Measure Amount of sediment in the coastal zone of the waters of the Great Lakes Basin.
Purpose This metric assesses the amount of water and suspended sediment entering the
Great Lakes through major tributaries and connecting channels, and is used to estimate the amount of
sediment available for transport to coastal ecosystems.
Features This metric offers information on climate, soil conditions, and land cover
types that provide information about how such parameters affect the presence and availability of
sediment to coastal ecosystems, as demonstrated by the use of remote-sensing and GIS data. Field-based
collection of land cover, soil data, and surface water data can also be accomplished by: surveys
(using global positioning systems); sketches; personal interviews; and record analyses at local, county,
or state offices.
Limitations To conduct such measures at a broad scale, the relationships between land
use, soil conditions, surface water loading, and coastal zone impacts need to be verified. This metric
will need to be validated fully with thorough field sampling data and sufficient a priori knowledge of
such endpoints and the mechanisms of impact. The development of indicators (e.g., a regression model
using soil and topographic characteristics) is an important goal, and requires uniform measurement of
field parameters across a vast geographic region to determine accurate information on calibrating such
Interpretation A thorough exploration of the potential hydrodynamic and biochemical
relationships, with ecological functions of affected coastal ecosystems, is essential for the proper
interpretation of these analyses. Human impact measures may be strongly correlated with this metric
(e.g., percent agriculture or impervious surfaces within a watershed), and the pattern of such human
impacts may exert a substantial influence on the results and interpretation of this metric. Because
land cover is temporally variable and is non-linear in spatial and temporal patterns, this metric is
complex. Thus, multiple-scale, multiple-season, multiple-year analyses of land cover and weather
patterns are required to develop a robust indicator. Additionally, this indicator may perform better
with greater specificity of land cover types or topography, and be most useful using contemporaneous
remote sensing data. Thus, contemporary and more specific data are currently under development by EPA/ORD
to improve this indicator.
Comments A thorough field-sampling protocol, properly validated geographic information,
and other remote-sensing-based data could lead to successful development of this metric as an accurate
indicator of coastal wetland function and ecological vulnerability. This indicator could be applied to
select coastal sites, but would be most effective if used at a regional or basin-wide scale.
Metric Maps The impact of surface water
runoff in the Great Lakes Basin is mapped for relevant coastal areas using remote-sensing-based
geographic information. In the examples, the relative amount of surface water export of sediment
throughout the entire Great Lakes Basin is demonstrated using several associated parameters. These
measures could be fine-tuned to focus solely on loading to coastal wetland regions, or can be calibrated
using field-based data and/or other finer scale GIS data (e.g., topographic or soil data).