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Summary SLM10306 Land degradation and Remediation
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This is a summary based on the lectures and guest lectures given during the course Land Degradation and Remediation
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LAND DEGRADATION ANDREMEDIATION – SLM10306
LECTURE 1: TYPES OF LAND DEGRADATION
Soil: Upper layer of earth’s crust composed of mineral parts, organic substance, water, air and living matter.
Result from interactions between inherent nature of parent material, prevailing environmental conditions and
human activities
Land: Ecosystem comprising soil, landscape, terrain, vegetation, inland water, climate
Soil degradation (SD):
- Human-induced process reducing current and/or future capacity of soil to support human life
- SD is the deterioration of soil quality, or partial/entire loss of one or more functions of the soil
Soils form slowly but degrade quickly.
Land degradation (LD):
- Lowering current and/or future capability of soils to produce (quantitatively and/or qualitatively)
- Decrease/loss of economic and biological productivity and complexity of land
- Reduced capacity of land to provide ecosystem goods and services over time for its beneficiaries
Sustainable Land Management:
Classification of land degradation:
- Type
o Physical
Erosion
Sedimentation
Compaction
Crusting
Surface sealing
o Chemical
Salinization
Soil pollution
Nutrient depletion
Acidification
, o Biological
Reduction in biodiversity
Loss of organic matter
Loss of ecological components
Quality and species composition change
o Hydrological
Aridification
Waterlogging
Changes in quantity of surface water
Changes in groundwater/aquifer level
- Degree or state
- Impact
o Decrease of productivity
o Biodiversity
o Water quality and quantity
o Human health
- Drivers
o Direct: poor land or crop management, deforestation, overgrazing
o Indirect: poverty, over- (or under) population,
o Legislation and policies, land tenure
- Trend or rate
- Extent
Sensitivity: How easy to degrade the land?
Resilience: How easy to restore the land?
LECTURE 2: PHYSICAL PROCESSES OF LAND DEGRADATION
Compaction: modifies pore volume and pore size distribution
- Causes: raindrop impact, tillage operations, wheel traffic, animal trampling
- Factors influencing compaction: soil type, soil wetness, weight of machinery
- Effects of compaction:
o few pores -> less infiltration and drainage in compacted layer -> more runoff and erosion
o Limitation to root growth -> lower yields
o Loss of aeration of soil -> effects on roots and soil biota
Crusting:
- Structural crust: surface layer of soil that is more compacted than material below
o Due to physical forces e.g. swelling and shrinking, animal trampling, machinery
- Depositional crust: when soil particles are deposited
- Biological crust: biological organisms bind the soil together (bacteria, fungi, algae)
- Effects of crusting:
o Reduction of infiltration rate -> increase runoff and erosion
o Seedbed: problems of germination
o Reduced air exchange between subsoil and atmosphere
Surface sealing:
, - Effects: less infiltration, more surface runoff, erosion and flooding
Desertification: not only the expansion of the desert!
- Causes: biophysical, natural, socio-economic, human induced
Fire effects:
- Diverse and complex
- Depends on:
o Fire behaviour, severity and frequency
o Fuel characteristics
o Nature of terrain
o Soil characteristics
- Directs effects:
o Removal of vegetation and litter
o Changing soil properties -> alter the hydrological response of soils
o Loss of nutrients during burning
- Indirect effects:
o Reduce rainfall interception, storage, transpiration, infiltration capacity -> overland flow
o Reduce structural stability -> increase erodibility
o Leaching of nutrients
o Water repellency
o Increase vulnerability to erosion and flooding
Basic principles of erosion
Erosion: unsteady, non-uniform
Areal: rain splash, interrill/sheet, wind erosion
Concentrated: rills, gullies, streams
Detachment -> transport -> deposition
Transport: function of transport capacity and sediment availability
LECTURE 3: CHEMICAL LAND DEGRADATION AND REMEDIATION
Contamination says that wrong chemicals are in the system. Pollution suggests that there is a risk.
Non-point pollution happens everywhere in the area of interest. Point source pollution is located in specific
places. Easy to identify, monitor and regulate.
Standards Netherlands:
- Orienting investigation: is something wrong?
- Closer investigation (if values may be of concern): is intervention needed?
- Intervention value/remediation investigation: how to remediate?
- Reference or background values for metals are depended on humus and clay content of the soil.
(standard: L (clay) = 25%, O/H (hummus) = 10%)
PHYSIO-CHEMICAL PROCESSES RELATED TO DEGRADATION AND REMEDIATION
Speciation:
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