Suspended sediment concentration and stream discharge relationship during storm events in tributaries of Smaquli Stream, Erbil, Iraq

Abstract EN

The primary objective of this study is to monitor and collect data from the main tributaries of Smaquli stream during rainfall storm events, which can be used to establish relationship between suspended sediment concentration and discharge.

The Smaquli catchment is divided into two sub-catchments namely Sarwchawa and Krosh with areas of 80.64 and 34.82 km2 respectively.

Jali dam is built at watershed outlet.

Rainfall, stream discharge, and suspended sediment concentration are monitored during ten rainfall storms in the water years (2012-2013) and (2013- 2014).

Analysis of the data from the two sampling sites, shows two different responses of suspended sediment concentrations.

The Krosh sub-catchment reacts rapidly to rainfall storms and the same behavior is shown in the suspended sediment that is resulted seven single and three double-peaked graphs.

On the other hand, the reaction of Sarwchawa sub-catchment was slower.

Moreover, analysis of cumulative flow and suspended sediment showed the Krosh sub-catchment ranks almost equally as one of the flow and sediment contributors to the Smaquli stream, in spite of the area difference between Sarwchawa and Krosh sub-catchments.

The peak stream flows are highly correlated with total and peak suspended sediments at Krosh station having correlation coefficients of (R=0.96 and 0.84) respectively.

In contrast, at Sarwchawa sub-catchment, the peak stream flow was weakly correlated with peak suspended sediment (R=0.47).

To reduce sedimentation, this study suggests changing the land use practices for example types of crops and frequent planting and less grazing of sheep and goats.