Mississippi River diversions, coastal wetland restoration/creation and an economy of scale
We tested the hypothesis that there is an economy of scale in ecological engineering projects designed to create or restore wetlands by using examples of coastal restoration/creation projects in the Louisiana coastal zone. Land gain and project cost are directly related to the amount of riverflow diverted from the main channel, as expected. However, the $/ha gained was dramatically and directly related to project size. A 1000 fold increase in project size is matched by a 100 fold increase in the cost/ha gained. The smallest river diversion projects ($20,000 each) create land at slow rates (@5 ha/year) and tend to be very cost effective ($20-$500/ha). These low cost/ha gained are in sharp contrast to that of the larger river diversion projects and most other local wetland restoration/creation projects funded by state/federal sponsored programs ($1000 to $100000/ha) on this coast. There is a 15 fold increase in $/ha gained as project size increases by a factor of 10. This situation of decreasing returns ($/ha gained) with project increasing costs may be called an 'inverse' economy of scale. We propose that there are generic economies of scale inherent to similar environmental management approaches that represent a compromise of at least three attributes: attempts to control ecosystem behavior (predictability and use), ecosystem complexity, and incomplete ecosystem knowledge.
Publication Source (Journal or Book title)
Turner, R., & Boyer, M. (1997). Mississippi River diversions, coastal wetland restoration/creation and an economy of scale. Ecological Engineering, 8 (2), 117-128. https://doi.org/10.1016/S0925-8574(97)00258-9