Theoretical and experimental research of river sediment has been one of JCI’s primary activities and has made JCI renown both domestically and globally. Field measurements of suspended sediment and bedload have been conducted at a large number of watercourses in Serbia, the former republics of Yugoslavia, and many countries abroad. JCI set up a Sedimentology Laboratory too support this research.

The Sedimentology Laboratory features standard equipment for drying, filtering, measuring, sieving, and other operations involving river sediment. Particularly notable are custom-designed and fabricated instruments, patented by JCI, including:   

• A suspended sediment vacuum sampler
• A bathymetric-bottle suspended sediment catcher
• A fraction selector for large suspended sediment particles

Sketches of these instruments are shown below:

Figure 1. А: Vacuum sampler, 10 or 40 l, original JCI design (1 – Sample chamber; 2 – Discharge chamber; 3 – Supply hose); B: Vacuum pump.	Figure 2. Bathymetric bottle, 1 l, JCI design.	Figure 3. V. Antić’s fraction selector: 1 - Tube; 2 – Water tank; 3 - Stopper; 4 – Fraction compartments.

Accurate determination of sediment grain-size distribution is particularly important in laboratory research of suspended sediment. Two parameters are of special interest:

• geometric particle size, and
• hydraulic particle size.

Geometric particle size of sediment is determined applying the sieving method, while hydraulic particle size is determined using the custom-made fraction selector mentioned above. The Sedimentology Laboratory also conducts comparative analyses applying conventional methods for determining particle sizes of suspended sediment, namely:

• Cumulative sedimentation
• Aerometry
• The Kachinsky pipette method
• The VNIGM pipette method

At present, JCI is the only institution in Serbia which conducts field measurement and theoretical research of river sediment. By necessity, all studies involving river hydraulics and all river engineering projects address river sediment issues, an area for which JCI is recognized both in Serbia and abroad.