Iran has different climatic and geographical zones (mountainous and desert areas), mostly arid and semi-arid, which are suffering from land degradation. Desertification as a land degradation process in Iran is created by natural and anthropogenic driving forces. Meteorological drought is a major natural driving force of desertification and occurs due to the extended periods of low precipitation. Scarcity of water, as well as the excessive use of water resources, mainly for agriculture, creates negative water balances and changes in plant cover, and accelerates desertification. Despite various political measures having been taken in the past, desertification is still a serious environmental problem in many regions in Iran. In this study, drought and aridity indices derived from long-term temperature and precipitation data were used in order to show long-term drought occurrence in different climatic zones in Iran. The results indicated the occurrence of severe and extremely severe meteorological droughts in recent decades in the areas studied. Moreover, the De Martonne Aridity Index (IDM) and precipitation variability index (PVI) showed an ongoing negative trend on the basis of long-term data and the conducted regression analysis. Rapid population growth, soil salinization, and poor water resource management are also considered as the main anthropogenic drivers. The percentage of the rural population in Iran is decreasing and the urban area is growing fast. Since the 1970s, the usage of groundwater in Iran has increased around fourfold and the average annual decrease in the groundwater table has been around 0.51 m. The results of the study provide a better ex-post and ex-ante understanding of the occurrence of droughts as key driving forces of the desertification in Iran. Additionally, they can enable policymakers to prepare proper regional-based strategic planning in the future. Desertification cannot be stopped or managed completely, but could be mitigated by the adoption of some proposed sustainable land management strategies.

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Agricultural production is predicted to double during the next century. To ensure food security in response to global population growth is a challenge and will require strategies that mitigate associated environmental damage in ways consistent with United Nation's Sustainable Development Goals. One possible approach is to utilize organic fertilizers from marine sources to improve soil structure by enhancing activities of soil organisms and restoring essential plant nutrients to the soil. Here we identify opportunities to develop organic fertilizers from two types of materials of marine origin: seagrass wrack and jellyfish biomass. Seagrass wrack often occurs as undesirable waste material on beaches. In many coastal areas around the world jellyfish bloom presents a nuisance because of negative impacts on marine ecosystem productivity. Several investigations have reported that organic fertilizers produced from seagrass and jellyfish could enhance coastal ecosystem services by reducing pollution, and by improving soil health and quality. Recent research indicates that seagrass litter improves soil water holding capacity and the nutritional value of crops; moreover, it can be used as multi-functional fertilizer, due to its content of valuable macro-and microelements. The application of jellyfish fertilizer increases soil contents of organic matter, nitrogen, phosphorus and potassium and enhances the growth and survival of seedlings significantly. In this overview we describe novel approaches regarding the utilization of seagrass and jellyfish as sources of fertilizer, and experimental studies on the influences of marine organic fertilizers on soil restoration, and implications for coastal management.

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Lake Urmia, the second largest saline Lake on earth and a highly endangered ecosystem, is on the brink of a serious environmental disaster similar to the catastrophic death of the Aral Sea. Progressive drying has been observed during the last decade, causing dramatic changes to Lake Urmia's surface and its regional water supplies. The present study aims to improve monitoring of spatiotemporal changes of Lake Urmia in the period 1975-2015 using the multi-temporal satellite altimetry and Landsat (5-TM, 7-ETM+ and 8-OLI) images. In order to demonstrate the impacts of climate change and human pressure on the variations in surface extent and water level, Lake Sevan and Van Lake with different characteristics were studied along with the Urmia Lake. Normalized Difference Water Index-Principal Components Index (NDWI-PCs), Normalized Difference Water Index (NDWI), Modified NDWI (MNDWI), Normalized Difference Moisture Index (NDMI), Water Ratio Index (WRI), Normalized Difference Vegetation Index (NDVI), Automated Water Extraction Index (AWEI), and MultiLayer Perceptron Neural Networks (MLP NNs) classifier were investigated for the extraction of surface water from Landsat data. The presented results revealed that MLP NNs has a better performance in the cases where the other models generate poor accuracy. The results show that the area of Lake Sevan and Van Lake have increased while the area of Lake Urmia has decreased by~65.23% in the past decades, far more than previously reported (~25% to 50%). Urmia Lake's shoreline has been receding severely between 2010 and 2015 with no sign of recovery, which has been partly blamed on prolonged droughts, aggressive regional water resources development plans, intensive agricultural activities, and anthropogenic changes to the system. The results also indicated that (among the proposed factors) changes in inflows due to overuse of surface water resources and constructing dams (mostly during 1995-2005) are the main reasons for Urmia Lake's shoreline receding. The model presented in this manuscript can be used by managers as a decision support system to find the effects of building new dams or other infrastructures.