An error of 1% in measuring the head of water over the crest of a triangular notch, produces an error in the discharge which is equal to

Therefore, an error of 1% in measuring H will produce an error of 0.00436% in discharge over a triangular notch. Conclusion: Hence, the correct option is D) 2.5% which is the closest option to the calculated error in discharge over a triangular notch.