Water kanalen in Syrie

Dit is een infostuk van Joshka, de dame achter Sapien Productions, die onderzoek naar het water probleem in Syrie heeft gedaan. Lees dit eens door, het is zeer interresant, en we zien hoe die kanalen nu echt werken, het is schijnbaar al echt heeeeeel oud en het zijn onder grondse tunnels/kanalen vanaf de moederbron naar kleine settelments en velden toe.

In the past major, cities and civilisations depended on underground water tunnels. Without their sustainable water supply, cities like Jerusalem, Esfahan and Damascus would not have existed. Ancient Roman and Persian civilisations would not have flourished. The Spanish would not have been able to spread through South America without them! And now the water tunnels are in danger, they are vanishing, silting up and collapsing but there is hope…..all can be seen in "Tunnel Vision" broadcast by TVE in the running up of the World Water Forum 2003. The production of "Tunnel Vision" is generously supported by the Swiss Agency for Development Cooperation.

In the summer of 2000, a small group of Syrian villagers living near the borders of the steppe Southeast of the Northern City of Aleppo renovated and cleaned their only water source with international help from Germany and the Netherlands. Their source is an ancient 1500-year old Byzantine water tunnel called qanat. They spent 3 months backbreaking work cleaning out the 600 meters’ long tunnel. Joshka Wessels led a research team based at the International Center for Agricultural Research in Dry Areas (ICARDA) and conducted a nation-wide survey of flowing Syrian qanats in 2001. They found a total of 42 qanat sites containing 91 qanats, of which 30 were still in active use. In one site, Dmeir, the qanats gave an average water supply of 20 litres per second. Although not much compared to Iranian or Omani qanats that can give up to 300 litres per second, the qanats of Dmeir give enough to irrigate vast amounts of land. Again renovation activities were started with the help of local government and farmers’ community. In this time of ecological farming and increasing environmental awareness “Tunnel Vision” explores what is the benefit of this sustainable water supply system within a changing social and economic environment?

WHAT ARE QANATS ????

Qanats are underground tunnels that tap the groundwater and lead the water artificially to a human settlement and agricultural lands using gravity flow conditions. The tunnels can be many kilometres long and very deep. The longest qanat is more than 40 kilometres long and 100 meter deep and can be found in Iran! In general a qanat system consists of an underground part and a part above ground surface. The underground part is divided in the "water production section" and the "water transport section". In the "water production section", the water is collected, either from a natural source or infiltration of groundwater. This section is underneath the groundwater level of the surrounding area. The "water transport section" transports the water to the surface. This section is usually lined with plastering on the sides to prevent leakage of water. The gradient of the tunnel is very precise and should not exceed 5 % in order not to let the flow erode the rock or sand in which the tunnel is dug. On the other hand, the gradient should not be too low because then the water can not be transported to the surface. The technique is similar to mining and originates from Old Persia (present day Iran) around 3000 years ago.

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