GEOGRAPHY OF KOCAELI
Kocaeli, lies on the Catalca-Kocaeli region of the Marmara Area, between 29°22'-30°21' eastern longtitude, 40 D 31 '- 41*13' Northern Latitude. Surrounded by Sakarya from its East and SouthEast, Bursa on the South, The İzmit gulf, Yalova and The Marmara sea and Istanbul on the west, and the Black Sea on the North. The Provincial Center is located on the 30° Eastern longtitude which is accepted as a base for Turkey's time zone. The surface of the province of Kocaeli is 3.505 km2. It is located on an important crossroad binding Asia to Europe. The Izmit Gulf which is a natural harbour is a busy maritime line. The Istanbul boarder to the NorthWest of the province passes to the East of Kemiklidere. On the SouthEast the Istanbul-Kocaeli boarder ends at the opposite shores of the İzmit Gulf with the soils of Yalova. The Bursa frontier is formed by the line passing through the Samanli Height. On the SouthEast this boarder leans on to Sakarya which is on the shores of the Sapanca Lake close to Masukiye.
The Samanli heights starting from the west side of the Sakarya river and reaching to Pamukova and North of The Iznik Lake until Bozburun are the dominant landmark to Izmit, Sapanca and Adapazari subsdied field. The peak of the Samanli Mountains is Keltepe(Kartepe) with 1.601 metres. The other prominent mountains are the dikmen mountain(1387 metres), Naldoken mountain (1.125 m), Naz mountain (917 m) and Cene mountain(646 m).
Main plains are the lowlands spread between Izmit and the Sapanca lake and Dilovasi. The area which is a Peplen within the boarders of the Kocaeli half-island consist of wavy plains.
Some part of the waters stemming from the provincial boarders flow into the BlackSea and the rest to the Marmara Sea.Since the surface of the mountains facing the marmara are shorter than the ones to the BlackSea the rivers flowing into the BlackSea are longer.The 71 km long Riva Stream stemming from the Tepecik Village of Gebze flows in to the BlackSea at the Eastern entrance of the Bosphorus in Istanbul.The Ağva Stream or the Göksu Stream in other words Göksu Deresi stems from the Karayakuplu Village and reaches the BlackSea at Ağva.The Yulaflı stream flowing into the BlackSea is 43 kms long. The Darlık Stram which hosts the Darlik Dam that provides water to Istanbul also stems from our soils.The Kocadere Stream stemming from the Denizli Village and flowing into the black Sea is 50 kms long.The Major Stream forming in the provincial soils and flows into the BlackSea withn is the Sansu in Kandıra County.The Kaynarca River joining the Sakarya river bfore it meets the Sea also is stemmes from Kandıra.Kirazdere from the Samanli heights flows into the Izmit Gulf. The dam on this stream the Kirazdere Dam has benn finished in 1997.The length of the Dilovası Stream in the Gebze county is 12 kms.It passes through the North of the Tavşanlı Village and South of pelitli village and flows into the Izmit Gulf..
The Sapanca Lake on with its 7 km coast on its West remaining in Kocaeli has a surface of 47 squarekilometers. The artificial lake that provides water for the city of Izmit covers an area of 1,74 km². Another artificial lake is the one made by the Great Izmit Municipality in order to provide water for Izmit and is formed by the waters collected behind the dam is the Yuvacik Dam Lake.
The Gulf coasts and the Black Sea coasts are mild and the higher regions have a harsher climate. It can be said that the climate of Izmit is a transition between Mediterranean and Black Sea climate. Summers are hot and with scarce rainfalls and winters are rainy and occasionally cold and snowy. Differences are obvious between the Marmara and Black Sea coasts of Kocaeli. While tha gulf coasts can be too hot sometimes the Black Sea coast is cooler. Highest ever temperature recorded in city center is 41,6 D C (11 August 1970), Coldest ever temperature is -8,7°C (4 February 1960), average annual temperature is 14,8°C. Average rainfall on the Black Sea coast exceeds 1.000 mm. average. This amount decreases as we go Southward, falls under 800mm s at Izmit.(784,6mm). On the shoulders of the Samanli Heights facing the gulf climate resembles the Black Sea climate.Rainfall is different in this area as well. Winds blow from North on Winter and NorthEast on Summers.
Having usually a typical Marmara region vegetation Kocaeli differs from coastal areas to higher points. And when gone Southward Mediterranean vegetation start replacing the Black Sea types.The areas beyond the Samanli Heights and the BlackSea coastal areas are covered with moisty forests. These forests consist of varipus types of trees including chestnut, reech and others. Higher regions of the Samanli Mountains are covered with pines to the North and East of the Izmit Gulf Meditteranean specific vegetation can be seen. Olive tree fields have been demolished at the north of the gulf in order to gain Industrial sites. The demolished forests are covered with step vegetation and fake scrubs.