TITLE:
Sensitivity Analysis and Evaluation of Forest Biomass Production Potential Using SWAT Model
AUTHORS:
Sunita Khanal, Prem B. Parajuli
KEYWORDS:
Sensitivity, Forest Biomass, SWAT, Crop Parameter, Watershed
JOURNAL NAME:
Journal of Sustainable Bioenergy Systems,
Vol.4 No.2,
June
25,
2014
ABSTRACT: Sensitivity
analysis of crop parameters and the performance of SWAT (Soil and Water
Assessment Tool) model to simulate potential forest biomass production were
evaluated for the Upper Pearl River Watershed (UPRW). Local sensitivity
analysis of seven crop parameters: radiation use efficiency (kg/ha)/(MJ/m2)
(BIOE), potential maximum leaf area index for the plant (BLAI), fraction of
growing season at which senescence becomes the dominant growth process (DLAI),
fraction of the maximum plant leaf area index corresponding to the 1st point on
the optimal leaf area development curve (LAIMX1), fraction of growing season
corresponding to the 1st point on the optimal leaf area development curve
(FRGRW1), plants potential maximum canopy height (m) (CHTMX), and maximum
rooting depth for plant (mm) (RDMX) reveals that only three parameters: DLAI,
BIOE and BLAI are sensitive to forest biomass production. Further, results
indicate moderate sensitivity of DLAI and BIOE and low sensitivity of BLAI
with relative sensitivity index of 0.44, 0.35 and 0.14, respectively. The
performance of SWAT to simulate potential forest biomass was evaluated by
comparing simulated data against three years of observed data that were
obtained from USDA Forest Service website. The results indicate satisfactory
performance of SWAT in predicting potential forest biomass, which is shown by
the high value of coefficient of determination (R2 = 0.83), small
root mean square error (RMSE = 11.11 Mg/ha), and small difference between mean.
Results also reveal that the UPRW has the potential to produce approximately 49
Mg/ha of average forest biomass annually, which is approximately 6% less than
the observed biomass.