CONSIDERATIONS FOR THE FIRST APPLICATION OF SOURCE CONTROL MEASURES FOR STORMWATER RUNOFF IN THE ATHENS METROPOLITAN AREA

摘要

The Greater Athens area consists of two main catchments, the catchmen s of the rivers Kifisos and Ilisos, which before the urbanisation, occurring during the last 50 years, possessed dense hydrographic networks. Both rivers drain to the Saronic gulf and their estuaries are only 1.5 km from each other. The main reach of the Kifisos has a total length of 21 km, draining an area of 390 km~2. The urban part of the catchment is continuously increasing, currently amounting to 60% of the total area. It is also important to point out that during recent years, extensive summer fires have drastically changed the behaviour of the non-urban part of the catchment. Over a length of 8 km upstream from its outlet, the Kifisos river is flowing in a closed section, with a capacity of 1400 m~3/s corresponding to a 50-year flow. Upstream from this section, the Kifisos has a variable open cross-section of structural concrete, wi h dimensions corresponding to various levels of flow, with some levels as low as 5 years. Along the river, a number of illicit connections continue to discharge industrial and domestic sewage into the river. During dry weather periods, baseflow and sewage are diverted 5 km upstream of the outlet to an adjacent sewage collector, which conveys them to the sewage treatment plant of Psitalia. During storm events, the river transports to the sea an important pollution load from domestic and industrial illicit connections already mentioned, but above all, from the wash-off of streets and the rest of urban surfaces drained. Taking into account the pertinent climatic conditions characterised by a long dry summer period, the first significant autumn rains have a shock effect on the sea environment.