Hydrology deals with water resources and their depletion and replenishment. It involves key components of the water cycle like precipitation, evaporation, evapotranspiration, surface water, and groundwater. The water cycle begins with precipitation falling to the surface and infiltrating subsurface soils and rock. Water can remain in shallow soils, seep into stream banks, or infiltrate deeper to recharge aquifers. It may travel long distances underground or remain in storage as groundwater. Water is also evaporated from surfaces and transpired by plants, returning to the atmosphere as vapor to form clouds and precipitation.

1. Hydrology
It deals with the
depletion and
replenishment of our
water resources.

2. 1. CYCLE COMPONENT CONCEPTS
Standard Concepts (Physical)
 Precipitation
 Evaporation/Evapotranspitation
 Surface Water
 Groundwater
2

3. Basic Cycle
Precipitation
Evaporation
Evaporation
Evaporation (ET)
Ocean
Infiltration
runoff
Aquifer
Precipitation
Evaporation/ET
Surface Water
Groundwater
3

5. Basic Cycle
5

6. Rain
Transpiration
Evapo-transpiration
Irrigation
Evaporation
Runoff
Root Zone
Water Storage
Below Root Drainage
Zone

7. Groundwater begins as
INFILTRATION
Precipitation falls and
infiltrates into the
subsurface soil and
rock.
•Can remain in shallow soil layer
•Might seep into a stream bank
•May infiltrate deeper, recharging an aquifer
•May travel long distances
•May stay in storage as ground water

8. EVAPORATION

9. DURING EVAPORATION
 Water turns from a liquid to a gas.
 Water moves from rivers and lakes
into the atmosphere in the form of
water vapor.
 Water vapor forms clouds.

10. SOLID TO A LIQUID

11. LIQUID TO A GAS

12. METHODS FOR MEASUREMENT OF
EVAPORATION
 Pan measurement method,
 Using Empirical formulae,
 Storage equation method, and
 Energy budget method.

13. PAN METHOD
Class A Pan
Standard at advanced
weather stations
Can be used to estimate
open water evaporation

14. USE OF EMPIIRICAL FORMULAE:
 (a) Meyer’s formula:
E=km(es - ea)(1 + v9/16)
(b) Rohwer’s formula:
E= 0.771(1.465 - 0.000732pa)
(0.44+0.0733 v0.6) (es – ea)

15. PRECIPITATION
 Single strongest variable driving hydrologic
processes
 Formed by water vapor in the atmosphere
 As air cools its ability to ‘hold’ water
decreases and some turns to liquid or ice
(snow)

16. Causes of Precipitation

18. TRANSPIRATION

19. Evapotranspiration (ET) is the term used to
describe the amount of water which is effectively
lost from the earth surface to the atmosphere by
soil surface evaporation and plant transpiration.
ET is mainly:
-an important component of the water cycle
-necessary for calculation of the soil water
balance,
-input variable in crop yield models or study
of ecosystem or study of
regional climate, among others.

20. Hill slope Hydrology
Runoff Processes:
Horton overland flow
Subsurface stormflow,
Water Flow
Return flow
Groundwater flow

21. Macropore flow,
Tennessee Valley,
California

22. THANK YOU
- Pankti Jethi
(HJD Institute of Technical Education And
Reserch)