手法を比較

	Water Footprint Analysis	Benefit Transfer Valuation
分野	Environmental Sociology	Environmental Economics
系統	Process / pipeline	Process / pipeline
提唱年	2011	2015
提唱者	Arjen Y. Hoekstra (with Chapagain, Aldaya & Mekonnen)	Robert J. Johnston, John Rolfe, Randall S. Rosenberger & Roy Brouwer
種類	Volumetric freshwater-appropriation accounting pipeline	Pipeline for transferring existing valuation estimates to new policy sites
原典	Hoekstra, A. Y., Chapagain, A. K., Aldaya, M. M., & Mekonnen, M. M. (2011). The Water Footprint Assessment Manual: Setting the Global Standard. Earthscan. ISBN: 9781849712798	Johnston, R. J., Rolfe, J., Rosenberger, R. S., & Brouwer, R. (Eds.). (2015). Benefit Transfer of Environmental and Resource Values: A Guide for Researchers and Practitioners. Springer.
別名	Water Footprint Assessment, Blue-Green-Grey Water Accounting, Virtual Water Analysis, Hoekstra Water Footprint	Value Transfer, Benefits Transfer, Environmental Value Transfer, Function Transfer
関連	3	3
概要	Water footprint analysis is a volumetric accounting method that measures the appropriation of freshwater used to produce the goods and services consumed by an individual, community, business, or nation. Formalized in Arjen Hoekstra's Water Footprint Assessment Manual of 2011, it decomposes water use into three components: the green water footprint (rainwater consumed, mainly through crop evapotranspiration), the blue water footprint (surface and groundwater consumed), and the grey water footprint (the volume of freshwater needed to dilute pollution to meet ambient quality standards). By tracing water through supply chains and aggregating these components, the method reveals how much and what kind of water lies behind products and consumption — including virtual water embedded in trade — and then assesses whether that appropriation is sustainable relative to local water availability and pollution-assimilation capacity.	Benefit transfer is the practice of using economic value estimates from existing valuation studies to estimate the value of an environmental change at a new policy site where conducting a fresh primary study is not feasible. As systematized in Johnston, Rolfe, Rosenberger and Brouwer's 2015 guide, it ranges from simple unit-value transfer — borrowing a willingness-to-pay figure from a similar study — to function transfer, in which an estimated value function is applied using the characteristics of the new site and population, and meta-analytic transfer that pools many studies into a single predictive function. Because primary valuation through choice experiments or travel-cost studies is expensive and slow, benefit transfer is the workhorse of routine policy appraisal, allowing analysts to value ecosystem-service changes quickly while explicitly managing the error introduced by adapting evidence across contexts.