The major types of variable displacement pumps are as follows: 1. Centrifugal Pumps 2. Jet Pumps 3. Air-Lift Pumps. Type # 1. Centrifugal Pumps: Centrifugal pumps are the most popular types of variable displacement pumps. They are capable of delivering large volumes of water against high as well as low heads with good efficiency. Besides, these pumps are relatively simple [...]
One of the following two methods is generally used for the estimation of irrigation requirement: 1. Method Based on 'Duty of Water': In this method, the designer has to first decide the duty of water for different crops in the command area of the system. Duty of water (or simply duty) for a given crop is defined as the area [...]
Any given volume, V of soil (Fig. 3.1) consists of: (i) Volume of solids Vs (ii) Volume of liquid (water) Vw, and (iii) Volume of gas (air) Va The porosity n, the volumetric moisture content w and the saturation s are defined as N = Vv/V Obviously, w = s.n. Further, if the weight of water in a wet soil [...]