Drainage system (geomorphology)

In geomorphology, drainage systems are the patterns formed by the streams, rivers, and lakes in a particular drainage basin. They are governed by the topography of the land, whether a particular region is dominated by hard or soft rocks, and the gradient of the land. Geomorphologists and hydrologists often view streams as being part of drainage basins. A drainage basin is the topographic region from which a stream receives runoff, throughflow, and groundwater flow. The number, size, and shape of the drainage basins found in an area vary and the larger the topographic map, the more information on the drainage basin is available.

Drainage patterns

According to the configuration of the channels, drainage systems can fall into one of several categories known as drainage patterns. Drainage patterns depend on the topography and geology of the land.

Accordant drainage patterns

A drainage system is described as accordant if its pattern correlates to the structure and relief of the landscape over which it flows.

Tigris

The Tigris (/ˈtaɪɡrɪs/) is the eastern member of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of southeastern Turkey through Iraq and empties itself into the Persian Gulf.

Geography

The Tigris is 1,850 km long, rising in the Taurus Mountains of eastern Turkey about 25 km southeast of the city of Elazig and about 30 km from the headwaters of the Euphrates. The river then flows for 400 km through Turkish territory before becoming the border between Syria and Turkey. This stretch of 44 km is the only part of the river that is located in Syria.

Close to its confluence with the Euphrates, the Tigris splits into several channels. First, the artificial Shatt al-Hayy branches off, to join the Euphrates near Nasiriyah. Second, the Shatt al-Muminah and Majar-al-Kabir branches off to feed the Central Marshes. Further downstream, two other distributary channels branches off (the Al-Musharrah and Al-Kahla), which feeds the Hawizeh Marshes. The main channel continues southwards and is joined by the Al-Kassarah, which drains the Hawizeh Marshes. Finally, the Tigris joins the Euphrates near al-Qurnah to form the Shatt-al-Arab. According to Pliny and other ancient historians, the Euphrates originally had its outlet into the sea separate from that of the Tigris.

Euphrates

The Euphrates (ⁱ/juːˈfreɪtiːz/; Sumerian: 𒌓𒄒𒉣: Buranuna, Akkadian: 𒌓𒄒𒉣: Purattu, Arabic: الفرات‎: al-Furāt, Syriac: ̇ܦܪܬ‎: Pǝrāt, Armenian: Եփրատ: Yeprat, Hebrew: פרת‎: Perat, Turkish: Fırat, Kurdish: Firat‎) is the longest and one of the most historically important rivers of Western Asia. Together with the Tigris, it is one of the two defining rivers of Mesopotamia. Originating in eastern Turkey, the Euphrates flows through Syria and Iraq to join the Tigris in the Shatt al-Arab, which empties into the Persian Gulf.

Etymology

The Ancient Greek form Euphrátēs (Ancient Greek: Εὐφράτης) was borrowed from Old Persian Ufrātu, itself from Elamite ú-ip-ra-tu-iš. The Elamite name is ultimately derived from the Sumerian Buranuna, possibly through the Akkadian name. In Akkadian the river was similarly called Purattu, which has been perpetuated in Semitic languages (cf. Syriac P(ə)rāṯ, Arabic al-Furrāt) and in other nearby languages of the time (cf. Hurrian Puranti, Sabarian Uruttu). The Elamite, Akkadian, and possibly Sumerian forms are suggested to be from an unrecorded substrate language. Gamkrelidze and Ivanov suggest the Proto-Sumerian *burudu "copper" (Sumerian urudu) as an origin, with an explanation that Euphrates was the river by which the copper ore was transported in rafts, since Mesopotamia was the center of copper metallurgy during the period.

Tigris and Euphrates

Tigris and Euphrates (German: Euphrat und Tigris) is a German-style strategy board game designed by Reiner Knizia and first published in 1997 by Hans im Glück. Before its publication, it was highly anticipated by German gamers hearing rumors of a "gamer's game" designed by Knizia. Tigris and Euphrates won first prize in the 1998 Deutscher Spiele Preis. A card game version was released in 2005.

The game is set as a clash between neighboring dynasties at the dawn of civilization. The game is named after the rivers Tigris and Euphrates in the region now called the Middle East. The rivers together formed natural borders for an area which harboured several grand ancient civilizations, including Sumer, Babylonia, and Assyria. The Greeks called this area Mesopotamia, which literally means "between the rivers".

Gameplay

The game can be played by 2, 3 or 4 people. The play offers both tactical and strategic objectives. As with many games, short term objectives gain prominence when more players participate, as players have fewer chances to follow up on previous moves. Luck plays a role, as players draw tiles from a bag, but it is seldom decisive. Players may selectively discard and redraw their tiles at the cost of one "action point", of which each has two per turn. The game does not use dice.