Slides with tables and figures from lesson 1-4

Dr. W.S. dandeniya

Distribution of water in the world

Oelkers et al., 2011

WSD / UOP

Liu et al., 2009

Water available cont.

Crop water requirement (CWR)

• Accumulated crop evapotranspiration over growth period

• CWR = Etc usually calculated per area m3/ha

• Etc = crop evapotranspiration = Et0 X Kc mm/day

ET0 = Reference crop ET and Kc = Crop coefficient

Water demand for paddy rice

WSD / UOP

Water available via rainfall

WSD / UOP

Blue water demand

WSD / UOP

Global average for rice (m3/t)

Product description

Green Blue Grey

Rice in the husk (paddy)

632 584 109

Rice, husked (Brown)

750 693 130

Rice, semi-milled or milled

761 704 132

Rice flour 801 741 139

WSD / UOP

Green/blue water footprint differs among crops

WSD / UOP

WSD

/ UO

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USA export more blue water than other countries

How about Sri Lanka?

WSD / UOP

WSD / UOP

WSD / UOP

Considerations for hydrological studies

Suggestions to add to new model?

WSD

/ UO

P

Water cycle

Spatial variability in fresh water resource recharge • Annual runoff

• River water

discharge

Taikan Oki, et al. 2006. Science 313, 1068

• A significant level of population lives in highly water stressed areas

WSD / UOP

W

SD /

UO

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