Water from Small Dams

Simple equipment for measuring levels and gradientsA levelling instrument, called a dumpy level,is expensive to buy and difficult to borrow.A much simpler levelling instrument can bemade from a one metre long length oftransparent hosepipe that is bent into a circleand filled halfway with water.When sighting along the two waterlevels in the hosepipe an exact horizontalline is projected forward.Horizontal contour lines are found by Gradients are found by sighting onto atwo persons having the same eye height. stick with measurements and measuringThe person who is sighting, tells the other the distance between the stick and themove up or down until his eye is at the same person.level.Source: Water from Dry Riverbeds and Water Surveys and Designs of this series.A simple tool made of 3 sticks can be used formeasuring out levels, gradients and distances.A mark is made at the exact middle of thehorizontal stick and a small stone is tied with astring to the top of the other two sticks. Tomeasure a horizontal line, the two legs musthave exactly the same length and the stringwith the stone must be perfectly aligned withthe mark. The tool seen to the left is made insuch a way that it will measure a gradient of3:100 for the floor of spillways.23