1. What Physical Variables Might We Measure?

2. Some Ideas
Flow
Discharge
Substrate
Temperature
Light

3. What’s the Hydrologic Cycle?

4. The hydrological cycle: What is it?
The next few slides provide a review the basic processes in the hydrologic cycle. Students need a basic understanding of the common terms and processes.
Basic Components
Precipitation & Condensation
Rain, dew, snow, frost, hail
Interception
- Interception loss is directly correlated to LAI, which determines the interception storage capacity.
- Intercepted rain may evaporate directly from vegetation and never reach the ground.
- Intercepted snow may sublimate. Usually 50-60% is redistributed to the ground.
Evaporation
Most from seas
Concentrates salts
Transpiration - Water in soil is absorbed by roots of plants and transported out of the plants from stomata. These are cells found on the back of leaves. It is a natural by-product of photosynthesis. and accounts for ten percent of the water evaporation on earth. (
Through plants, not always significant
Evapotranspiration- Water that evaporates from soil and vegetation. (
Infiltration - A process in which water enters the soil. (
Source of pollution
Filtering mechanism
Percolation - Vertical and lateral movement of water through spaces between soil and rock layers caused by gravity. (
Downward flow to water table, relatively fast
Run-off (overland flow)
Moved by gravity in surface channels or depressions
Interflow- Lateral movement of percolated water. Some water that is precipitated seeps through soil and continues to follow the slop. This water is eventually discharged into a river, stream, or lake. (
Groundwater Recharge- Some of the water that precipitates will flows on the ground surface (surface runoff) or seeps through soil first, then flows laterally (Interflow), and some continues to percolate deeper into the soil. This body of water will eventually reach a saturated zone and replenish or recharge groundwater supply. (
-> has some simple animated slides of each process

5. The hydrologic cycle: Active model
Precipitation, infiltration, groundwater flow and discharge to a surface water body

6. The hydrologic cycle: Water cycle active model
The water cycle includes:
Precipitation events: rain, fog, mist, snow
Infiltration and ground and surface water flow events with eventual discharge into creeks and rivers
Intercepting this process is the vegetation process of root adsorption
Water enters back into the atmosphere in the form of water vapors through transpiration (plants) and evaporation
Vapors condense, form clouds, and result in another precipitation event
Animation from:
AGAIN - The water cycle includes:
Precipitation events: rain, fog, mist, snow
Infiltration and ground and surface water flow events with eventual discharge into creeks and rivers.
Intercepting this process is the vegetation process of root adsorption.
Water enters back into the atmosphere in the form of water vapors through transpiration (Plants) and evapotransporation (Water bodies)
Vapors condense, form clouds, and result in another precipitation event.

7. So we have plenty of water to drink right?

8. Distribution of water on earth
ga.water.usgs.gov/edu/charts/waterdistribution.gif
The amount of water in rivers at any one time is tiny in comparison to other storage volumes. Only 3% of the world’s total water occurs on land. The largest volumes of water found occur in ice caps and glaciers (2.8%), groundwater (0.61%), lakes (0.009%), the atmosphere (0.001%), and in rivers (0.0001%).
Distribution of water on earth

9. The hydrologic cycle: Global cycle
Graphic from C. Svendsen

10. Fig. 1. 1: Global Hydrological cycle
Fig.1.1: Global Hydrological cycle. Flows, in km3 yr-1 down arrows = precipitation up arrows = evapotranspiration
atmospheric transfer sea->land
runoff land -> sea

11. What does this slide mean about evaporation of water on land?

12. Fig. 1. 1: Global Hydrological cycle
Fig.1.1: Global Hydrological cycle. Flows, in km3 yr-1 down arrows = precipitation up arrows = evapotranspiration
atmospheric transfer sea->land
runoff land -> sea

13. What is a “watershed”?

14. Watershed definition Watershed:
An area of land that drains water, sediment and dissolved materials to a common receiving body or outlet
The term is not restricted to surface water runoff and includes interactions with subsurface water
Watersheds vary from the largest river basins to just acres or less in size
Emphasize that a watersheds can vary greatly in size. Each watershed describes an area that drains down slope to an arbitrarily selected waterbody at its lowest point. Every tributary, stream, river, pond, or lake has an associated watershed. Watersheds can usually be delineated using a topographic map.

15.
The concept of watershed is a very important one because it pertains to everyone. No matter where someone lives, they live in a watershed. A watershed (also called a drainage basin or a catchment) is defined as an area of land that intercepts and drains precipitation through a particular river system or group of river systems. In other words it is a region of interconnected rivers and streams which functions as a unified system for water transport. The term can be used with reference to a particular stream, river, lake or ocean.
Watersheds may be of various forms: a closed watershed empties into an inland body of water, whereas an open watershed drains to the ocean. A multiple open watershed empties into the ocean through more than one mouth. A watershed is defined topographically by break points or ridges (e.g., mountain crests) which separate it from the next watershed.
What is a watershed?

16. Watersheds

17. Organization of watersheds:
A divide represents the boundary of a watershed
Larger watersheds can often be divided into smaller units called subbasins, drainage areas, or water resource inventory areas
Divides can usually be identified from topographic maps.

18. Watersheds
(figure from found in 6/03)
Note how selection of a point defines the watershed in which that point is included. This point is located on a stream segment which is a section of stream channel that connects two successive junctions, a junction and an outlet, or a junction and a drainage divide.
As can be seen from this series of diagrams, several smaller watersheds identified for each stream segment (boundaries noted in read) make up the watershed drainage (noted in green) that contributes to our selected point.

19. What is your watershed?

20. Pocono drainage basins: Lackawanna (A) Delaware (B) Lehigh (C)

21. Brodhead Sub-watershed Drainage: 285 mi2
Marshalls
Upper Brodhead
Lower Brodhead
Paradise
Pocono
McMichael

22. Upper Brodhead Sub-watershed: Drainage area = 65.9 mi2 =170.68 km2

23. 1st - 1st point that stream flows year-round, typical year
2nd- where 2, 1st order streams merge
3rd - where 2, 2nd order streams merge
4th - where 2, 3rd order streams merge
Stream Order

24. What happens when a 1st order stream joins a 3rd order stream?

25. Watershed components Vegetation and impervious surfaces Latitude
Albedo
Climate
Geology
Topography
Land Use:
Vegetation and impervious surfaces
The divide defines a watershed, but these major categories of watershed components provide the context for the hydrologic cycle dynamics in a watershed. Each of these has a major impact on hydrologic events in a watershed. There are also important interactions among the components.

26. Which of these categories can humans most easily impact?

27. Watershed components: Latitude
Energy input into a watershed depends on solar height and length of daylight hours
Determined by the latitude and season
May 21, Seattle, WA solar altitude at noon is
January 21, Seattle solar altitude at noon is
Impact on Climate?
Graphic from C. Svendsen
Calculations can be performed according to:
The solar energy input to a region affects temperature, evaportranspiration, snow melt, and vegetation growth.
The dominant winds and weather also relate to latitude and the coriolis effect (earth rotational effect on wind patterns) on the atmosphere.
A = 90 + d – l
A – solar altitude at noon
d – solar declination:  23.45
l – latitude in degrees
For example:
May 21, Seattle, Northern Hemisphere, Solar Declination +20 :
A = 90 + 20 
Solar Altitude at Noon: 62.5
Jan 21, Seattle, Northern Hemisphere, Solar Declination -20 :
A = 90 - 20 
Solar Altitude at Noon: 22.5

28. Watershed components: Albedo
Albedo is the reflectance of a surface. The higher the reflectance the less energy input into a watershed.
Surface Cover
Albedo (%)
Water
5-10
Bare soil (light colored, dry)
20-35
Marsh and Bogs
15-20
Forest (dense spruce)
Forest (hardwoods in leaf)
Snow (fresh)
80-95
Snow (old)
40-70
The solar altitude provides one limiting factor for energy input into a watershed, but two areas watershed with the same solar altitude may still have very different energy input because of the albedo (surface reflectance). Students witness this difference in sunny situations when they compare the heat gained by a dark car versus a light one.
Diverse geographic locations also receive different amounts of cloud cover. Clouds decrease energy input from the sun (short-wave radiation), but reduces long-wave radiation from the watershed.

29. Albedo and Water Discharge and Albedo Turbidity Water Color
Angle of incidence

30. Watershed components: Climate
Temperature regime
Relative humidity
Precipitation patterns
Climatic regions can be mapped according to a variety of data.
The map on the left is based on heading degree days (HDD) and cooling degree days (CDD). It’s one indicator of climate as it affects people. [See
The EPA map “coverage was intended for displaying seasonal maps of precipitation and temperature in the National Water Summary series of reports.” A key to the zones can be found at

31. Watersheds: Average annual precipitation
Graphic from C. Svendsen
Precipitation is not distributed evenly across the country and seasonal distributions are also very uneven.
You may choose to discuss some of the reasons for variations – exp: the pacific Northwest with 250+ at the coast while areas on the lee side of the mountain ranges receive a magnitude less rain fall.

32. Watersheds: Potential evapotranspiration
Graphic from C. Svendsen
Evapotranspiration is affected by several factors: the solar energy captured by the land and vegetation, temperature, and wind.
E = c(es – ea)
E – evaporation
c = coefficient dependant on wind speed, surface roughness, and barometric pressure
es = saturated vapor pressure
ea = vapor pressure of free air
Transpiration
Generally, transpiration is directly correlated to Leaf Area Index LAI.
LAI – measured in: m2m-2
LAI of vegetation ranges from:
0.5 m2m-2 (range) – 12 m2m-2 (oldgrowth forest)

33. Watersheds: Water surplus or deficit
Graphic from C. Svendsen
Bruce – What is this deficit referring to? What determines the surplus or deficit? Some type of usage vs. recharge? Is this a water budget slide? Would this be better suited latter in the program? (before or after slide 68) or not at all?
Discuss what factors may cause the patterns of surplus or deficit in your specific region. What may cause the significant surplus in areas such as the Pacific Northwest? How about the deficits in southern California and Arizona.

34. Geology: seasonal variation in watershed runoff
Graphic from C. Svendsen
Discuss with the students which depiction of source area run off would represent each season based upon the previous slide.

35. Effect of climate
Rivers are very dependent on climate and their characteristics are closely related to the precipitation and evaporation regimes in their drainage areas.
Rivers are very dependent on climate and their characteristics are closely related to the precipitation and evaporation regimes in their drainage areas. Three main types of rivers have been distinguished:
(a) Perennial or permanent rivers have a constant flow of water (although there may be considerable seasonal variation in amount of flow) and occur in regions where precipitation generally exceeds evaporation (such as Canada).
(b) Periodic rivers may run dry occasionally but have streamflow during regular periods of variable duration. These occur in regions where evaporation exceeds precipitation on an annual average but periodically precipitation is greater.
(c) Episodic rivers only rarely and fleetingly have water in their channels. These occur in very arid climates (such as desert regions).

36. What impacts might climate change have?

37. Cross-section a). gaining stream, humid regions b)
Cross-section a) gaining stream, humid regions b) losing stream, arid regions

38. Watershed components: Geology
Bedrock
Type and distribution of soils
Depth, orientation (refers also to bedding plains and fracture zones), and type of bedrock material all significantly affect deep percolation, the water table, and groundwater flow.
Soils vary in their composition, particle size, and permeability. The type and distribution of soils affects infiltration, percolation, runoff, and sediments generated. Discuss differences in soils and bedrock that can be observed in your region.
Photos:
1.) Note the fault zone in the center of the photo on the left – beds are oriented vertically on the left side of the photo and at a 45o angle on the right. How would this affect infiltration and groundwater flow?
2.) Photo on the left – comment on the thickness of the soil layer and factures in the basalt. What would effect flow in this case? Would you expect seepage and runoff at the interface of this unit? How would groundwater move through the basalt?

39. Geology: soil pore space and water content
Total porosity of a soil determines maximum water content at saturation
Soil Water Content
Also Determines Permeability
Photos from left to right:
1.)
2.)
Soil porosity (n ) is the % of rock or soil that is void of material and consists of both the following:
Textural Porosity (often referred to as primary porosity) or the spacing between arrogates or grains, and
Structural Porosity (secondary porosity) - represents voids with in the individual aggregates and includes factures in bead rock (for example a volcanic basalt, a dissolved limestone, or a high fractured granite will have a high secondary porosity).
n = structural porosity + textural porosity
Figures came from the following sources:
1.) - parking lot aggregate depicts size and poor spacing between particles (however in this case the voids have been filled with another material making the packing arrangement much less porous).
2.) - fractured limestone bedrock shows secondary porosity due to fracturing.
Porosity will determine the maximum water content at saturation. Soils at saturation generally refers to soils in the saturated zone, or beneath the groundwater table. Surface soils in the unsaturated zone or zone of aeration (above the capillary fringe) are seldom saturated, but could become so temporarily from infiltration (discussed in following slides 52 and on) due to a major melt, rain fall or flood event.
Porosity can be calculated by:
n = Vv / VT where: Vv = volume of the voids (both primary and secondary)
VT = TOTAL volume of the material (soil or bed rock) including the voids
ALSO:
n = ℮ / 1+ ℮ where ℮ is the void ratio and ℮ = Vv / Vs where Vs is the volume of the solid portion
℮ or the void ratio usually falls in the range of 0-3.
Porosity can also be calculated using a laboratory determined Bulk Density (defined below) as follows:
n = 1 – Db/2.65
Where: Db is the bulk density (defined below) in g/cm3
2.65 g/cm3 is an average practical density for most rocks and soils
Bulk Density = mass of dry soil per unit bulk volume gcm-3 or the weight of the dry soil (or rock) divided by the TOTAL volume VT, including the porosity

40. Geology: Soil permeability
The ease with which water penetrate or pass through a bulk mass of soil or a layer of soil
Photo 1 depicts a relatively loose and in turn porous soil horizon.
Photo 2 depicts a fat clay considered relatively impermeable.
Photo 3 depicts a conglomerate of well weathered bedrock which in turn would allow for significant infiltration through the poor spaces and along fractures and fissures.

41. Can Humans Impact Permeability, Porosity and Water Retention?

42. Watershed components: Topography
Slope
Aspect
Aspect refers to the direction faced by a slope. Elevation, latitude and climate interact to determine the type(s) of precipitation that most commonly affects a watershed.
“Topographic relief, or the slope and aspect of the land, has a strong influence on the distribution of soils on a landscape. Position on a slope influences the soil depth through differences in accumulation of erosional debris. Slope affects the amount of precipitation that infiltrates into soil versus that which runs off the surface. Aspect, or the direction a slope is facing, affects soil temperature. In northern hemisphere sites, south-facing slopes are warmer than those facing north. Differences in moisture and temperature regimes create microclimates that result in vegetational differences with aspect. Differences in weathering, erosion, leaching, and secondary mineral formation also can be associated with relief.” (
Slope and aspect are critical parameters in modeling runoff such as the Precipitation-Runoff Modeling System ( It uses basin characteristics such as slope, aspect, elevation, vegetation type, soil type, land use, and precipitation distribution.

43. Watershed components: Topographic interactions

44. Watershed components: Land use and vegetation
Slows runoff
Reduces soil compaction
Prevents soil erosion
Reduce soil material moving downslope
Influences timing of snowmelt runoff
Vegetation is affected by soils, climate, elevation, & topography. The hydrologic processes or interception and transpiration are affected by the types of vegetation present in the watershed. Grasslands and forests have differ in both interception and transpiration. Vegetation is a critical parameter in modeling the hydrologic cycle for a watershed.

45. Land use: Stormwater discharge vs. land use
Graphic from C. Svendsen
Discuss how the listed land uses (urban, ag, ag and forest, and forest affect vegetation). Why does an urban environment have the greatest discharge while forested the least (remember not only run off but the hydrologic cycle an processes such as interception and root adsorption in forests) How would the types of vegetation (or lack there of) in these areas effect the following discussed on the previous slide?
Slows runoff
Reduces soil compaction
Prevents soil erosion
Reduces pace of raindrop splash
Reduce soil material moving downslope
Influences timing of snowmelt runoff
Influences water yield

46. Watershed components: land Use
Graphic from Carl Richards
Discuss the effects of impervious surfaces and their role in the increase in not only runoff but evaporation.

47. Water on the Web
This presentation includes material from Water on the Web (WoW)
WOW Water on the Web - Monitoring Minnesota Lakes on the Internet and Training Water Science Technicians for the Future - A National On-line Curriculum using Advanced Technologies and Real-Time Data.
University of Minnesota-Duluth, Duluth, MN
Authors: Munson, BH, Axler, R, Hagley C, Host G, Merrick G, Richards C.
I would also like to thank Dr. Jewett-Smith for her contributions to this presentation