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determination of nutrient loads to east coast canals >
1999 proposal
USGS WATER RESOURCES DIVISION
CONTINUING PROJECT WORK PLAN - FY 1999
IDENTIFYING INFORMATION
PROJECT CHIEF: Arthur C. Lietz
PROGRAM: INTEGRATED NATURAL RESOURCE SCIENCE PROGRAM
ELEMENT 3: MODELING AND SUPPORT STUDIES FOR SOUTHERN INLAND COASTAL
BACKGROUND NARRATIVES
PROJECT SUMMARY: The ecological health of bays and estuaries
has become a matter of concern throughout the country. Biscayne Bay, which
is a shallow, oligotrophic, subtropical estuary along the southeastern
coast of Florida has been adversely impacted in certain locations by the
increase in nutrient loads from tributary canals that have resulted from
agricultural, urban, commercial and industrial processes. The ecological
health of the Bay, as well as development of restoration efforts is dependent
in part on understanding loads to the bay. This project will attempt to
quantify nitrogen and phosphorus loads to the Bay based upon models developed
from ordinary least squares regression techniques and examine which historical
methods of sampling accurately represent nutrient concentrations in the
water column of south Florida canals. Also, spatial and temporal water-quality
trend analysis will be conducted on data from two former National Stream
Quality Accounting Network (NASQAN) sites on canals that have a direct
impact on the south Florida ecosystem. Information derived from this project
will be of immense importance to water managers and planners, particularly
in light of recent Everglades restoration plans to restore historical hydropatterns
now altered as a result of the extensive water management system.
PROJECT OBJECTIVES AND STRATEGY: This objectives of this project
are threefold: 1.) To determine if historical water-quality data collected
as grab samples at 0.5 and 1.0 meter below the surface near the centroid
of flow adequately represent stream cross-sectional chemistry, and 2.)
To develop reliable estimates of nitrogen and phosphorus loads for east
coast canals based upon statistical models developed from utilizing the
techniques of ordinary least squares regression, and 3.) To summarize water-quality
data and determine temporal trends for water-quality constituents at two
sites that are strategic to Biscayne Bay and the south Florida ecosystem.
During Phase I of the project an intensive field sampling and data collection
effort was undertaken. This consisted of the collection of water samples
for nitrogen and phosphorus species upstream of coastal discharge points
for the major tributary canals. Data collection occurred during various
seasons and flow conditions in order to obtain samples truly representative
of the hydrologic cycle. Depth-integrated samples collected by the equal-width-increment
method as well as grab samples were collected at each canal during Phase
I. During Phase II of the investigation, which is now in progress, data
analysis and report preparation are being undertaken. This entalls using
statistical procedures to compare the two sampling methods and regression
analysis in order to develop load models for nitrogen and phosphorus species
for each site as well as determining temporal trends at two long-term water-quality
sites critical to ecosystem restoration. This analysis will provide important
information for the understanding of processes that may have affected water-quality
over the years.
Potential impacts and major products: The ecological health of
Biscayne Bay is dependent on nutrient loads. Understanding the hydrologic
processes that control nutrient loadings to the Bay is necessary in order
to properly develop restoration efforts. In order to accomplish this, reliable
estimates of loads to the Bay are necessary. Much of the nutrient data
that have been collected historically has been from point samples by the
Dade County Department of Environmental Resource Management. The degree
to which these samples adequately represent nutrient concentrations within
the water column of the canals of south Florida is presently unknown and
limits confidence in loading estimates. Furthermore, the relationship between
flow and concentration that occurs in natural, uncontrolled streams in
other parts of the country may not apply to the artificially controlled
canals of south Florida. Both of these issues need to be addressed in order
to develop nutrient budgets and to plan effective restoration strategies
now and in the future. Also, water-quality trend analysis on data collected
at two former NASQAN sites will provide insight into processes that have
affected nutrient and pollutant loading to the Bay as well as the south
Florida ecosystem as a whole. Information documented as a result of this
project will provide water managers and planners critical information that
is relevant to the restoration of historical hydropatterns in the south
Florida ecosystem and in particular to the plans for the diversion of water
from the agricultural/urban corridor to Everglades National Park. Major
products include two reports: ěPredictive Models for Estimating Nitrogen
and Phosphorus Loads from East Coast Canals to Biscayne Bay,î currently
in review and ěAnalysis and Interpretation of Water-Quality Trends at two
former NASQAN Sites, 1966 -1994.î which will be completed during the 1999
water year.
COLLABORATORS AND CLIENTS: During the duration of the project
close collaboration and exchange of technical information has been and
will continue to be maintained with other projects of the South Florida
Ecosystem Restoration Initiative, particularly the Fresh Surface Water
Discharge to the East Coast project. This project used the Acoustic Doppler
Current Profiler to develop discharge ratings for the east coast canals.
Also close collaboration with the south Florida NAWQA program and other
agencies such as the U.S. Army Corps of Engineers will continue. This investigation
has interfaced closely with the south Florida NAWQA program in that it
has contributed to the process of defining the relationship between land
use and water quality conditions and helped identify water quality trends
in south Florida. Coordination of sampling efforts and exchange of information
will also be maintained and continued with DERMís Biscayne Bay monitoring
program. Determination of nutrient loads to Biscayne Bay and long-term
trends at NASQAN stations will aid regulatory agencies such as SFWMD and
DERM in water resource management particularly with proposed plans to redirect
flow from the urban/agricultural corridor to Everglades National Park.
Logistical support in gaining access to control structures during sampling
-events was provided by the SFWMD field offices.
WORK PLAN
FY 1999 ACTIVITIES: During the 1999 water year a interpretative
report will be prepared, reviewed and published. This report will entail
the determination of temporal trends at two long-term surface water sites
that are critical to ecosystem restoration. Both of these sites, Miami
Canal at S-26 and Tamiami Canal - forty mile bend to Monroe, were part of the NASQAN program. Data
collected from Miami canal under the NASQAN program spans the years 1974
to 1994. Data collected from Tamiami canal under the same program includes
the years 1978 to 1993. However, considerable water-quality data exists
from both sites since 1966. The methods to be used in determining trends
at these two sites are documented in the report entitled, ěThe Computer
Program Estimate Trend (ESTREND), a System for the Detection of Trends
in Water-Quality Dataî by Schertz, Alexander and Ohe (1991). This program
contains methods for dealing with the two main causes of unwanted variation
in water-quality data: seasonality and effects of discharge. The program
documents a non-parametric statistical approach to dealing with water-quality
data by applying the Seasonal Kendall Trend test to flow-adjusted residuals
determined by developing statistically significant concentration/discharge
models on specific parameters where possible. Statistically significant
trends may be determined on unadjusted concentration data as well as flow-adjusted
concentration data, whichever provides the best trend result as determined
by a significance level (p-value) of <0.10. The program will determine
trend slopes for specific parameters when a statistically significant trend
is determined. The program provides methods for dealing with censored as
well as uncensored data. Summary and descriptive statistics for specific
parameters will also be included in the final interpretative report as
well as maps with spatial symbols indicating uptrends, downtrends or no
trends. Locally weighted scatterplot smoothing (LOWESS) will also be used
to describe the non-linear, short-term variations that have occurred in
the data over the period of record. A synopsis report will be prepared
that summarizes results of the investigation, its relevance to management
issues and collaboration with other agencies and recommendations for future
studies
FY 1999 DELIVERABLES/PRODUCTS: The report entitled ěAnalysis
and Interpretation of Water-Quality Trends at Two Former NASQAN Stations
in South Florida, 1965-1994î will describe the project study area including
the physiography, climate, population, land use and the flow regime of
south Florida. Data collection methods and procedures will also be described
as well as sample processing and preservation. Methods for the determination
of water-quality trends will be described including methods for dealing
with variation in water-quality data caused by the effects of streamflow
and seasonality. Criteria for determining trends on censored and uncensored
data will be described. An analysis and interpretation of water-quality
trends will be made on physical properties and field measurements, major
inorganic constituents, nitrogen and phosphorus species, suspended sediment
and bacteriological parameters. A two page synopsis will be prepared describing
in detail project accomplishments, its relevance to management issues and
to future studies.
FY 1999 OUTREACH: Outreach will be directed to other federal
agencies such as the U.S. Army Corps of Engineers as well as state agencies
such as the South Florida Water Management District and local agencies
that have an interest in the health of the south Florida ecosystem, particularly
the Dade County DERM which has regularly collected nutrient data on east
coast canals. Outreach will also include the production and dissemination
of a two page synopsis report as a fact sheet that summarizes project accomplishments.
ACCOMPLISHMENTS, OUTCOMES, PRODUCTS AND OUTREACH
FY 1998 ACCOMPLISHMENTS AND OUTCOMES, INCLUDING OUTREACH: The
first draft of an interpretative report entitled ěPredictive Models for
Estimating Nitrogen and Phosphorus Loads from East Coast Canals to Biscayne
Bay, Dade County, Florida, 1996-1997î was completed and is currently in
review. This report is based on data collected during the 1996 and 1997
water years. Non-interpretative sections of a second report on determining
temporal trends on water-quality data from two long-term water quality
stations are in progress. Periodic progress reports have been prepared
and distributed to interested clients and collaborators. Outreach has included
contacts and close association with the south Florida NAWQA program as
well as with other agencies, both federal, state and local that have an
interest in the Everglades ecosystem restoration. particularly the Dade
County Department of Environmental Resources Management and the South Florida
Water management District.
FY 1998 DELIVERABLES, PRODUCTS COMPLETED: First draft of interpretative
report mentioned in the previous section was completed and is in review.
PROJECT SUPPORT REQUIREMENTS
Other required expertise for which no individual has been identified:
None
Major equipment/facility needs: None
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U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal Geology This page is: http://snowball/proposals/1999/methodp99.html Comments and suggestions? Contact: Heather Henkel - Webmaster Last updated: 11 October, 2002 @ 09:31 PM (KP) |
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