Design of Dam Spillway Cum Downstream Wave Basin Physical Model for Kalpasar Project—A Case Study

Government of Gujarat has major proposal of development a multipurpose project, Kalpasar in the Gulf of Khambat. This project consists of constructing a 30 km long dam and concrete spillway of about 2.3 km length with 105 numbers of gates. After completion of this project, it is estimated that about 10,000 mm3 of fresh water could be made available to the Saurashtra Peninsula; along with this other benefits were perceived related to use of the dam to support a transportation link between Surat and Bhavnagar districts, to fisheries development etc. Since year 1995 various feasibility and other studies had been carried out for the project by various research and academic institutes. Various studies are also under progress at CWPRS for the development of Kalpasar project; one of them is hydraulic physical model study to finalize the design of spillway by simulating discharge over spillway along with the effects of sea waves on the downstream of the dam. This dam spillway cum wave basin is a captive model housed in hanger of size 60 m × 40 m and developed to the scale of 1:55 G.S. (geometrically similar). In this model at one end spillway with about 90numbers of gates and on downstream of spillway at a distance of 31.79 m (about 1750 m in prototype), a unidirectional random sea wave generator having wave flap of length 33 m controlled by SCADA is proposed. On this model, it is proposed to test discharging capacity of spillway with full and partial operation of gates along with performance of energy dissipater for various tidal levels with superimposition of waves, water surface profiles for entire range of discharges, pressures over spillway surface under the influence of waves and tides for entire range of discharges. This paper presents the glimpses of the hydraulic design of dam spillway cum downstream wave basin physical model for Kalpasar.