Eight main drainage basins may be discerned, of which two cross the country’s frontiers and six are entirely within Turkish territory. The smallest, in the far east of the country, is that of the Aras River, which rises south of Erzurum and flows east for some 250 miles (400 km) to the frontier with Azerbaijan, eventually reaching the Caspian Sea. The bulk of eastern Turkey, however, is drained by the Euphrates (Fırat) and Tigris rivers, which flow south for some 780 miles (1,250 km) and 330 (530 km) miles, respectively, before entering Syria and then Iraq, where they converge to enter the Persian Gulf (see Tigris-Euphrates river system).
There are two basins of inland drainage. In the far east a small area drains to Lake Van from which there is no surface outlet. The main inland basin is in west-central Anatolia; its two main centres are the Lake Tuz and Konya basins. Several smaller, separate catchments in this basin contain lakes such as Eğridir and Beyşehir. The remainder of the country drains to the four surrounding seas—Black, Marmara, Aegean, and Mediterranean—and can thus, in a sense, be considered a single system that eventually drains to the Mediterranean. Most of the rivers flowing to the Black Sea are short torrential streams incised into the Pontic Mountains, but several have developed lengthy inland sections and tributaries running parallel to the east-west ranges of northern Turkey. These rivers include the Yenice (Filyos), Çoruh, Kelkit, Yeşil, and Kızıl. One of the largest basins is that of the Sakarya River, which covers about 500 miles (800 km) from its source, southwest of Ankara, to its mouth, north of Adapazarı.
Yeşil RiverThe Yeşil River flanked by a gorge (right), Amasya, Turkey.Maynard Williams/Shostal Associates
Numerous small rivers drain into the Sea of Marmara; the largest is the Mustafakemalpaşa. Most of European Turkey lies in the Ergene-Maritsa basin, which drains into the northern Aegean. The main elements of the Aegean drainage are the parallel rivers flowing west from the Anatolian interior: the Gediz, Küçükmenderes, and Büyükmenderes. Along the section of the Mediterranean coast bounded by the Taurus Mountains, numerous rivers descend rapidly to the sea, including the short Aksu, Köprü, and Manavgat and the longer Göksu. Two much larger rivers—the Seyhan and the Ceyhan—flow into the Gulf of Iskenderun; their broad combined delta forms the greater part of the fertile Adana Plain. Lakes
Turkey has about 50 lakes with areas larger than four square miles and more than 200 smaller ones. By far the largest are Lakes Van (1,434 square miles [3,714 square km]) and Tuz (about 600 square miles [1,550 square km]); the latter is very shallow, expanding and contracting with the seasons. Being centres of inland drainage, both are saline.
The largest freshwater lakes are those in the lake district on the north side of the Taurus system, which include Lakes Akşehir, Eğridir, and Beyşehir. Another freshwater lake is Lake İznik, northeast of Bursa. The development of hydroelectric power has produced a number of artificial lakes, of which the largest are those connected with the Atatürk and Keban barrages on the Euphrates, the Hirfanlı on the Kızıl, the Sarıyar on the Sakarya, the Demirköprü on the Gediz, and the Seyhan on the Seyhan. Soils
Turkey’s relief features and climatic variations produce major contrasts in soil types between the interior and the periphery. The detailed pattern, however, is complex; zonal soil types are broken by variations in relief and parent material, and thus a variety of azonal soils are present. Seven main soil groups may be distinguished, each containing several soil types.
Red and gray-brown podzolic soils, along with brown forest soils, represent the most extensive group, covering about one-third of the country. These occur mainly in mountainous areas as a broad belt around the northern, western, and southern sides of the Anatolian interior and are associated with the more humid climatic zones. The red and gray-brown podzolic soils are moderately leached and somewhat acidic, the red type occurring in the wetter, warmer areas. Brown forest soils are generally developed on calcareous rocks and are less acidic than the red and gray-brown podzolic soils.
Brown and reddish brown soils are characteristic of the driest parts of the country, mainly in the semiarid zones of central Anatolia and in the southeast; covering about one-fifth of the country, they support extensive dryland grain production. These soils are for the most part calcareous and are more productive when irrigated.
Noncalcic brown soils with rendzinas and grumusols are found in slightly wetter climates. Noncalcic brown soils are a zonal type, less strongly leached and less acidic than the podzols; they are most extensive in lowland Thrace but also occur in patches along the Aegean. Rendzinas—highly calcareous azonal soils derived from limestones—occur mainly along the Mediterranean; grumusols, found mainly in Thrace, also are calcareous but are deeper and heavier.
Chestnut soils are found on a smaller scale in the same regions as the brown and reddish brown group but under slightly more humid conditions where the parent materials are calcareous.
Serozems—highly alkaline semidesert gray soils—are found in the driest areas, notably in the Konya basin and the Aras valley.
Terra rossas and red prairie soils are the products of limestone weathering under Mediterranean climates; the red prairie soils occur under warmer and damper conditions and are slightly more leached than the terra rossas. Both occur in patches along the Aegean and Mediterranean, notably in the Antalya and Adana lowlands.
Alluvial soils, which cover only a small portion of the country, are the most valuable type and support the most-intensive agriculture. These soils are found mainly in the valleys of the Marmara and Aegean regions, the deltas along the Black Sea, the basins of central and eastern Anatolia, and the Adana lowland. Climate Overview
Turkey’s varied climate—generally a dry semicontinental Mediterranean variant—is heavily influenced by the presence of the sea to the north, south, and west and by the mountains that cover much of the country. The sea and the mountains produce contrasts between the interior and the coastal fringes. Several areas have the winter rainfall maximum typical of the Mediterranean regime, and summer drought is widespread. However, the elevation of the country ensures that winters are often much colder than is common in Mediterranean climates, and there are significant contrasts between winter and summer temperatures.
January mean temperatures are below freezing throughout the interior, and in the east there is a sizable area below 23 °F (−5 °C); extremely low temperatures occur at times, with minima from −4 °F (−20 °C) in the west to −40 °F (−40 °C) in the east. The duration of snow cover ranges from two weeks in the warmer areas to four months in some mountainous areas in the east. The coastal fringes are mild, with January means above 41 °F (5 °C). Summers generally are hot: July means exceed 68 °F (20 °C) in all but the highest mountain areas, 77 °F (25 °C) along the Aegean and Mediterranean, and 86 °F (30 °C) in the southeast. Precipitation is strongly affected by relief; annual totals of 12–16 inches (305–406 mm) are characteristic of much of the interior, whereas the higher parts of the Pontic and Taurus ranges receive more than 40 inches (1,000 mm). Climatic regions
Contrasts between the interior and the coasts produce six main climatic regions.
The Black Sea coastlands are the wettest region, with rain throughout the year and a winter maximum. Annual totals exceed 32 inches (813 mm), reaching 96 inches (2,438 mm) in the east. Frosts can occur, but winters are generally mild, with January means of 43–45 °F (6–7 °C); summers are hot, with July means above 68 °F (20 °C) at sea level.