Lecture (1)Irrigation and Drainage Engineering

Hydrologic Cycle:

P = PrecipitationE = EvaporationT = TranspirationET = EvapotranspirationGW= GroundwaterI = Infiltration

P

Clouds Clouds

E

UnsaturatedEI I I

R

PT

TT

E E

ET

Water Table

Ground water (GW)Saturated

R

P

R

ET

GW

Moisture

Water Cycle for the Earth :

Land 30 % Oceans = 70 %Land ET

P 72 cm/yr. 41 cmrunoff to oceans 31 cm

Oceans 112 cm/yr +

* Lakes and rivers 270 x 1012 m3/yr Egypt share 55 x 109 0.02% of the world fresh water

≅≅

↑=× (E) cm 125 0.70.3 31

≅

Irrigation : It is an artificial mean of water application to soil to ensureenough moisture essential for plant life

Drainage: It is an artificial mean of removal of excess groundwater from the root zone

Water Budget:

P + RI + GI = ET + Ro + Go.+ΔSm + ΔSg

P = ET + ΔR + ΔG + ΔSm + ΔSg

IR oR

gS

mS

ET ET P

IGoG

P

River

Rainfed Versus Irrigated Agriculture:

Regions P (mm/yr) Irrigation DrainageHumid 1500-2000 Forrests ------Semi-Humid 1000-1500 Rainfed May beSemi-Arid 500-1000 Supplementary May beArid 250-500 Irrigation May beDesert Less than 250 Irrigation May be

Cultivated Versus Irrigated Areas:Country Cultivated Area (106 fed.) Irrigated %Egypt 8.1 7.8 96China 275.0 13.0 47France 77.0 6.0 8Japan 14.5 8.0 55USA 300.0 30.0 10

Total Irrigation area in the world 500 x 106 feddans≅

Irrigation Process

WaterSystem

IrrigationApplication

Delivery Field

Method

Irrigation

Quality Canals SourceTraditionalSurface WaterGround Water

Non-TraditionalAgr. Drainage Reuse

Treated Wastewater ReuseDesalinizationFog CollectionCloud Seeding

• Fresh• Saline

Irrigation Str.Pump Stations

DripSurface Sprinkle Amount (Depth)Frequency

(Soil Inf. Rate and ET)