Hydro-Electricity Survey of India Volume II Second Report on the Water Power Resources of India Ascertained during the Season 1919-1920

the direction of the Survey was in the hands of Mr.-1Vteares who prepared the Preliminary Report and made the arrangements for the -work of the cold weather of 1919-29. [...] The gross head in high and medium falls is the vertical difference in height between the point of application to the wheel and the water-level at the pile intake ; while for low head the difference between the level of the head an tail waters must be taken. [...] On high and medium head8.—Generally speaking in the case of high and medium-head plants a low diversion dam is all that is neceeery sufficient to ensure the possibility of getting the water into the channel or pipe under normal conditions and also to' protect the stiealh at this point from scouring out the channel and endangering the supply in times of flood. [...] "In order to prevent the channel being overfilled at the headworks a method often used is to place a diverting place in the fairway at a point near the headworks such that any flow beyond the capacity of the channel is skimmed of and discharged "hapk to the stream. [...] s(This of pourse assumes that the width of the sill is greatly in excess of the with of the channel.) The spillway' and scour valves rq the reservoir should be near this point where most of the mud will collect.