Assignment 3 – Hydrosphere

Name _________________________________

GEO 200: Introduction to Physical Geography

Assignment 3 – Hydrosphere

Hydrologic Cycle

Water transfers between global storage areas through the processes of evaporation, advection (horizontal transport), precipitation, and surface runoff in the hydrologic cycle. The majority of evaporation occurs over ocean basins, while over landmasses, the loss of water to the atmosphere occurs through evapotranspiration (the combination of evaporation and transpiration).

Water vapor remains in the atmosphere for only a period of hours or days, but during this period, water vapor can be advected considerable distances before precipitation to the surface. The processes of evpotranspiration and precipitation balance globally, but not at smaller spatial scales. Precipitation exceeds evapotranspiration over continents, and evaporation exceeds precipitation over oceans.

Image: The hydrologic cycle processes and storage zones.

Table: Percentages of Global Precipitation and Evaporation Over Oceans and Continental Surfaces.

	Surface Area	Precipitation	Evaporation/Transpiration
Oceans	71%	77%	84%
Continents	29%	23%	16%

Once precipitated to the surface, the water can remain in storage at the surface in water bodies or snow pack, transfer as surface runoff, or infiltrate into the soil. Infiltration recharges the soil moisture and groundwater supplies. Soil moisture is the water available in the zone of aeration for agricultural purposes, and groundwater is water available in the zone of saturation often used as a freshwater supply.

Image: Subsurface zones of moisture storage.

Consider the information on the hydrologic cycle, and answer the following questions.

Describe the potential impacts to the hydrologic cycle transfer processes and/or storage areas from the following situations:

1. Deforestation

2. Urbanization

3. Warmer global temperatures

4. Colder global temperatures

Infiltration

Rates of infiltration into the soil are controlled by the porosity and permeability of the soil. Porosity is the amount of pore space between particles, and is controlled by particle size and any moisture present in the soil from prior precipitation events. Permeability is the rate at which water will move through the soil, and is controlled by soil type. Soils that are sandy will be more permeable than soils that are primarily clay, and hardpan surfaces such as deserts or urban surfaces covered by concrete or asphalt are extremely impermeable. The porosity and permeability relationship can be assigned an infiltration value according to surface conditions and moisture already present in the soil. The lower the infiltration value, the faster the water will infiltrate the soil.

Table 1: The Relationship Between Surface Conditions and Infiltration (Adapted from J.R. Mather: The Climatic Water Budget in Environmental Analysis).

Surface Conditions	Infiltration Value:Dry Soil	Infiltration Value:Saturated Soil
Sandy Beaches	5	13
Active Agriculture, Golf Courses, Urban Parks	21	59
Fallow Agriculture, Ponderosa Pine Forests	59	89
Urban Areas, Deserts	81	97

If the amount of precipitation received during a rainfall event exceeds the rate at which water can infiltrate the soil, runoff and the potential for flooding increases. Flash flooding can occur quickly in urban areas where hard surfaces act as conduits for runoff. The time between peak rainfall and peak stream discharge is greatly reduced.

Table 2: The Relationship Between Infiltration and Amount of Daily Precipitation Needed to Produce Runoff (Adapted from J.R. Mather: The Climatic Water Budget in Environmental Analysis).

Infiltration Value	Amount of Daily Precipitation Neededto Produce Runoff (inches)
100	0
95	.10
90	.27
85	.36
80	.50
75	.67
70	.86
65	1.07
60	1.33
55	1.64
50	2.00
45	2.44
40	3.00
35	3.72
30	4.66
20	8.00
10	18.00
5	38.00

Consider the relationship between surface conditions and potential for runoff, and answer the following questions.

5. Which surfaces and soil saturation levels have the largest infiltration values (meaning that very little precipitation is needed to produce runoff)? Refer to Table 1 and list the surface types and the values for dry and saturated surfaces.

6. How much daily precipitation is required to produce runoff on the surfaces that you listed in question 5? Refer to Table 2.

7. Explain why urban environments are susceptible to flood events.

8. What happens to precipitated water during a rainfall event if there is not enough daily precipitation to produce runoff?

Coastal Processes

Coasts are highly susceptible to geomorphic change from water and wind. Globally, these locations support substantial components of the leisure and transportation industries; millions of people live along coastlines. Identifying the physical processes at work in coastal locations assists in the proper management of these valuable yet vulnerable resources.

The idealized profile of a beach provides a baseline for studying change in coastal environments. The backshore is usually only impacted by large storms, the foreshore is affected by daily tidal action, and the offshore is the outer extent to wave action.

Image: An idealized beach profile.

9. Which portion of the shore is subject to daily erosion and deposition?

10. Where is the best place to put your beach towel and cooler during your all-day beach trip?

Refer to the Provincetown, MA quadrangle.

11. What type of depositional landform is Long Point?

12. What is the direction of the longshore current along Long Point? What physical evidence supports this conclusion?

a. The current is moving from ___________ to __________.

b. The evidence is:

Refer to the Point Reyes, CA quadrangle. It will also be helpful to refer to Point Reyes using Google Earth or Google Maps.

13. Give the name of a barrier spit on the map.

14. List the name of one lagoon and one estuary on the map.

15. If you were in a small boat near Point Reyes, would you consider docking your boat at Chimney Rock, or at Limantour Beach? Explain your preference.

Fluvial Geomorphology

Refer to the topographic map of Philipp, MS.

16. Describe the topography in this area (is it flat, hilly, mountainous?).

17. What is the geomorphic term for Hampton Lake?

18. Describe the process that formed Hampton Lake.

19. The Tallahatchie River exhibits what form of channel (braided, meandering, or straight)?

Refer to the City of Alexandria flood map provided for the Old Town area.

20. According to the legend in the upper-right corner of the document, the blue-dotted areas are Special Flood Hazard Areas, subject to:

21. How often, statistically, would you expect these areas to be subject to flooding?

22. Describe the location of, or name the areas of Old Town that are designated as SFHAs. Are any homes located in these areas?

Glacial Processes

Refer to the topographic map of Mount Rainier and the Google Earth or Google Maps image of Mount Rainier.

23. Where is Mount Rainier located (which US state)?

a. What type of landform is this mountain?

b. What is the tectonic significance of this location?

24. What is the geomorphic term for Success Cleaver?

25. What is the geomorphic term for the landform named Sunset Ampitheater?

Refer to the topographic map of Jackson, MI.

26. Locate and identify by name the prominent esker on the map.

27. What is the elevation of the esker?

28. What is the geomorphic term for Green Lake, Hammer Lake, and Peter White Lake? Describe how these lakes formed.

29. What is the name for the drainage pattern that is visible on this landscape?

30. Is this area well or poorly drained? Explain your answer.

31. Were these features formed by an alpine or continental glacier?

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