Project Summary
Riparian agricultural lands in northern California face the dual problem
of increasing exposure to environmental hazards, especially floods, and
decreasing availability of natural habitats to sustain a healthy ecosystem.
Several public agencies in California have identified restoration of healthy
ecosystems with functional hydrogeomorphology as an important element in
the solution to the state's agricultural flooding problem. Despite the widespread
recognition of the value of ecosystem restoration, little scientific knowledge
exists to guide on-going and future efforts.
The purpose of this study is to determine the geomorphic and hydrologic
potential of northern CaliforniaÕs riparian agricultural lands to revert
back to healthy ecosystems that reduce financial losses from floods. The
geomorphic potential is defined as the elevational, stratigraphic, and
sedimentary conditions necessary for riparian habitats to exist at all.
The hydrologic potential interacts with the geomorphic conditions and
is defined as the flow magnitude, duration, frequency, timing, and flashiness,
which together drive many ecological processes and functions in riparian
systems. Specific objectives with respect to a northern California riparian
agricultural system include the quantification of the relative proportion
of vertical accretion due to alluvial influx of inorganic sediment versus
in situ biomass accumulation, the characterization of the spatio-temporal
distributions of habitats, the determination of the amount and direction
of energy driving changes in sediment patterns, the assessment of historical
and pre-historical physical stability, and the simulation of the natural
flow regime resulting in a hydrogeomorphically viable restoration.
The approach proposed to meet the study objectives is to use a combination
of environmental reconstruction and computer modeling to assess a study
area that is a representative riparian agricultural system. The study
area will be the Cosumnes River Preserve- a land owning partnership of
more than 13,000 acres of agricultural riparian land that seeks to restore
and safeguard the integrity of the Cosumnes River and its surrounding
landscape. The first four specific objectives will be met by reconstructing
environmental conditions in the study area. This will involve characterizing
the general lithologic and stratigraphic framework using a large number
of cores taken from sites and then selecting a subset of those cores for
dating and detailed paleoenvironmental analysis. Knowing the historical
hydrogeomorphology of the system will enable development of a conceptual
model of what would constitute a geomorphically viable ecosystem restoration
for the riparian agricultural land under study. Given the geomorphic criteria
established in the conceptual model, a 2-D hydrodynamic computer model
(RMA2) will be used to simulate potential physical changes to the study
area that will help generate a natural flow regime that improves the functioning
of the ecosystem there.
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