TB207: A Manual for Remote Sensing of Maine Lake Clarity (original) (raw)
Related papers
Inland Waters, 2016
Using data collected with 3 different methods, we found no decreases in the average water clarity of Maine (USA) lakes over different periods of time. Field measurements of Secchi disk depths in the summer months by volunteer samplers in several hundred lakes showed a small, statistically significant increase in water transparency during the period 1976 through 2013. A reanalysis of satellite-inferred Secchi depths between 1990 and 2010 showed no trend over time. In addition, diatom-inferred Secchi depths from short sediment cores in a randomly selected group of Maine lakes analyzed by the US Environmental Protection Agency showed no statistically significant difference between the average Secchi depths in a pre-1850 time period and the early 1990s. Lake maximum depth was the most important morphological variable associated with water clarity among Maine lakes. In individual lakes, both water color and chlorophyll were inversely correlated with Secchi disk depths. The statewide annual average Secchi depths for the summer months were inversely correlated with water color and the amount of precipitation for the months of January through June. Drought years led to increased Secchi depths.
Journal of Earth Science Research, 2016
Water clarity is an important criteria for not only water quality monitoring but also the environmental management of a lake and surrounding watershed. This research focuses on the evaluation of Landsat 8 for the modeling water clarity in Lake Mattamuskeet, North Carolina. The main objectives of our study was to determine the relationship between remotely sensed data and secchi disk trancperancy (SDT) measurements in Lake Mattamuskeet using publically available SDT data and Landsat imagery. To adress this objective, the following quaestions were eximend in this study. Can in-situ SDT measurements be used to adequately model water clarity from remote sensed data despite non-extensive field sampling? Based on previous remote sensing studies, can comparable estimates of water clarity using Landsat 8 for the east and west sides of Lake Mattamuskeet,
Drivers of change for lakewater clarity
Lake and Reservoir Management, 2008
Baker, L.A., J.E. Schussler and S. A. Snyder. 2008. Drivers of change of lake clarity. Lake Reserv. Lakes in the Upper Midwest have undergone extensive lakeshore development over the past 30 years, raising concerns about eutrophication. We examined 11 case study lakes in Minnesota that had undergone substantial shoreline development over the past 30 years to evaluate drivers of change in clarity. Relationships between current Secchi disk transparency (SDT) and the density of permanent equivalent houses (PEHs) and between change in SDT and change in density of PEHs were not statistically significant. For lakes with large watershed area-to-lake area (WSA: LA) ratios, modeled worst-case scenarios for impacts of shoreline housing show that phosphorus (P) inputs may not be sufficient to reduce SDT. For sensitive lakes, improved P management policies may counteract increased shoreline development, at least in part. For lakes with large WSA:LA ratios, activity outside the shoreline area, particularly agricultural activity, is probably more important than shoreline development in affecting SDT. Although policies considered "lake management" operate at fairly small scales, drivers of change in SDT operate at various temporal and spatial scales, from household to global.
2015
Dirnberger, J. M. and J. Weinberger. 2005. Influences of lake level changes on reservoir water clarity in Allatoona Lake, Georgia. Lake and Reserv. Manage. Vol. 21(1):24-29. In Allatoona Lake (Georgia USA), secchi transparency (measured every 2 to 4 weeks during a Phase I U.S. EPA Clean Lakes Study) was typically 5- to 8- fold greater in summer than late autumn and winter. The intensity of storms increased in late autumn and winter resulting in high sediment loads from the watershed, but lake level was also drawn down, confounding the influence of external sediment load with that of resuspended lake sediments. For 4 of the 5 years studied, decreases in water clarity were more closely synchronized with lowering of lake level than with storms. Continuous automated sampling of turbidity and other water quality parameters at 15-minute intervals allowed us to assess whether turbidity increases were derived from erosion of the exposed shoreline (i.e., by rain and runoff), or wave-driven r...
Water clarity of the Upper Great Lakes: Tracking changes between 1998–2012
Journal of Great Lakes Research, 2017
Water clarity trends in three upper Great Lakes, Lakes Superior, Michigan, and Huron, were assessed via satellite imagery from 1998 to 2012. Light attenuation coefficients (Kd 490) from SeaWiFS and Aqua MODIS satellites compared favorably with in situ measurements. Significant temporal and spatial trends and differences in Kd 490 were noted within all three of the lakes. Lake-wide average Kd 490 for Lake Superior did not exhibit any changes between 1998 and 2012. Annual Kd 490 values for Lake Huron, however, showed a significant negative trend during the study period using both SeaWiFS and MODIS datasets. Similarly, annual Kd 490 values of Lake Michigan declined between 1998 and 2010. Only in the offshore waters (N90 m depth) of northern Lake Michigan did Kd 490 increase but just after 2007. Photic depth increased significantly in both Lake Michigan (≃5 m), and Lake Huron (≃10 m) when comparing annual Kd 490 for pre-(1998-2001) and post-dreissenid mussel (2006-2010). At seasonal level, significant decreases in Kd 490 in lakes Michigan and Huron were mainly noted for the spring/ fall/winter mixing periods. After these recent changes in water clarity, lake-wide photic depths in lakes Michigan and Huron superseded Lake Superior; thus, making Lake Superior no longer the clearest Great Lake. Several factors (e.g. filtering activities of quagga mussels, phosphorus abatement, climate change, etc.) are likely responsible for these large changes.
Remote Sensing of Environment, 2012
Water clarity is a reliable indicator of lake productivity and an ideal metric of regional water quality. Clarity is an indicator of other water quality variables including chlorophyll-a, total phosphorus and trophic status; however, unlike these metrics, clarity can be accurately and efficiently estimated remotely on a regional scale. Remote sensing is useful in regions containing a large number of lakes that are cost prohibitive to monitor regularly using traditional field methods. Field-assessed lakes generally are easily accessible and may represent a spatially irregular, non-random sample of a region. We developed a remote monitoring program for Maine lakes > 8 ha (1511 lakes) to supplement existing field monitoring programs. We combined Landsat 5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+) brightness values for TM bands 1 (blue) and 3 (red) to estimate water clarity (secchi disk depth) during 1990-2010. Although similar procedures have been applied to Minnesota and Wisconsin lakes, neither state incorporates physical lake variables or watershed characteristics that potentially affect clarity into their models. Average lake depth consistently improved model fitness, and the proportion of wetland area in lake watersheds also explained variability in clarity in some cases. Nine regression models predicted water clarity (R 2 = 0.69-0.90) during 1990-2010, with separate models for eastern (TM path 11; four models) and western Maine (TM path 12; five models that captured differences in topography and landscape disturbance. Average absolute difference between model-estimated and observed secchi depth ranged 0.65-1.03 m. Eutrophic and mesotrophic lakes consistently were estimated more accurately than oligotrophic lakes. Our results show that TM bands 1 and 3 can be used to estimate regional lake water clarity outside the Great Lakes Region and that the accuracy of estimates is improved with additional model variables that reflect physical lake characteristics and watershed conditions.