where Q 5 flow (m3/s), n 5 a roughness coefficient, B 5 width (m), H 5 depth (m), and S 5 slope. You are applying this formula to a stream where you know that the width 5 20 m and the depth 5 0.3 m. Unfortunately, you know the roughness and the slope to only a 6 10% precision. That is, you know that the roughness is about 0.03 with a range from 0.027 to 0.033 and the slope is 0.0003 with a range from 0.00027 to 0.00033. Use a first-order error analysis to determine the sensitivity of the flow prediction to each of these two factors. Which one should you attempt to measure with more precision?