تحديد معامل التجانس لمواد الأصل للترب المتاخمة لنهر دجلة أسفل و أعلى سدة الكوت

الملخص EN

This study was conducted in Wasit province / city of Al-Kut to study the pattern of deposition of soils adjacent to the River Tigris and the impact on them of Al-Kut Dam.

Four sections representative of the deposits on the left bank of the Tigris River were chosen, two of which are located at the lower part of Al-Kut Dam represented by (A and B) and the other two at the upper Al-Kut Dam and represented by (C and D).

The soil samples were collected from each horizon of the area sections under study after divided the section in to layers depending on the variation in morphological and lithological properties.

The results showed clear variations in the percentages of the sand, clay and silt fractions of the soil samples taken from the study sections, both between the layers of a single section or between different sections.

The most significant difference appears when we compare the sections at the upper part with the sections at the lower part of the dam.

This follows the sand percentages ranging between (2.5 -87.5%), where the lowest percentage was at depth of (0.50 to 0.60 m) of section D at the upper part of the dam, and the highest percentage was at the depth of (1.26 to 1.56 m ) of section A.

The silt fractions ranged between (2.5 to 47%) and the highest percentage of silt was at the depth of (0.30- 0.50m) of section D at the lower part of the dam and the lowest percentage was at the depth of (0.45 to 0.55 m) at the lower part of section A.

Similarly, the clay fractions percentages ranged between (10- 75%), where the highest percentage was at the depth of (0.0-0.30m) of section D, which amounted to (75%), while the lowest percentage was at the depth of (0.2-0.35 m) of section A at the lower part of the dam.

The results indicate the presence of heterogeneity as evident in the values of uniformity coefficient of the parent materials for the original study sections.

The highest value was recorded for the coefficient of homogeneity in section B, located in the lower part of the dam amounting to 1.63 and the lowest value recorded in section C located at the upper part of the dam was 0.02.

The reason lies in the instability of the sediment accumulated at the upper part of the dam, which puts them in a state of change as a result of continuous additions of mobile deposits with the course of the river, while at the lower part of the dam there is a kind of relative stability of deposits as a result of the absence of an obstacle behind the dam.