Spatio-Temporal Patterns of Saltwater Intrusion in A Narrow Meandering Channel

Saltwater intrusion has become a crucial issue for water resources management across the globe. Consequently, this issue leads to problems such as encroachment on water intake zone, loss of freshwater vegetation and also disturbance to aquatic life habitat. Undeniably climate change increases the saline water flow into the river system. The meandering rivers are common, and the hydraulics is more complex than straight rivers. An experimental hydraulic investigation was carried out in the Universiti Teknologi Malaysia to elucidate the hydrodynamic interactions between saline water and freshwater in a narrow meandering channel. The spatio-temporal salinity profiles along the river are discussed in this paper. The findings prevailed a typical characteristic of a salt-wedge estuary and indicated the processes of estuarine mixing. As the saltwater flows upstream, the salinity level drops due to the dilution process. Salinity levels and densimetric Froude number were mainly driven by freshwater discharge in the channel. A variation of dilution rate in a narrow meandering channel were up to 78.9% due to strong velocity forces produced by a high freshwater discharge. Furthermore, the flow resistance induced by the channel boundaries and meander planform itself influenced the salinity intrusion profiles along the channel

The effect of flow and sediment matrix to the formation of mid-channel bar in river / Mohd Zulkhairi Mat Salleh

Mid-channel bar is one of the issues that are found in river. It contributes to flood occurrence along flood plain. The formation of mid-channel bars is related to various factors such as flow, sediment, vegetation and others. Previous researchers had carried out many studies but the understanding of mid-channel bar is still lacking because of lesser knowledge on the fundamental of their formation. Therefore, this study is conducted to determine the relationship of flow and sediment to the formation of midchannel bar. It is based on the analysis of experimental works. The dimension of straight physical river model used was 200 cm length and 4 cm width. The river is produced in sand bed condition with the size of sand (Dso = 0.8mm). The findings proved that the flow and sediment has critically contributed to the formation of mid-channel bar. The erosion and deposition occurred along the channel. Mid-channel bar is only formed at transported and deposition zone. It is formed from mechanism which are cut-off point bar and deposition of sediment in the channel. Two different shapes of bars are formed which are lunar and ellipse shapes. The analysis is also based on the analysis of shear velocity profile. The bars are formed at minimum location and stable values of shear velocity. Lastly, the findings of the study are very significant to the issues of mid-channel bars with providing a basic knowledge on effect of flow and sediments

Prediction of bed profile due to complexity of sediment properties in the channel

Numerous data on bed profile have been investigated yet the analysis to predict bed profile formation especially related to sediment properties are still insufficient. Objectives of this study to determine significant bed elevation profile pattern formed based on the complexity of sediment properties especially related to sediment size. The investigation is made by carried out a computer simulation of straight channel pattern with the fixed bank and movable sand bed. The study included the various hydraulic characteristics with steady flow rates and sediment properties. The simulations focus on three different sediment sizes with other variables namely channel size, flow rate and bed slope were kept constant. Analysis has included the discussion on a significant difference of bed elevation profile formed along the lateral and longitudinal distance. As a conclusion, the sediment size alone does not significantly change the bed elevation profile as its only gave minor effect to the bed profile changes