c$Author: fredfox $
c$Date: 2001-09-27 20:37:46 $
c$Revision: 1.2 $
c$Source: /weru/cvs/weps/weps.src/hydro/satvappres.for,v $
      real*4 function satvappres( airtemp )

c     returns the saturated vapor pressure for water (kPa)
c     Approximation from Jensen ASCE manual 70 evapotranspiration
c     valid in normal climatic condition range

c*** Argument declarations ***
      real*4 airtemp, c1, c2, c3
c     airtemp    - the temperature of the air (C)
c     c1, c2, c3 -  coefficients for saturated equation
      parameter (c1 = 0.611)
      parameter (c2 = 17.27)
      parameter (c3 = 237.3)

      satvappres = c1 * exp( c2 * airtemp/( airtemp + c3 ) )

      return
      end