Hydrology

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

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1. CYCLE COMPONENT CONCEPTS

Standard Concepts (Physical)

Precipitation Evaporation/Evapotranspitation Surface Water Groundwater

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Basic Cycle

Ocean

EvaporationEvaporation (ET)

runoff

Precipitation

Aquifer

Infiltration

Evaporation

PrecipitationEvaporation/

ETSurface WaterGroundwater

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Basic Cycle

Evapo-transpiration

Transpiration

Evaporation

Rain

Runoff

Drainage

Root ZoneWater Storage

Irrigation

Below RootZone

Groundwater begins asINFILTRATION

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

EVAPORATION

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.

SOLID TO A LIQUID

LIQUID TO A GAS

METHODS FOR MEASUREMENT OF EVAPORATION

Pan measurement method, Using Empirical formulae, Storage equation method, and Energy budget method.

PAN METHOD

Class A PanStandard at advanced weather stations

Can be used to estimate open water evaporation

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)

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)

Causes of Precipitation

TRANSPIRATION

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.

Water F

low

Hill slope Hydrology

Runoff Processes:Horton overland flowSubsurface stormflow,Return flowGroundwater flow

Macropore flow,Tennessee Valley,California

THANK YOU

- Pankti Jethi

(HJD Institute of Technical Education And Reserch)