A few ideas. The size of basin with respect to drainage area and expected storm flow. The residence time for suspended solids to settle before discharge. The length or path distance that sediment would have to move within the sediment basin before being discharged. The type of sediments - storing clays is especially difficult to settle without sufficient storage time. Maintenance of sediment basin - will it be maintained on regular schedule, or just built and left. Sediment sources and activities in watershed. If capacity is exceeded, would the sediment basin fail or have emergency overflow? How long is sediment basin supposed to operate, short term associated with an activity and mitigation, or long term due to recurrent sediment issues and need for low sediment to support downstream uses, water treatment, etc. Consider type of upstream contributing streams - gullies and steep gradients deliver sediments efficiently, while upstream braided streams are result of high sediment load, and they also tend to be accumulating sediment (aggrading). What is potential for contributing upstream activities such as channelization, road development and land clearing, urbanization, etc. If not familiar with Roehl (about 1962), he developed sediment delivery ratio from drainage size using ponds and dams. His results suggest that the larger the contributing drainage area and associated reservoir, the greater efficiency at removing sediments, and one might also assume that larger watersheds often have ability to store some sediment on their floodplains.
I think its necessary to understand your meaning, the function of sediment tank is to reduce the suspended particles volume so more efficiency more sediment
Efficiency of sedimentation basins depend of many factors from which can be mentioned: Detention period, Displacement efficiency, Surface loading, Basin dimensions, Inlet and outlet arrangements, Sludge removal devices.
A short description of these factors you can see in:
An important factor which leads to increase the effectiveness of setting is the inlet and outlet arrangement. That because, a well-designed and optimised arrangement assures the equalization of flow distribution in the cross-section of the basin reducing thereby the created perturbances in inlet and outlet area.
An example in this regard you can see my paper published in 2013:
HYDRAULIC SOLUTION FOR REDUCING THE OVERLOADING OF SEWAGE TREATMENT PLANTS USING SEDIMENTATION TANKS COUPLED WITH INFILTRATING BASINS
Good questions, there are many factors such as, soil texture and soil types, sediments types, physical properties of soil, vegetation, depth and length of cross section, and efficiency of sediment basin. infiltration of precipitation into soil.
Hi! Like every engineering work, it must be well dimensioned according to the expected performances. The efficiency depends on this. Factors that must be considered for a good design of the sedimentation basin are: the soil type, the land cover, the drainage area, the slope, the type of precipitation (the erosion process depends on runoff and on the impact of drops on the surface of the ground). Once the volume of sediment to be stored is determined, other important factors are the dimensions of the basin, the materials and the spillways.