Watersheds

Fish 7380, Dr. e. irwin

Goals Review components of catchments Understand structure and function of

watersheds Faunal relations and/or ecological

processes Restoration and management: where are

the pressure points?

Why do we care? Watersheds provide boundaries for

management. Definition is possible: it makes sense to

manage on a waters.hed basis versus by political boundaries. Requires all land owners and water users in

watershedmultiple-use ecosystems

Definitions Watershed-any sloping land surface that

sheds water; more functionally-all land enclosed by a continuous hydraulic drainage divide and lying upslope from a specific point on a stream. USGS-HUCs (define)

Drainage divide

Topology Does a

watershed need water to be one?

Evolution of dynamic understanding RCC Watershed Landscapes Structure and function of multidimensional

systems ecological processes Human impacts versus natural variation

Anaxagoras of Clazomenenae (500-428 B.C.)

“Rivers depend for their existence on the rains and on the waters within the earth, as the earth is hollow, and the water in its cavities”

Function of a watershed=produce water Flow regime

Quantity (magnitude and duration) Timing (duration and frequency)

Quality-or nutrient budgets

Factors that control streamflow Climate Topography Geology Vegetation

Riparian-Upland interactions Most dynamic component of watersheds

Diverse areas; based on disturbance and heterogeneity of habitats

Riparian Function Dissipate flood energy Moderate drought Store surface waters Recharge ground water Moderate instream

temperatures Reduce erosion Add instream habitat diversity Transport corridors

Fish and wildlife Energy and materials Sediment

Riparian-River interactions Size and number of pools

LWD, boulders from upslope areas Regulate sediment inputs via riparian

vegetation

Riparian - Vegetation Function of climate, soils, topography and

land use Controls timing and amount of water yield Controls amount of soil for downstream

transport

Example 48 inches of rainfall (P); 1000 acre watershed

50% is realized as streamflow (48 x 0.5 =24 inches)

Total volume of water yield/year =2,000 acre feet (24 inches x 1,000 acres x 1 ft/12 inches)

Average discharge/year = 2.72 cfs (2,000 acre feet/year x 43,560 ft2/acre-ft x 1yr/365d x 1d/86,400 s)

US precipitation-annual average = 30 inches

4.75 billion acre-feet 3.4 billion (70%) lost to ET

3% lost consumptively, remaining 27% is streamflow In general, the % of precipitation resulting in

streamflow increases with increased precipitation. ET is the most constant variable in the water equation.

When requirement met, the rest is available for runoff. As elevation increases, runoff increases Water supply problems often are not related to water

quantity; timing is important

Channel morphology Strait river channel Meandering river channel

http://earthsci.terc.edu/content/visualizations/es1306/es1306page01.cfm?chapter_no=13

Braided river channel

Strait river channel

Braided river channels

Meandering river channels

Name that river…..

Erosion and sediment transport Sediment is a major product of watersheds

Important to measure Estimated 80% of WQ degradation results from

erosion Sediment interacts strongly with other WQ

components Sediment yield is directly affected by land use

activities Erosion is removal and sedimentation is

deposition

Types of erosion Surface Mass movement Channel cutting

Stream power = the rate at which a stream does work

Restore and protect = priority Importance of riparian zones outweighs the

minor proportion they comprise in the watershed.

National priority: NRC 1992 Broad perspective needed (watershed)

Scale? Must identify key ecological processes that

historically provided structure and function

Water balance equation P = R + ET + S

Where: P = precipitation during time interval t R = total water yield or streamflow at t ET = Evapotranspiration at t

S = storage as t , S approachs zero

Rearrange R = P – ET - S

ET

Transpiration and evaporation are difficult to measure

Equation for ET

The Etowah Regional Habitat Conservation Plan

The unique fish of the Etowah face an uncertain future as rapid development degrades their habitat. Federal regulations to protect the fish can impose costly delays and restrictions on growth. The solution is to develop a regional Habitat Conservation Plan that minimizes the impacts of growth, ensuring long-term environmental and economic health for the region.

http://www.etowahhcp.org/index.html

Counties:

Bartow County

Cherokee County

Cobb County

Dawson County

Forsyth County

Lumpkin County

Paulding County

Pickens County

Cities:

City of Canton

City of Cartersville

City of Dallas

City of Dawsonville

City of Emerson

City of Holly Springs

City of Kennesaw

City of Marietta

City of Roswell

City of Waleska

City of Woodstock

PartnersOther Agencies and Organizations:

Atlanta Regional Commission

Cherokee County Water & Sewer Authority

Chestatee-Chattahoochee Resource Conservation & Development Center

Etowah Water & Sewer Authority

The Georgia Conservancy

Georgia Department of Natural Resources

Georgia Land Trust

Georgia Mountains Regional Development Center

Georgia Regional Transportation Authority

Kennesaw State University

Lake Allatoona Preservation Authority

Limestone Valley Resource Conservation & Development Center

Mountain Conservation Trust of Georgia

The Nature Conservancy

U.S. Army Corps of Engineers

U.S. Fish & Wildlife Service

University of Georgia

Upper Etowah River Alliance