Environmental flow requirement: Fırtına stream case

Certain quantities of water are required to support and maintain healthy aquatic ecosystems such as rivers, streams, wetlands, lakes, and deltas, as well as meet environmental goals. This scientifically determined quantity required to maintain the ecosystem functions and services expected from the stream is defined as the environmental water requirement. The environmental water requirement approach as a generic name encompasses different scientific methods to determine the quantity of water required by stream ecosystems. There are many methods to estimate environmental water demand. In this thesis, environmental water requirement calculations were made on a monthly basis with the GEFC method, one of the hydrological estimation methods, for Fırtına stream and its branches. Firtina stream was divided into 28 sub-basins whose calculations were made separately for each sub-basin. According to the GEFC method, a minimum of 73.5% and a maximum of 82.2% of water potential for A quality environmental management class; a minimum of 53.5% and a maximum of 68.2% of water potential for B quality environmental management class; a minimum of 38.7% and a maximum of 58.2% of water potential for C quality environmental management class; a minimum of 28.4% and a maximum of 52.3% of water potential for D quality environmental management class; and A minimum of 22.0% and a maximum of 48.6% of water potential for E quality environmental management class; and a minimum of 18.3% and a maximum of 46.5% of water potential for F quality environmental management class should be located in the stream bed. The basin-wide averages found in the sub-basins are 79.27% for class A, 63.94% for class B, 53.17% for class C, 46.44% for class D, 42.08% for class E, and 39.45% for class F. for. Currently, the basin has been declared as a national park. For these reasons, it is recommended to manage the stream with the target of A quality environmental management class. According to the results obtained for this quality class, the minimum annual average environmental water demand is 0.394 m3/s in the R4 sub-basin, while the maximum annual average environmental water demand is 35.56 m3/s in the R16 sub-basin.