Spatial total load rating curve for a large river: a case study of the Tigris River at Baghdad

Abstract

The Tigris River in Baghdad is a large sand-bed river, supply-limited because of the implementation of a water flow regulation scheme comprising a series of reservoirs and barrages. The significant reduction in the water discharge has affected the hydraulic performance of the river and turned it into an under-fit river of complicated morphology where many islands and bank deposits have been showed up across an 18 km reach in addition to the essential sinuosity. Measuring sediment load at individual cross-sections in the river gives misleading estimates and the corresponding sediment rating curve has a locally limited using. A spatially sediment rating by investigating sediment loads over the complicated reach is required to overcome the local limitations. Sediment transport rates have been investigated at 16 cross-sections along the study reach by collecting suspended load, bed load and bed material samples. Velocity profiles were measured at the sampling stations using an Acoustic Doppler Current Profiler (ADCP). The measurement results indicated that the suspended load is the dominant mode of transport (93.5%). However, bedloads were considered in determining the total loads. A spatial total load rating curve in the form of a power function was established and examined against the sediment measurements. Twenty-two previously published total load formulae where applied at the same sections and of these the Colby 1964 formula gave the closest fit to the measured loads. Based on the results from this study a recommended procedure is established for using a spatial total load rating curve to estimate sediment transport rates for similar morphologically complicated rivers. Average annual transport rates during the period 2009-13 was estimated at 3.21 million tons. ARTICLE HISTORY

Sediment flux from Lesser Zab River in Dokan Reservoir: Implications for the sustainability of long‐term water resources in Iraq

“…Then mass concentration of delivered sediment was calculated considering sediment density of 1,200 kg m −3 as 1,500 g m −3 . This mass concentration is almost eight times higher than the average measured concentration in the Tigris River in Baghdad (Ali, Al‐Ansari, Al‐Suhail, & Knutsson, ) and approximately 2.3 times the estimates by Ezz‐Aldeen et al ().…”

Evaluation of Current and Post-Development Carrying Capacity of Tigris River Reach in Mayssan Province

“…Much research had been conducted for Tigris River, related to bed sediment load, calibration and validation of Manning's coefficient, water quality models and estimation of discharge capacity. However, as the river flows downstream the problems mentioned above become more evident, hence it is required to pay more attention to study the performance of the river in view of these changes [6,7]. As the river section is reduced due to sedimentation during the low flow season, its flow carrying capacity is affected and that may be a problem during the high flow season, especially during a flood season.…”