watersheds and the hydrologic cycle. the global hydrologic cycle

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Watersheds and the Hydrologic Cycle

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Page 1: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Watersheds and the Hydrologic Cycle

Page 2: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

The Global Hydrologic Cycle

Page 3: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Water Cycle in Florida

Page 4: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Florida Water Facts• Surface Area = 170,452 km2

• Average Rainfall = 140 cm (55”)– Total Annual Rain = 238 billion m3 (62.6

trillion gallons)• River and Stream = 51,858 miles• Largest River = Apalachicola (Q =

25,000 ft3/s = 22 km3/yr)• Lake Area = 12,100 km2 • Springs ~ 8 billion gallons/ day• Groundwater supplies 95% of water

– 7.2 billion gallons/day; 80% to S. Florida• Low relief – travel time for water

(rainfall to sea) can be decades

Page 5: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

The Hydrologic Check-Book• Mass Balance

– Water mass is conserved– Therefore: Water In = Water Out

• Sources– Rain, Snow, Groundwater, Human Effluent

• Sinks– Ground, River, Atmosphere, Humans

• Stores– Wetlands, Lakes, Rivers, Soil, Aquifers

Page 6: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

The Water Budget (Exam 1)

P= Q + ET + G + ΔSPrecipitation

Surface runoff

Evapotranspiration

Groundwater

Storage

INFLOW OUTFLOW

Page 7: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Rainfall (~ 140 cm)

Infiltration to Deep Aquifer (~5 cm, though upto ~ 40 cm)

Subsurface Runoff (~ 32 cm)

Interception (~ 30 cm)

Transpiration (~ 70 cm)

Annual Water Budget - Flatwoods

Surface Runoff (~ 3 cm)

Page 8: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Rainfall (~ 140 cm)

Infiltration to Deep Aquifer (~5 cm, in areas much higher)

Interception (~ 15 cm)

Transpiration (~ 80 cm)

Annual Water Budget – Ag Land

Surface Runoff (~ 20 cm)

Subsurface Runoff (~ 20 cm)

Page 9: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Rainfall (~ 140 cm)

Infiltration to Deep Aquifer (~ 2 cm)

Interception (~ 20 cm)

Transpiration (~ 50 cm)

Annual Water Budget – Urban Land

Surface Runoff (~ 60 cm)

Subsurface Runoff (~ 5 cm)

Page 10: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

In > Out ?

Out > in ?

In = Out ?

What if Inmeasured > Outmeasured

AND water level is falling?

Changes in Internal Stores• ΔStorage = Inputs – Outputs

– Usually easy to measure (e.g., lake volume)

Page 11: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Volume = Depth x AreaDepth = Volume / Area

Rules of Water Balances• Water balance terms must be in common units

– (usually meters depth over the watershed area). • Precipitation and ET measured in depth (m/yr)• Water flows measured as volumes (m3/yr).

Page 12: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Catchment Water Balance• Area = 100 ha (10,000 m2 per ha)• Annual Measurements:

– Rainfall = 2 m (tipping-bucket rain gage)– Surface outflow (Q) = 2,000,000 m3 (weir)– ET = 1.5 m (evaporation pan)– Groundwater = 1,000,000 m3 (shallow wells)– Assume ΔS=0

Page 13: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Budget: P= Q + ET + G + ΔS• Area = 100 ha; 1 ha = 10,000 m2

• P = 2.0 m• Q = 2,000,000 m3/(100 ha * 10,000 m2/ha)

= 0.2 m• ET = 1.5 m• G = 1,000,000 m3/(100 ha * 10,000 m2/ha)

= 0.1 m• ∆S = 0

• 2.0 = 0.2 + 1.5 + 0.1 + 0 (?!)

Page 14: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Watersheds

• A land area from which all rainfall drains to the same point.– The “watershed” is technically the divide between

two such areas (called basins)

Page 15: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Delineating Watersheds1. Identify

outlet point2. Identify

high points3. Link high

pts crossing contour lines at right-angles

1

2

3

Page 16: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

High-Relief Watersheds

Page 17: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Why Watersheds?

• Control boundaries– Water that falls either comes out the bottom or is

abstracted• Imagine a water budget if you weren’t sure

where the water was going…

P + Qin1 + Qin2 = Qout1 + Qout2 + ET + G1 + G1 + ΔS

Page 18: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Experimentation – Paired Watersheds• What is the

effect of forest management on:– Water yield– Sediment yield– Nutrient export– Water

temperature– Time of

transport

Page 19: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Paired Watershed Response

Page 20: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Paired Watershed Study of Forest Harvest Effects on Peakflows

Beschta et al. 2000 – H.J. Andrews Experimental Forest (OR)

LOGGING ROAD BUILDING

Page 21: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Does watershed delineation work in Florida?

• Low-relief– Delineation of boundaries

hard– In parts of Florida, water

flows depend on:• where it rained, • where the wind is blowing

and • where people put the

canals and roads• National contour maps

too coarse (5 ft)• Roads act as flow

delineators

????

Page 22: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

“Delineating” Watersheds in

Florida

Page 23: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Paired Watersheds in Florida

• Shown that (Riekerk 1983):– High intensity logging increased water yields by

250%– Low intensity logging increased water yields 150%– Clear cutting altered nutrient export rates– All forest operations (fire?) were less than

urbanization (much more on this later)

Page 24: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Stream Patterns

• Dendritic patterns follow Strahler Order– 1st order is unbranched– 2nd order occurs when two

1st order reaches converge– Increased order requires

convergence of two reaches of the same order

– What are springs?

Page 25: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Network Forms

• Regional landform dictates shape

• Regional geology dictates drainage density

• Regional climate (rainfall) dictates density and maturation rate

Page 26: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Stream Order Distribution

Page 27: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Watershed Networks• Mass transport is optimal at

minimum work– Reach and network scales at the

SAME time• Necessary conditions for

dendritic drainage– Minimal energy expenditure at

any link in the network– Equal Energy Expenditure per

unit area– Minimum Energy Expenditure in

the Network as a whole

Rodriguez-Iturbe et al. (1992) - WRR

Page 28: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Water Convergence Across Scales

- St Johns River Basin- Ocklawaha River Basin

- Orange Creek Sub-Basin- Newnans Lake Watershed

- Hatchett Creek Watershed- ACMF “Hillslope”

- Lake Mize catchment

Page 29: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Lake Mize hillslope Lake Mize

Conference Center

Page 30: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Austin Cary Forest

Waldo Road

HatchettCreek

LakeMize

Page 31: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Hatchet Creek Catchment

HatchettCreek

Page 32: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Newnans Lake

WatershedNewnans

Lake

Gainesville

Santa FeSwamp

HatchettCreek

Lake ForestCreek

PrairieCreek

Page 33: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Orange Creek Basin

NewnansLake

LochloosaLake

OrangeLake

PaynesPrairie

Page 34: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Ocklawaha RiverBasin

Orange CreekBasin

LakeApopka

RodmanReservoir

Ocklawaha River

SilverSprings

Page 35: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

St. Johns River Basin

(and Water Management

District)St. Johns River

Page 36: Watersheds and the Hydrologic Cycle. The Global Hydrologic Cycle

Next Time…

• Precipitation– Where it falls– When it falls– How it’s made– How we

measure it