This document discusses hydroelectric power plants. It covers the basic terms, types and classifications of hydroelectric plants based on factors like head, flow, capacity, and fall. The classifications include low head scheme, high head plant, concentrated fall plant, divided fall plant, microhydel plant, medium capacity plant, high capacity plant, and super plants. The general arrangement of a hydro power project depends on available head, flow, topography, power house location, power potential, industrial power needs, and economic factors. Surge tanks and draft tubes are also principal components discussed.