River Flow

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Chesapeake Bay Program Indicator Framework

Reporting Level Indicators

Indicator and Data Survey

A.  Category/Name/Source/Contact

(1) Category of Indicator

_x_ Factors Impacting Bay and Watershed Health

___ Restoration and Protection Efforts

___ Watershed Health

___ Bay Health

(2) Name of Indicator: Total Freshwater Flow to the Bay 

(3) Data Set Description:  

For what purpose(s) were the data collected? (e.g., tracking, research, or long-term monitoring.) These data are used to track conditions in the bay and the rivers draining to the Chesapeake.

Which parameters were measured directly? Flow at the River Input stations was measured.

Which were obtained by calculation? Flow from several areas not monitored by the River Input. Seehttp://md.water.usgs.gov/monthly/bay.html

(4) Source(s) of Data:

Is the complete data set accessible, including metadata, data-dictionaries and embedded definitions? The data set is available and a description of the methods can be found at http://md.water.usgs.gov/publications/ofr-68-Bue10/.   If yes, please indicate where complete dataset can be obtained. Data set can be obtained from Katie Foreman at CBPO.

(5) Custodian of Source Data (and Indicator, if different): Joel Blomquist USGS

(6) CBPO Contact: Katie Foreman (CBP/University of Maryland Center for Environmental Science 800 YOUR-BAY)

B.  Communication Questions

(complete either part 1, 2, or 3)

1.  Restoration and Protection Efforts indicators only

(7a) How much has been completed since 1985 (or baseline year)?  How much has been completed since 2000?

(8a) How much was done last year?

(9a) What is the current status in relation to a goal?

(10a) What is the key story told by this indicator?

(11a) Why is it important to report this information?

(12a) What detail and/or diagnostic indicators are related to this reporting level indicator? (Detail and diagnostic indicators can be spatially-specific, parameter-specific, temporally-specific information, etc.)

2.  Bay Health or Watershed Health indicators only

(7b) What is the long-term trend?  (since start of data collection)

(8b) What is the short-term trend? (3 to 5 year trend)

(9b) What is the current status in relation to a goal?

(10b) What is the key story told by this indicator?

(11b) Why is it important to report this information?

(12b) What detail and/or diagnostic indicators are related to this reporting level indicator?

3.  Factors Impacting Bay and Watershed Health indicators only

(7c) What is the long-term trend?  (since start of data collection)

Between 1938 and 2009, river flow to the Bay has averaged 48.4 BGD and has ranged from 21.9 to 78.2 BGD.

The Climate Change and the Chesapeake Bay State-of-the-Science Review and Recommendations: A Report from the Chesapeake Bay Program Science and Technical Advisory Committee (STAC) highlighted an examination of the 1957 to 2000 record of annual streamflow into the Chesapeake and found substantial interannual variability as well as decadal variability characterized by dry conditions during the 1960s, wet conditions during the 1970s, and relatively normal conditions since then. There was no obvious long-term trend. 

 (8c) What is the short-term trend? (10 year trend) 

The last 10 years have had highly variable flow. Between 2000 and 2009, river flow decreased from 34.34 to 30.84 BGD. 

(9c) What is the current status?

Total river flow to the Bay during the 2009 water year (October 2008-September 2009) was 30.84 billion gallons per day (BGD). This is 6.5 BGD less than 2008 and 17.56 BGD less than the 48.4 BGD average flow from 1938-2009. 

 (10c) What does this indicator tell us?

Flow to the Bay has fluctuated considerably in recent years. These changes in flow control pollutant loading and alter the salinity and stratification of the Bay. 

(11c) Why is it important to report this information?

Flow is a fundamentally important force shaping the conditions in the Bay and thus influence the water quality and habitat conditions for most species living in the Bay. 

(12c) What detail and/or diagnostic indicators are related to this reporting level indicator?

Detailed diagnostic indicators exist for this indicator although these indicators have not been linked to the flow indicator at this time.

C.  Temporal Considerations

(13) Data Collection Date(s): Water year 1938-2009

(14) Planned Update Frequency (e.g. - annual, bi-annual):

(a) Source Data: Monthly

(b) Indicator: Annual (water year)

(15) For annual reporting, month spatial data is available for reporting: Provisional water year data usually available by beginning of March.

D.  Spatial Considerations

(16) Type of Geography of Source Data (point, line polygon, other):

(17) Acceptable Level of Spatial Aggregation (e.g. - county, state, major basin, tributary basin, HUC):

(18) Are there geographic areas with missing data?  If so, where?

(19) The spatial extent of this indicator best described as:

(a) Chesapeake Bay (estuary)

(b) Chesapeake Bay Watershed

(c) Other (please describe): _______________________

Please submit any appropriate examples of how this information has been mapped or otherwise portrayed geographically in the past.

(20) Can appropriate diagnostic indicators be represented geographically?

E.  Data Analysis and Interpretation

(Please provide appropriate references and location of documentation if hard to find.) Bue, C.D., 1968, Monthly surface-water inflow to Chesapeake Bay: U.S. Geological Survey Open-File Report, Arlington, Va., November 1968, 45 p.

(21) Is the conceptual model used to transform these measurements into an indicator widely accepted as a scientifically sound representation of the phenomenon it indicates?  (i.e., how well do the data represent the phenomenon?)  YES

(22) What is the process by which the raw data is summarized for development and presentation of the indicator?   Historical daily values of streamflow are summarized into annual and monthly indicators.

(23) Are any tools required to generate the indicator data (e.g. - Interpolator, watershed model)

(24) Are the computations widely accepted as a scientifically sound? YES

(25) Have appropriate statistical methods been used to generalize or portray data beyond the time or spatial locations where measurements were made (e.g., statistical survey inference, no generalization is possible)?  

(26) Are there established reference points, thresholds or ranges of values for this indicator that unambiguously reflect the desired state of the environment? (health/stressors only) 

F.  Data Quality

(Please provide appropriate references and location of documentation if hard to find.)

(27) Were the data collected according to an EPA-approved Quality Assurance Plan?  

If no, complete questions 28a – 28d: According to USGS documented methods and quality assurance practices

(28a) Are the sampling design, monitoring plan and/or tracking system used to collect the data over time and space based on sound scientific principles? YES

(28b) What documentation clearly and completely describes the underlying sampling and analytical procedures used?  

(28c) Are the sampling and analytical procedures widely accepted as scientifically and technically valid? YES

(28d) To what extent are the procedures for quality assurance and quality control of the data documented and accessible? Web available

(29) Are the descriptions of the study or survey design clear, complete and sufficient to enable the study or survey to be reproduced?  YES

(30) Were the sampling and analysis methods performed consistently throughout the data record? YES

(31) If datasets from two or more agencies are merged, are their sampling designs and methods comparable?

(32) Are uncertainty measurements or estimates available for the indicator and/or the underlying data set? NO

(33) (Do the uncertainty and variability impact the conclusions that can be inferred from the data and the utility of the indicator?

(34) Are there noteworthy limitations or gaps in the data record?  Please explain.

G.  Additional Information

(optional)

(35) Please provide any other information about this indicator you believe is necessary to aid communication and any prevent potential miss-representation.

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