Hydrology is the science of water which deals with the spatial and temporal characteristics of the earth's water. In other words, hydrology is the study of water in all its phases, including the occurrence, movement, distribution, circulation, storage, exploration, development and management. The atmospheric air always contains moisture. Under favourable conditions, this moisture gets condensed and water drops are formed. [...]
Over a large area like watershed (or catchment) of a stream, there will be several such stations, and the average depth of rainfall over the entire area can be estimated by one of the following methods: 1. Arithmetic Mean Method: This is the simplest method in which average depth of rainfall is obtained by obtaining the sum of the depths [...]
Most commonly used methods for stream gauging are: 1. Area-Velocity Method 2. Area Slope Method 3. Discharge Measuring Structures. 1. Area-Velocity Method: It should be noted that depth of flow varies in a section of a stream across the main flow direction. Likewise, the velocity of flow too varies from point to point within a cross-sectional area of the stream. [...]