اسم المؤلف:
جميلة فاخر محمد
اسم المشرف:
اسحق صالح العكام
المستخلص:
Alluvial fans are one of the most prominent features of water deposition in the avid and semi avid regions.It separates between the nature of the center flow within the drainage basin runoff which spread easily on the environment of sedimentation.The study of Alluvial fans by two trends; the first of which is geomorphology an independent unit, with characteristics that distinguish the fan floodplains from the rest of the units basin water drainage through the study of the mechanism of formation, growth, the factors affecting it, the characteristics and environmental features, geomorphological processes that take place over it. The other trend was the study of alluvial fans as part of the integrated flood that is influenced by processes that take place with full parts of the basin, where the reached inputs affect geomorphological processes that occur on the surface of the basin. Their effects are shown on all parts of the basin, including the alluvial fan. The study consists of six Alluvial fans with the drainage basins.It contains extends in most AL - Najaf plateau and parts of the provinces of Al - Diwaniya and AL - Muthanna. The extends between (29.49 - 32.9)North Latitudes and between (42.29 - 45.1)east Longitudes. The study area Occupyies (23155)km2 of the surface area of Iraq.It occupied alluvialfans(156.1)km2, of basins (22998.9)km2of the regions of the whole area.The study takes the north - east direction.The emergence of depositions alluvial fans at the end of the canyons, where these sediments formed (156.1 km 2), with a rate of (0.67%) from the area configurations. It is an index of the consecutive periods of deposition and erosion by changes in the time Blaistaseen, These formations have continued in the deposition until the time of the Holocene ,it was reached to the forms of alluvial fans by comparing the geometry where the same model figure fans have included fans (Alkur, Abu doab, Abu Shinan). The fans that have triangle shapes include two fans (hasap, Alheiazi), whereas Valley Faraj fan, has an abnormal shape.It was concluded that the shape or (semi - turbofan). It was concluded that applying Milton coefficient, and the coefficient of the deposition rate (R) fans the study area, that the fans have reached an advanced stage of the surface construction. It has begun to move from construction to demolition. A laboratory quantitative analysis of the sizes of the surface sediments, where it has (18) samples and (3) samples of each fan, through the analysis that the large - scale sediment was deposited at the scope of fans flood peaks. It appeared that the gravels are the types of sediments which are prevalent in the tops of the fans.The results of the analysis of deposits amid fans have shown the medium sand deposits feet fans over silt and clay analysis. Thus, it appears that the volumes of thesediments across its parts.A morphological analysis of surface deposits that exceed the size (2mm), was conducted where pebbles were analyzed. (324) pebbles are of high proportion of round gravel and a good rotation that rates to (26.67%, 28.15%) in samples amid fans. It has adopted a method called (Krombaan) in the extraction spherical surface sediments, where it became clear which spherical sediments are high in general. The study has reached a spherical proportion of deposit peaks fans flood was (0.68%) where the deposits amid fans spherical sediments reached (0.73%), and the forms of sediments depend on (Zing classification was reached through it to the sharp form (roofing) is the dominant form of grit fans tops.It shows that its average rate is (43.78%) of the percentage of forms of gravel in the fans tops, as a square shape is the dominant form in deposits amid fans flood, where the rate stood at an average (37.04%) of the percentage of forms gravel deposits in the center of the fans. It reached to the degree of risk of floods that occur on the surface of the fans, were divided into three levels, and these levels varied in the areas within the fans, reaching high - risk area of land (57.13 km2), and by(36.6%) of the total fan area , while the medium - risk land area (52.17 km 2) and by (33.42%), while the few dangerous land area has reached (46.8 km 2) and by (29.98%) The classification of land use and land cover in the fans flood relying on the US Geological System (U.S.G.S) by drawing classification maps for uses of Alluvial fans, and the field study of these fans, where the uses were identified land down to the third level of the surface of fans.
