I have water reservoir at the top of my hill and I want to get free running water. I would like to go for 4 inch diameter pipe.
I have two options. 1. Dig a trench and lay the pipe from the bottom of the reservoir. This will ensure that water will flow any time due to gradient. But the problem is I have to dig a trench and in between there could be few huge boulders and it may become expensive to go for trench. 2. In this option, I can use siphon system. Cost of trenching will not be there and no risk of getting boulders while trenching. But if air gets inside, I need to flush out the air and I may need to pump water from other sources to the pipeline until the delivery pipe is filled with water.
My questions: a. Does the diameter of the pipe matters in Siphon system? Any upper limit for the diameter of the pipe (I want Practical limit and not theoretical value). I need to use 4 inch pipe size b. Is there any difference in water discharge rate between option 1 and 2 (assume that water pipe length variation between two options is around 15% (more in siphon system). Do I get same amount of water per hour in both the options?