Introduction:Rapid urbanization is one of the main challenges in the face of water shortage taking into consideration that 70% of the world population is expected to live in cities by 2050 with continuous migration from rural areas. In this context, primary problems concerning water resources are depletion and degradation stemming from population growth and anthropogenic activities. Inevitably, the rise in water demand is putting more stress on scarce water resources. The situation is further exacerbated as investment requirements both for maintenance of the existing infrastructures and wastewater management increase. Thus, cities are continuously being challenged to develop practical integrated urban water management models to fulfill the expectations; however current management models are not sufficient enough in terms of cost effectiveness, technical performance, social equity, and environmental sustainability. In this regard, integrated urban water management is an indispensable multifaceted concept incorporating water supply, sanitation, sustainable use of water resources and climate change adaptation in order to achieve sustainable cities by bringing multiple stakeholders together. The aim of this paper is to identify the existing problems in urban water management and present a roadmap for efficient water management solutions in urban areas by referring to Istanbul as a sample case. The methodology of this paper is based on literature reviews involving a descriptive analysis of the water related challenges and providing suggestions for sustainable water management.
Methods/Materials:Cities have always been the center of attraction for citizens, offering better opportunities compared to rural areas. At the same time, adequate quality and quantity of water are indispensable constituents of economic growth and development of cities. Nonetheless, it is not possible to appraise the economic and ecological value of efficient water use without proper management of water resources.
Istanbul, as the financial and socio-cultural center of Turkey, is a metropolitan city with an exponentially increasing population exceeding 14 million in 2013. The city has faced water supply challenges throughout history; however the situation escalated in the past decade due to migration and rapid population growth. One of the early precautions taken by the municipality to overcome the water related problems climaxed following the dry period in 1993, was to reduce non-revenue water by replacing the old water transmission lines. During the renovation, 97% of the transmission lines were replaced which in return reduced the losses from 65% to 24%. The next step was the rehabilitation of existing polluted reservoirs and water treatment plants. However, these measures were not enough to meet the demand of an ever-growing population. Thus, new water resources were investigated to supply water from creeks located close to the city. Another compelling challenge for the metropolitan city was the spread of illegal settlements on the watershed zones. This situation posed a major threat to most of the water reservoirs in Istanbul, since most of the wastewater from households was being discharged to the scarce resources. Local authorities were forced to take immediate actions to avoid further contamination and eutrophication in reservoirs of Istanbul. Today, there are preliminary, biological and advanced wastewater treatment plants in Istanbul with a total treatment capacity of 5.449.460 m3/day. Even though most of the challenges have been handled in time, the demand of an ever-growing population is still to be met. An immense water transfer project (Melen Project) has been inaugurated for this purpose to supply water from Melen River located 187 km east of Istanbul. The aim was to meet the city's forecast demands until the year of 2040 which will be around 3 million m3/day. Water transferred from Melen River will be treated on the Asian side of Istanbul and will then be pumped to the European side, using a water tunnel that crosses the Bosphorus. The capacity of this newly constructed water treatment plant will be 3.120.000 m3/day. The total capacity of drinking water treatment plants in Istanbul will reach to 6.728.000 m3/day upon the completion of the new treatment plant.
Results and Discussion:Istanbul, with its growing population pattern, is a proper example demonstrating the water related challenges faced in developing cities explicitly. A roadmap defining the constituents of urban water management can be derived by defining the problems encountered in this case. The main challenges in a city's water management can be defined as non-revenue water, inadequate supply system, wise use of water, wastewater reuse, lack of legal clarity and cooperation among stakeholders.
Non-revenue water should be the top priority of authorities in order to achieve sustainable urban water systems, since a substantial amount of energy is lost with water as well. Wastewater collection and treatment is also a major issue, because discharge of wastewater opens a major gap in water cycle of cities. This gap can be closed if wastewater is assessed as an alternative resource of water, energy and nutrients. In return, wastewater recycling will provide more water for ecosystem and minimize the water footprint of cities. Another factor that compounds insufficient water services is stated as the lack of regulations and legal clarity among the duties of different authorities. As seen in the case of Istanbul, the water management plans were basically based on supply management. Actions have been taken as different needs emerge, however, the demand constantly increases with population growth. Thus, a shift from water supply management to demand management is required in all sectors. This shift can be facilitated by using various tools, by encouraging citizens to use water wisely or by using alternative water resources, such as rainwater harvesting and grey water reuse. Integrated urban water management plans shall not overlook the vitality of ecosystems for sustainable cities as well as flood and drought management issues. Nevertheless, a successful implementation of these measures cannot be achieved without interdisciplinary collaboration, effective regulations and a tailor-made urban water management plan that takes into account all aspects of a city.
Conclusion:Potential solutions and suggestions for water management that can be derived from this study underlines the importance of minimization of non-revenue water for efficient water management. Additionally, wastewater need to be considered as a valuable resource of water, energy and nutrients, to close the gap in water cycle of cities. Ecosystem services has to be integrated into water management to sustain healthy communities. Yet, cooperation among stakeholders and taking a multi-disciplinary approach is vital for building trust between authorities and citizens.
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