1. Sources Quantities/ Flow rates Stream types Chemistry Temperature Habitat Kimmins 1996

2. - The land area that drains into a selected stream or water body - Can by very small or very large - Called catchments in much of the world - Usually based on surface topography: subsurface features may not mimic surface ones as far as drainage is concerned

5. Graphic method of measuring area Count the vertices within the area Each vertix represents the center of the area around it Scale 51 vertices

6. Graphic method for area Trace your watershed on vellum or other transparent paper Lay the area over graph paper with grids Count the number of vertices Use the scale on your map to figure out how much area one square of your graph paper represents Multiple the area of one square by the number of vertices you counted

7. Other measurement methods Can trace your watershed using a planimeter Can use GIS or other electronic methods if you have the data layers Can do a site survey with a level and rod

8. Watershed areas Area is a basic piece of information that one needs for many purposes, e.g., –Trees /area –Runoff / area –Soil nutrients / area –Watershed area defines the area that delivers water, sediment and nutrients to a water body; a river or stream is the usual transfer path

9. What is typically measured in watersheds and streams? Precipitation Soil infiltration rates Streamflow – quantity, timing, quality Organic and nutrient input to streams – LWD Sediment input to streams Shade and temperature of streams Biological communities Channel characteristics – slope, bank full width, substrate, pools, riffles

10. Soil Infiltration and Infiltration Rates Precipitation either enters the soil or runs off as overland flow Water enters the soil through pores; this water will move slowly through subsurface soil laterally to streams or go to deep seepage; water is cleansed and enters the stream slower and longer after a storm Impermeable surfaces will increase overland flow by preventing infiltration; this is a problem in many urban areas

11. How do we measure Infiltration? Ideally, use a double-ring infiltrometer with a constant head Need rings, timer, and volumetric water container Infiltration Rate= V / A * t where V = volume, A = area, t = time

12. Sample calculation: Area of center infiltration ring:100 cm 2 Volume of water added:500 cm 3 Time for infiltration: 1 min Infiltration Rate = 500 cm 3 / 100 cm 2 * 1 min = 5 cm min -1

13. A slightly simplified method is also often used: - Double-ring infiltrometer - Measure infiltration rate of a known volume - Repeat

14. What factors can affect infiltration results? - Porosity of soil, particularly of soil surface - Water content of the soil - Hydrophobicity - Possible sources of errors include those from equipment and technique: poorly installed rings leaking, compacting surface during installation, not determining when all water has entered the soil accurately….

15. Stream Measurements: Stream Type Discharge Rate (varies by precipitation, infiltration, overland flow, topography, bankfull width etc. Bottom substrate Large woody debris Channel characteristics Biology Temperature Chemical composition :

16. Water types in Washington S – shorelines F – Fish bearing Np – Non-fish bearing but perennial flow Ns – Non-fish bearing, only seasonal flow See http://www.dnr.wa.gov/sflo/frep/watertyping/ for more information

17. How do we measure how much water is in a stream? Volumetric measurements- –Work on very low flows, collect a known volume of water for a known period of time Volume/time is discharge or Q Cross-section/velocity measurements Dilution gauging with salt or dye Artificial controls like weirs

18. Stream Velocity – area method of discharge measurement By measuring the cross-sectional area of the stream and the average stream velocity, you can compute discharge Q = discharge (units are L 3 /t (volume/time) = V * A where Q is discharge V is velocity (e.g., cm/time) A is cross-sectional area (e.g., cm 2 )

19. Bankfull width Slide by Jeff Grizzel

21. Discharge Measurement Slide from U. Mass. Boston

22. Water surface Tape measure- horizontal location of measures taken from tape Velocity measured 0.6d from water surface (0.4d from bottom) Record x value (tape distance), y value (total depth at measurement site, and velocity at 0.6d Measurement represents mid-section of a polygon Velocity – Area method of discharge measurement

23. Equation for computing subsection discharge - q i Equation for computing q in each subsection X = distance of each velocity point along tape Y = depth of flow where velocity is measured V = velocity Q = total discharge = sum of q i

24. How many subsections? Ideally: Subsections should be at least 0.3 feet or ~0.1 m wide Each subsection should have 10% or less of total discharge Number of subsections should be doable in a reasonable amount of time

25. Photo from Black Hills State University

26. Float method of discharge measurement Gives good estimates when no equipment is available Use something that floats that you can retrieve or is biodegradable if you can’t retrieve it –E.g. oranges, dried orange peels, tennis balls

27. Float method of velocity measurement Three people are needed to run the float test. One should be positioned upstream and the other downstream a known distance apart, one in the middle to record data. The upstream person releases the float and starts the clock and the downstream person catches the float and signals to stop the clock. The recorder writes down the time of travel of the float. Velocity is the distance traveled divided by the time it takes to travel that distance. V = distance/time You should conduct at least 3 float tests and take an average velocity. With an estimate of cross-sectional area, discharge can be computed as Q = V * A where V is average velocity

28. Float Method surface velocity = distance / time average velocity = (0.8*surface velocity)

29. Channel Substrate Substrate size (particles that line the channel) is an important component of habitat Substrate size is important for fish habitat and macroinvertebrate habitat Changes in land use/land cover can change substrate size distributions

30. Substrate categories 1.Sand, silt, clay. <0.25" or <0.8 cm (smaller than pea size) 2.Gravel. 0.25" -1" or >0.8-2.5 cm (pea to golf-ball size) 3.Large Gravel. >1" - 3" or >2.5-7.5 cm (golf-ball to baseball size) 4.Small Cobble. [>3"-6" or >7.5-15 cm (baseball to cantaloupe size) 5.Large Cobble. >6"-12" or >15-30 cm (cantaloupe to basketball size) 6.Small Boulders. >12"-40" or >30cm-1.0 m (basketball to car-tire size) 7.Large Boulders. >40" or >1.0 m (greater than car- tire size) 8.Bedrock

31. Substrate expectations Pools usually have finer substrates –Velocity in pools is slower and finer particles settle out Riffles usually have coarser substrates –Velocity in riffles is faster and finer particles are swept downstream

32. Tomorrow: Go to a small stream at Ravenna Park: –discuss infiltration versus overland flow –measure infiltration rates in two different areas –look for evidence of overland flow –measure stream flow rates using flow method –measure cross sectional area of stream –record stream bank characteristics –record channel substrate characteristics –stream type? Everyone needs to be dressed appropriately for the weather and for standing in water—if you have rubber boots, wear them!