Evapotranspiration

Review Of Current Chapter

25” of PET annually (approx. 83% of annual ppt)

35” of Evaporation annually (UM value)

Growing Season: Operating deficit of 8.9” (2.7” PET + 6.2” EC)

TREND ANALYSIS

EVAPOTRANSPIRATION

Excess has decreased over the past decade

Thornthwaite

y = -0.5259x + 9.0047

-2

0

2

4

6

8

10

12

14

16

18

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Year

Exc

ess

Pre

cip

(in

)

Yearly Thornthwaite Excess Period of Record AvgLinear (Yearly Thornthwaite Excess)

TREND ANALYSIS

EVAPORATION

Evaporation excess has decreased over the past decade

Evaporation Coefficient

y = -0.5259x - 1.2353

-12

-10

-8

-6

-4

-2

0

2

4

6

8

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Year

Exc

ess

Pre

cip

(in

)

Yearly Excess Period of Record Avg Linear (Yearly Excess)

Implications

Coefficients for the District are “published” values but should be monitored

Excess precipitation is dependent on volume of precipitation received

Expectations

Less Excess Precipitation = Less Natural Recharge

Less Excess Precipitation= Losing Lakes and Wetlands

Questions?

Thank You

Coon Creek Watershed District