نشاطات العمليات الجيومورفولوجية لنهر دجلة وأثره في تشكيل ترب سهله الفيضي ما بين سامراء وبغداد
College of Education The Activity Of Geomorphological Processes Of Tigris River And Its Effect On The Formation Of The Flood Plain Soils Between Samarra And Baghdad
The study area is located in the northern part of the sedimentary plain in the centre of Iraq, specifically within the confined area between southern Samarra and north of the Iraqi capital, Baghdad, and it takes a longitudinal shape according to the nature of the river flow from north to south and an area of (1178.7 km2). The length of the Tigris River within the study area is (117.95) km And with an area of (36.2) km2, distributed over three governorates, which are Salahad Din, Baghdad, and Diyala, the study area is astronomically determined within the geographical coordinates between the longitude (34ْ 50.00 - 44.00-29.30) east and two latitude latitudes (33 33366 .00 _34.05.05) north.
The study shows the role of geomorphological processes contributing to the formation of the soils of the flood plain of the Tigris River through carving, transportation and sedimentation, as well as the role of frequent floods and fusion of islands and their role in building the flood plain, the role of the water drainage system and fluctuation from time to time in repeated sedimentation processes and the nature of the various river payloads.
In the light of previaus studies and pre-prepared maps, thirteen locations of pedon soil were investgated in the area which distributed in four strip paths: The first strip path is located north of the study area starts from south of Samarra district east of the Tigris River towards the district of Dhuluiya and represents the pedons (1,2,3) The second strip path includes the pedons (4,5,6,7), the third strip path includes the pedons (8 9,10), and the fourth strip path represents the pedons (11, 12,13.).
The results of the study suggest that all soil textures ranged between silt loam, silt clay, loam and sandy loam, which reflect the influence of geomorphological processes, especially sedimentation processes, and the results of electrical conductivity indicated that the soil of the areas under study ranged between Unsalted soils to medium salinity and low salinity soils with the exception of the two pedons (7,8), which were classified as high salinity, while the values of the interaction of soil PH ranged between simple basic, moderate acid and simple acidic soils.
The results of the study rivear tht, through morphological description, physical and chemical characteristics, that all pedons soils of the flood plain of the Tigris River under study were classified into a level under the great groups that fall within the undeveloped soils belonging to the Entisols level according to the modern American system USDA ((2001)) as these include The soil is a newly formed and undeveloped soil that has no indices of development, because it contains the surface diagnostic horizon type Ochric and the absence of subsurface diagnostic horizons. This soil is also characterized by the stratificationphenomenon that spreads in areas near the riverbeds, which follows the horizons of the soil estuary. It is of type (AC), and it is one of the common soils in Iraq, except the Paidon No. (1), which is related to the rank of Aridisols, in which the horizon B has developed as a result of the accumulation of high gypsum content below the surface.
Through out the morphological description of the pediatric soil sections of the study area and the results of laboratory analyzes, the soil region of the study area was classified in to a level under the group and the results showed that there are two types of them:
: (Typic torrifluvents)
The study points out that in its final results related to the characteristics of the soil used in calculating the suitability of the land for agricultural crops in the study area that the prevailing soil texture for most pedon soil soils is a mixture of silt loam, silt clay, loam and loamy sand, and that these textures in general did not conseder as limititayion for the cultivation and production of grain crops, orchards and vegetables at the study area.
The results of applying the Sys equation offirm that there are four varieties suitablitiy for growing cereal crops. The results show that the pedons (3, 4, 5, 6, 9, 13) fall within the category of lands that are very suitable S1 Very suitable for growing cereal crops, included the second category S2 Suitable on pedons (10,11,12), and the medium-adapted variety, Moderate suitable, S3 in pedons (1), the little-suitable type S4, Little suitable in soil units represented by pedon (2,7,8), the results also indicated that there are five classes suitable for cultivation Orchards and it was found that the pedons (3, 4, 6, 9, 13) fall within the category of S1 Very suitable lands, while the S2 Suitable category is unique to the pedon (5) and the Moderate suitable S3 category prevailed in the pedon (10,11, 12), represented a little suitable type S4, Little suitable in the pedon (1), while the inappropriate type N No Nsiutable was determined by pedons (2,7,8), and the results also state that there are five categories suitable for planting vegetables and show that pedons (4, 5 , 9, 13) falls within the category of S1 Very suitable, while it includes P. S2 Suitable land is classified on the pedons (3,6,10,12), and the Moderate suitable S3 category is confined to the two pedons (1,11), and the S4, Little Suitable category represents the two pedon s (2,8), while the cultivar Inappropriately N No Nsiutable concentrated in the pedon (7) .