Drought management plan for Ankara, Turkey
Drought is a natural phenomenon that exists when precipitation has been significantly below normal recorded levels, causing serious hydrological imbalances that adversely affect land resource production systems (UNCCD,1994).
Since the 1970s, in the eastern Mediterranean basin and some cities of Turkey having a Mediterranean rainfall regime, significant decreases have been observed in annual total rainfall depending on the decrease in winter rainfall, although they have higher variability between the years. The latest intensive and widespread drought events occurred in 2006 and 2007. It has also been noted that such intensive and widespread hazards cause great damage on most socio-economic sectors due to the absence of a drought management plan.
Vulnerability of societies to drought is affected by population growth, urbanization, demographic features, technology, water-use trends, governmental policies, social life and environmental sensibilities. These factors change consistently. Moreover, the sensibility of societies increases or decreases, depending on these changes. For example: growth in population increases the stress on water and other resources. The more populaitons increase, the more they need water. Although drought is a natural phenomena, it is possible to reduce its negative affects. Thus, an increase can be seen of the risks associated with dry periods. An increasing risk associated with dry periods can be seen. Drought mitigation plans give decision makers the chance to in order to prevent great damages with small cost
The importance of drought management in Turkey
Turkey is exposed to drought hazards rather frequently. Spatial and temporal analyses of drought hazards in Turkey have not yet been completed but, for instance, intensive drought periods in 1804, 1876 and 1928 caused the loss of crops and animals and the migration of farmers to other areas. In particular, drought in 1876 caused the loss of more than 200 000 people because of famine and disease epidemics.
It also recalledd that one of the main reasons for the great migration of Turks from Middle Asia in 375 BC was the intensive drought, followed by famine and epidemic diseases that occurred in that region, associated with the change in climate.
Moreover, in 1915, the 1930s and between 1970 and 1974, Turkey experienced serious drought hazards. Also, 1988 and 1989 were the hardest drought years for the south-eastern Anatolia Region. The flow of the Euphrates River decreased to 50 m3/s in these drought years.
It has been shown that river flows are decreasing according to the long-term average over most parts of Turkey (Figure 1).
Since Turkey is located in the Mediterranean macroclimate region in the sub-tropical zone, great rainfall variations can be seen between the years. This causes regional and widespread droughts in various intensities. Thus, drought is one of the main problems for Turkey (Figure 2).
On the most parts of the Central Anatolia Region which have 640 mm of annual average rainfall, recurrence period of drought conditions is more than 1 in 4 years (Figure 3).
Topographic and demographic features of Ankara
The metropolitan city area of Ankara is located between 39°50' and 40°00' N and 32°35' and 33°00' E. The city of Ankara is located on the Ankara plain which has an altitude of 800-850 m. The Ankara plain is formed by the Çubuk River and its branches. This plain is surrounded in the north by the Çiçek Mountains, which form the south parts of the Mire Mountains, from the east by the west end of the Idris Mountains, and from the south by Çaldagi and Elmadag (Figure 4). The plain is open to the west and is connected to the Mürted plain which is formed by the Ova River. These topographic characteristics determine the distribution of the settlement areas and cause significant changes on the continental climate which is dominant in Ankara (Çiçek and Türkoğlu, 2005).
In Turkey, the first census was held in 1927, and since then the annual increase of population has always been over 2 per cent, except in the Second World War years and in 2000. The population increased from 13 348 270 in 1927 to 67 803 927 in 2000. As a result of this rapid population increase and industrialization in the 1950s, a heavy migration to cities took place and the population of these settlements increased rapidly. The city population, which was 23 per cent of the total population in 1950, surpassed the village population for the first time in 1985. In 2000, urban population in the whole country reached 64.9 per cent of the total population. The population growth in Ankara was similar to that in Turkey. Ankara, which was a small town with a population of 74 553 in 1927, reached a population of 3 203 362 in 2000 (Figure 5). The annual increase rate of population in Ankara was recorded as being 5 per cent between the years 1927 and 2000. This rate was nearly two times the average population increase rate in Turkey in the same period. The population increase rate was 2 per cent between 1990 and 2000 in Turkey, whereas it was 8.8 per cent within the same period in Ankara. In parallel with population growth, the urban area also expanded rapidly in Ankara, from 3 km2 to 2 020 km2 in the 1927-2002 period, i.e. an expansion of 673 times.
Temporal distribution of drought in Ankara
According to the Thornthwaite classification, the climate in Ankara is a first-degree. mesothermal semi-arid climate (D B'1, s2 b'3) with intensive water shortage in the summer months (Çiçek, 1996). The mean temperature of Ankara and its surroundings is above 20.0°C in three months (June, July and August); between 10.0°C and 20.0 °C in four months (April, May, September and October); and below 10.0°C in five months (November, December, January, February and March) (Çiçek, 2000). The values of some meteorological parameters for Ankara are as follows: the annual mean temperature is 11.7°C; the mean temperature in January is -0.1°C; the mean temperature in July is 23.1°C; the mean annual precipitation is 377.6 mm, the mean annual relative humidity is 60 per cent.
Because of its geographic features, intensive drought conditions occur at least one in each eight-year period. During the last 80-year period, 1926-27-28-29-30, 1932-33-34, 1941, 1944-45, 1950, 1953, 1956, 1959, 1968, 1973, 1977, 1984, 1992-93-94, 2000, 2003-04, 2007 were drought years in Ankara.
Precipitation reconstruction from tree-rings of the central Anatolia region (where Ankara belongs) during the last 350 years showed that the years 1757, 1759, 1761, 1763, 1768, 1789, 1794, 1802, 1813, 1815, 1830, 1834, 1840, 1849, 1852, 1861, 1870, 1878-79-80, 1886-87, 1890, 1909 can be characterized as drought years (Akkemik et al., 2005).
Drought management plan for Ankara
Data and Method
In this study, daily net water quantities in the reservoirs that supply the water requirements and daily water consumptions for each person in Ankara for the period of 1993-2000 were used.
Drought management plan
The Ankara Drought Management Plan, which was based on the recommendations in the Maryland Statewide Water Conservation Report, was published in the USA in 2000.
According to the population growth and associated water demands, four critical drought levels were determined for the reservoirs: Normal, Watch (Phase 1), Warning (Phase 2) and Emergency (Phase 3) levels.
In order to monitor potential drought conditions, two indicators of water sufficiency were used, based on the amount of precipitation and reservoir storage (Table 2 ).
Precipitation amount was reported by comparing current precipitation amounts with historical precipitation values as a percentage of normal precipitation. Normal is defined as the mean precipitation for a 30-year record for the area and time period being evaluated. Since the significance of precipitation deficit changes as the year progresses, drought stages will trigger at different percentages of normal, depending upon the date of evaluation (Table 3).
The frequency of evaluation will increase if the drought intensifies as indicated below:
Stage 1 – Normal
Stage 2 – Watch
Stage 3 – Warning
Stage 4 – Emergency
Stage 1 – Normal
Stage 2 – Watch
Stage 3 – Warning
Stage 4 – Emergency
For each level mentioned above; mandatory and voluntary water conservation ways for each sectors in Ankara was identified. A sample indicator level based on the reservoir storage is shown in Figure 6.
The beginning of a drought is difficult to determine. Several weeks, months or even years may pass before people know that a drought is occurring. The end of a drought can occur as gradually as it began.
The first evidence of drought is usually seen in records of rainfall. Within a short period of time, the amount of moisture in soils can begin to decrease. The effects of a drought on flow in streams and rivers or on water levels in lakes and reservoirs may not be noticed for several weeks or months. Water levels in wells may not reflect a shortage of rainfall for a year or more after a drought begins.
When droughts occur, there is not enough water to supply all needs. If water is diverted from streams in irrigated crops, streamflow will decrease. Reservoirs that may already be at low levels will be drawn even lower to supply water for power generations, to supply water to downstream cities and towns or to maintain river levels high enough for navigation. Decreasing water levels in rivers, lakes and reservoirs may cause problems for fish and wildlife that depend on wetlands or water bodies to survive.
Balancing the needs of all users of a water supply during a drought can be difficult. Local or State agencies must take decisions on how water will be used to satisfy the most critical needs and to reduce economic and environmental problems. In times of severe drought, water users must cooperate and share the limited mount of water available to protect the critical needs of people, fish and wildlife, agriculture, and industry.
Most of the studies showed that the population of Ankara is growing rapidly but, conversely, the water resources are limited and insufficient to meet demand. The latest drought conditions in Ankara showed that it is essential to prepare an effective drought management plan immediately.
In this study, a drought management plan was designed for Ankara in order to reduce the adverse affect of drought conditions.
Akkemik, Ü. et al., 2005: Drought and wet years during the last 350 years in Anatolia, Quvaterner Symposium, Istanbul, Turkey.
Çiçek, İ., 1996: Climate Classification of Turkey According to Thorthwaite Method, Ankara University Journal, Volume 40.
Çiçek, İ., 2000: Duration and dispersion of dry periods in Turkey, Firat University Journal, Volume 13.
Çiçek, İ., and Türkoğlu, N., 2005: Urban effects on precipitation in Ankara, Atmosfera 18 (3), 172-186
Maryland Statewide Water Conservation Advisory Committee, 2000: Final Report.
UNCCD, 1994; Elaboration of an international convention to combat desertification in countries experiencing serious drought and/or desertification, particularly in Africa.
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