What is a sinkhole? How does it form? How do sinkholes relate to caves? What will be an ideal ...

(Answer to question 1 )  A sinkhole is a depression on the Earth's surface caused by the collapse of surface rock and regolith into a large underground cavity. It forms when ground water dissolves the rock, and the unstable roof collapses. It is most common in limestone and evaporites.

(Answer to question 2 )  Recharge is the addition of water to the saturated zone. Natural recharge occurs when surface water infiltrates the unsaturated zone to reach the saturated zone. Injection of treated wastewater returns water artificially.

(Answer to question 3 )  Ground water velocities at the 150 wells in Cape Cod were different and ranged from 0.33 to 0.51 m/ day. The concentration was also very diluted indicating the tracer spread out into a much greater volume of water. This is likely due to water flowing around grains, thus slowing its velocity and spreading the flow out.

(Answer to question 4 )  Potential energy and pressure energy drives ground-water flow. Gravity moves water downward, with potential energy driving the motion. Pressure exerted by the thickness of water also drives motion, either horizontally or vertically. Water flows through permeable and porous materials, from high energy to low energy. It flows in a curved path. Ground water can flow upward due to the pressure energy.

(Answer to question 5 )  An artesian well is a well or spring in which water rises above the elevation of the aquifer due to high pressure at the bottom of the well. These often occur in a confined aquifer recharged at high elevation. The water is flowing horizontally and when a well is drilled, rises up as a function of the elevation of the recharge area and the distance between the recharge area and the discharge point.