Water supply assessment and ranking of watershed dams in Georgia
Abstract
Jordan, Jones & Goulding, Inc. (JJG, teamed
with Schnabel Engineering, LLC) was selected by the
Georgia Soil and Water Conservation Commission
(Commission) to inventory and evaluate the water supply
potential for 166 existing Watershed Dams in Georgia.
Because of tremendous growth in the past several decades,
water supply sources are increasingly in demand in
Georgia, particularly in North Georgia. Also, environmental
permitting requirements associated with constructing
new reservoirs are increasingly stringent. Expansion
of existing reservoir structures may be more acceptable to
resource agencies, because many of the environmental
impacts associated with existing reservoirs have already
occurred.
The Commission wanted a methodology to assess its
existing dams and to rank their relative suitability for water
supply; but inventory, assessment and ranking of 166
dams and their potential for expansion is no small task.
JJG employed a GIS-based approach to the inventory and
evaluation process. Available data resources were accessed
and pertinent information on many factors was
obtained, including wetlands, streams (including trout
streams), protected species, cultural resources, numbers of
affected structures and roads, impaired streams [303(d) or
305(b) listed], and distance to existing surface water intakes.
Use of these data coverages made the organization
of this huge amount of information manageable.
The available environmental resource data was compared
to potential reservoir yields, potential for pumpedstorage
operation, and distance/cost of pumping to existing
water systems. This information was assembled into
an electronic matrix that enabled ranking of the various
economic and non-economic factors according to their
perceived importance. By iterations of the matrix, sensitivity
analyses of the alternatives were done to look at
their robustness under various yields and operating conditions.
The top twenty alternatives that emerged from the
ranking process were physically surveyed by JJG ecologists
and engineers to refine the previously-collected data
under “real-world” field conditions. Field data sets were
collected using global positioning system (GPS) equipment,
enabling the more accurate information to be
downloaded directly into the GIS database. This in turn
enabled a rapid re-evaluation of the rankings of the 20
most suitable alternatives.