AE 822.3 Soil Hydrology of Semi-Arid Environments
Charles Maulé (Rm 1A01, ext. 5306)
Course Description: The course will provide the student with an working understanding of
processes within the soil hydrological system with specific reference to, but not limited
to, semi-arid environments. The soil hydrological system is physically defined by the
plant, from the canopy to the bottom of the root zone. Proper study thus includes the near
surface atmosphere (its effect upon evapo-transpiration) and the groundwater regime (its
role in transport away and to the soil system). Examples from field investigations will be
used to realize the hydrological processes. Field instrumentation and computer
simulation techniques will be covered.
Semi-arid essentially refers to a climatological region where there is a water deficiency
(evaporation is greater than precipitation) yet it is not severe enough that plant growth is
severely inhibited such as within desert regions (arid regions). Natural vegetation of
semi-arid regions is normally that of grass. Drylands go by many names: plains, prairies,
grasslands, savannas, steppes or pampas. These regions have formed the ‘breadbasket’ of
earth’s population because here many grain crops are possible. Dryland farming is
possible in these regions, however moisture conservation methods or irrigation are often
necessary for production of economically successful crops. The deficit and the
importance of moisture has significant and controlling roles in common problems
encountered within these areas: drought, salinity, groundwater use, and contamination
due to inappropriate management.
Objectives:
1. Develop a conceptual understanding of transport and storage processes within the
soil hydrological system.
2. Obtain familiarization with soil hydrology field instrumentation techniques.
3. Develop the ability to construct hydrological simulations.
Marking: Module exercises (4-7) 30%; Course project 30%; Final exam 40%
Course project: Detailed review or analysis of a soil hydrological process as applied to a
specific problem. Projects can utilize literature review, field data, laboratory and/or
computer simulation methods for problem analysis. Specific topic to be decided upon
consultation.
Course reference material:
Reading material will generally entail journal articles. Having access to a general
hydrological, groundwater, and/or soil physics textbook will help your understanding.
Tentative Course Outline (depends upon student’s background and interest)
MODULE 1; Introduction
Week 1
Establishment of basic terminology and units used in soil physics, agricultural
meteorology, hydrology, and hydrogeology. Course overview.
MODULE 2; Atmospheric System
Weeks 2-3
Potential evaporation; temperature; water vapour; latent heat of vaporization,
vapour pressure, psychrometric constant, wind, radiative exchange, total
energy balance. Combined equation, Thornthwaite, Baier-Robertson,
measurement. Precipitation; amount, form, spatial and temporal distribution
intensity, effective amount. Climate classification:
Exercise:
1. Potential evaporation models.
Exercise:
2. Monthly Soil hydrological balance.
MODULE 2; Soil System
Weeks 4-8
Soil moisture; content, energy, active zone. Infiltration; measurement and
simulation, frozen and unfrozen conditions, land management effects.
Redistribution and drainage; macroporosity, preferential flow, retention,
solute transport. Evaporation; soil water conservation. Measurement
methods; instrumental, interpretation, analysis, and simulation.
Exercises:
3. Review; Soil moisture methods.
4. Unsaturated flow representation
MODULE 4; Groundwater System
Weeks 9-11
Transport between soil and groundwater systems. The vadose zone. Effect of
seasonality, episodic events, winters. Solute movement.
Exercise:
5. Recharge and solute movement.
MODULE 5; Case Studies
Weeks 12-13
Topics to be decided in conjunction with class but would possibly include:
Soil moisture conservation techniques for dryland agriculture. Conservation
tillage systems. Climate change. Drought forecasting. Desertification.
Climate change. Sustainable water utilization. Economic and social
importance of water in semi-arid environments
Exercise: 6. Discussion and critique of selected readings
ABE 822. Reading List (Jan – April 2003)
1.
Introductory Lectures; Semi-Arid Hydrology
Rodier, J.A. 1985. Aspects of Arid Zone Hydrology, Chap 8, pp 205-226, note this is not the complete
chapter. In: Facets of Hydrology, Volume II, J.C. Rodda (ed.).
Dan, J. 1973. Arid-Zone Soils. Chapter 2 In: Arid Zone Irrigation. B. Yaron, E. Danfors, and Y. Vaadia
(eds.). Springer-Verlag. pp. 11-28.
2.
Precipitation Lecture;
McKay, G.A. 1964. Relationships between snow survey and climatological measurements for the Canadian
Great Plains. Proceedings of the Western Snow Conference, Nelson, B.C. April 21-23, 1964, pp 9-18.
Eltahir, E. A.B. and R.L. Bras. 1996. Precipitation Recycling. Reveiws of Geophysics 34 (3): 367-378.
3.
Potential Evaporation
Evapotranspiration, BIORE 898 Notes. D. M. Gray. 1996? Division of Hydrology, University of
Saskatchewan.
Granger, R.J. 1989. An examination of the concept of potential evaporation. J of Hydrology 111: 9-19
Baier, W. and G.W. Robertson. 1965. Estimation of latent evaporation from simple weather observations.
Can. J. Plant Sci. 45:277-284.
4.
Water Balance and climate
Strahler, A.N. and A.H. Strahler. 1983. The soil-water balance and world climates, Chapter 10. In: Modern
Physical Geography, pp 154-173.
De Jong, R and A. Bootsma. 1988. Estimated long-term soil moisture variability on the Canadian Prairies.
Can. J. Soil Sci. 68:307-321.
5.
Soil Moisture, Content and Potential; Methods of Measurement
TBA
6.
Soil water flow; basic principles
Rawls, W.J., L.R. Ahuja, D.L. Brakensiek, and A. Shirmohammadi. 1993. Infiltration and soil water
movement. Chap 5 In: Handbook of Hydrology. D.R. Maidment (ed.). McGraw-Hill, Inc. New York.
7.
Preferential Flow
Bouma, J. 1981. Soil morphology and preferential flow along macropores. Agricultural Water Management,
3: 235-250.
Miller, J.J., B.J. Lamond, N.J. Sweetland, and F.J. Larney. 1999. Water Qual. Res. J. 34(2):249-266.
8.
Unsaturated flow and fitting functions
Campbell, G.S. 1974. A simple method for determining unsaturated conductivity from moisture retention
data. Soil Science. 117(6):311-314.
Van Genuchten, M. Th. 1980. A closed-form equation for predicting the hydraulic conductivity of
unsaturated soils. Soil Sci. Am. J. 44:892-898.
Wagner, B., V.R. Tarnawski, G. Wessolek, and R. Plagge. 1998. Suitablity of models for estimation of soil
hydraulic parameters. Geoderma 86:229-239.
9.
Recharge
Allison, G.B., G.W. Gee, and S.W. Tyler. 1994. Vadose-zone techniques for estimating groundwater
recharge in arid and semiarid regions. Soil Sci. Am. J. 58:6-14.
Flint, A.L., L.E. Flint, E.M. Kwicklis, J.T. Fabryka-Martin, and G.S. Bodvarsson. 2002. Estimating
recharge at Yucca Mountain, Nevada, USA: comparison of methods. Hydrogeology J. 10:180-204.
Christie, H.W., D.N. Graveland, and C.J. Palmer. 1985. Soil and subsoil moisture accumulation due to
dryland agriculture in southern Alberta. Can. J. Soil Sci. 65:805-810.
10. Landscape and waters
Rockstrom, J. and P-E. Jannsson, and J. Barron. 1998. Seasonal rainfall partitioning under runon and runoff
conditions on sandy soil in Niger. On-farm measurements and water balance modeling. J. Hydrology
210:68-92.
Hayashi, M., G. van der Kamp, and D.L. Rudolph. 1998. Water and solute transfer between a prairie
wetland and adjacent uplands, 1. Water balance, 2. Chloride cycle, J. Hydrology 207: 42-55, 56-67.
Edmunds, W.M. and S.W. Tyler. 2002. Unsaturated zones as archives of past climates: toward a new proxy
for continental regions. Hydrogeology J. 10:216-228.