Aysegul Tanik

Water quality in drinking water reservoirs of a megacity, istanbul.

Providing clean water at relevant quality and quantity is a challenge that regulatory authorities have to face in metropolitan cities that seem to develop at their limits of sustainability. Istanbul strives to face such a challenge for its population of over 10 million, through six surface water resources. Two approaches of classification for the reservoirs are presented, one based on current regulations and an alternative based on a more detailed classification. The results have shown that nutrient control is the primary issue, and one of the reservoirs has already exceeded the limits of being eutrophic, one is at mesotrophic conditions, and the remaining four are at the limit of being eutrophic, indicating the significance of making the correct decision and taking pertinent measures for management and control. It has been observed that the only mesotrophic resource, which also has the best general quality class, has no industry and a very low population density, whereas the one that is already eutrophic is also the one with the lowest quality class, has the highest population density, and has the greatest percentage of urban land use within its watershed.

Use of Remotely Sensed Data for Analysis of Land-Use Change in a Highly Urbanized District of Mega City, Istanbul

The study forms an example on monitoring and understanding urban dynamics by using remotely sensed data. The selected region is a rapidly urbanizing district of the mega city Istanbul, Gaziosmanpasa, whose population has almost doubled between years 1990 and 2000. The significance of this district besides its urban sprawl is that 61% of its land lies within the boundaries of an important drinking water reservoir watershed of the mega city, the Alibeykoy Reservoir. The land-use/cover changes that has occurred in the years of 1987 and 2001 are analyzed by utilizing a variety of data sources including satellite images (Landsat TM image of September 1987 and Landsat ETM+ image of May 2001), aerial photographs, orthophoto maps, standard 1:25000 scale topographic maps, and various thematic maps together with ground survey. Land-use changes are analyzed on the basis of protection zones of the reservoir watershed and the conversion of bare land and forests to settlements are clearly observed despite the national regulation on watershed protection. The decline of forests within the protection zones was from 69% to 63.6% whereas the increase in settlements was from 0.8% to 3.9%. The associated impact of establishing new residential sites with insufficient infrastructure is then linked with the water quality of the reservoir that has already reached to Class III characteristics regarding the recently revised national legislation stating that any class exceeding Class II cannot be used as a drinking water supply that in turn, had consequences on regulating the water services such as upgrading the existing water treatment plant. The paper aims to help the managers, decision-makers and urban planners by informing them of the past and current land-use/cover changes, to influence the cessation of illegal urbanization through suitable decision-making and environmental policy that adhere to sustainable resource use.

Application of Watershed Modeling System (WMS) for Integrated Management of a Watershed in Turkey

Watershed models, that enable the quantification of current and future pollution loading impacts, are essential tools to address the functions and conflicts faced in watershed planning and management. In this study, the Watershed Modeling System (WMS) version 7.1 was used for the delineation of boundaries of Koycegiz Lake-Dalyan Lagoon watershed located in the southwest of Turkey at the Mediterranean Sea coast. A Digital Elevation Model (DEM) was created for one of the major streams of the watershed, namely, Kargicak Creek by using WMS, and DEM data were further used to extract stream networks and delineate the watershed boundaries. Typical properties like drainage areas, characteristic length and slope of sub-drainage areas have also been determined to be used as model inputs in hydrological and diffuse pollution modeling. Besides, run-off hydrographs for the sub-drainages have been calculated using the Rational Method, which produces valuable data for calculating the time variable inflow and input pollution loads to be further utilized in the future water quality models of the Creek. Application of WMS in the study has shown that, it is capable to visualize the results in establishing watershed management strategies.

A long‐term management plan for a watershed in a world metropolis – Istanbul

Omerli reservoir is the major reservoir of Istanbul in terms of water supply potential. However, rapid population increase, unplanned and illegal housing, irrelevant industries and motorways passing through the protection zones of the catchment area, together with insufficient infrastructure, cause the water quality of the reservoir to tend towards the eutrophic stage from the mesotrophic stage parallel to the land use profile. In order to achieve a long‐term water supply from the reservoir and to arrive at sanitary solutions, new land use plans should be developed. Therefore, the key idea of this paper is to develop a convenient protection strategy to keep the reservoir from further deterioration, in light of the guidelines of a new land use plan, and to allow the watershed to be used in accordance with the tendencies of society in a controlled manner, so as to maintain the sustainability of the reservoir for drinking water supply and to assure continuing control by implementing economic sanctions.

Chemical treatability of dairy wastewater

Chemical treatability of dairy wastewater originating from a dairy and dairy products plant at Istanbul was investigated on the basis of chemical oxygen demand (COD) parameter as a pre‐treatment alternative. FeCl3, FeSO4 and alum were used as coagulants in the jar‐test experiments of four sets of daily composite wastewater samples taken once every month. The effect of acid cracking has also been searched through acid addition and pH adjustment. Characterisation studies demonstrated that wastewater characteristics varied within a wide range in spite of no significant production changes at the plant during the experimentation period. Optimum coagulant dosage has been determined as 200mg l–1 for all the coagulants with the optimum pH values between 4 and 4.5 for FeCl3 and FeSO4, and 5‐6 for alum. Maximum overall COD removal efficiencies were obtained as 72 per cent, 59 per cent and 54 per cent for FeCl3, FeSO4 and alum, respectively. Nevertheless, COD removal efficiencies were found to be inadequate to meet the current discharge standards of Greater Metropolitan Istanbul to sewer systems indicating that chemical treatment is insufficient for discharging chemically pre‐treated dairy wastewater to a sewage system, which was actually the main objective of the study. The results showed that the wastewater composition greatly influences the maximum removal efficiencies and also the conditions for optimum coagulation. However, attention to such chemical treatment studies on dairy wastewater has started to accelerate within the last decade in various countries of the world, such as United Arabic Emirates and Scandinavian countries where the targets of applying chemical treatment varied. In Scandinavian countries, biodegradable coagulants have been applied to use the sludge arising from the system for livestock feeding, leading to reuse of sludge. In Arabic Emirates, chemically treated dairy effluents are utilised for irrigation purposes. These recent studies point out that application of chemical treatment to dairy wastewater with various coagulants lead to a variety of utilities apart from being a pre‐treatment alternative.

Multi-Temporal Analysis and Mapping of Coastal Erosion Caused by Open-Mining Areas

Coastal zones are exposed to erosion due to natural and human-induced activities around the world. The land use of the coastal zone in the northern part of Istanbul, Turkey, has been changing due to open-pit coal mining begun in 1980. The objective of this study is to determine the changes that occurred in a selected coastal zone by utilizing interpretations of multi-temporal LANDSAT satellite data. Satellite images of the zone taken during the years 1984, 1992, and 2001 were transformed to the universal transverse mercator (UTM) coordinate system, and 17 bands of images for each of these years were interpreted using layer-stack method. A new red, green, and blue (RGB) image including infrared band of each year was created. These findings show that 304.7 ha area of sea was filled with soil between years 1984 and 1992. However, the total area filled between 1984 and 2001 was only 67.7 ha, due to the fact that 237.0 ha was removed by coastal erosion after year 1992.

Application of Water Quality Modelling as a Decision Support System Tool for Planned Buyuk Melen Reservoir and Its Watershed

Istanbul, the largest metropolis of Turkey and one of the most crowded metropolises in the world, is facing the risk of water scarcity. Analyses indicated that one of the alternative solutions coping with this problem is water transfer from a watershed that is located outside the administrative boundaries of Istanbul. Due to its water potential and relatively less degraded water quality, Buyuk Melen Watershed was considered to be the most feasible option. As the result of analyses, State Hydraulic Works (DSI) has planned construction of a reservoir in the Buyuk Melen Watershed to supply the required amount of water for Istanbul also in low flow seasons. Since the reservoir will be located at the downstream region of the watershed, its water quality will be affected by human-induced activities, thus measures need to be taken to prevent pollution prior to reservoir construction. Quantifying the response of the planned reservoir to external pollution loads is an important step in the planning and management of the watershed. Mathematical modelling is a useful tool for estimating the future water quality and understanding the possible responses of the reservoir to various pollution loads. In this study, a water quality model capable of simulating hydrodynamics, transport and water quality in reservoirs is used for preliminary estimation of possible impacts of several management options in the watershed. Model results indicated that, all of the point sources in the watershed must be controlled by advanced wastewater treatment and should be diverted from the streams and the planned reservoir. Model results also indicated that reduction of agricultural diffuse loads by 30–40% is expected to have a perceptible improvement of reservoir water quality.

Efforts towards setting eutrophication assessment criteria for coastal marine ecosystems

Eutrophication of coastal marine environments is a widespread and transboundary problem necessitating consideration of measures to conserve and restore the marine environments that have been adversely affected. As of now, there exist no criteria set for eutrophication of coastal marine waters due to the difficulty to establish single national/international assessment criteria for eutrophication applicable to all coastal waters with different geographic and climatic conditions. However, there appear to be a number of joint and integrated studies among coastal countries to harmonise the outcomes of their scientific research and monitoring activities that might change the natural attributes of the environment. The common findings may then be utilised to develop guidelines on establishing eutrophication criteria together with application of policies and strategies. This study attempts to review the recent efforts of certain groups gathered together and of some countries to develop and improve approaches for assessment of eutrophication in coastal marine waters. Studies of OSPAR Commission, USEPA, and Australia and New Zealand related councils, will also be referred to.

Prioritization methodology of dangerous substances for water quality monitoring with scarce data

Monitoring and control of dangerous substances discharged into receiving waters have attracted more attention lately. Since it is not possible to analyze every single substance, a prioritization methodology is needed for the selection of those to be monitored. Existing well-developed models require significant amount of data for reliable outcomes. This paper presents a methodology to prioritize the dangerous substances having adverse effects on freshwaters in Turkey, where data are scarce. Such a methodology will also serve as a solid model for other countries with limited background data. The adopted methodology enabled the elimination of chemicals to generate a candidate list composed of 608 substances among more than 5000 substances. Further screening and prioritization were conducted using different assessment methods (i.e., Total Hazard Value, Total Impact Value, Combined Monitoring-based, and Modelling-based Priority Setting) to obtain a proposed Final Candidate Specific Pollutants List of 150 dangerous substances. The proposed Candidate National Pollutant List of Turkey was established by combining 45 priority pollutants of the European Union with a list of candidate specific pollutants. According to the outcomes of this study, monitoring and controlling of 195 dangerous substances in freshwaters are recommended. Further detailed studies should be conducted in order to observe the actual levels of these dangerous substances in freshwaters followed by a review of the monitoring list accordingly. Moreover, further revisions might be required in the proposed list due to some possible versatile conditions in terms of sampling points (i.e., change in the location of industries).

Use of remote sensing and geographic information systems in the determination of high-risk areas regarding marine traffic in the Istanbul Strait

Istanbul Strait, Bosphorus, is one of the important waterways of the world due to its combination of natural beauty, human resources, and the high number of oil-carrying tankers passing through it. A considerable increase in the number of vessels over the past decade has indicated the high potential for oil spillage and fire hazards. This study aims to determine the coastal areas that are under an oil spill/fire/explosion risk in the Istanbul Strait by using geoinformatics. Remote sensing technology, providing relatively quick and low-cost analysis of large areas, is used for classifying the shoreline and land-use activities in the fore-scene and back-scene zones followed by assigning risk scores to various GIS data layers and suitability evaluation based on the weight of each score. The risk components are prioritized and layers are allocated according to their risk scores. Major components that classify risk-posing areas are accident likelihood, number of historical assets, human-use resources, population, and lack of critical facilities. Segment-wise risk levels that resulted in comparatively higher scores indicate the vulnerable areas along the Strait to draw the attention of the society and the decision-makers who are responsible for the policy implications. The study acts as a guideline for developing coastal management strategies and implementing corresponding human policies.