A Climatic Eco-geomorphological Transect Across the Major Climatic Belts of Israel—Processes, Patterns, and Desertification

In this chapter, the typical landforms and processes along the climatic eco-geomorphological transect running from the arid region near the Dead Sea, through Mildly-arid and Semi-arid regions, to the Mediterranean climate region in the Judean Mountains, are described and analyzed. Based on field measurements of the spatial and temporal variability of rainfall and temperature, as well as soil properties and hydro-geomorphological processes, the trends at the regional scale and the spatial patterns at the plot scale are discussed. Regarding the regional scale, a high correlation was found between the average climatic conditions and the relevant variables and processes such as soil aggregate stability and organic matter content, infiltration rate, and runoff coefficient. However, a step-like threshold exists at the semi-arid area which sharply separates between the Mediterranean eco-geomorphic system and the arid systems. This sharp change indicates that these systems are controlled by different processes. While the Mediterranean eco-geomorphic system is controlled by biotic processes, the arid eco-geomorphic systems are controlled by abiotic factors. Regarding the plot scale, the spatial response to rainfall in both the Mediterranean climate system and the arid system is homogeneous, but in opposite directions. While in the Mediterranean climate zone infiltration is the dominant process all over the hillslopes, in the arid zone overland flow is generated over the entire hillslopes. In contrast, the semi-arid zone is characterized by a mosaic-like pattern, containing source patches that contribute overland flow and sink patches in which the direct rain and the water inflow infiltrate. The sharp difference in the geomorphic processes between the Mediterranean climate region and the arid region and the expected climate change in Israel means that Israel is threatened by desertification even in the case of relatively small climatic change. On the basis of the findings in this research, the expected spatial distribution changes of the surface cover components in the Mediterranean climate region and the semi-arid region are described.