The drainage systems will not continue to function properly without a well-planned, on-going preventive maintenance programme of inspection, desilting and repair. This forms a vital part of flood hazard management. The Government ensures that problematic road gullies, stormwater intakes, drains and watercourses are inspected on a regular basis especially before and during the rainy season.

In 2007, about 2,022 km (79% of total) of drains and watercourses are inspected by DSD every year. About HK$100 million was spent on such maintenance works. Extensive closed circuit television surveys have been employed for existing drains where man-entry inspections are not possible. Timely repairs to the drains will be carried out before major problems arise. Regular desilting and dredging of tidal channels are conducted so that their flood carrying capacities would not be adversely affected by sediment washed down from the upstream areas.

Clearing blockages with water jetting

Inspection of stormwater drain by closed-circuit television. (inner) A view inside a drainpipe

A special programme of inspecting flood control installations including flood water pumping stations and flood warning systems, is conducted each year to ensure that they would be fully operational in times of rainstorm. Coordinated efforts amongst relevant departments are in place to keep the streets clean in order to prevent rubbish from blocking the roadside gullies and catchpits.

Computer models have been developed and continuously upgraded so as to provide quantitative information on the risk of flooding, impacts of development and the performance of various flood loss mitigation options. A computerised stormwater drainage asset inventory and maintenance system is also being developed under the DMP studies. The system will provide an accurate up-to-date record of the inventory and the hydraulic and structural performance of DSD's drainage assets. All these technological developments will serve as a useful management tool to identify deficiencies, and to derive action plans and maintenance schedules for the drainage systems, thereby reducing flood hazards.

Drainage Asset Management System

Emergency Planning