Geoscience Reference
In-Depth Information
Possible changes in basin characteristics over the period covered by the tree-
ring record impose on streamflow reconstructions a layer of uncertainty not
amenable to assessment with statistics on calibration accuracy or validation accu-
racy. Reconstruction models assume that the statistical relationships derived for the
calibration period are stable over the long term, and this assumption may be vio-
lated if basin conditions have changed. For example, if the vegetative cover of the
basin was drastically reduced (e.g., by fire) during some intervals, the runoff from
the basin at those times would be greater than expected from a statistical model cal-
ibrated under modern conditions. On the other hand, an error of this kind may be
unimportant to water managers who are interested in the possible effects of climate
variability on runoff given existing vegetation coverage.
8.4.4 Communication
The extended records of hydroclimatic variability provide valuable information
about the range of natural variability beyond that provided by gauge records alone.
This information has important implications for water resource planning and policy
making. The challenge is to move from these implications to determine the ways
these data can actually be applied to water resource management. Collaborative
work between water management agencies and paleoscientists, as described in the
example above with Denver Water, has demonstrated the potential usefulness of
these data in planning and management. In the spring of 2002, a workshop was held
tists and water management agency personnel with interests in the Colorado River
basin. Group discussions during the workshop brought to the forefront some of the
challenges in applying paleodata to water resource planning and management. First
and foremost was the need for better communication between paleoscientists and
water management personnel to improve scientists' understanding of management
decision-making concerns, as well as water managers' understanding of the science
behind the data. Part of that challenge is finding water managers willing to look
beyond traditional management tools, and dendrohydrologists willing to think about
alternative approaches to standard dendrohydrological methods. Forming success-
ful partnerships is a time-consuming process for all parties involved. However, due
to the impact of recent droughts, coupled with increased demands on water supplies
and the potential for anthropogenic climate change, the water resource community
has begun to recognize the value of these extended records. Our challenge is to
improve communications with water management personnel so that we can find
better ways to provide the data and information needed for planning and decision
making.
8.4.5 Climate Change
The regional impacts of climate change on water resources are becoming evident
in the declining snowpack in the mountains of the western United States, and
