Watershed Basics Outline Bottom Line: One-Page Summary

Outline “A river is the report card for its watershed.” ‐ Alan Levere • Definition and examples of watersheds • Why watersheds are important; Watershed Basics Fundamental/Enduring understandings • How watersheds are affected by man/nature ADEQ SW Short Course • How to find watershed boundaries June 13, 2013 Phoenix, AZ

Bottom line: one‐page summary What comes to mind when you hear “Watershed”? The Continental Divide is a line that separates waters that flow into the Atlantic Ocean or Gulf of Mexico from those that flow into the Pacific • Think “draining water” when you see/hear Ocean. It runs north‐south along the crest of the Rocky Mountains (in Mexico and Canada too) and is sometimes called The Great Divide. “watershed” • Importance: We all live in a watershed ‐ Watersheds aggregate upstream flows • Many events result in “flashier” post‐impact hydrographs • Use drainage networks or drainage divides to map a watershed

ADEQ SW Short Course The University of Arizona © 2013 3 ADEQ SW Short Course The University of Arizona © 2013 4 www.nationalatlas.gov/ condivm.html Major Rivers Watershed Definitions Major Western Rivers & River Basins in Arizona • The area that produces runoff to a downstream point (Handbook of Hydrology)

Columbia Yellowstone • A region draining into a river or lake (Am. Heritage Dict) Snake Klamath Sacramento • The area contained within a Platte drainage divide above a San Joaquin specified point on a stream (Dict. Of Geologic Terms) • A drainage basin that divides the Rio Gila Grande landscape into hydrologically defined areas. (Environment Canada) WYN2K: WS are often named after rivers ag.arizona.edu/watershed/

Drainage Divide Drainage Basin Valley •A region or area bounded by a drainage divide and occupied by a • An elongated lowland between drainage system; ranges of mountains, hills, or •Specifically, an area of land that other uplands, often having a gathers water that starts as river or stream running along precipitation, which then runs off the the bottom. land into a stream channel or system • An extensive area of land of channels, or to a lake, reservoir or other body of water. drained or irrigated by a river system. deutschverderber.wordpress.com •The original meaning of the term • A depression or hollow signifies a “water parting” or the line, resembling or suggesting a valley ridge, or summit of high ground valley, as the point at which separating two drainage basins. two slopes meet.

Source: Glossary of Geology, 3rd Ed.,1987, AGI http://www.alpinezone.com/hiking/01images/older/KNIFEDGE.jpg ADEQ SW Short Course The University of Arizona © 2013 7 ADEQ SW Short Course The University of Arizona © 2013 8 States’ contributing area to Watershed Colorado River flow Synonyms:

Basin Upper Basin • CO Catchment • WY Catchment Area • NM Catchment Basin • UT Drainage Area Lower Basin USBR, 2000 Drainage Basin • AZ Watershed • NV • CA Valley

Which of the following is the best Importance: We all live in a watershed description of a watershed? Watersheds are: A. protected upland areas that supply water to cities and towns. B. mountainous regions that receive snow, which melts into streams as temperatures warm. C. based on rivers and valleys. D. areas that produce runoff to a downstream point. Watershed Visualization: Module 2 web.sahra.arizona.edu/hwr203/wsviz ADEQ SW Short Course The University of Arizona © 2013 11 ADEQ SW Short Course The University of Arizona © 2013 12 Watersheds –what you need to know Watersheds –what you need to know 1. Watershed: a region that drains into a river or lake, and is 2. Components and processes of a defined by high points in the watershed include: soil, topography surrounding the vegetation, topography, land area. cover, land use, partitioning of - Sub-watersheds are smaller precipitation betw. runoff and areas nested within a larger recharge, stream flow, flooding, watershed (or “basin”). atmospheric exchanges, drainage patterns, erosion, deposition, ecosystems/ biomes and settlement patterns.

www.hydro.washington.edu/Lettenmaier/Models/VIC/index.shtml

Watersheds –what you need to know Watersheds –what you need to know

4. Watershed management is 3. Watershed management is complicated because of physically complex the many ways it affects because of the many each of us and interacts interactions of its different with culture, economics, systems, where a change in politics, social constructs, one part will affect the scientific studies and dynamics of the entire aesthetics. system. 5. Some water users or stakeholders within a watershed include urban, rural, agricultural, forestry, business & industry, energy, recreation, fish and http://www.des.ucdavis.edu/faculty/lubell/Teaching/WaterPolicy/WatershedScoping_files/image002.gif wildlife and earth systems.

6. Watersheds provide valuable 7. Watersheds change over time ecosystem services, such as: water both naturally (e.g. flooding, storage & purification, flood fire) and because of mitigation, habitat, climate anthropogenic (human) causes regulation, carbon cycling, timber (e.g. damming a river, water products and recreation. rights, water withdrawals).

Which of the following is the best How are Watersheds Affected by… reason to foster watershed protection? Natural impacts A. Watersheds are interconnected systems that funnel upstream impacts toward • Fire downstream users. – following slides B. Watersheds provide many ecosystem • Drought services that are easily degraded. – decreases runoff – increases susceptibility C. We all live in a watershed. to invasives and pests

D. All of the above • Bark beetle John McColgan (USFWS, 2000) – increases above impacts

• Interception • Photosynthesis • Radiation Effects ‐ shading • Evapo‐Transpiration (ET) • Infiltration • Soil Moisture (SM) Storage • Decomposition • Soil formation • Deep recharge • Surface flow / runoff (erosion/deposition) • Land surface / topography • Land cover / Land use • Habitat / Biomes

Post‐fire Runoff Runoff Magnitude and Timing Garden variety storms can Hyetograph produce post‐fire Stalagtite--Stalagmite debris flows. slide

LOSS OF Rainfall peak COVER Time lag Runoff Peaks for Unburned and Burned Hydrograph from Hydrograph from RAIN SPLASH burned watershed unburned watershed IMPACT & “flashy” SURFACE SEALING

WATER REPELLENCY & INCREASED CONNECTIVITY

ADEQ SW Short Course The University of Arizona © 2013 23 Rainfall Rate of Runoff or ADEQ SW Short CourseTime The University of Arizona © 2013 24 Slide: Youberg/S. Cannon & D. Martin Slide: Youberg/Deb Martin, USGS Miller Canyon, Post‐Aspen Fire Flood in Romero Canyon 10 July 2011

Post‐fire debris • Hydrologic Modelling debris flows initiate scour to in channels on bedrock in flows: steep, severely larger • intense runoff – Largest Predicted Qp100 (COT) 6,500 cfs burned hillslopes channels • channel bank • Aerially reduced 100‐yr, 1‐hr rainfall depth = failure 2.53 “/hr (M. Zeller) • channel scour – Indirect Discharge Estimates deposit coarse boulder fans • HEC‐RAS from 5 surveyed cross‐sections • Qp 8,000‐10,000 cfs Since 1977, the main channel reloaded enough to produce

sediment for debris flows in 2011. Modified from House, P. K . , and Baker, V.R., 2001, Paleohydrology of flash floods in small desert watersheds Slide: A. Youberg, AZGS in western Arizona: Water Resources Research, v. 37, p. 1825‐1839. ADEQ SW Short Course The University of Arizona © 2013 25

Wildfire Effects on Aquatic Environments How are Watersheds Affected …

‐increased solar radiation Anthropogenic impacts • Logging ‐increased water temperatures – loss of canopy = heating – loss of interception ‐change in water chemistry including – greater erosion ASH • Urbanization ‐increased erosion and – less infiltration sedimentation – faster peak flow • ‐ increased water yields Mining – water quality impacts – suspended sediment Example from the 1996 Buffalo Creek Fire – air quality impacts Slide from Bob Gresswell, USGS ADEQ SW Short Course The University of Arizona © 2013 28 Urbanization ‐ Tucson How are Watersheds Affected …

Climate Change • warming, drier • greater ablation –less snowpack • earlier runoff –before greatest need • lower runoff –water Impact: supply disruptions • greater water demand • increased RO • less hydro power • WQ degradation McCabe and Wolock, Geophysical Research Letters, 2007 ADEQ SW Short Course The University of Arizona © 2013 29 ADEQ SW Short Course The University of Arizona © 2013 30 Gallo, SWH, Jan 2010

What separates watersheds? Drainage Networks How can you identify watershed boundaries?

fractalfoundation.org/images/photo /3251420948/river‐drainage‐network.html

1) Drainage Divides 2) River Networks 3) Contour Lines boto.ocean.washington.edu/gifs/purus.gif Reynolds and Johnson daac.ornl.gov/LBA/guides/CD06_CAMREX.html

Hydrologic Unit Code (HUC) Stream Classification scheme

Strahler number

en.wikipedia.org/wiki/Hydrological_code

Watershed Sub‐watershed USGS Watershed Classification Stream Gauge Classification

2 digit –Major River basin; 6 digit – Downstream order

HUC: HUC: 14-15 1401-1508

ADEQ SW Short Course The University of Arizona © 2013 35 ADEQ SW Short Course The University of Arizona © 2013 36 Tell me how comfortable you are Seeing Watersheds Activity working with contour maps? 1: Trace the main channel of the river from its mouth A. I dream in 3‐D. to the headwaters. 2: Trace the major tributaries (start at the coast/Gulf). B. I regularly use contour maps in the field. 3a: Find the drainage divides by marking a dot above C. I can read a map, but contours make be the top of each river, midway to the adjacent queasy. watershed. 3b: Connect the dots (start at the mouth) to form the D. My spouse does all the navigating (or asks for watershed boundary. directions) 4: Identify sub‐watersheds of major tributaries

WYN2K: a watershed boundary only crosses a river at its lowest point.

Lets review a few features of contour maps and then apply this to finding watershed boundaries …

Contour Lines ‐ Valley 1) Identify outlet/gauge point

“V”’s pointing “V”’s pointing up hill down hill

river Drainage divide

4) Identify lower tributaries 5) Continue tracing drainage divide

“V”’s pointing “V”’s pointing up hill down hill

river Drainage divide

ADEQ SW Short Course The University of Arizona © 2013 47 ADEQ SW Short Course The University of Arizona © 2013 48 6) Move downhill from ridge to gauge Outlining Watersheds ‐ Summary • Identify gauge point –lowest area • Identify river valleys –low areas • Identify drainage divides lines –high areas “V”’s pointing down hill • Identify lower tributaries for clarification • Continue tracing drainage divide Drainage divide • Move downhill from ridge to gauge • Watershed boundaries only cross the stream at one point (lowest elevation)

Example 2 –Try it! Example 2

• Think “draining water” when you see/hear “watershed” • Importance: We all live in a watershed ‐ Watersheds aggregate upstream flows • Many events result in “flashier” post‐impact hydrographs • Use drainage networks or drainage divides to map a watershed