Enviromnetal evaluation of Attica 's streams. The case study of Picrodafni stream

Water is the most precious commodity to mankind. Since antiquity and to all civilizations the element has been a source of life and has enabled the development of all sectors of human civilization (trade, the arts, philosophy, astronomy, etc). From early on humanity has realized its worth and for that reasonrivers, streams and torrents deified and worshipped as the ultimate life form. Thus it is no coincidence that all notable ancient civilizations were flourished on the banks of large rivers. Greek civilizations flourished in a relatively arid climate, in areas that had no major water sources. The local rivers were inadequate to cover the needs of residents, so from very early on a need to manage water resources existed. The hydraulic works in ancient Athens were many and highly admirable. A number of them are still in service today. The residential development of Athens from the establishment of the fledgling Greek nation till today has been directly influenced by the large historical, social and economic changes that have taken place. The transfer of the capital of the Greek nation to Athens in 1834, the exchange of populations as a result of the Asia Minor disaster in 1922, the Second World War and the Greek Civil War totally altered the size of the population and its needs which led to the unregulated and unplanned expansion of the city. During this process many streams were rerouted, filled in, transformed into sewer drains or covered by parts of the cities roads. Today’s Athens in no way reminds one the old one as the majority the waterways have been covered over. The importance of streams to residential areas is immense, as they act as natural receivers of rain runoff and offer flood protection, they attract a variety of flora and fauna to their banks and surrounding areas, they influence in positive way the microclimate of the area and they reduce the atmospheric and noise pollution while refreshing the atmosphere. From a fiscal viewpoint, the streams with suitable maintenance and preservation by the government act as a very economic means of creating urban green spaces and tourist attractions. Furthermore, they can bolster the educational and social component as they can act as a spark for the active participation of citizens in voluntary organizations as well as in protecting the streams, associating socially, communication and pleasure as well as essentially lending to an aesthetic upgrade of the degraded urban landscape and the raising of the living standards of the residents. The problems that have arisen from the incorrect management of Athens streams are many and whose roots can mainly be found in the non-existent or faulty land planning, but also in the fragmentation of the responsibilities of the various bodies put in charge of managing the streams thus making it difficult to implement any project. If we were to correlate the above with the high population concentrations and activities which lead to an increased deterioration of the quality of life, as a result of atmospheric and aquatic pollution, then we can surmise that we have a dual disturbance of the aquatic ecosystem: hydraulic and natural. There are a number of ways to approach and solve this problem. The hydraulic approach calls for the introduction of preventive measures and protection of surrounding areas from the consequences of heavy rainfall through a thorough intervention to the basin and a rescue of any remaining streams. While, according to the architectural approach, that which is utmost importance is to realize the overall character of the stream, protect its entity and its exploitation as a natural feature of the city. This research subject represents a case study of a degraded urban stream, the stream of Pikrodafni, which stems from western foothills of Imittos and flows in the Saronikos Gulf, traversing a very dense urban web. It is one of the few remaining streams of Athens that retains a large degree of its natural components despite numerous human interventions. Specifically, the open part of the stream is studied, starting from Vouligmenis avenue, with research of the history of previous interventions, but also with in field observation and documentation of numerous problems: hydraulic inefficiency, instability of banks, pollution by uncontrolled dumping of sewage and waste and ecological imbalance. The interventions which are proposed have a mild and restorative nature that focus on the hydraulic restoration of the stream and prevention of flood risks but also in the protection of the ecosystem, the removal of pollutants and the aesthetic upgrade of surrounding areas without excluding the basin area as a single and indivisible whole.