Abstract
Desertification is a major global environmental issue exacerbated by climate change. Strategies to combat desertification include prevention which seeks to reverse the process before the system reaches the stable desertified state. One of these initiatives is to implement early warning tools. This paper presents SAT (the Spanish acronym for Early Warning System), a decision support system (DSS), for assessing the risk of desertification in Spain, where 20% of the land has already been desertified and 1% is in active degradation. SAT relies on three versions of a Generic Desertification Model (GDM) that integrates economics and ecology under the predator-prey paradigm. The models have been programmed using Vensim, a type of software used to build and simulate System Dynamics (SD) models. Through Visual Basic programming, these models are operated from the Excel environment. In addition to the basic simulation exercises, specially designed tools have been coupled to assess the risk of desertification and determine the ranking of the most influential factors of the process. The users targeted by SAT are government land-use planners as well as desertification experts. SAT tool is implemented for five case studies, each one of them representing a desertification syndrome identified in Spain. Given the general nature of the tool and the fact that all United Nations Convention to Combat Desertification (UNCCD) signatory countries are committed to developing their National Plans to Combat Desertification (NPCD), SAT could be exported to regions threatened by desertification and expanded to cover more case studies.
Highlights
Desertification is defined as land degradation in drylands resulting from various factors, “including climatic variations and human activities” [1]. e magnitude of desertification, which was the first major environmental issue to be recognized as occurring on a global scale [2], was significant enough to set the United Nations Convention to Combat Desertification (UNCCD), a degree of importance only achieved by the Conventions on Biodiversity and Climate Change
SAT was implemented for five case studies (Figure 3), each one of them representing a DL identified in the Spanish National Plans to Combat Desertification (NPCD) [24]: (DL1) “Woody crops affected by erosion”; (DL2) “Rainfed herbaceous crops with erosion risk”; (DL3) “Overgrazed agroforestry-pastoral systems”; (DL4) “Irrigated areas with desertification risk”; and (DL5) “Degraded shrublands and wastelands.”
(iii) GDM3: hydrological models linked to groundwater-based irrigation agriculture [36, 47, 48] for Eastern La Mancha aquifer in Ciudad Real and Albacete provinces apply to DL4
Summary
Desertification is defined as land degradation (i.e., reduction or loss of the biological or economic productivity of the land) in drylands (i.e., arid, semiarid, and dry subhumid areas) resulting from various factors, “including climatic variations and human activities” [1]. e magnitude of desertification, which was the first major environmental issue to be recognized as occurring on a global scale [2], was significant enough to set the United Nations Convention to Combat Desertification (UNCCD), a degree of importance only achieved by the Conventions on Biodiversity and Climate Change.Drylands occupy 47% of the terrestrial surface [3] and are home to over 38% of the world human population [4]. Desertification is defined as land degradation (i.e., reduction or loss of the biological or economic productivity of the land) in drylands (i.e., arid, semiarid, and dry subhumid areas) resulting from various factors, “including climatic variations and human activities” [1]. E magnitude of desertification, which was the first major environmental issue to be recognized as occurring on a global scale [2], was significant enough to set the United Nations Convention to Combat Desertification (UNCCD), a degree of importance only achieved by the Conventions on Biodiversity and Climate Change. 90% of the human settlements in drylands are located in developing countries [5]. It is valued that severe ecosystem degradation is present in 10–20% of drylands, and its consequences are estimated to affect around 250 million people in the developing world [6].
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