residents, is situated on the shores of False Bay at the foot of the Hottentots Holland Mountains, and forms part of the Helderberg Basin, along with Somerset West and Gordon`s Bay. It is situated in a floodplain, since it is adjacent to a river that is inundated by floods occurring in the river. Because there is no upper limit to the magnitude of a flood, there is also no definite boundary to the floodplain, but the higher the elevation of a point on the floodplain the smaller is the probability that floods will inundate it. Unfortunately, the Strand, as well as Somerset West, located at sea level, are at risk.

"Therefore, from a developmental perspective, flooding is not seen as only an act of nature. Rather, it is increasingly viewed as an expected consequence of poor risk management over the long-term," Oxley comments.

"Both risk reduction and disaster management are clearly multi-disciplinary processes, engaging a wide range of stakeholders, such as the CMC, CS Holdings and Stewart Scott."

Most of the information needed for the early-warning systems such as this one designed by CS Holdings, is data already collected by government departments for their own monitoring needs and planning. The strength of the early-warning system comes from the integration of data from different sources, and from the predetermined channels for ensuring that information is in a useful format, and reaches decision-makers promptly.

Therefore, the Adroit SCADA is connected to several outstations via a Motorola Moscad radio telemetry system. The Adroit SCADA in turn connects to the central station via an RS232 Modbus communications link. Information from the rainfall and river level gauges at the outstations is transmitted back to the central unit and this information is displayed, collected and manipulated within the Adroit SCADA system.

CS Holdings used Adroit`s open database connectivity tools to log the rainfall and river level information to a MS SQL database at regular intervals. This was done to provide long-term data collection in an open tool that allows integration and interrogation, using other packages and over a network.

The Adroit SCADA also uses the SQL database to interface with a flood prediction algorithm, which was developed by Stewart Scott. The algorithm takes the current data together with a two-hour history and predicts the expected river levels taking the terrain and water run off data into consideration.

The results of this algorithm are then available as a graphical trend display from within the Adroit SCADA. The algorithm also calculates a severity index of 0 - 10. This value is displayed and in the case of potential flooding, alarmed on the Adroit SCADA mimic screens.