Technical English Language for Range and Watershed...

86
1 University of Tehran Faculty of Natural Resources Department of Arid and Mountainous Regions Reclamation Technical English Language for Range and Watershed Management A. Moghaddam Nia [email protected]

Transcript of Technical English Language for Range and Watershed...

Page 1: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

1

University of Tehran

Faculty of Natural Resources

Department of Arid and Mountainous Regions Reclamation

Technical English Language

for Range and Watershed Management

A. Moghaddam Nia

[email protected]

Page 2: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

2

Reference Books

• Principles of Language Learning and

Teaching, H. Douglas Brown, Prentice Hall

Regents.

• Second Language Teaching & Learning. David

Nunan. (1995). H& H.

• Other resources from the Internet

Page 3: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

3

Page 4: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

4

Page 5: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

5

Writing about the kind of change (increase/decrease)

1. Verbs: to increase/to go up/to rise ≠ to

decrease/to go down/to decline

2. Nouns: an increase/a rise ≠ a decrease/a

fall/a reduction

Page 6: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

6

Writing about the kind of change

(increase/decrease)

1. Verb + dramatically = dramatic + Noun

Example: The figure rose dramatically.

2. Verb + significantly = significant + Noun

Example: There was a dramatic rise.

Page 7: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

7

Writing about the kind of change

(increase/decrease)

1. Verb + a little = small + Noun

Example: The figure decreased slightly.

2. Verb + slightly = slight + Noun

Example: There was a slight decrease.

Page 8: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

8

Writing about the kind of change

(increase/decrease)

Examples:

• Between 1980 and 1990 the figure fell a little.

• Since 1980 it has increased slightly.

Page 9: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

9

Writing about comparing changes

• + whereas + Verb phrase

Example:

In 1980, 30% of rural dwellers had a drinking water

supply, whereas in 1990 50% had it.

Page 10: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

10

Writing about comparing changes

• more / fewer than

Example:

More urban dwellers have a water supply than rural

dwellers.

Fewer rural dwellers have a water supply than

urban dwellers.

Page 11: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

11

• Three stages of Reading Process (Wallace, 1992; 2003):

1. Pre-reading: the topic of the text, the choice of the topic, the

way the topic was written, alternative ways to cover the topic,

and the relationship between write and reader.

2. While-reading: deciphering the implications of the text and

negotiate them with other members of the discourse

community.

3. Post-reading: what happened after reading the text; is there any

change in attitudes or improvement of knowledge, for example?

Page 12: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

12

1. Sample Passage

A number of methods have been proposed for estimating the

initial abstraction. It can be assumed that the initial

abstraction consists of all rainfall that occurs prior to the

start of direct storm runoff. As an alternative, the initial

abstraction may be assumed to be a constant volume

(depth). The SCS method assumes that initial abstraction

is a fixed fraction of the maximum retention but varies

with soil and land use since the retention is a function of

the soil group and land use. Viessman (1968) found that

for small urban watersheds a value of 0.1 inch was

reasonable. For rural and forested watersheds, a larger

volume would be expected.

Page 13: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

13

1. Sample Passage

• The initial abstraction:

a) is dependent on the separation of baseflow.

b) can be a constant volume.

c) would be larger for an urban watershed than for rural

watershed.

d) is not a function of land use.

• The word “consists of” in line 2 is closest in meaning to

…………… .

a) comprise b) exclude c) undergo d) acquire

Page 14: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

14

2. Sample Passage

Designs based on peak discharges have a long historical basis. In a

historical review of the literature on engineering studies of

hydrologic determination of waterway areas, Chow (1963)

included a few of the historical events relating to design

methods using peak discharges. The early attempts at

hydrologic design suggest that dominant factors in peak

discharge estimation were recognized as the drainage area, land

use, rainfall intensity, and slope. These factors are the heart of

many of the equations used today. Current methods attempt to

develop more precise criteria for selecting values of the

empirical coefficients and include additional variables as input.

Although these additional variables are probably not as

important as drainage, land use, and rainfall, they should

nevertheless improve the accuracy of prediction.

Page 15: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

15

2. Sample Passage

• The word “relating to” in line 4 is closest in meaning to ………

.

a) concern b) respect c) respectfulness d) concerning

• The word “precise” in line 8 is closest in meaning to ………. .

a) facile b) untrue c) exact d) reasonable

Page 16: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

16

3. Sample Passage

A primary design variable in hydrology is the peak

discharge, which corresponds to the maximum water surface

elevation during a storm event. Specifically, a peak discharge is

the maximum volume flow rate passing a particular location

during a storm event; it has units of volume per time, such as

cubic feet per second, cubic meters per second, or acre-feet per

hour.

The peak discharge is a primary variable for the design of

stormwater runoff pipe systems, storm inlets and culverts, and

small open channels. It is also used for some hydrologic

planning such as small detention facilities in urban areas. It is an

acceptable design variable for designs where the time variation

of storage is not a primary factor in the runoff process.

Page 17: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

17

3. Sample Passage

• According to the above passage, which one of the

following is true or false?

The peak discharge is:

1. a criterion for classifying hydrologic models.

2. a primary design variable.

3. the total volume of flood runoff.

4. the maximum volume flow rate passing the watershed outlet

during a storm event.

Page 18: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

18

As urban areas continue to grow land that

was once covered with more natural land

cover such as forests, fields, and lawns is

replaced by manmade land covers such as

roads, parking lots and rooftops.

Page 19: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

19

Reading • Choose the best heading from the options A,B,C or D for

the following paragraph.

The vast majority of people in the developing countries live in

rural areas, on farms, in villages or in rural market towns. In some countries, such as Rwanda, Burkina Faso and Malawi more than 90 per cent of the total population lives in the rural areas.

A. Rural poverty B. Insufficient access to education C. Rural populations of developing countries D. Education in developing countries

Page 20: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 21: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 22: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

22

Reading Comprehension

Read the following passage and choose the best choice (1), (2), (3) or (4).

In meteorology, precipitation (also known as one of the classes of hydrometers, which

are atmospheric water phenomena) is any product of the condensation of

atmospheric water vapor that is pulled down by gravity and deposited on the Earth’s

surface. The main forms of precipitation include rain, snow, ice pellets, and graupel.

It occurs when a local portion of the atmosphere becomes saturated with water

vapour and the water condenses, falling out of solution (i.e., precipitation).

1. We may understand from the passage that precipitation has a meaning ……….

1) if it reaches the Earth.

2) as one of the main branches of meteorology.

3) as rain, snow, ice pellets, and graupel.

4) if water vapour gets condensed.

Graupel : گفته کریستالها چسبيده بهم توده به) برف گلوله یا برف دانه .ملایم منجمد نيمه تگرگ :آلمانی کلمه ریشه (شود می

Page 23: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

23

Reading Comprehension

Two processes, possibly acting together, can lead to air becoming saturated: cooling the air

or adding water vapour to the air. Virga is precipitation that begins falling to the earth but

evaporates before reaching the surface; it is one of the ways air can become saturated.

Precipitation forms via collision with other rain drops or ice crystals within a cloud.

Moisture overriding associated with weather fronts is an overall major method of

precipitation production. If enough moisture and upward motion is present, precipitation

falls from convective clouds such as cumulonimbus and can organize into narrow rainbands.

1. The passage mentions that ……………

1) graupel is extremely saturated rainfall.

2) air can become saturated through vigra.

3) air can be cooled by adding water vapour it.

4) there are many tiny ice crystals in a cloud.

Virga : ابرهای از که هستند رگبار سنگين قطرات CB از قبل و رسند نمی زمين به هيچگاه قطرات این اما بارد، می . شوند می تبخير سریع بسيار زمين به رسيدن

Page 24: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

24

CLOZE TEST

It is extremely difficult for students to deal with such

cloze test due to the following problems:

1. difficulties in comprehending the text

2. unfamiliarity with sentence structures

3. insufficient mastery of grammar

4. vocabulary lack of knowledge of English

5. inadequate mastery of synonyms and prepositions

Page 25: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

25

Page 26: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

26

Page 27: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

27

Page 28: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

28

Page 29: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

29

Page 30: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

30

Page 31: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

31

Page 32: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

32

Page 33: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

33

Page 34: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

34

Page 35: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

35

Page 36: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

36

• The more you have to say, the more people will want to talk with you.

• Notice what they say and how they act.

• Learn from people at school or work.

• Be a good listener, and let people talk about themselves.

• Have confidence in yourself.

Page 37: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

37

The population of the world is increasing rapidly. By 2020,

there could be 7.5 billion people on the earth. Will there be

enough food for all this people, or will we have a food

shortage?

Page 38: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

38

Urban farming has important advantages for city people. First, it's

good for the environment. The crops reduce the amount of carbon

dioxide (CO2) and increase the oxygen (O2) in the air. As a result,

they help clean the air. Second, locally grown food is fresher. It

doesn't have to travel long distances, so it is less expensive, too.

Urban residents also benefit from the enjoyment of farming. It can

reduce the stress of city life.

Page 39: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

39

Page 40: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

40

Cloze Test

Read the passage and decide which choice (1), (2), (3), or (4) best fits each

space.

The effects of an earthquake are often (1) ---------.

Earthquakes have (2) ------- the death of many human beings, much suffering, and

great (3) --------.

1- 1) chemical 2) superior 3) terrible 4) formal

2- 1) provided 2) caused 3) required 4) designed

3- 1) damage 2) source 3) impression 4) variety

Page 41: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

41

Reading Effectively

The purpose of your reading determines how you will read. You are not

expected to read every reading on your reading list carefully from beginning to

end, word for word. Skimming, scanning and careful, deliberate reading, are

all skills which can be applied to reading academic texts, depending on the

‘purpose’ of your reading.

SKIMMING - If reading a chapter for background to a lecture, you might

quickly skim the reading. Read the introduction/conclusion; check the

headings and sub headings for main ideas; read the topic sentence for each

paragraph; read any bolded or italicised material; and look at any diagrams

or other visuals. Once you have established an overview of the main points in

the article, you would then review any sections relevant to your assignment.

Page 42: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

42

Reading Effectively

SCANNING - If you are looking for a specific piece of information e.g. the

answer to a question for a lab report, you might use scanning. Scanning

involves reading quickly to locate specific information. You use this skill when

you find a number in a telephone directory. To help locate the specific term

you are looking for, you could use the index of a book, chapter headings or

scanning quickly through the chapter.

DEEP READING - After skim reading through a series of relevant

articles/chapters for an essay, deep reading is necessary. You must read each

slowly and carefully, making notes as you go, critiquing the reading and

outlining in your own words what the material is about.

Page 43: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

43

Page 44: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

44

Useful Resources / Websites

http://unilearning.uow.edu.au/reading/1a.html

http://www.lc.unsw.edu.au/onlib/read.html

http://www.monash.edu.au/lls/llonline/reading/effective-reading/index.xml

http://cms.unimelb.edu.au/studentservices/asu/reading/strategies

Page 45: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

45

Page 46: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

46

Page 47: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

47

Page 48: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

48

Page 49: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

49

Page 50: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

50

Watershed Water Balance

From a hydrologic viewpoint, the first step of watershed management is to evaluate past,

present, and proposed management practices on a watershed with respect to the watershed

water balance. Watershed water balance refers to the balance between the inflow of water

to a watershed as precipitation and the outflow of water from the watershed as

evapotranspiration, ground water discharge, and stream flow. Basically, watershed water

balance is an accounting tool to keep track of the hydrologic cycle of a watershed over time.

When the watershed water balance concept is used in conjunction with probability analysis

one can evaluate the hydrologic, economic, and ecological feasibility of past, present, and

potential activities on a watershed.

Page 51: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

51

Vegetation effects on hydrologic processes

Infiltration and runoff are regulated by the kind and amount of vegetation, edaphic, climatic,

and topographic influences. Vegetation is the primary factor that influences the spatial and

temporal variability of soil surface processes, which affects infiltration, runoff, and interrill

erosion rates on arid and semiarid rangelands. Each plant-soil complex exhibits a

characteristic infiltration pattern.

The impact of vegetative cover to infiltration is not constant from one range-soil complex to

another. In semiarid climates, vegetal cover has a minimal influence on infiltration: the

erosion process is more complex and is a function of plants, soils, and storm dynamics.

Page 52: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

52

Each plant community type must be evaluated in terms of what variables affect hydrology

on the site. No one factor ever varies alone, especially with regard to hydrologic processes.

Some variables are not consistently correlated in natural rangeland plant communities. The

variables include:

• above- and below-ground plant morphology

• total production

• production of individual plant species

• total canopy cover

• canopy cover of individual plant species

• plant architecture

• sod forming growth form

• bunchgrass growth form

• interspace

• shrub coppice

• soil physical properties

• soil chemical properties

Page 53: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

53

Semiarid rangelands throughout the Western United States have significant spatial and

temporal variations with regard to hydrologic and erosion processes. The spatial distribution

of the amount and type of vegetation has been shown to be an important factor in

modifying infiltration and interrill erosion rates on rangelands. On rangeland, shrub-coppice

sites have a significantly higher infiltration rate under both frozen and unfrozen soil

conditions than that in interspace areas.

Page 54: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

54

Page 55: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

55

Page 56: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

56

Page 57: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

57

Page 58: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

58

Page 59: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

59

Page 60: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

60

Page 61: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

WATERSHED Development

• Watershed Characteristics.

• Hydrology of watershed.

Watershed (ha) Classification

50,000-2,00,000 10,000-50,000 1,000-10,000 100-1,000 10-100

Watershed Sub-watershed Milli- watershed Micro-watershed Mini-watershed

Page 62: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

Parameters of Watershed

• Size

•Shape

•Physiography

•Climate

•Drainage

•Land use

•Vegetation

•Geology and Soils

•Hydrology

•Hydrogeology

•Socioeconomics

Page 63: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 64: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 65: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

65

Page 66: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

66

Page 67: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

67

Page 68: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

68

Climate change is likely to affect soil erosion by water through its effects on

rainfall intensity, soil erodibility, vegetative cover, and patterns of land use.

Estimates of changes in erosion risk can be made from a knowledge of projected

changes in these factors. General circulation models (GCMs) can provide a range

of climate scenarios, but these alone are not sufficient to predict future erosion

risk, particularly because GCMs are currently poor predictors of changes in

rainfall intensity and surface windspeed. In addition to more regionally reliable

GCMs, accurate and reliable databases of parameters such as vegetation cover,

soil properties, land use, and management systems are needed. These databases

are important for the assessment of biophysical processes and biomass

productivity (Rosenzweig et al., 1993) and are needed at scales appropriate to

regional and global degradation processes (Bliss, 1990; Bouwman, 1990; Batjes et

al., 1994). Such databases have not yet been developed.

Erosion by Water

Page 69: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

69

Soil erosion occurs when wind transports soil particles by suspension, surface creep,

or saltation over distances ranging from a few centimeters to many kilometers. Wind

erosion not only transports soil particles around arid and semi-arid landscapes but

provides inputs into ecosystems around the world and may even alter global climatic

patterns. Wind erosion is particularly problematic on sandy and organic soils

subject to low soil moisture, patchy vegetation, sporadic rainfall, and periodic

winds. Even soils resistant to wind erosion can be blown away if the soil is damaged

by trampling of animals, loosening by ploughing and tillage, pulverization by traffic

(human and animal), and denudation of natural vegetation by the expansion of

agriculture, excessive grazing, or fire. Wind erosion is mainly a feature of arid and

semi-arid conditions but may occur in moister zones where soil damage occurs

during or just prior to periods of high wind velocity.

Erosion by Wind

Page 70: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

70

More than 60 years of experience are available in the development of conservation

techniques and soil protection, following the U.S. Dust Bowl and similar phenomena

elsewhere in the world (Kirkby and Morgan, 1980; FAO, 1983; Morgan, 1986;

Schwertmann et al., 1989; Lal, 1990). A serious problem, however, is that many of

these conservation techniques have not been adopted. Nevertheless, they are

available and could be used for or adapted to changing climatic conditions. The

most important requirement is that governments recognize the problem of soil

erosion and set in motion the appropriate conservation mechanisms. Future erosion

risk is more likely to be influenced by increases in population density, intensive

cultivation of marginal lands, and the use of resource-based and subsistence farming

techniques than by changes in climate.

Adaptive Strategies for Mitigating the Impact

of Climate Change on Soil Erosion

Page 71: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

71

Agroforestry may play an extremely important role in the development of semi-arid

and arid lands and in the struggle against desertification (Le Houérou, 1980;

Baumer, 1987; Le Houérou and Pontainier, 1987). Agroforestry techniques have

been developed for centuries in some rural civilizations—such as Kejri [Prosopis

cineraria (L) Druce] in northwest India (Rajasthan); Faidherbia albida (Del.) Chev.

in various parts of intertropical Africa; saltbushes in various arid zones of the

world; Argania spinosa (L.) Sk in southwest Morocco; Quercus ilex L. and Q. suber

L. in Spain and Portugal; and Espino (Acacia caven Mol.) and Algarrobo (Prosopis

spp) in Latin America. Such techniques permit high rural population densities in

arid zones (e.g., 60–80 people/km2) with Faidherbia in southern Sahel, and similar

densities in Rajasthan with Prosopis cineraria and in southern Morocco with

Argania (the latter region receives <150–300 mm/yr rainfall).

Agroforestry

Page 72: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 73: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 74: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 75: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 76: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed
Page 77: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

77

Page 78: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

78

An important question in hydrology is how much stream flow

occurs in a river in response to a given amount of rainfall.

To answer this question:

we need to know where water goes, when it rains, how long does

water reside in a watershed, and what pathway does water take to

the stream channel.

These are the questions addressed in the study of rainfall – runoff

processes, or more generally surface water input – runoff processes.

Rainfall – Runoff Processes

Page 79: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

79

Label the locations depicted in the figure associated with runoff

generation processes.

Page 80: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

80

Label the Rainfall-Runoff processes depicted in the figure.

Page 81: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

81

Infiltration excess overland flow occurs anywhere that surface

water input exceeds the infiltration capacity of the surface.

This occurs most frequently in areas devoid of vegetation or

possessing only a thin cover. Semi-arid rangelands and

cultivated fields in regions with high rainfall intensity are

places where this process can be observed. It can also be seen

where the soil has been compacted or topsoil removed.

Infiltration excess overland flow is particularly obvious on

paved urban areas.

Page 82: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

82

High intensity short duration rainfall is much more likely to exceed

the capacity of the soil to infiltrate water and result in overland

flow than a longer less intense rainfall. In arid climates with deep

water tables, spatially concentrated rainfall on a small area may

generate local runoff that then infiltrates downriver, whereas a

more humid area with shallow water tables is less likely to be

subject to stream infiltration losses and even gentle rainfall when

widespread and accumulated over large areas may lead to large

stream flows.

Page 83: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

83

Infiltration excess overland flow is more likely to occur in:

1) A short gentle rainstorm

2) A short intense rainstorm

3) A long gentle rainstorm

4) A snow blizzard

Page 84: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

84

Infiltration capacity is also referred to as infiltrability. When surface water

input exceeds infiltration capacity the excess water accumulates on the soil

surface and fills small depressions. Water in depression storage does not

directly contribute to overland flow runoff; it either evaporates or

infiltrates later. With continued surface water input, the depression

storage capacity is filled, and water spills over to run down slope as an

irregular sheet or to converge into rivulets of overland flow. The amount of

water stored on the hillside in the process of flowing down slope is called

surface detention. The transition from depression storage to surface

detention and overland flow is not sharp, because some depressions may

fill and contribute to overland flow before others.

Page 85: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

85

Interception of precipitation by vegetation can play a significant

role in reducing runoff, especially in forested environments. Much

intercepted water is eventually evaporated back to the atmosphere.

Water retained in the vegetation canopy for some period, however

short, after rain has struck the vegetative material above the soil

surface (Tischendorf, 1969).

Page 86: Technical English Language for Range and Watershed ...can.ut.ac.ir/.../EnglishCourse-lecture139495.pdfWatershed Water Balance From a hydrologic viewpoint, the first step of watershed

86

Interception is most likely to

1) Result in a large capillary fringe

2) Increase the infiltration capacity

3) Reduce the infiltration capacity

4) Increase erosion

5) Occur in an urban area

6) Lead to increased infiltration excess overland flow

7) Reduce the amount of runoff generated in a forested area