Behehe

1. Land use and land cover
management and cultural practices

2. Land Use and Land Cover (LULC)
• Land use and land cover are often related, but they have different
meanings. Land use involves an element of human activity and
reflects human decisions about how land will be used.
• Land cover refers to the vegetative characteristics or manmade
constructions on the land’s surface.
• For example, after a timber harvest land cover has changed, but the
land use of that area will not have changed if seedlings were planted
or natural regeneration is occurring and it will continue to be used for
timber production.

3. • Land use is generally determined by surveys based on field
observations or enumeration, while land cover is generally
determined using remote sensing techniques or aerial photography
interpretation.
• In short, while land use is characterized by the arrangements,
activities and inputs people undertake in a certain land cover type to
produce, change or maintain it, land cover is the observed biophysical
cover on the earth's surface.

4. Agricultural Practices and LU/LC
• Since the invention of agriculture, ~10,000 years ago, humans have
modified or transformed the land surface. Agricultural production has
caused greater environmental change to the biosphere than any other
land use.
• It is estimated that 50% of the world’s land is used for agriculture and
animal production while only 5% is unmanaged lands, parks and
preserves. The major mode of human land transformation has been
through agriculture.
• It is estimated that over the last 300 years, globally, 20% of forests and
woodlands, 1% of grasslands and pastures (although most grasslands
were converted to pastures) were lost while croplands expanded by
466%.

5. LU/LC Management of Watersheds
• Land use can disrupt the surface water balance and the partitioning of
precipitation into evapotranspiration, runoff, and groundwater flow.
Surface runoff and river discharge generally increase when natural
vegetation (especially forest) is cleared.
• Water demands associated with land-use practices, especially
irrigation, directly affect freshwater supplies through water
withdrawals and diversions. Agriculture alone accounts for ~85% of
global consumptive use.
• As a result, many large rivers, especially in semiarid regions, have
greatly reduced flows, and some routinely dry up. In addition, the
extraction of groundwater reserves is almost universally unsustainable
and has resulted in declining water tables in many regions.

6. • Water quality is often degraded by land use. Intensive agriculture
increases erosion and sediment load, and leaches nutrients and
agricultural chemicals to groundwater, streams, and rivers. In fact,
agriculture has become the largest source of excess nitrogen and
phosphorus to waterways and coastal zones.
• Urbanization also substantially degrades water quality, especially
where wastewater treatment is absent. The resulting degradation of
inland and coastal waters impairs water supplies, causes oxygen
depletion and fish kills, increases blooms of cyanobacteria (including
toxic varieties), and contributes to waterborne disease.

7. The principles adopted for land-use planning at the
watershed level may include the following components:
1.Integrated Utilization of Natural Resources
2.Sustainable Farming Systems
3.Interactive and Pro-active Community Farming Systems
4.Community Participation
5.Conservation Measures
6.Development of Models for Sustainable Land-use Systems

8. A sustainable farming system needs to focus on the social
conditions, especially poverty alleviation, and may include
the following components:
• Food Component
• Fodder Component
• Fuel Component
• Income Generation Component

9. Role of Cultural Practices as Land Management
Cultural land management practices can be classified
into following basic categories.
1.Shifting Cultivation
2.Nomadic Pastoralism
3.Continuous Cultivation
4.Mixed Subsistence Farming

10. Shifting Cultivation
• Shifting cultivation, swidden or slash and
burn agriculture is a common means of food
production in the tropics. It is well suited to
nutrient poor soils in areas of low
population density.
• The natural vegetation is cut and burned,
followed by up to five seasons of growing
then several years of fallow. Once the area is
allowed to go fallow, another area is chosen
and the process repeated.

11. Nomadic Pastoralism
• Nomadic pastoralists raise domesticated relatives of
wild undulates such as goats, cattle, camels and sheep.
They live almost exclusively off animal product such as
milk, meat and blood, though diets are often
supplemented with plant products gathered in
incidental foraging.
• The people tend to migrate extensively in search of
water and pasture. This system allows humans to
occupy areas unsuitable for rain-fed agriculture,
although usually at low population densities.
• The animals are able to convert low quality plant food
(grass), which are unusable by humans, into high
quality foods such as milk and meat. The population of
the animals varies considerably depending on rainfall.

12. Continuous Cultivation
• Under continuous cultivation, fields are used year
after year with only brief fallow periods. Weeds,
pests and losses of soil nutrients are frequent
problems. Thus, a higher level of cultural energy
input is required.
• Frequently, such areas are dependent on nutrient
inputs from seasonal flooding or alluvial
sediments in paddy water. In paddy fields,
nitrogen can also be added by N2-fixing
cyanobacteria. The net energy gain for continuous
cultivation is less than in shifting cultivation.
• This system can be very sustainable, much of the
traditional farming, in India and Southeast Asia is
based on continuous cultivation.

13. Mixed Subsistence Farming
• The majority of farmers employ a combination of farming
techniques. Mixed agriculture, with livestock and crops
integrated into a single ecosystem, is very common in Asia,
Africa and the Americas.
• Farmers are often highly dependent on animals as a key
component of the farming system. The animals provide
meat, milk, fuel, fertilizer, draft power, transportation and
can be fed largely with agricultural waste products.
• Additionally, farmers are frequently engaged in a
combination of agricultural and economic pursuits. They can
barter for food or labor, sell agricultural products or work for
others.
• The choice of cropping system can be based on several
factors; climate, soil types, local economies, markets,
availability of labor and land, knowledge base and traditions
all influence the decision.

14. Common Characteristics
• Focus on risk reduction
• Year round vegetative cover of soils
• System diversity: farm systems based on several cropping systems,
cropping systems based on a mixture of crops, and crops with varietal
and other genetic variability
• Trophic complexity approaching natural systems. Multiple interactions
between plants, weeds, pathogens and insects
• High net energy yields because energy inputs are relatively low
• Low levels of inputs and high degree of self-sufficiency

15. Effect of Land Use Land Cover on
Watershed Hydrology

16. Methods of Watershed LU/LC Estimation
• Land use land cover information has been of interest for planning
resources as well as to understand the condition of the area since
long. Earlier it was used to develop by surveying the area at regular
interval of time.
• However, with the development of technology and growing need of
getting reliable/accurate information within less time, new techniques
have been developed and being employed.

17. Using Aerial Photographs
• Aerial photographs have been used in the mapping
of vegetation since 1920, but their development as
a major tool in forestry and related fields has come
in use since 1940.
• Modern techniques involving the use of aerial
photographs have been made possible by the
availability of high-grade photographs at a low cost,
coupled with the development of simple
photogrammetric instruments, and of photo-
mensurational techniques.
• The principal advantage of aerial photographs in
vegetation and land-use surveys lies in the fact that
they provide a permanent record of conditions
which is available in the office for detailed analysis.

18. Using Remote Sensing Imagery (RS)
• Land cover mapping is one of the most important and
typical applications of remote sensing data. Generally
land cover does not coincide with land use.
• A land use class is composed of several land covers.
Remote sensing data can better provide land cover
information rather than land use information.
• Initially the land cover classification system should be
established, which is usually defined as levels and
classes.
• The level and class should be designed in consideration
of the purpose of use (national, regional or local), the
spatial and spectral resolution of the remotely sensing
data, user's request and so on.

19. Category Sub-categories
Urban or Built-up Land
Residential, commercial, services, transportation, communications utilities,
industrial and commercial complexes, mixed urban or built-up land, other
urban or built-up land
Agricultural Land
Cropland and pasture orchards, groves, vineyards, nurseries, and ornamental
horticultural areas, confined feeding operations, other agricultural land
Rangeland Herbaceous rangeland, shrub and brush rangeland, mixed rangeland
Forest Land Deciduous forest land, evergreen forest land, mixed forest land
Water Streams and canals, lakes, reservoirs, bays and estuaries
Wetland Forested wetland, non-forested wetland
Barren Land
Dry salt flats, beaches, sandy areas, bare exposed rock, strip mines quarries,
and gravel pits, transitional areas mixed barren land
Tundra
Shrub and brush tundra, herbaceous tundra, bare ground tundra, wet tundra,
mixed tundra
Perennial Snow/Ice Perennial snowfields, glaciers

20. Effect on Runoff/Stream Flow
• Urban watersheds are dominated by buildings, roads,
streets, pavements, and parking lots. These features
reduce the infiltrating land area and increase
imperviousness.
• Because drainage systems are artificially built, the
natural pattern of water flow is substantially altered.
For a given rainfall event, interception and depression
storage can be significant but infiltration is considerably
reduced As a result, there is pronounced increase in
runoff.
• Thus, an urban watershed is more vulnerable to
flooding if the drainage system is inadequate. Once a
watershed is urbanized, its land use is almost fixed and
its hydrologic behavior changes due to changes in
precipitation.
Urban Watersheds

21. Agricultural Watersheds
• An agricultural watershed experiences perhaps
the most dynamically significant land-use
change. Changing land use and the treatment
usually lead to increased infiltration, increased
erosion, and/or decreased runoff.
• Depression storage also is increased by
agricultural operations. When the fields are
barren, falling raindrops tend to compact the
soil and infiltration is reduced.
• There is lesser development of streams in
agricultural watersheds because small
channels formed by erosion and runoff are
obliterated by tillage operations.

22. Forest Watersheds
• Interception is significant, and
evapotranspiration is a dominant component of
the hydrologic cycle. The ground is usually
littered with leaves, stems, branches, wood, etc.
• The subsurface flow becomes dominant and
there are times when there is little to no surface
runoff. There is greater recharge of groundwater.
• Because forests resist flow of water, the peak
discharge is reduced, although inundation of the
ground may be increased. Complete
deforestation could increase annual water yield
by 20 to 40 %.

23. Mountainous Watersheds
• The landscape of these watersheds is
predominantly mountainous. Because of higher
altitudes, such watersheds receive considerable
snowfall. And such watersheds have substantial
vegetation and thus interception is significant.
• Due to steep gradient and relatively less porous
soil, infiltration is less and surface runoff is
dominantly high for a given rainfall event.
• Flash floods are a common occurrence. The areas,
downstream of the mountains, are vulnerable to
flooding. Due to snow melt, water yield is
significant even during spring and summer.

24. Desert Watersheds
• There is little to virtually no vegetation in
desert watersheds. The soil is mostly sandy
and little annual rainfall occurs. Sand
dunes and sand mounds are formed by
blowing winds. Stream development is
minimal.
• Whenever there is little rainfall, most of it
is absorbed by the porous soil, some of it
evaporates, and the remaining runs off
only to be soaked in during its journey.
There is limited opportunity for ground
water recharge due to limited rainfall.

25. Coastal Watersheds
• The watersheds in coastal areas may partly be
urban and are in dynamic contact with the sea.
Their hydrology is considerably influenced by
backwater from wave and tidal action.
• Usually, these watersheds receive high rainfall,
mostly of cyclonic type, do not have channel
control in flow, and are vulnerable to severe local
flooding.
• The water table is high, and salt water intrusion
threatens the health of coastal aquifers, which
usually are a source of fresh water supply.
• The land gradient is small, drainage is slow, and
the soil along the coast has a considerable sand
component.

26. Marsh or Wetland Watersheds
• Such lands are almost flat and are comprised
of swamps, marshes, water courses, etc. They
have rich wildlife and plenty of vegetation.
• Evaporation is dominant, for water is no
limiting factor to satisfy evaporative demand.
• Rainfall is normally high and infiltration is
minimal. Most of the rainfall becomes runoff.
• Erosion is also minimal, except along the
coast.
• The flood hydrograph peaks progress
gradually and lasts for a long time.