Browsing by Author "Erdem, Osman"

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A Hydrologic Restoration Attempt of the Dried Akgol Wetland (Central Anatolia, Turkey)
(Springer, 2017) Karakus, Huseyin; Aydin, Harun; Erdem, Osman
The Akgol Wetland has been subject to extensive drainage processes by anthropogenic factors that have almost caused the wetland to disappear since the 1970s. In this contribution, as a one of the pioneering work on wetland restoration in Turkey, we present hydrological studies aiming to restore the natural function of the Akgol wetland and post-restoration observations. Considering the water budget of the wetland, three scenarios focusing on restoring the wetland hydrology were developed. The open water surface area and volumetric water storage relations for each scenario were simulated using GIS-based tools. The most appropriate scenario for restoration of the Akgol Wetland was chosen by taking the original state of the wetland prior to drainage as the primary criterion. As the first stage, functioning of the central channel draining the wetland was ceased by refilling it. Following this, an artificial bank was constructed at the narrowest part of the wetland, which resulted in an open water surface that cover all current and former ponds. The wetland has start to hold surface runoff and groundwater inflows since September 2011. Since rewetting, the Akgol Wetland is regaining its ecosystem functions and the increase in avian population indicate the proposed restoration effort was successful.
The Salinity Problem at Yelkoma Lagoon (yumurtalik-Adana) and Its Restoration by Mixing With Freshwater From Ceyhan River
(Parlar Scientific Publications (p S P), 2015) Aydin, Harun; Karakus, Huseyin; Erdem, Osman
The Yelkoma Lagoon located at Ceyhan River Delta has been significantly deteriorated due to dam construction activities that cause lower freshwater inputs. Compared to the Mediterranean (similar to 40 ppt), high salinity of the Yelkoma Lagoon (up to 116.0 ppt), has adversely affected the ecological life in the lagoon as evidenced by the number of fish deaths. In addition to less freshwater input, high evaporation rates and structure of the inlet channel between the lagoon and the Mediterranean are determined as major causes of high salinities. In this study, we applied End-Member Mixing Analysis to calculate the monthly amount of freshwater that should be contributed from the Ceyhan River to the Yelkoma Lagoon to decrease salinity and ensure sustainability of ecological life and fisheries. As a first stage of the study, a conceptual hydrological model of the Yelkoma Lagoon has been developed based on water volume and its salinity. A bathymetric map of the lagoon was produced allowing measurement of the area and volume of each sector in the lagoon. Monthly salinities were obtained from field surveys for all components of mixing equations. The optimum salinity of the lagoon water has been foreseen to be between the salinity of the Ceyhan River and the Mediterranean. Based on the conceptual model and using a mass balance equation, contributions of saline and freshwater end-members were calculated. As a result of mixing calculations, monthly required flow-rates of freshwater from the Ceyhan River to the Yellcoma Lagoon were determined to be in the range of 0.199 m(3)/s to 3.698 m(3)/s. The calculated freshwater has been given to the lagoon since March 2009, and positive developments have been observed in terms of ecological life.