I am working on a project that requires me to control the flowrate of a water using Arduino, my initial idea is to use a control valve that allows me to set the opening of the gate of the valve from 0% to 100% so I can set any number between these two. However, I could not see any type of valves that is applicable with Arduino to achieve that. So I am thinking if I can install a water pump and control its rpm to control the flowrate. Is that possible?
If not, could anyone provide me some help to achieve this goal?
Yes, depending on the type of water pump. You could use a submersible pump or what is called a positive displacement pump. Look for either type. However, the water flow will have to be calibrated if you want to know the exact flow volume. All but the positive displacement will have non-linear water flow. A positive displacement pump will also be called a diaphragm pump.
That is a difficult question to answer correctly. What hp is the pump, how much current at what voltage, what type of pump? Is the motor rated to operate at a variable speed. Have you looked up "remote control adjustable valve" There are a lot of choices.