The Omerli Watershed (OW) is the most important among the seven Mediterranean watersheds that provide drinking water to Istanbul, a megacity with over 10 million people. The OW is threatened by urban development in, and around of, its drinking water sources. It faces the most acute, unplanned pressures of urbanisation with serious impacts on water quality and biodiversity. The proposed Urban Biosphere Reserve (UBR) attempts to reconcile urban development, water quality and biodiversity conservation in a more sustainable way through integrated urban aquatic habitat management.

Omerli Dam and neighbouring heathlands (DHKD Archives).

Background

The Istanbul Province is the most populated part of the country, with over 10 million people (in 2000), experiencing a population growth of about 5% annually since the 1950s. The last two population censuses indicate that the growth rate has been slowing down to around 3% annually (SIS 2000). The province increased almost 700 percent in the built-up area as its metropolitan population grew from about 1 200 000 in 1955 to about 9 119 000 in 2000 (Tezer 1997; Tezer Kemer 2004). Such drastic rates of growth of urban population and land area have inflicted widespread and devastating impacts on ecological life support systems of the region, especially on the structure of aquatic habitats and biodiversity. Over the last two decades, urban development in Istanbul has been taking place in and around its drinking water sources. Forests and water basins located to the north of the city have been experiencing considerable degradation since the 1980s, and the continuous 'building amnesties' encouraged extensive illicit and unplanned developments.

Extensive areas of grasslands and prairies on the European side and the heathlands on the Asian side were replaced by urban developments with little attention to habitat's characteristics and ecosystem services. Aquatic habitats especially have been seriously contaminated as a result of intense urbanisation pressures as in the case of the Kucukcekmece catchment which can not be used for drinking water supply at present. The other two freshwater catchments, Alibeykoy and Elmali, are not supplying drinking water efficiently for similar reasons.

The Turkish Society for the Protection of Nature (DHKD) prepared a research report titled "Important Plant Areas (IPA) and Important Bird Areas (IBA) of Turkey" in 2005. The definition of IPA was proposed by the Planta Europa's Steering Committee as: "an Important Plant Area is a natural or semi-natural site representing exceptional botanical richness supporting an outstanding assemblage of rare, endangered and endemic species" (Ozhatay et al., 2005). According to the report, 122 sites were designated as "IPA" all around Turkey. Istanbul contains 10 different IPAs according to these criteria (Fig. 9.26) (Anon, 1999). Although this report does not mean that there will be a complete formal protection status declared for these areas, it points out comprehensively the importance of the natural character of the 122 sites.

Key aquatic habitat issues in urban water management

Although Istanbul's cultural heritage is widely known, the uniqueness of its natural heritage has not always been as significant as the cultural one. The exceptional geographic location forms natural habitats and ecosystems with astonishingly diverse and rich floral character. Ista nbul, with an area of 5512 km², accommodates more than 2000 native-vascular floristic and fern species in five different habitats: wetlands, grasslands, heathlands, coastal dunes and forests. This number is higher than the UK's and the Netherlands' native-vascular species. There are 18 species in the Bern Convention List to be protected and 7 of them grow in aquatic habitats.

Except for the IPA/IBA No.4: Hills on the North Bosporus and the IPA/IBA No.7: Hadimkoy, Kemerburgaz Grasslands and Heathlands, the rest of the 10 IPA/IBAs in Istanbul are mainly aquatic habitats.

Since the major consequences of biodiversity loss and environmental degradation have resulted from urban-based activities, it is necessary to examine the applicability of the Man and the Biosphere (MAB) Programme to define an urban based biosphere reserve (BR) approach. Designing cities compatible with their ecological background will have a considerable impact on the establishment of sustainable landscapes at local level.

Conservation, development and logistic functions of BRs can be supported by urban green areas with a biological conservation hierarchy, starting with undisturbed ecosystems of a high biodiversity value through urban green systems and biodiversity improvement practices. The conservation function of BRs can be broadened to include degraded ecosystems and habitats to enhance biodiversity. In other words, the major goal of BRs, "to protect unique habitats and ecosystems," has to be expanded to the areas under pressure because of urban development caused degradation.

Objectives of the Case Study

The Statutory Framework of the World Network of Biosphere Reserves defines the departing point of UNESCO's MAB Programme in the Introduction section as "BRs are established to promote and demonstrate a balanced relationship between humans and the biosphere without distinctive definition of size, context and compounds of balanced interactions". BRs promote conservation of landscapes, ecosystems, species and genetic variation for: fostering of ecologically, socially and culturally sustainable development, and providing logistic support for environmental education, training, demonstration projects, monitoring and research-related local, regional, national and global issues of biodiversity conservation and sustainable development. "Urban Biosphere Reserves (UBRs)" indicate compatibility with the context of the Statutory Framework and the Seville Strategy and may have crucial potential to promote urban sustainability in environmental, economic and social dimensions (MAB Urban Group Policy Paper, 2003; Dogsé, 2004).

The Asian Side Heathlands and the Omerli Watershed (IPA No.8) can be a proper node to start up the process of the management of UBR concept in Istanbul. The reasons for selection of this site are the "very urgent" protection need of aquatic habitats and water quality of the most important catchment with respect to Istanbul's freshwater sources; the existence of a significant amount of urban development pressures, and finally potential deterioration of globally and locally important aquatic and terrestrial ecosystems. UBR concept will necessitate an integrated planning approach for research, development, implementation and monitoring phases. Additionally, the UBR concept has a potential of multi-participatory and multi-objective character with its integrated management structure. Therefore it has to coordinate related institutions for the common goal of sustainable use and development of urban ecosystems and habitats. The objective of this initiative is to reconcile unsustainable urban development pressures with sustainable use of the exceptional biodiversity value, aquatic habitats and water quality of the basin with a UBR approach. Ecosystem approach is a key tool here to foster sustainability of the aquatic habitat and biological diversity through management of the three functions of the BRs.

Stakeholders

The conservation function of UBRs has to be extended to degraded or potentially to be degraded areas in and out of core zones. Stream restoration efforts will have significant impact on the protection of biodiversity and water quality in the watershed area. MGI has a key role in the implementation of the UBR concept in the province. UNESCO MAB Program, local universities (ITU and IU), DHKD and other nature protection NGOs, Conservation Councils (CC) of Istanbul, Ministry of Environment and Forestry (MoEF)-Nature Protection Directory and also citizens' organizations should take part in the process of developing and implementing UBRs for Istanbul.

See References