Question

Surface wells may by unlined and​

Answer 1

Explanation:

Water well is a hole or shaft, usually vertical, excavated into the earth for bringing groundwater to the surface (Todd, 1980). Wells also serve other purposes such as for observation/exploration, artificial recharge and disposal of wastewaters (very restricted these days due to environmental concern). Wells of horizontal extent (known as ‘horizontal wells’) are sometimes constructed because of special groundwater situations. Horizontal wells are advantageous in the situation where groundwater is to be derived primarily from infiltration of streamflow (e.g., collector wells) or in the situations where aquifers are thin, poorly permeable or underlain by permafrost or saline water (e.g., infiltration galleries, and small-diameter perforated pipes drilled into hillsides). Interested readers are referred to Todd (1980), Raghunath (2007), Michael et al. (2008) and Sarma (2009) for the details about different types of horizontal wells.

Answer 2

Lined wells

They are of two types only mainly :-

=> Unlined

=> Lined