This document discusses various topics related to water resources including fresh water, sources of fresh water, groundwater usage, floods, droughts, conflicts over water, and dams. It notes that fresh water supply is decreasing while demand is increasing. Surface water comes from rivers, lakes, and wetlands, and is replenished by precipitation, while groundwater resides underground in aquifers and provides over 20% of water usage. Floods occur when rivers exceed their capacity and can have devastating human and economic impacts. Drought is caused by reduced rainfall and affects agriculture, wildlife, and communities. Water conflicts have occurred and will continue between nations that share river systems. Dams have played an important role in water storage and irrigation worldwide.

1. WATER
RESOURCES
J.Dhanushiya
II BSc. Chemistry

2. Introduction:
• Water resources are sources of water that are useful or
potentially useful.
• Uses of water include agricultural, industrial, household,
recreational and environmental activities.
• Virtually all of theses human uses require fresh water.

4. Fresh Water
• Fresh water is a renewable resource,
yet the world’s supply of clean, fresh
water is steadily decreasing.
• Water demand already exceeds
supply in many parts of the world
and as the world population
continues to rise, so too does the
water demand.

6. Sources of Fresh Water
• Surface Water is water in a river, lake or fresh water wetland.
• Surface Water is naturally replenished by precipitation.
• It is naturally lost through discharge to the oceans, evaporations, and sub-surface
seepage.

7. Sub-Surface Water or Groundwater
• One of our most valuable resources is the water beneath our feet.
• Groundwater is fresh water located in the pore space of soil and rocks.
• It is also water that is flowing within aquifers below the water table.
• Sometimes it is useful to make a distinction between sub-surface water that is
closely associated with surface water and deep sub-surface water in an aquifer
(sometimes called “fossil water”).

11. How much do we depend on groundwater?
• According to United States Geological Survey (USGS) figures,
groundwater provides an estimated:
• 22% of all freshwater withdrawals
• 37% of agricultural use (mostly for irrigation)
• 37% of the public water supply withdrawals
• 51% of all drinking water for the total population
• 99% of drinking water for the rural population

12. FLOODS
Floods are Natural Phenomenal
Floods are Water Related Disaster
A flood occurs when the Geomorphic Equilibrium in the river
system is disturbed because of intrinsic or extrinsic factors or
when a system crosses the geomorphic threshold.
a) Flooding in a river due to aggradation of river bed
(intrinsic threshold).
b) Flooding in a river due to heavy rainfall (extrinsic threshold).

13. Types Of Floods
*Flash floods
*River floods
*Coastal floods
*Urban flood
According to their duration flood can be divided into different
categories:
1. Slow-Onset Floods: Slow Onset Floods usually last for a
relatively longer period, it may last for one or more peeks, or
even months.
2. Rapid-Onset Floods: Rapid Onset Floods last for a relatively
shorter period, they usually last for one or two days only.
3. Flash Floods: Flash Floods may occur within minutes or a few
hours after heavy rainfall, tropical storm, failure of dams or
levees or releases of ice dams. And it causes the greatest
damages to society.

14. FLOODS IMPACTS
• Human Loss
• Property Loss
• Affects the Major Roads
• Disruption of Air / Train / Bus
Services
• Spread of Water-borne
Communicable Diseases
• Communication Breakdown
• Electricity Supply Cut off
• Economic and Social Disruption
• Increase in Air / Water Pollution

15. Drought
• Rains are very unpredictable. This leads to periods where there is serious scarcity of
water.
• Drought prone areas are faced with irregular periods of famine as farmers have no
income.
• Drought prone areas Development Programs:
• Under this scheme, People are given wages in bad years for activities like building
roads, minor irrigation works and plantation programs.
• It is a major problem in arid and semi arid regions.
• Drought affects home, agriculture, industry, leads to malnutrition problems in
children due to food shortages.

16. • Major factor responsible for drought is
deforestation.
• Due to denuded forest cover the
rainwater rushes down the river and is
lost.
• Forest cover permits the water to remain
in the same area and gradually seep into
the ground.
• This charges the underground stores of
water in natural aquifers. Which later
can be use during the period of no
monsoons.

17. CAUSES OF DROUGHT
Natural / Physical causes:
• Weather: Increased amount of anticyclone
weather (hot + dry) means air holds less
moisture so you get less rain.
• Global warming: Weather patterns
change (e.g. Sahel is becoming hotter +
drier).
• Hotter weather = more evaporation than
precipitation.
• EI Nino: random weather event that
reverses normal weather patterns (e.g.
Australia has years of drought + then
ears of flood)
Human causes:
• Overpopulation: too many people living in
an area using too much water.
• Overcultivation: planting too many crops
which use up too much water.
• Overextraction: removing too much water
from wells so they dry up.
• Deforestation: cutting down trees which
otherwise store water + hold soil together.
• Politics: fighting over water, or companies
being greedy + taking too much water to
then sell on.

18. Conflicts over water:
• Multiple conflicts between countries.
• Around 20 major cities in India face chronic or interrupted water shortages.
• Around 100 countries all around the world share the waters of 13 large rivers and
lakes.
• The upstream countries could stare the downstream countries leading to political
instability. E.g. Ethiopia (Upstream) and Egypt (Downstream) are highly dependent
on the river Nile for their water supply.
• International accords the look at fair distribution of water will become critical to the
world peace.
• India and Bangladesh already have a pact for fair usage of water of Ganges River.

19. DAMS-Introduction
• There are more than 45000 all dams all
around the world which play an
important role in communities and
economics that harness these water
resources for economic development.
• 30-40% of the irrigated land worldwide
relies on dams.

22. THANK YOU