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Setting the Course for I d W t Q litImproved Water Quality
Hydrology in y gyWatershed SystemsSystems
Photo by Don Berger Minnesota Pollution Control AgencySession 5A: A TMDL training program for local government leaders g p g f g
and other water resource managers wq-iw3-55a
Hydrology is one of many disciplines i l d i TMDL t di
cy
involved in TMDL studies
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S i l
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sciencesWater chemistry
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In this presentationcy
In this presentation
B i i i l f h d l
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Sources and pathways of
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Importance of hydrology to TMDL studies and water
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Watersheds integrate physical, h i l bi l i l
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chemical, biological processes
A watershed is an area
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genc A watershed is an area
of land that drains to a common pointTMDL t di
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tro TMDL studies use watersheds as the biophysical basis for
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p ywater quality planning and managementWatersheds integrate
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physical, chemical and biologicalprocesses
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This module
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What is “hydrology?”cy
What is hydrology?ol
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“The study of water in all its forms (liquid gas
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all its forms (liquid, gas, and solid) on, in and
over the land areas of
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n the earth” – Michigan DEQ
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Hydrology is important at a global regional or watershed scale
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Hydrologic processes affect water lit
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quality
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The movement of surface and
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delivery of pollutants
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n delivery of pollutants to waterbodies
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The hydrologic cyclecy
The hydrologic cycle ol
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c/o US EPA
Why is hydrology important to TMDL t di ?
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TMDL studies?
Hydrology is critical to
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an impaired waterbody, we must understand
Hydrology is critical to understanding the sources and movement
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tro we must understand watershed hydrology of water (and pollutants)
to a waterbody
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Addressing water quality problems in water bodies will require addressing hydrologic pathways
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(i.e. reducing surface runoff, increasing infiltration, etc.)
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Sources of water affecting t fl
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stream flow
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Precipitation is the major source of new Each watershed also
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major source of new water in watersheds
Each watershed also stores existing water
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Types of precipitation contributing t t t h d
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water to watersheds
i f ll
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drizzle
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frost
Precipitation affects the amountamount timing distribution
litquality of water moving through a watershed
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tro They can control land use decisions and human activities that can change how much precipitation is
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n how much precipitation is intercepted and stored in watersheds
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Water storage and t
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movementA watershed is essentially
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yan enormous precipitation collecting, storing and routing device
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Storage and movement of water within watersheds i l l
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n involves a complex combination of many smaller processes
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Infiltration and storage of precipitation minimizes surface runoff and reduce
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Water storage on earth can be t l d
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natural or man-made
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Depression storage
any natural or man-made surface where water collects and either seeps or evaporates (lakes wetlands ponds
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storage evaporates (lakes, wetlands, ponds, reservoirs, etc.)
Soil water water held within the soil
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Vegetation used by plants
G d t t t d ( if )
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Channel storage
water held within the channel (stream river ditch)
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– Adapted from Peter Block, 2002
Water movement in a watershedcy
Water movement in a watershedol
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tro involves a combination of surface and sub-surface processes
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Difficult to separate the various pathways of flow
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Water can move between sources
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Hydrologic pathways in a watershedy g p y
PrecipitationEvapotranspiration
ChannelSurface
ff Channel interception
runoff
Infiltration &subsurface Water
flow
Groundwater or base flow
table
Channel storage(stream flow)
or base flow
Adapted from Kenneth Brooks, et. al., 2003
Ground water recharge and di h i t h d
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discharge zones in watersheds
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Recharge the process of water soaking into the ground to replenish ground water aquifers
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Discharge a process by which subsurface water becomes surface water
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n becomes surface water
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Groundwater recharge zones ithi t h d
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within a watershed
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specific areas of a
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pwatershed
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The nature and timing of
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excessive water infiltration and percolation beyond plant roots
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Groundwater recharge and di h
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discharge zones
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ollu
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Groundwater discharge zones i t h d
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in a watershedTime needed for water to move from recharge
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gzones to discharge points can be minutes to years
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tro Groundwater discharging to surface waters is mostly unseen, but if observed, is typically seen as springs or seeps
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n seen as springs or seeps
Groundwater discharges to surface waters can greatly affect temperature dissolved oxygen
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and other characteristics of water which can affect aquatic life
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Drainage systems may impact the h f d if
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recharge of some deep aquifers
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Subsurface tile drainage
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lake
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Deep aquifer
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Surface / groundwater
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ginteractions in watersheds
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Surface water / groundwater i t ti
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interactionsGround and
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are often treated as
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tro treated as separate
systems –
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n yhowever, they are
inextricably They should
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They should be studied as an integrated
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Surface water / groundwater i t ti
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interactionsPathways of the interaction
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yare complexInteractions are neither
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tro constant, nor consistently separateGroundwater is the major
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n Groundwater is the major source of base flow in many Minnesota streams
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Groundwater / surface water interactions can lt i i i l i t hresult in gaining or losing stream reaches
GainingGaining LosingLosingGaining Gaining stream reachstream reach
Losing Losing stream reachstream reach
W bl
Water tableGro nd ater
Water table
Groundwater
Wetlands are an expression of ground-t d f t i t ti
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water and surface water interactions
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Photo: BWSR Photo: BWSR
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Photo: NRCS
Wetlands with unusual d t i t ti
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groundwater interactions
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c/o
Sco
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Bogs Fens
P h d
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Ground –water rich in calcium
Perched water table
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Summarycy
Summary
Hydrology concerns water in all its forms on, in
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Hydrology concerns water in all its forms on, in and over the land areas of the earth
The hydrologic cycle feeds flow in our streams
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tro The hydrologic cycle feeds flow in our streams, ultimately affecting water quality
W t t d t i l
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n Water storage and movement involves a complex combination of many processes
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Summarycy
Summary
Specific areas within a watershed serve as
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Specific areas within a watershed serve as recharge and discharge zones
Surface water in lakes streams and wetlands
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tro Surface water in lakes, streams and wetlands interacts with groundwater
B d t di h d l i th
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n By understanding hydrologic pathways, we can influence water quantity and quality
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Now what?cy
Now what?ol
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What do we do with that knowledge?
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Use the following modules and worksheets to h l d l j
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What’s next?cy
What s next?
Future modules will address other disciplines
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Future modules will address other disciplines related to watershed management:
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Biology
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Water chemistry
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(watershed assessment: land use, land cover, geography, soils, etc.)
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Final thoughtcy
Final thought
“A watch is complicated, but a
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p ,watershed is complex. Remove one gear from the thousands in a watch
and it predictably stops working
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and it, predictably, stops working. Pollute one river and the whole
watershed is likely to shift and change
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n y gin a thousand ways, but nobody can be quite sure if or when a toxic algal
bloom will appear in the lake ”
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- Dr. Judith Van HoutenUniversity of Vermont
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