Summary of Methodology
This project encompasses many different disciplines, including teams from entomology, genetics,
rangeland ecology, and resource economics. Due to the multi-disciplinary nature and early stages
of this project, a form of the Delphi technique was employed to estimate the impacts of
biological control, whereby several experts were repeatedly interviewed until a consensus was
reached among the experts. The USDA-ARS provided data of the acreage infested with giant
reed. The study and release of the biological-control agents are still under investigation as
primary data continue to be collected. Thus, the results presented are preliminary.
This research involves several steps to estimate the impacts of the biological controls.
The temporal biology of the plant must be approximated, along with water use to establish a base
for estimating savings and effectiveness. The estimated level of control of Arundo is then used
to determine the associated water savings. Recognizing water savings over future years, the
value of this water is estimated assuming it is used to irrigate crops. Lastly, a benefit-cost
analysis and the economic and employment impacts of the water savings are estimated.
Plant Growth
To model the amount of water saved from the control of the plant, an unmitigated base
situation is estimated with continued Arundo donax plant growth and acreage expansion. This
benchmark is established by estimating the number of acres present, and then using an expansion
rate of the plant to project the number of acres in future years. From this base situation, the
expected water savings and associated potential value of saved water (due to the control of
Arundo from the release of the biological-control agents) are estimated. Although the
mathematical results in this analysis identify water saved from the reduction of acres infested