Ulf Helldén
Professor emeritus
LU-CDM, A Conceptual Model of Desertification
Författare
Summary, in English
This paper presents a generic system dynamic model to simulate and analyze a desertification system and its stability for different desertification syndromes.
The study is one of many desertification related modelling approaches carried out by different project partners within the frames of DeSurvey (A Surveillance System for Assessing, Monitoring and Modelling Desertification; 2005-2010). DeSurvey is an EU FP6 Integrated Project (IP) on desertification considering the inter-action and importance of socio-economy, climate and landscape vulnerability to land degradation.
The human-environment coupled model integrates socio-economic drivers with bio-physical drivers of land degradation and desertification. It is based on the UN and GEF definitions of desertification. It illustrates the concept of desertification through differential equations, simulation output graphics and through causal loop diagrams demonstrating the existing feed-back mechanisms. It may be useful for land use system stability/equilibrium condition analysis and for sustainable strategic land policy and management decision support.
The model relates population pressure and dynamics over time to the removal and availability of biomass resources. The population stock is described as a function of growth rate, death rate and resources dependent in and out migration of people. The relative growth rate of the stock of resources is modeled as a function of climate and exploitation pressure affecting soil erosion and water availability. Biomass recovery from serious degradation/desertification events follows the logistic growth function modified by population pressure, erosion and water availability conditions.
The conceptual desertification model is applied for the Sahelian syndrome using input data to illustrate and simulate a 150 years period (1900-2050) in Kordofan, Sudan. The model indicates that it is difficult to generate irreversible desertification in a system where there is an open market and free population mobility unless serious climate change and/or extremely serious soil erosion creates long term wasteland conditions leading to ultimate land abandonment
The study is one of many desertification related modelling approaches carried out by different project partners within the frames of DeSurvey (A Surveillance System for Assessing, Monitoring and Modelling Desertification; 2005-2010). DeSurvey is an EU FP6 Integrated Project (IP) on desertification considering the inter-action and importance of socio-economy, climate and landscape vulnerability to land degradation.
The human-environment coupled model integrates socio-economic drivers with bio-physical drivers of land degradation and desertification. It is based on the UN and GEF definitions of desertification. It illustrates the concept of desertification through differential equations, simulation output graphics and through causal loop diagrams demonstrating the existing feed-back mechanisms. It may be useful for land use system stability/equilibrium condition analysis and for sustainable strategic land policy and management decision support.
The model relates population pressure and dynamics over time to the removal and availability of biomass resources. The population stock is described as a function of growth rate, death rate and resources dependent in and out migration of people. The relative growth rate of the stock of resources is modeled as a function of climate and exploitation pressure affecting soil erosion and water availability. Biomass recovery from serious degradation/desertification events follows the logistic growth function modified by population pressure, erosion and water availability conditions.
The conceptual desertification model is applied for the Sahelian syndrome using input data to illustrate and simulate a 150 years period (1900-2050) in Kordofan, Sudan. The model indicates that it is difficult to generate irreversible desertification in a system where there is an open market and free population mobility unless serious climate change and/or extremely serious soil erosion creates long term wasteland conditions leading to ultimate land abandonment
Avdelning/ar
- Institutionen för naturgeografi och ekosystemvetenskap
Publiceringsår
2008
Språk
Engelska
Publikation/Tidskrift/Serie
FP6, DeSurvey IP, Sub-deliverable 1.3.3.8 (1), Deliverables data base
Fulltext
- Available as PDF - 773 kB
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Dokumenttyp
Rapport
Förlag
DeSurvey IP & Department of Physical Geography and Ecosystems Analysis, Lund university
Ämne
- Physical Geography
Nyckelord
- land degradation
- system dynamic modelling
- human-environment coupled model
- desertification
Status
Published
Projekt
- FP6, DeSurvey IP 2005-2010, A Surveillance System for Assessing and Monitoring Desertification
Report number
1.3.3.8