Hi Thanika, cant quite ...

Hi Thanika, cant quite visualise your situation, but it seems you have constructed or are planning to construct channels to collect and direct the rainfall runoff to a surface storage reservoir.  It may be wise to consider an approach whereby you install rock structures (or gabions) in the channels to slow down the flow in the channels to minimise erosion and reduce velocities.  Using the standard rainfall-runoff and open channel flow equations (e.g. rational method) you can estimate your flows, velocities, depth of flow in the channels and sediment transport potential.  

Not sure if this is what you are asking? 

If the challenge is to get sufficient runoff during a rainfall event to direct to your storage reservoir, you could consider methods to improve runoff on un-cultivated areas through compaction, spraying with a dust suppression polymer or other options.