Assessment of land Sensitivity to Desertification Hazard Using System Dynamics Approach in the Jazmurian Watershed

Abstract Desertification relates to the both the process and end state of dry lands degradation. This process, with an impact range in more than 100 countries has affected about 1 billion people in the world and is the result of complex interactions among various factors, such as climate change and human activities.The objective of this study is forecasting of effects of climatic and management scenarios on the desertification phenomena in the Jazmurian catchment, located in the Kerman, and Sistan and Baluchestan provinces, using system dynamic modelling approach. Based on field reconnaissance and literature review, data was collected. In the next step, reference diagrams were created to presenting the causal relationships and feedback based on which the conceptual model for the desertification of the Jazmurian catchment has been developed. The conceptual model was then converted into a model of stocks and flows and run in the Vensim software environment. Model verification was carried out through behavior reproduction tests. Different scenarios of vegetation management and climate were simulated and the outputs of each scenario were compared to the outputs of existing condition. Based on the results, soil criteria, with a score of 1.73, is the most effective factor for land sensitivity to desertification in the Jazmurian catchment. Desertification Sensitivity Index was in critical class with a score of 1.37. The results of scenario analyses for a 30-year period showed that, change in policy and management (1), management of land cover (1.18 and 1.25), and climate change (1.25) are the preferred scenarios for decreasing the Desertification Sensitivity Index. Based on the evaluations and studies, the average weight of the desertification intensity for the current state of desertification based on four factors was 1.37. By comparing this value with the ESAs, desertification intensity class for the entire area is estimated between the fragile and critical (a). Examining the results of implementing the cover management scenarios is observed that if 10 and 20 percent change in vegetation cover and protection against erosion occurs, the sensitivity index after 30 years will reach about 1.25 and 1.18 in order, this shows the importance of managing coverage to Combat Desertification, especially in watershed Jazmourian. Also, management measures in the studied area can stop the desertification process and improve the current situation. The research indicates that the system dynamic approach, as one of the integrating approaches for the assessment of desertification sensitivity in the Jazmurian catchment, is a useful and efficient approach which helps stakeholders enhances their understanding of the causal relationships and feedback in the system.