Changes in hydraulic parameters in canals with sides lining

Today, as a result of deformation and filtration in the channel, the hydraulic efficiency and operational reliability of irrigation networks in our Republic is decreasing, as a result, the efficiency of irrigation networks is 0.63 percent. In order to provide agricultural producers with the required amount of water on time, systematic work is being carried out to increase the efficiency of irrigation networks on the basis of several state programs. Concreting the channel can be an effective solution to these problems, but the economic costs involved are causing delays in the implementation of the works. When reconstructing irrigation canals, choosing a concreting scheme taking into account the deformation and type of filtration can be a solution to the problem. Under conditions of limited filtration, concreting both sides of canal leads to economic and hydraulic efficiency. However, there is a problem to connect the roughness coefficients of natural soil and concrete in the hydraulic calculation of canals. The article presents result of the research conducted in the 4th section of the Big Fergana Canal, according to the results, n=0.0195 in the two-sided concreted (PK-2010+85) part, and n=0.022 in the earthen part (PK-2020+85). When the channel was modeled in HEC-RAS 5.0.1 based on the hydraulic elements of the channel in PK-2010+85, the roughness coefficient of the canal was n=0.0199.