? asked in Science & MathematicsGeography · 1 decade ago

What are the Beneficial and harmful effects of the yearly flooding of the Tigris and Euphrates rivers?

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  • 1 decade ago
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    -- Beneficial effects :It irrigates the farm lands and harmful effects:It is subject to catastrophic flooding . Physical features » Hydrology

    The regime of the Tigris and Euphrates depends heavily upon winter rains and spring snowmelt in the Taurus and Zagros mountains. The Euphrates traverses a considerably greater distance than the Tigris from its mountain basin to the point where it meets the Mesopotamian alluvial plain at Al-Ramādī in Iraq. On its long, gently sloping route through Syria and northern Iraq, the Euphrates loses much of its velocity and receives only two tributaries, the Balīkh and the (western) Khābūr, both of them spring-fed and entering from the left. The rate of evaporation on the river has increased to as much as 50 percent with the creation of large reservoirs and related irrigation areas behind a number of dams. The Tigris, in contrast, flows down the edge of a long, multichanneled catchment basin and is fed by four strong tributaries, the Great Zab, Little Zab, ʿUẓaym, and Diyālá rivers, all of which derive their water mainly from snowmelt in Turkish, Iranian, and Iraqi Kurdistan. The precipitous flow of its tributaries makes the Tigris more susceptible than the Euphrates to short-term flooding, and its short length brings its annual flood period a month earlier.

    As it reaches the Mesopotamian alluvial plain above Sāmarrāʾ, the Tigris is a bigger, faster, more silt-laden, and more unpredictable river than the Euphrates at the corresponding point, Al-Fallūjah. This character is expressed in the Arabic name Dijlah, meaning “Arrow.” The mean annual discharge of the Tigris, before control by modern dams, was estimated at 43,800 cubic feet (1,240 cubic metres) per second, and the silt load at approximately one ton per second. These estimates are roughly twice those calculated for the Euphrates. In flood time the two rivers together carry as much as three million tons of eroded material from the highlands in a single day. Some 90 percent of the water and silt that pass Baghdad and Al-Ramādī, however, never reaches the gulf; the water either evaporates or is absorbed in the extensive irrigated areas and marshes, and the silt settles upstream from the Shatt al-Arab. The water and sediments in the Shatt al-Arab derive mainly from the left-bank tributaries, the Karkheh and Kārūn, which rise in Iran.http://www.britannica.com/EBchecked/topic/595616/T... ------

    Hydrology

    The regime of the Tigris and Euphrates depends most heavily upon winter rains and spring snowmelt in the Taurus and Zagros mountains. The Euphrates traverses a considerably greater distance than the Tigris from its mountain basin to the point where it meets the Mesopotamian alluvial plain at Ar-Ramadi. On its long, gently sloping route through Syria and northern Iraq, the Euphrates loses much of its velocity and receives only two tributaries, the Al-Balikh and the (western) Al-Khabur, both of them spring-fed and entering from the left. The Tigris, in contrast, flows down the edge of a long, multichanneled catchment basin and is fed by four strong tributaries, the Great Zab, Little Zab, Al-'Uzaym (Adhaim), and Diyala, all of which derive their water from snowmelt in Anatolian, Iranian, and Iraqi Kurdistan. The precipitous flow of its tributaries makes the Tigris more susceptible than the Euphrates to short-term flooding and brings its annual flood period a month earlier.

    As it reaches the Mesopotamian alluvial plain above Samarra`, the Tigris is a bigger, faster, more silt-laden, and more unpredictable river than the Euphrates at the corresponding point, Al-Fallujah. This character is expressed in the Arabic name Dijla, meaning "Arrow." The mean annual discharge of the Tigris is estimated at 43,800 cubic feet (1,240 cubic meters) per second, and the silt load at approximately one ton per second. These estimates are roughly twice those calculated for the Euphrates. In flood time the two rivers together carry as much as three million tons of eroded material from the highlands in a single day.

    http://www.geocities.com/leucretia/bginfo/geo/euph... --------

  • Anonymous
    1 decade ago

    I don't know of any harmful effects, from what i have learned the flooding of these rivers is gentle and predictable, and deposits fertile soil that is good for farming.

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