Calculation of Head Losses and Analysis of Influencing Factors of Crossing Water-Conveyance Structures of Main Canal of Middle Route of South-to-North Water Diversion Project

The main canal of the middle route South-to-North Water Diversion Project has risk excess head loss in crossing water-conveyance structures, but assessment this faces difficulties such as lack sufficient monitoring points inside current flow rate being lower than design maximum rate, and verification data. Monitoring data were collected 2022, prototype observations carried out, verified, a method for calculating using combined coefficient was proposed. 143 structures showed that 40 had losses, including 31 inverted siphons, four aqueducts, underdrains, one culvert. total residual 3.05 m, accounting 9% distributed head. In addition to natural aging, freshwater mussel algal attachment, sediments, undesirable regimes all important influencing factors caused increase. It is recommended take measures regular removal sediments algae attachments, optimization inlet outlet shapes, application roughness-reducing materials.