The important methods that are available for drilling tubewells are as follows: 1. Percussion Drilling (Also Known as Cable Tool Method), further classified as: (i) Hand boring by rope or rod, and (ii) Mechanical boring with power rigs. 2. Rotary Drilling, further classified as: (i) Direct circulation hydraulic rotary, (ii) Reverse circulation hydraulic rotary, and (iii) Rotary-air percussion drilling. 3. [...]
The yield of an open well can be found by the following two practical methods or yield tests: 1. Constant Level Pumping Test 2. Recuperation Test. 1. Constant Level Pumping Test: In this test water is pumped from the open well so that the water level in the well is depressed by an amount h known as depression head (or [...]
In this article we will discuss about how to construct tube wells. Construction of Shallow Tube Wells: Shallow tube wells are constructed by boring, driving and jetting. The wells constructed by these methods are designated as bored wells, driven wells and jetted wells. These methods are briefly described below: (i) Bored Wells: Where, water table exists at a shallow depth [...]
Before pumping, the water level in the well stands up to the same elevation as the water table or piezometric surface depending on the type of aquifer. When pumping starts, the water is removed from the aquifer surrounding the well, and in and around; the well the water table or piezometric surface is lowered and assumes the shape of an [...]
A water well is a hole or shaft, usually vertical, excavated in the ground for bringing groundwater to the surface. Water wells may be classified as: 1. Open Wells or Dug Wells: Open wells are the wells which have comparatively large diameters but low yields (or discharges) and are not very deep. The diameters of the open wells usually vary [...]
The underground (or subsurface) sources of water are of the following four forms: 1. Infiltration Galleries 2. Infiltration Wells 3. Collector Wells or Radial Wells 4. Springs. From each of the first three forms relatively small quantity of groundwater is obtained and hence these may be considered as the minor forms of the underground sources of water. On the other [...]
Before pumping, the water level in the well stands up to the same elevation as the water table or piezometric surface depending on the type of aquifer. When pumping starts, the water is removed from the aquifer surrounding the well, and in and around; the well the water table or piezometric surface is lowered and assumes the shape of an [...]
The velocity of underground water can be determined by the following formulae: (A) Slichter's Formula: where v = velocity of ground water flow in m/day k' = a constant, whose value is approx. 400 S = slope of the hydraulic gradient line D10= effective size of the particles in the aquifer µ = dynamic viscosity of water depending on the [...]
In this article we will discuss about the artesian wells and calculation of its yield. Artesian Wells: This is the name derived for the well from which water flows automatically under pressure. The water from these wells flows out in form of foundation to a height of 2.5 metres depending on the hydrostatic pressure. In some artesian-wells water flows continuously [...]
In this article we will discuss about the construction of infiltration well with the help of a suitable diagram. Infiltration wells are shallow wells constructed under the beds or rivers and nallas. These wells are very suitable for Indian conditions where there are deposits of sand and porous material at least 3 m deep in river beds. In the sandy [...]