MODULE 2.2 Flashcards
General Determinants of Land Use (3)
- Physical factors
- Social factors
- Economic factors
Physical Determinants
§ Soil
§ Topography
§ Geology
§ Climate
§ Drainage
Physical determinants can serve as one of the considerations for assessing the _____________ or ________________ of land to support certain
uses
capability, suitability
Considered when the intended use of the land is an input to production process e.g. agriculture, forestry, mining and quarrying, livestock raising
physical determinants
Land as site or platform (e.g. settlements and urban development), geophysical characteristics of land are important land use considerations (constraint to devt. and entail additional cost)
physical determinants
affects cost of production, development, laying networks and infrastructure, conveyance of water, drainage and sewerage, and rate of erosion
Topography
Major topographic features
slope, shape, size, position, relief, land cover
refers to the gradient of inclination of a surface expressed as the ratio of the vertical rise to the horizontal run, usually expressed in percent; defines relative steepness or flatness of a land surface (e.g. lower slopes – higher suitability)
Slope
Slope ranges >18%
permanent forest
Slope ranges 30% slope as the limit
urban and agricultural uses
Slope ranges 3% minimum
drainage and sewage
flow
Slope ranges 7% as the maximum
road construction
important in sitting of certain activities for maximum capture of sunlight, shelter from storms or wind (leeward) or when strong wind velocity is desired
aspect
refers to the general configuration of the earth’s surface characterized by unevenness or differences in altitudes and slopes; affects the cost of development as leveling or grading may be necessary; some relief features are interesting enough for viewing and are better left untouched
relief
when the site is relatively isolated and inaccessible, or is located in high elevations, increases development and operating costs; elevation of land defines its climatic regimes (altitude inversely
proportional to temperature – 1,000m rise in altitude, 1 degree C drop in
temperature)
position
interference in operations e.g. small
irregularly shaped farm lots cannot be easily be subjected to a mechanized farming
size and shape
cover
either in the form of vegetation or rock outcrops can reduce the productivity of the land; natural covers such as full
grown trees or interesting rock formations add value to the land
understanding the rock and mineral structure of the earth’s crust is vital in identifying the appropriate land use and determining the intensity of such use
geology
refers to the different landforms occurring on the surface of the earth
geomorphology
landforms with a rise in height of not less than 300m, have narrow summits and steep slopes; affect microclimate conditions of an area
mountains
usually low-lying flat lands with elevations ranging from 0 to 200m; very suitable to a variety of land development but are also susceptible to flooding
plains
wet spongy lands saturated with water supporting a natural vegetation predominantly of shrubs, trees and grass
swamplands or marshes
thin upper layer of the surface of the earth composed of a mixture of
fragments of rocks, water, air and organic matter; links the biotic and abiotic; soil properties result from the integrated effect of climate and living matter acting upon parent material as conditioned by relief over long periods of
time
soils
helps establish the content, chemistry, texture and nutritive contents of any land unit (defines the suitability of soils for all forms of plant life and establish certain limits for their use
soil surveys
Characteristics of the soil
Texture
Structure
Fertility
size of fragments (clay, silt, sand) determines water holding capacity
texture
form and shape of particles (e.g. granular to platy) affects root penetration and water infiltration
structure
amount of OM present in any given soil is determined by the presence of organisms e.g. N-fixing bacteria and earthworms helps in aeration of the soils
fertility
pertains to the subsurface water or aquifer; structure of the subsoil affects the lateral flow (transmissivity) while soil texture affects the vertical flow (permeability or recharge) of the aquifer
hydrogeology
Factors affecting aquifer recharge
- Rainfall intensity
- Slope of the land
- Porosity of rock formation
- Permeability of rock formation
- Nature of rock strata
- Presence of vegetation
- Atmospheric humidity
covers a range of factors (e.g. temperature, sunlight, precipitation,
humidity, wind velocity and atmospheric pressure) influencing the physical and
biological processes; it also sets the limits for plant and animal life and regulate many of man’s activities
climate
two major categories of climate
macro-climate
micro-climate
refers to the meteorological conditions and patterns over a large or regional area; affected by physical conditions such as mountains, ocean currents, prevailing winds and latitude
macro-climate
refers to the meteorological conditions found within small spaces or local areas; small variations are usually caused by slope, orientation of the ground surface, soil type, moisture and vegetation (type
and height)
micro-climate
in land use planning, the understanding of _________________ are essential
climatic factors
For agriculture, ________________ are entirely dependent on the climate
cropping patterns
Land capability is used in a number of land classification systems, notably that of the _________________________________
Soil Conservation Service of the U.S. Department of Agriculture
soil mapping units are grouped
primarily on the basis of their capability to produce common cultivated crops and pasture plants without deterioration over a long period of time
in the USDA system
inherent capacity of land to perform at a given level for a general use, while
suitability as a statement of the adaptability of a given area for a specific kind of land use
capability
classification of land primarily in
relation to degradation hazards, whilst some regard the terms “___________” and “capability” as interchangeable
suitability
lands are very good agricultural lands with level to nearly level (0-3% slope), deep soil, well-drained and with high natural fertility.
class a
lands have slight limitations in use like drainage or excess water, soil and erosion problem due to slightly sloping relief from 3-8%.
class b
lands are moderately good lands that should be cultivated with intensive conservation practices like contour tillage, terracing, cover cropping, on account of sloping to rolling relief of 8-18% slope.
class c
lands are fairly good lands but require careful management and complex conservation practices like terracing, contour tillage and cover cropping.
class d
lands are level to nearly level but too stony or too wet for cultivation.
class l
lands are steep with slopes of 30-50% may be severely eroded or too shallow for cultivation.
class m
Suited only to pasture or forest
use with careful management.
class m
This land is limited to pasture or forest use with careful management.
class l
This land is rolling, strongly with 18-30% slope, good for limited cultivation but is best suited to permanent tree crops.
class d
This land class can be cultivated safely to clean-tilled or row crops with simple but good farming practices
class a
This land can be cultivated safely to clean-tilled crops provided easily applied conservation practices like contour tillage and cover cropping are practiced
class b
The limitations may be erosion, excess water or soil condition.
class c
lands are very steep with more than 50% slopes, too shallow, rough or dry for cultivation and are best suited to forest use with careful management
class n
lands are wetlands that cannot be economically drained
class x
These include mangrove swamps and marshes
class x
lands are suited for fishponds or for recreational uses or are simply conserved for their aesthetic value.
class x
lands are very hilly, mountainous, barren and rugged
class y
This class includes badlands, river wash areas and sand dunes.
class y