Pond Boss Forums POND CONSTRUCTION Selecting a site Measuring potential inflow

I'm planning to build a one to three acre pond by damming a small arroyo. The creek bed is dry except after heavy rains. The primary channel is about ten feet wide with cut banks about three feet high. I've seen it run full and assume it occasionally overflows the banks but could not find any evidence of such. I'd estimate the flow speed at about five to seven mph when full. After heavy rains, it runs full for a couple of hours then tappers off to nothing within 24 hours after the rain stops.

I'm not sure how to convert the above estimates into potential water volume going into my planned pond. I'm also not sure how to determine the proper size for spillways. I'd prefer to install a culvert pipe(s) for the primary spillway and add an emergency spillway to overflow around the side of the dam.

Determining the expected inflow will help me decide how large and deep to make the pond. No sense digging a big hole that has no realistic potential of filling with water.

I guess I should also mention that the top of the dam will double as a road bed for crossing the arroyo. Hence the desire to use culvert pipes as the primary spillway.

I plan to seal the pond using locally mined bentonite clay.

Any answers, comments, suggestions, or questions would be appreciated.