A
Knowledge and Assessment Guide to Support the Development of Payment
Arrangements for Watershed Ecosystem Services (PWES).
(2004). Prepared by Sylvia S. Tognetti, Guillermo F. Mendoza, Bruce
Aylward, Douglas Southgate & Luis Garcia, for the World Bank Environment
Department with support from the Bank-Netherlands Watershed Partnership
Program, Washington, DC. [Download/English
pdf]
Guía
para el desarrollo de opciones de pago por servicios ambientales (PSA)
de las cuencas hidrológicas. [Download/Español
pdf]
This
Assessment Guide focuses on identification and quantification of watershed
services found in a specific context, highlighting Rules-of-Thumb
that emerge from a review of research and case studies. Following
an overview of existing initiatives, the Guide identifies the kinds
of information needed from a site-specific assessment and provides
a framework for organizing it in a way that is relevant and useful
for decision-making. Special attention is given to estimation of the
water-balance, as a basic framework for investigating ecosystem processes
that underpin specific services, and for estimating their magnitude
and direction. A subsequent section discusses the use of this information
to estimate economic significance of these processes, absent which
they cannot properly be considered "services", and for evaluating
trade-offs. This is then placed in the context of institutional challenges,
although these are not a key focus of the report. The Rules-of-Thumb
are only meant to provide a working hypothesis, and thereby serve
as a point of departure for the assessment of payment initiatives.
Given the broad range of relevant knowledge and perspectives needed
to consider the contribution of watershed processes to human well-being,
in a specific social and economic context, and large spatial and temporal
scales that often make it difficult to link multiple causes and effects
of watershed degradation and thereby identify threats to watershed
services, this guide should be regarded as preliminary, to be further
developed and improved as lessons are learned from implementation.
The Flows Bulletin will supplement the guide by covering special topics
in assessment as new information emerges, identifying lessons learned
from their implementation, and considering their implications for
practice.
