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  • D05.1 Case Study Report (Turkey): The Gediz basin in western Turkey has changed considerably in the past decade, moving from being a comparatively water-rich basin to one that is now closing

SMART Report Summary

Project ID: ICA3-CT-2002-10006
Funded under: FP5-INCO 2
Country: Turkey

D05.1 Case Study Report (Turkey): The Gediz basin in western Turkey has changed considerably in the past decade, moving from being a comparatively water-rich basin to one that is now closing

The Turkish case study has focused on two major problems in western Anatolia along the Aegean Sea. The first one is the case of the Gediz River Basin, neighbouring the city of Izmir, where water scarcity is a significant problem. Water shortage is due basically to competition for water among various uses (water allocation problems) and environmental pollution. There are serious institutional, legal, social and economic drawbacks, which enhance water allocation and environmental pollution problems.

The second issue investigated is the sustainable management of water resources in the Izmir urban and rural area where coastal interactions are significant. The above two cases are essentially in close interaction as the inland practices of water and land management in the Gediz Basin lead to coastal problems in the Izmir Bay. Thus, the region as a whole requires analysis on sustainable management of natural resources from various perspectives.

The case of the Izmir Bay was studied via the use of the TELEMAC model and the following results were obtained:
- Within each TELEMAC scenario, it is observed that the pollution from the Gediz River tends to move along the coast line toward the entrance of the inner bay, while the point source pollution from the discharge points tends to cover the biggest part of the inner bay in the east-west direction.

- The effect of the NW winds is to slow down the movement of the pollution from Gediz toward the entrance of the Inner Bay; yet, it still creates a pollution risk for the eastern coast of the biggest island (Uzunada) in the bay.

- The scenarios also indicate that the pollution from the Cigli treatment plant tends to expand into the Inner Bay so that it can reach the Izmir port area even at the end of a very short simulation period of 1 day.

The following results are derived through WaterWare (the analytical tool of SMART) scenarios run for the Gediz Basin:
- Water quality management responses could not be effectively analyzed due to lack of sufficient data. This is an unfortunate situation since one of the two key problems in Gediz is water pollution. This response could only be included in the analyses in the form of low flow augmentation.

- The economic efficiency of the Gediz system for water use/water supply issues cannot be evaluated due to lack of sufficient and reliable data. It is difficult to state the economic value per unit of water used in the basin.

- The results of WRM scenarios indicate that irrigation demand will be affected the most in the future by water scarcity. If water scarcity occurs due to natural drought conditions, industrial water demand cannot be met due to low groundwater levels.

- Changes in crop patterns do not significantly affect the irrigation demand. On the other hand, improvement of the irrigation schemes, either in conveyance systems or in the method of field irrigation, is positively reflected in the water budget of the basin. This is due to the fact that 75% of the surface waters are consumed by irrigation. The current efficiency of the irrigation schemes is in the order of 60-70%; but this figure may be increased to 90% if improvements in the irrigation systems can be realized.
- Following from the above point, system reliability in scenarios with no irrigation system improvements (pessimistic scenarios) remains below 80%; whereas it increases to above 90% for Business as Usual and optimistic scenarios.

- The wetland ¿Bird Paradise¿ is currently fed by the existing irrigation system. If improvements can be realized in the irrigation schemes, these will positively affect the wetland as well.

- Industrial water demand is met by groundwater resources only; thus, all pessimistic scenarios lead to restrictions on industrial supplies.

- The major conclusion to be derived from the available scenarios is that, if the situation in the Gediz Basin is evaluated on the basis of water budget only, the first steps to be taken for better management of the basin would be to improve the current status of the irrigation schemes by reverting to conveyance systems and field irrigation methods that minimize water losses.

- The two key problems in the Gediz Basin were identified to be water allocation and water pollution problems. The analysis of both problems is hindered to a certain extent by data limitations. Yet, water allocation could be rather well analyzed as it deals with water quantity, and data on quantities are generally available. The basic limitation here is the lack of systematic data on groundwater levels and groundwater consumption. The problem of water pollution could not be investigated in depth within the scope of this project due to significant lack of systematically and frequently monitored data.

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