Table 'h.'-Vatev budget aomponents for an average water-year on the CCW at different stages of succession 



■ 



Vegetation^ : 

 status : 



Streamf low 



Streamf low 

 +ASM 



Runoff2 



nnc 3 



; QF 





AGWL 



SEEP 



:TRAN 



RINT 



C T \"T" 







Inches 



Inches 



Percent 











— - — = 



















98-1-1 



21 



3 



23 



3 



49 



6 



7 1 

 J) . O 



15 . 





I . U 



1 





9 



9 



5 









. 



1 . 7 



90-9-1 



21 



3 



22 



9 



48 



7 



3 . I 



15 . 



8 



1 . 6 



1 . 8 



5 



9 



9 



9 





\ 



. 1 



1 . 7 



80-19-1 



20 



9 



22 



5 



47 



9 



3 . 



15 . 



f, 



1 . 6 



1 . 7 





9 



10 



3 



] 



\ 



. 1 



1 . 6 



70-29-1 



20 



6 



21 



9 



46 



6 



2 . 8 



1 5 . 



4 



1 . 3 



1 . 9 





^ 



1 1 



1 



1 



1 



. 1 



1 . 6 



60-39-1 



20 



3 



21 



4 



45 



5 



2 . 7 



1 5 . 



3 



1 . 1 



1 . 8 



5 



5 



\ \ 



7 



J 



2 



. 2 



1 . 5 



50-49-1 



20 



3 



21 







44 



7 



2 . 6 



15 . 



4 



. 7 



1 . 8 







1 2 







J 



2 



• 



1 . 5 



40-59-1 



20 



2 



20 



2 



43 







2 . 4 



15. 



4 



. 



1 . 9 



6 



6 



12 



7 



1 



2 



. 2 



1 . 4 



30-68-2 



20 







20 







42 



6 



2 . 3 



15. 



4 



. 



1 . 8 



6 



6 



12 



9 



1 



3 



. 3 



1 . 4 



20-78-2 



19 



9 



19 



9 



42 



3 



2 . 6 



15. 







. 



1 . 7 



6 



5 



13 



1 



1 



3 



. 3 



1 . 3 



20-68-12 



18 



2 



18 



2 



38 



7 



1 . 8 



14. 



7 



. 



1 . 7 



5 



9 



IS 



2 



1 



4 



. 5 



1 . 3 



20-58-22 



16 



9 



17 







36 



2 



1.2 



13. 



4 



. 1 



1.6 



5 



5 



16 



5 



1 



5 



. 7 



1.2 



20-47-33 



16 



5 



16 



5 



35 



1 



. 9 



13. 



3 



.0 



1.8 



5 



3 



16 



8 



1 



6 



1.0 



1.2 



20-36-44 



16 



1 



16 







34 







. 7 



13. 



1 



- . 1 



1.7 



5 





17 



1 



1 



7 



1.2 



1.1 



20-25-55 



15 



8 



16 



1 



34 



3 



.8 



12. 



8 



. 3 



1.8 



4 



9 



16 



9 



1 



8 



1.4 



1.1 



20-15-65 



15 



4 



15 



6 



33 



2 



.2 



12. 



9 



2 



1.6 



5 



2 



17 



1 



1 



9 



1.7 



1.1 



20-5-75 



15 





15 



3 



32 



6 



. 3 



12. 



6 



. 1 



1.8 



4 



9 



17 



4 



~> 







1.9 



1.0 



^Percent watershed areal cover composed of grass-forb, aspen, and conifer types, respectively. 

 ^Runoff percent is equal to [Streamflow + SM)/precipitation. 

 ^See figure 1 for an identification of alphabetic codes. 



'*aSM and AGWL represent the net annual change in soil moisture and ground water level, respectively. 



Predicted annual water budgets for the "average" year for different combinations 

 of vegetation types are given in table 3. In the CCW test area, the principal sere 

 following burning or clearcutting is visualized as less than 4 years' dominance by a 

 grass-forb type, which is quickly followed by aspen dominance, which in turn is pro- 

 gressively replaced by conifers. Approximately 20 percent of the area is considered 

 grass-forb climax, and thus stabilizes at this level. Each line in the table refers to 

 a position assumed for the watershed on the grass-forb to conifer sere. The length of 

 the sere is not specified, since this may vary widely from site to site. The value 

 for QCHP is a constant value (0.314 in) for all conditions. The values for QMCH, QGW, 

 and RVAP exhibited the following minor trends from beginning to end of the sere: 0.29 

 to 0.28 in for QMCH, 1.77 to 1.71 in for QGW, and 2.66 to 2.87 in for RVAP. Several 

 components of the water budget (TRAN , RINT, SINT, and SVAP) exhibited rather consistent 

 trends along the sere. The other values in table 3 reflect the interaction of vegeta- 

 tion change with the timing and amount of moisture input and moisture loss due to evapo- 

 transpiration . The value for streamflow plus soil moisture change is presented since 

 net change from the initial soil moisture at the end of the year will affect the follow- 

 ing year's runoff (the soil storage compartment must be recharged prior to the runoff 

 season). The amount of streamflow reduction plus the change in soil moisture for 

 different stages of succession are illustrated in figure 9. By the time aspen dominates 

 the watershed, a net reduction in water available for streamflow of 3.4 in has occurred. 

 As the watershed proceeds from aspen to climax conifer conditions, an additional 4.6 

 in is lost. 



Annual streamflow under a variety of precipitation conditions was found to vary 

 substantially along the successional gradient (table 4). Variable precipitation appears 

 to alter the efficiency with which the watershed generates runoff: decreased runoff 

 efficiency accompanies years of below-average precipitation. Late serai stages (conifer 

 dominance) accentuate the reductions in streamflow for relatively dry years. 



13 



