Chapter 1.pptx:INTRODUCTION TO 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.
is fundamental to the functioning of the Earth as it recycles water, and has a role in modifying and regulating the Earth's climate.

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 o f 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%.

12. 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.

13. 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

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

15. 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

16. 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 km 3 , representing about 20% of global water withdrawals.

17. 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.

18. 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/science-environment-17775211

19. 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