Characterizing Your Watershed: Chapter 7a e s ed C ap e

Estimating Pollutant Loads: Sections 8.1-8.2

www.fs.fed.us

Where We’ve BeenWatershed Characterization

1st Step: Gather existing data2nd Step: Fill data gaps3rd Step: Identify pollutant sources through data

l ianalysis

Goals of This SectionDiscuss methods for describing dataExamine data variabilityDescribe watershed features and activitiesLink features and activities to water qualityPrioritize issues for further analysis

Basic ProcessDescribe your dataStudy data variabilityExamine watershed featuresEstablish likely cause/effect relationshipsTarget needs for source load analysis

Summary StatisticsBasic descriptors of data can help you more easily notice trends

RRangeTendencyVarianceVariance

Rangewhat are the minimum and maximum values?maximum values?

www.epa.gov

Tendencywhat are the mean and median? Are these two values different?

www.syque.com

Variancewhat is the standard deviation or coefficient of variance?of variance?

www.mathstuff.com

Spatial VariabilityHow do data vary from one location tolocation to another?

TendencyTendencyRangeVariability

www.wunderground.com

Spatial AnalysisGives general location of water quality conditionsMay help locate areas of concern or important sourcesMay indicate impact from particular sources

Temporal VariabilityDo data vary across time?

L t hLong term changesSeasonallyDiurnallyDiurnally

www.sciencebuddies.org

Temporal AnalysisLong-term changes may be associated with development or other changes in land cover\land useuseSeasonal changes may be associated with climatic conditions vegetative cover seasonal flow changesconditions, vegetative cover, seasonal flow changes, temperature, or use of chemicals in the watershedDiurnal changes may be associated with point g y psources, temperature, or aquatic life

Climatic VariabilityAre changes in water quality associated withassociated with hydrologic events?Temperature?Low flow conditions?

www.crcwater.org

Similar ConstituentsDo some constituents show similar behavior?

Across locationAcross timeAcross climate

Si il it i di t th t th tit tSimilarity may indicate that these constituents come from similar sources

Land Cover and Land UseNatural and man-made landscape featuresfeaturesHow do they vary across locationacross locationHave they changed over time

?

www.tceq.state.tx.us

SoilsWhat soils are present in your watershed?I th l ti hiIs there a relationship between soil type and land cover/land use?land cover/land use?

www.tx.nrcs.usda.gov

TopographyHow does elevation change across your watershed?watershed?

Where are slopes steeper?pWhere are flatter areas located?

www.wru.umt.edu

Point Source LocationsWhere are point source discharges located within yourlocated within your watershed?

www.migrate6.kinetic.more.net

Personal ObservationsVisually inspect the watershed– do you see any potential problems?GGather stakeholder input– are there concerns about water quality issues?Historical perspectives how has the watershedHistorical perspectives– how has the watershed changed over a long period of time?

ComparisonsWhere and when are problems occurring?How do your data compare to watershed

?characteristics?Land cover and useSoils and topographySoils and topographyLocal knowledge

Can you identify points/activities in the watershedCan you identify points/activities in the watershed that warrant additional study?Can constituents with similar sources be grouped?g p

Next StepsDo you need additional data to draw conclusions? Data gathering is often iterative

fYou may be able to focus additional data collection on potential areas of concernAreas of concern also can be a focus for estimationAreas of concern also can be a focus for estimation of pollutant loadsAreas of concern may also help you identify anAreas of concern may also help you identify an appropriate scale for BMP implementation