Irrigation & Hydrology (General Engineering) (SSC JE)

Catchment area– The area of land draining into a stream or a water course at a given location is known as the catchment area. It is also called drainage area or drainage basin. In the USA, it is known as watershed.
• The areal extent of the catchment is obtained by tracing the ridge on a topographic map to delineate the catchment and measuring the area by a planimeter.

Rain gauge–
• The type of rain-gauge commonly used in India for measuring rainfall is given by symon's rain gauge.
• The commonly used rain gauge is float type.

Natural syphon type–
• Natural syphon type is adopted at the standard recording type rain gauge in India. It is also known as float type gauge.

Osmosis–In plants, water enters the root cells by osmosis and moves into tubes called xylem vessels to be transported to the leaves, water molecules inside the xylem cells are strongly attracted to each other because of hydrogen bonding (It is called cohesion).

An artesian aquifer is the one where water is under pressure between two impervious strata.

Trap efficiency of a reservoir is the percent of inflowing sediment which is retained in reservoir. The trap efficiency is a function of the ratio of reservoir capacity to the total inflow, i.e.
Factor affecting trap efficiency–
• Size of reservoir and stream.
• Velocity of flow of stream.