Towards design of compound channels with minimum overall cost through grey wolf optimization algorithm

The significant role of open channels in agriculture include supplying drinking water, industry, irrigation and flood control, making these hydraulic structures an integral part of the water conveyance system. Determination of optimum dimensions with minimum construction costs is considered as the primary concern when designing artificial open channels. To achieve this, the compound channels were evaluated with the following constraints, viz. composite roughness, velocity, Froude number and channel stability. Grey Wolf Optimization (GWO) was used to determine the optimal geometry of the channel. Optimization results clearly showed that the variation of roughness coefficient and the increase of factor of safety increased costs of 60 and 20% respectively. The optimum suitable cross-section for the compound channels was obtained by conducting various model scenarios.

Turbulence Scale in Compound Channel

<p>The study of turbulence in a compound channel would address the nature of sedmient transport and bank erosion activity. The study would also give insights of embankment and levee breaches at the time of high flood. Experimental investigations were conducted on two compound channels of 31<sup>0</sup> and 45<sup>0</sup> bank angle in the laboratory flume to study the turbulece scale. Velocity data were recorded with Nortek Velocimeter at seven different locations (3 locations at the upstream, 3 locations at the downstream and 1 location at the middle) of the compound channel. Turbulence scale like Taylor microscale (λ<sub>T</sub>) estimates the length scale of the inertial sub- range. The Taylor scale is calculated as:</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.0042175ca60061700501161/sdaolpUECMynit/12UGE&app=m&a=0&c=2968072e536f82f8e38df248a26aa4a7&ct=x&pn=gepj.elif&d=1" alt="" width="199" height="148"></p><p>The Taylor microscale analysis showed dominance in the main channel for 45<sup>0</sup> bank angle as compared to 31<sup>0</sup> bank angle. In the location of slope midpoint and floodplain region of the compound channel, Taylor microscale was more dominant for 31<sup>0</sup> bank angle. Another important observation in both the compound channels (31<sup>0</sup> and 45<sup>0</sup> bank angle) is the dominance of Taylor microscale at the upstream section of the channel as compared to the downstream part of the channel. The results from the study would help us to get a better understanding of the role of turbulence in the morphological changes in a compound channel with different bank angles.</p>