This article provides a paragraph on well irrigation. The amount of water stored in the earth's crust is estimated to be around 8 billion cubic kilometres, half of which is at depths less than 800 metres. This volume of water is about 35 times the combined storage of all the world's rivers, fresh water lakes, reservoirs and inland seas. Ground [...]
After reading this article you will learn about the open wells and tube wells with the help of a diagram. Water wells can be classified either open wells or tube wells. Open wells have relatively large diameter (generally 1 to 5 m) and low yields (generally less than 30 m3/hr), and are not very deep (generally 3 to 15 m). [...]
The subsurface occurrence of ground water can be divided into two zones (Fig. 4.1): (i) Vadose zone or unsaturated zone or zone of aeration, and (ii) Phreatic zone or saturated zone or zone of saturation. In the saturated zone, all pores or voids are filled with water, whereas in the unsaturated zone, pores contain gases (mainly air and water vapours) [...]