Keywords: river channel, flood, flood risk zone, flood control hydraulic engineering measures, flood runoff, functional cost analysis, profitability investment index

// Мелиорация.– 2020. – №4(94) – P 41–48

The article outlines the methodological principles for choosing options and parameters of hydro technical measures to protect river channels and valleys from floods. The options for hydro technical measures are proposed to be assessed on the basis of a functional-cost analysis according to the measure of the effectiveness of measures, which is defined as the ratio of the achieved functional effect of measures to the value of costs (investments) for their implementation. At the stage of making design decisions, the functional effect of hydraulic engineering measures to increase the throughput of river channels is assessed. The substantiation of the choice and calculation of parameters of three variants of hydro technical measures, increasing the flow rate of flood runoff from the flood risk zone, is given: strengthening of river beds; straightening of river beds; construction of coastal dams. At the stage of making managerial decisions, the functional effect of hydraulic engineering measures is assessed by the amount of prevented damage in the flood risk zone, and the indicator of the effectiveness of hydraulic engineering measures is the profitability index on investment.