A number of us got together on this cloudy Saturday morning to get some hands-on training with stream flow measurement and to conduct a little surveying. Stream flow is important in evaluating the capacity of a surface water resource to support livestock, irrigation, or other activities. It will be important for us to estimate the volume, quality, and reliability of the water supply in Zuncallo. Methods for determining flow in open channels range from very detailed and precise to “quick and dirty.” Pete was in charge of the stream flow measurement and he constructed a simple weir device to demonstrate the concept.
Weirs are structures which are inserted in the channel to measure flow. As water flows over the weir, the depth or “head” of the water is measured. Weirs can be made with plywood or with l-inch boards and 2 x 4’s. The reliability of weir measurements is affected by construction and installation, but when properly constructed and installed, weirs are one of the simplest and most accurate methods of measuring water flow.
A given water resource may or may not provide a reliable, sufficient amount of water for a particular purpose. We know there are definite seasonal variations in the water volume and we must limit the irrigation to that which can be adequately supported by the water resource. Our site assessment will occur during the dry winter period when stream volume will be lowest. This is also the time when the irrigation system will be most needed so the timing is fortuitous.
Our survey training did not progress well as we had equipment failure. The level we planned to use has developed some optical problems and would not focus. Better to find that out now than down in Bolivia! When we can locate another level or repair this one we will reschedule our survey training.
We have gotten all of our ducks in a row and received final approval to travel to Bolivia from EWB-USA. The travel dates are 16-24 May. We are working diligently to get the final loose ends tied up here and coordination completed with our Bolivian support group. The travel team will consist of three members of the Professional Chapter and three members of the Air Force Academy Student Chapter. I will lead the group.
