The type of sediment load that is carry by the specific amount of water supply-Sediment load is most important variables to determine channel pattern and hydraulic geometry. Sediment load of a river are two types – a) suspended sediment load, b) bed material load. The transportation of Suspended sediment load depends on turbulence and channel velocity, bed loads transportation depends on shear of the channel bed.
Suspended sediment load- The very fine sediment that is carried in suspension for a certain period without the contact with the bed. There are so many techniques (Grab, Pumping, point integrating isokinetic, traps, pressure differential) to measure suspended sediment movement. I consider Grab Samples for per my research study.
Grab Samples- This is the simplest process to collect suspended sediment sample. A container is needed to dip at a fixed point into the stream for a specific time period so that it can well mixed. The sediment deposited in container gives the volume of concentration of sediment and when the concentration of sediment correlate with the rate of flow gives the rate of sediment discharge.
Bed load sediment- The coarser sediment which is move along the bed by rolling, sliding called bed load sediment. Bed material sample are often collected with the suspended –sediment samples at the same point but specification is available for the US BM-54 sampler.
US BM-54 sampler – The sampler is useful for shallow medium deep water and sediment range from clay to gravel. The bed material sample is collected by a revolving bucket up to 5 cm of the stream bed rotating from a position and grabs the samples, ensuring that the sample is not washed out when the device is raised out of the water surface.
The velocity of the water flow-velocity means the speed of water flow within channel and it is determined by bed gradient, volume of water, friction, and channel shape. The most applicable & popular method of river flow measurement in India is velocity area method.
Velocity Area Method- In this method, First River basin is divided into some segments and computation of discharge through each segment is calculated by multiplying the average velocity of each segment by the segment area. The sum of the velocity of each segment gives the discharge rate.
The gradient of river bed- Stream gradient means ratio of decrease in elevation of a stream per unit horizontal distance usually expressed in m/km or feet/mile. It is measured using clinometers tied with ranging rod set up in suitable distance into the river. Usually the distance is standardizing according length of lower course. As per length of lower segment of Damodar River is almost 145km so, 15-16m stretch may be suitable for reading. The angles are observed of one pole from other pole.
River channel pattern –The channel pattern means the types of waterways formed by sedimentary deposition. Generally, channel pattern have straight, meandering, or braided category. The variables types of waterways have different type of depositional characteristics and all the depositional features are the result of velocity changes.
Sinuosity(SI) of a river channel-
SI=LC/LV Where, LC-Channel Length
LV- Valley Length
When sinuosity index 1.05-