According to given condition
a) This is due to the over use of water that depletes the ground water.
b) Cities and towns have vast areas and asphalted roads where soils are concreted. Accordingly, the rainwater cannot percolate to boost groundwater. So, the underground water level further decreases. Villages or other similar places have larger areas of open soil surface. At that place, minimum asphalted roads and concrete surfaces are available. So, larger soil surface area is available for water or rain to percolate into the soil so easily and refill the underground water. As a result, even shallow bore wells drain water.