Botan River

The Botan River is located in the Siirt Province of southeastern Turkey. The upstream of the Botan River is often called Çatak, which flows mostly in the Van Province.

There is Botan Valley National Park in the area. The uppermost part of the Çatak River, west of the town of Çatak, is sometimes called Norduz. It originates in the high mountains around the Nordüz Plateau, near the border between Van and Hakkâri, and flows westwards before it turns to the northwest. The river has shaped a canyon on its way. The altitude difference between the valley and the top of the mountains reaches about 1,000 m (3,300 ft). The Çatak River is joined by the Büyükdere River at Çukurca, near Pervari in the Siirt Province, after which it is named Botan Suyu (Uluçay). Running westwards by east of Aydınlar and Siirt, it reaches Bostancık locality. Here, the rivers Zorava and Bitlis join the Botan. Finally at Çattepe in Siirt Province, it joins the Tigris River, after which the Tigris sharply turns southwards.

The discharge of Botan River from spring to mid-summer averages about 100–300 m³/s (3,500–11,000 cu ft/s), while it reaches in April and June about 400–600 m³/s (14,000–21,000 cu ft/s, and in May it peaks at about 700–1,000 m³/s (25,000–35,000 cu ft/s and sometimes more. At this time, it looks much bigger than the Tigris River. At the end of summer or in the fall, its depth is not less than 1 m (3.3 ft), and its outflow not less than around 60–80 m³/s (2,100–2,800 cu ft/s).

Crossing is only possible by boat. The river runs in narrow, deep and steep valleys. Lowlands are rare on its way, preventing it use for irrigation.