Advanced Approach for S)'TIoptic Monitoring of a Lake Ecosystem
173
These different operational modes present the optimization of survey effort
versus patchiness resolution and maximal coverage of the lake area. Although we
chose to cover the maximal lake area possible within a limited survey time (6 h),
only two thirds of the lake surface area, and less than that of the lake volume, were
measured, mainly due to operational and safety limitations of the U-TUMS.
3.2 Identification of Local Phenomena
The relatively high salinity of Lake Kinneret (chloride concentration above
200 mg 1-1) is attributed to fluxes of saline waters entering the lake from several
on-shore and off-shore springs as well as from off-shore underwater unfocused
seepages. Identification and quantification of salinity fluxes from unmonitored
saline sources is essential for accurate salt balance in an attempt to control lake
water salinity. A high-resolution (small-scale) survey was made with the U-TUMS
over a relatively small area at the western shore of Lake Kinneret, next to the
Fuliya offshore saline springs. The results depicted a very distinct zone of
relatively high salinity (ca 10% higher than in the center of the lake), which
seemed to correspond to underlying lake floor seepages (Fig. 5). These data
demonstrated for the first time the presence of a relatively large area of high
salinity near the shoreline north of the known Fuliya Springs. Slightly higher
salinity was recorded in deeper water layers, suggesting the presence of nonpoint
salinity seepages, which spread over an area of ca. 700 m by 150 m. Additional
surveys carried out south of the Fuliya area indicated the presence of a high
salinity patch at 3 m depth (data not shown). Further analysis revealed the
presence of a salinity plume, which apparently originated from a site near the
lakeshore and dispersed upward and southward from the source along the
shoreline.
This type of survey allows for rapid identification of saline sources and their
seasonal variability. Moreover, the data collected in these surveys is essential for
quantifying the discharge rate of salinity from unfocused seepages by calculating
the surplus of salinity inventory coupled with separate monitoring of local water
flow velocity.
173
These different operational modes present the optimization of survey effort
versus patchiness resolution and maximal coverage of the lake area. Although we
chose to cover the maximal lake area possible within a limited survey time (6 h),
only two thirds of the lake surface area, and less than that of the lake volume, were
measured, mainly due to operational and safety limitations of the U-TUMS.
3.2 Identification of Local Phenomena
The relatively high salinity of Lake Kinneret (chloride concentration above
200 mg 1-1) is attributed to fluxes of saline waters entering the lake from several
on-shore and off-shore springs as well as from off-shore underwater unfocused
seepages. Identification and quantification of salinity fluxes from unmonitored
saline sources is essential for accurate salt balance in an attempt to control lake
water salinity. A high-resolution (small-scale) survey was made with the U-TUMS
over a relatively small area at the western shore of Lake Kinneret, next to the
Fuliya offshore saline springs. The results depicted a very distinct zone of
relatively high salinity (ca 10% higher than in the center of the lake), which
seemed to correspond to underlying lake floor seepages (Fig. 5). These data
demonstrated for the first time the presence of a relatively large area of high
salinity near the shoreline north of the known Fuliya Springs. Slightly higher
salinity was recorded in deeper water layers, suggesting the presence of nonpoint
salinity seepages, which spread over an area of ca. 700 m by 150 m. Additional
surveys carried out south of the Fuliya area indicated the presence of a high
salinity patch at 3 m depth (data not shown). Further analysis revealed the
presence of a salinity plume, which apparently originated from a site near the
lakeshore and dispersed upward and southward from the source along the
shoreline.
This type of survey allows for rapid identification of saline sources and their
seasonal variability. Moreover, the data collected in these surveys is essential for
quantifying the discharge rate of salinity from unfocused seepages by calculating
the surplus of salinity inventory coupled with separate monitoring of local water
flow velocity.