| Summary: | This experiment was designed to study the hydrologic
response of three first order watersheds to the inputs of
precipitation, especially those inputs received during storm
events. The study was conducted in the Gregory Creek
watershed in the Rennell Sound area of the Queen Charlotte
Islands.
There were six data collection sites, two in each of
three sub-basins. Groundwater levels and surface flow were
monitored over an 82 day period from November 26th, 1991 to
February 15th, 1992. Precipitation data were collected over a
40 day period from November 26th, 1991 to January 4th 1992.
The data were analyzed by comparing precipitation data to
groundwater levels and surface flow using time-series and
regression analysis. Storm precipitation was compared to
groundwater levels and surface flow (for the same time as the
storm event). Including antecedent precipitation in this
analysis did not increase the number of significant
regressions relationships.
Time-series analysis revealed strong correlations
between groundwater levels at wells within the same site. The
two sites in watershed number one produced more significant
relations between storm precipitation and groundwater
response than watersheds two and three when analyzed using
time-series analysis.
The watershed that produced significant results using
time-series analysis did not produce significant regression
results. Alternatively, one watershed which did not produce
significant time-series results did produce significant
regression results.
Mean groundwater level changes during storm events were
significantly greater at the upper site in one watershed, the
lower site in another and inconsistent in the third. There
was a wide range in the mean time to peak for all sites
during storm events (5.6 hr - 12.1 hr), but the differences
were not statistically significant.
An analysis of covariance indicated that there was not a
common regression equation that defined the relation of
changes in groundwater levels or time to peak during storm
events for all three watersheds in the study.
It is hypothesized that the differences between sites
and watersheds may be a result of individual differences in
geologic characteristics at each site and instrument
location.
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