Types of Wells | Geology Optional Notes for UPSC PDF Download

Dug Well

• Hacking at the ground with a pick and shovel is a method used to create dug wells. These wells are suitable when the ground is soft, and the water table is close to the surface.
• In the past, people excavated dug wells manually using a shovel until the water level inside the well surpassed the rate at which the digger could bail out the water.
• Dug wells were typically reinforced with materials like stones, bricks, tiles, or other substances to prevent the well from collapsing.
• To protect the well from external elements and ensure safety, a covering made of wood, stone, or concrete was placed over the top.
• Dug wells have a limitation in depth as they cannot be dug much deeper than the water table level.

Driven Wells

• Description: Driven wells remain a prevalent method in contemporary times. These wells are constructed by forcefully inserting a narrow pipe into soft ground, typically sand or gravel.
• Components: A crucial component of a driven well setup is a screen fixed at the pipe's base. This screen serves the purpose of filtering out unwanted materials like sand and other particles, ensuring the purity of the extracted water.
• Functionality: The primary function of the screen in a driven well is to prevent the entry of debris and sediments into the pipe, thus maintaining the quality of the water source.
• Common Usage: One can commonly find driven wells in areas where the soil composition is suitable, such as regions with sandy or gravelly terrain. These wells are efficient in such contexts due to their construction method and filtering mechanism.

Drilled Wells

• Modern wells typically utilize drilling methods, involving the use of complex and costly drill rigs mounted on large trucks.
• Various types of drill bits are employed, including rotary bits for cutting rock, percussion bits for smashing rock, and auger bits for softer ground.
• Drilled wells can reach depths exceeding 1,000 feet, allowing access to water sources deep underground.
• In many cases, a pump is installed within the well at a certain depth to facilitate the upward movement of water to the surface.