The document provides an introduction to hydrology, detailing its significance in understanding the movement, distribution, and quality of water, as well as its applications in engineering including water resource management, flood control, and urban drainage. It explains the hydrological cycle, its foundational role in Earth's climate, and the global distribution of water resources, emphasizing the importance of groundwater. Additionally, it discusses how human activities impact the water cycle, highlighting challenges faced by regions with limited freshwater resources.

1. CHAPTER I
INTRODUCTION TO HYDROLOGY

2. HYDROLOGY
It is the science of occurrence, movement and distribution of water
above/below the land surface or in the atmosphere.

3. Scope of Hydrology
 For knowing the sources of water in an area.
 For knowing quality and quantity of water in an area.
 For distribution of river water for full filling of different
 area`s forming needs.
 Tremendous importance is given to the hydrology all over
 the world in the development and management of water
 resources for irrigation, water supply, flood control,
waterlogging
 and salinity control, Hydro power and navigation.
 The maximum probable flood that may occur at a given site
 and its frequency; this is required for the safe design of
 drains and culverts, dams and reservoirs, channels and other
 flood control structures.

4. Application of hydrology in Engineering areas
• Hydrology is used to find out maximum probable
flood at
• proposed sites e.g. Dams.
• The variation of water production from catchments
can be
calculated and described by hydrology.
• Engineering hydrology enables us to find out the
relationship between a catchment's surface water and
groundwater resources.
• Hydrological investigation helps us to know the
required reservoir capacity to assure adequate water
for irrigation or municipal water supply in droughts
condition.
• Used in connection with design and operations of
hydraulic structure

5. Application of hydrology in Engineering areas
• Hydrology is an essential tool in planning and building hydraulic
structures.
• Hydrology is used for city water supply design which is based on
catchments area, amount of rainfall, dry period, storage capacity.
• Dam construction, reservoir capacity, spillway capacity, sizes of
water supply pipelines all are designed on basis of hydrological
equations.
• Determining the water balance of a region.
• Mitigation and predicting floods, landslides and drought risk.
• Flood forecasting and flood warnings.
Designing dams for water supply or hydroelectric power generation.
• Designing bridges.
• Designing sewers and urban drainage system.

6. Application of hydrology in Engineering areas
Predicting geomorphologic changes, such as, erosion or
sedimentation.
• Assessing the impact of natural and anthropogenic environmental
change.
• It tells us what hydrologic hardware (e.g. rain gauges, stream gauges
etc) and software (computer models) are needed for real-time flood
forecasting.

7. Hydrologic cycle
All the rivers run into the sea; yet the sea is not full;
unto the places from whence the rivers come, thither
they return again.’
The Bible, Ecclesiastes, 1:7

8. Hydrologic cycle
• Where the world’s water supply is stored
• The pathways of moisture in the hydrologic cycle
• The fate of precipitation on the land
• Water covers 75% of the Earth's surface.

9. Hydrological Cycle
• At any given time, the atmosphere holds, on
average, sufficient moisture to give every
place on the Earth 2.5 cm of rain.
• There is a constant recycling of water
between the oceans, atmosphere and land
– achieved through the hydrological cycle.

10. Hydrological Cycle
is fundamental to the functioning of
the Earth as it recycles water, and
has a role in modifying and
regulating the Earth's climate.

11. Facts and figures
Nearly 98% of the Earth's water is in the
oceans.
Fresh water makes up less than 3% of water on
earth, over two thirds of this is tied up in polar
ice caps and glaciers.
Fresh water lakes and rivers make up only
0.009% of water on Earth and ground water
makes up 0.28%.

13. Facts and figures
• Water is essential for all life forms.
• For example it makes up 60 to 70% by weight of all living
organisms and is essential for photosynthesis.
• The viability of all life on Earth is determined chiefly by the
presence of water, which is not evenly distributed on the
planet.
• If it were, it would cover the entire surface to a depth of 3 km.

14. Hydrological cycle (water cycle)
• It is a closed system in which water is continuously moved
from the world's oceans, through the atmosphere, falls to
earth as rain, then travels back to the ocean in an endless
loop.
• It operates using a series of flows (or transfers) and
stores
• Water flows or is transferred through the system in
many ways. One way is via rivers, another way is
through the soil. The movement of water through the
soil is called throughflow.
• Water is stored in a number of ways - for example,
in lakes or as groundwater in deep aquifers

17. The Hydrologic Cycle
Solar Energy is the driving force behind the
hydrologic cycle
Gravity helps keep water moving.

18. Pathways of Moisture in the
Hydrologic Cycle
– All the world’s water comes from the
oceans and returns there via:-
– Evaporation
– Condensation
– Precipitation
– Evaporation
– Transpiration
– Surface water runoff
– Groundwater flow

20. Groundwater represents over 90% of the
world's readily available freshwater
resource.
About 1.5 billion people depend upon
groundwater for their drinking water supply
The amount of groundwater withdrawn
annually is roughly estimated at ~600-700
km3, representing about 20% of global
water withdrawals.

23. Many countries in Africa, the Middle East,
Western Asia, and some Eastern European
countries have lower than average
quantities of freshwater resources available
to their populations.

24. Scientists say the
notoriously dry
continent of Africa is
sitting on a vast
reservoir of
groundwater.
They argue that the
total volume of water
in aquifers
underground is 100
times the amount
found on the surface
'Huge' water
resource exists
under Africa
http://www.bbc.co.uk/news/scien
ce-environment-17775211

25. Human activities that alter the
water cycle include:
• agriculture
• industry
• alteration of the chemical composition of the
atmosphere
• construction of dams
• deforestation and afforestation
• removal of groundwater from wells/boreholes
• water abstraction from rivers
• urbanisation