Lines Composed In a Small Shop
Here's a quick look into a project I helped work on in Tolongoina. As part of Madagascar's initiative to increase rural-electrification, several micro hydro schemes will be installed in the district of Ikongo. One of the challenges in the design of these systems is obtaining an accurate measurement of dry-season flow in the streams and rivers under consideration. The stream at Tolongoina comes directly from the forest corridor and is strewn w/ bolders and waterfalls and standing pools. This makes streamflow measurement almost impossible.
One method we've been using is the conductivity meter method. By adding a salt solution to the water upstream one can measure the salinity downstream after proper mixing. A stream w/ low flow doesn't dilute the salt as much so the electrical conductivity will be high. The flow rate is inversely proportional to the degree of conductivity of the salt mix passing the probe and the time it takes for this mix to pass. Because we were unsure of the accuracy of this method in our stream (it works best w/ larger flows), we decided to also use the weir method. This requires a relatively straight channel of water, something non-existant in our stream. However, by creating conditions at the weir similar to those already tested in a lab (fully contracted flow, sharp crested v-notch, and free flowing nape) we can measure the head on the weir and find the flow using an empirical equation. Take a look at the video to get an idea of how we solved this problem. You'll also get an idea of the kind of environment we work in.
Lastly, I leave you with a touch of entertainment from my village. This took place on the 26th of June during the independance day festivities. I thought about entering my name to the roster but remember experiencing a strange pain in my ankle at the time (similar to the reoccuring pain I experience at weddings or dance parties when asked to prove my talents).