Future of Water Resources in Turkey

Of 501 billion m3 of annual precipitation in Turkey, 274 billion m3 is assumed to evaporate from surface and transpire through plants. 69 billion m3 of precipitation directly recharges the aquifers, whereas 158 billion m3 forms the precipitation runoff. There is a continuous interaction between surface runoff and groundwater, but it is estimated that a net 28 billion m3 of groundwater feeds the rivers. So, average annual surface water potential is 186 billion m3, with the surface runoff of 7 billion m3 coming from neighboring countries, total surface runoff within the country reaches 193 billion m3.

However, not all of the renewable water resources can be utilized because of economic and technical reasons. Exploitable portions of surface runoff, inflow from bordering countries, and groundwater are 95, 3, and 12 billion m3, respectively. Thus, the total of exploitable water resources amount to 110 billion m3.

The State Institute of Statistics (SIS) has estimated Turkey's population as 100 million by 2030 [4]. Consequently, the annual available amount of water per capita will be about 1,000 m3 by 2030 (Fig. 31.1). The current population and economic growth rate will alter water consumption patterns. As population increases, annual allocated available amount of water per person is expected to steadily decrease.

1960

2000 Year

2030

Fig. 31.1 Annual available amount of water per capita in Turkey (Adopted from SIS [7])

1960

2000 Year

2030

Fig. 31.1 Annual available amount of water per capita in Turkey (Adopted from SIS [7])

The projections for future water consumption would be valid on the condition that the water resources are protected from pollution at least for the next 25 years. It is imperative that available resources have to be evaluated rationally so as to provide clean and sufficient water resources for the next generation.

Because of the climatic conditions of Turkey, the precipitation-flow relationships can change not only seasonally but also from year to year and natural water supply can falls to minimum levels in summer time, when the demands are at the highest levels. The country's water resources are very sensitive to climatic conditions, and droughts are generally present in periods of every 15 years. In these dry periods the mean annual water yield decreases to one third of the annual average long period value [5].

Climate change is also one of the important factors effecting water resources in all the Mediterranean Region. Precipitation in the Mediterranean Basin as a whole has decreased by 20% in the last 25 years. It is also expected that decreasing trend will continue and a serious drop in precipitation is predicted in Turkey's semi-arid Mediterranean, Aegean and Central Anatolian regions [6].

It is estimated that summer temperatures in Turkey will rise by 3°C and winter temperatures by 1-2°C. According to results from the General Circulation Model (GCM), winter precipitation in southern areas will considerably decrease. A project concerned with the climate change effects on agricultural production in arid areas predicted that winter precipitation in Turkey would fall by 42-46% by the 2070s, at the same time that crop requirements would rise by 5-10% [5]. In Turkey, water problems are increasing due to the following reasons:

• In the last few years, Turkey has lost some of its wetlands an area as large as the triple surface area of the Lake Van, i.e. the largest lake of the country, with a surface area of 3,713 km2.

• So far, no detailed and thorough environmental feasibility study has been conducted in Turkey.

• Only 36% of Turkey's total water potential is used for irrigation, as well as for industrial and domestic activities [5, 8].

• 75% of Turkey's available water sources are used for agricultural irrigation, 94% of this water is used as surface irrigation water [7, 9, 10].

• Water resources are getting more contaminated due to urbanization, industrialization and agricultural activities.

• Global warming affects the water resources, and desertification is observed in some areas of Turkey.

• Water demand increases due to the population increase.

• Natural pollution has also been recently identified in many places in Turkey. For example arsenic pollution has been detected in groundwater supplying water to the cities of Ankara and Izmir.

According to UNDP [11], Turkey, due to its physiographic environment combined with its past cultural and economic heritage and the current socio-economic situation of land users, is highly vulnerable to desertification, with 86.5% of its total land area, and 73% of its arable land at risk of erosion, land degradation and desertification. Regarding climatic factors and sparse and vulnerable vegetation cover, Southeastern Anatolia and continental interiors of Turkey appear to be the arid lands that are prone to desertification. When natural and anthropogenic factors, such as high topography, unsustainable use of agricultural land and forest fires are taken into account, the Mediterranean and Aegean regions could be considered as areas that may be more vulnerable to the desertification process in the future [11].

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