Water is essential for life but only 1% of the world's water is usable, with most being saltwater in the oceans. The hydrological cycle describes how water is recycled and redistributed through evaporation from oceans and precipitation over land, though only rain provides readily accessible surface and groundwater resources that humans and ecosystems rely on. Proper management of limited freshwater supplies is important given that lack of access to water could cause death more quickly than lack of food.

1. Water Resources
Chapter-17
By Jayanarayan Jayakumar

2. Water its Importance
• Our Earth seems to be unique among the other
known celestial bodies. It has water, which covers
three-fourths of its surface and constitutes 60-70
wt % of the living world. Water regenerates and
is redistributed through evaporation, making it
seem endlessly renewable. So why worry?

3. Why?
• Actually, only 1% of the world's
water is usable to us. About 97% is
salty sea water, and 2% is frozen
in glaciers and polar ice caps. Thus
that 1% of the world's water
supply is a precious commodity
necessary for our survival.
Dehydration (lack of water) will
kill us faster than starvation
(lack of food). Since the plants and
animals we eat also depend on
water, lack of it could cause both

4. Hydrological Cycle

5. Hydrological Cycle

6. Hydrological cycle
• The water cycle, also known as
the
hydrologic cycle or H2O
cycle, describes the continuous
movement of water on, above
and below the surface of the

7. Precipitation
• Precipitation is the primary source ofwater.
• Forms are : SOLID , LIQUID, GASIOUS .
• Rain is the most useful form of precipitation.
• The water sources are divided into:
• Surface Water – river,lake,streams,ponds,etc.
• Ground water- Wells and tube wells.