Water Conservation and Management

The hydrological cycle requires evaporation (liquid to gas) and condensation/precipitation (gas to liquid). Water vapor movement in the atmosphere completes the cycle by transporting evaporated water from oceans to land where it precipitates. River tides, sea flow, and groundwater movement are secondary processes, not essential cycle components.

This is the right answer.  Drainage system is meant to take away excess water,  which is not of our use. Generally we drain dirty water in drainage system.

Groundwater is water located beneath the earth's surface and this water can be use to serve multiple purposes such as water plants, domestic use, etc.

Most of the hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. The power extracted from the water depends on the volume and on the difference in heights of the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head.

Dam is a barrier constructed to hold back water and raise its level, the resulting reservoir being used in the generation of electricity.

Study of water is hydrology. Meteorology is the study of atmosphere, geology is the study of solid earth and pedology is the study of soil. 

A hydropower plant helps in irrigation and in controlling floods.

The water cycle, also known as the hydrologic cycle or the H₂O cycle, describes the continuous movement of water on, above and below the surface of Earth. The water moves from one reservoir to another, such as from river to ocean or from ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, runoff and subsurface flow.

Khadin, also called dhora, is a construction designed to harvest surface runoff water for agriculture. It was first designed in western Rajasthan in the 15^th century.

It does not provide breeding ground for mosquitoes as this water is below ground and not available to mosquitoes for breeding.

Plants need water. If there is no water, all plants will die as water helps them to grow, to prepare food etc.

 Major source of groundwater replenishment is by rain.

In-stream water use refers to water utilized without being removed from its source. Hydroelectric power generation is a major in-stream use because water flows through turbines while remaining in the river. Irrigation, domestic use, and waste treatment consume or remove water from streams.

Same amount of rain water does not fall in different places at same time. The rainfall totally depends on the weather conditions and all places do not have same type of weather at same time.