River safe yield with the constraint of a contracted rectangular weir for surface water supply

Aydin et al. introduced the weir velocity concept in 2011 for discharge measurement in contracted rectangular sharp-crested weirs. Gharahjeh et al. further reinforced this formula in 2015 to allow discharge to be computed using only weir velocity and crest width. These newly introduced expressions are tested and demonstrated to determine surface water yield of Tapah River in Sarawak. Aydin and Gharahjeh's formula is found to perform similarly to the improved discharge coefficient developed by French in 1986, but is simpler and easier to use. Exploring Aydin and Gharahjeh's formula through theoretical, experimental, and field approaches, it has been found that the formula performs well in a controlled environment. Discharge computations based on field data were determined to have been formerly underestimated, with the reason as yet undetermined.