John Haines introduced the efforts
of USGS coastal geologists and oceanographers to understand the
relationship of geology to coastal response with the goal of forecasting
coastal change. Though USGS programs are broad, addressing many
issues and many environments, the focus here was on the erosion
and evolution of sandy beach systems. The talk had three primary
sections:
1) describing the development of
a conceptual (partly quantitative) "sediment budget" model
for regional coastal systems by mapping (sidescan, ground penetrating
radar, seismics) and interpreting the geology,
2) outlining efforts to monitor (LIDAR, GPS topography and bathymetry)
and model the coastal response at and near the shoreline at a variety
of time scales, and
3) based on the geologic framework and shoreline response apply
field experiments and a variety of models to refine and test our
understanding of coastal change.
The elements described above provide
the science and information base needed to forecast coastal change
given realistic scenarios for future natural and human influences.
Finally the presentation indicated some of the many ways efforts
to forecast coastal change in sedimentary systems supports broader
environmental and resource management issues.
@
|
|
Kenichi
Torii of NILIM described the natural setting of the Japanese coast
resulting in large sediment volumes delivered to the coast; with the
historic and current sedimentary system heavily influenced by river
modification, sand & gravel removal, and coastal structures. NILIM
analyses provided an overview of the scale and location of erosion
problems around the Japanese coast. This set the background for describing
coastal systems in terms of sedimentary cells that extend from the
river basin to the coastal limits of transport - with the river mouth
as a critical area for understanding processes. Two NILIM projects
were described:
1) Efforts to understand the processes
of sediment transport and sedimentation in the Abe river sediment
cell. Significant changes in the rates of removal of gravel from
the river were related to coastal response. The project sets the
stage for providing scientific guidance to linked, and potentially
conflicting, issues related to flood hazard control and coastal
erosion.
2) Mouth area - where river and
coastal processes interact. Research approaches to describe the
sedimentary system and the processes by which it responds were described.
These projects provide a broad framework
(the sediment cell) for research on coastal systems and identify
a critical segment (the river mouth) and critical issues (storm
processes, sediment availability) for research.
|
There
is much in common between the interests and approaches of the two
agencies. Both are approaching coastal issues as systems defined by
the regional sediment budget, and both are striving to enhance process
understanding so as to better understand coastal change. Both agencies
recognize that understanding the processes of sediment transport and
sedimentation has application to a wide range of environmental issues.
NILIM has, naturally, an approach that is reflective of their engineering
mission to improve the activities of their parent Ministry. This is
reflected in the close connection between their research and the past
and potential future human alterations of coastal systems. This reflection
of engineered systems, and the responsiveness to complex and conflicting
uses of coastal resources, may inform the USGS as it strives to link
its science to decision-making in much the way that NILIM already
does.
The particulars of Japanese and
U.S. coastal systems have some similarities - and some differences.
In striving to better understand coastal systems, as research colleagues,
we can learn from efforts where systems are similar (processes at
river mouths, storm impacts on sandy shores) and where systems differ
(sediment starved versus sediment rich systems). There may be opportunities
to share data that, for both agencies, enhance the data available
to address fundamental research questions. There is, as with all
scientific pursuits, much to be gained by sharing knowledge of capabilities
and technologies that have application to shared interests.
|