Aaron Yair
Hebrew University of Jerusalem, Israel
Title: Opposite eco-geomorphological responses to climatic changes, during the Upper Pleistocene and Holocene periods, in the South-Eastern Mediterranean area
Biography
Biography: Aaron Yair
Abstract
Dryland areas are usually regarded as highly sensitive to climatic changes. A positive relationship between average annual rainfall and environmental variables is often assumed for such areas. However, the global climatological models fail to address an important issue. With decreasing annual rainfall water resources may be highly dependent on surface properties and rainfall characteristics at a rainstorm level, which greatly influence the degree to which rainwater will percolate, or will be transformed into runoff, thereby significantly affecting the spatial redistribution of water resources. In other words, a climate change in dryland areas would be expected to have differential hydrological effects in a sandy area, a rocky area or in loess covered area. Differential hydrological effects would also be expected within each of the areas listed above. The Northern Negev desert offers unique conditions for the study of the possible effects, along a rainfall gradient, under changing surface conditions. Two case studies are considered. The first deals with the environmental effects of loess penetration into the area during a wet climatic phase. The second considers the differential effects of biological. Topsoil crusts on the water regime in a dry sandy area. Data obtained draw attention to the complex relationships between average annual rainfall, surface properties, water resources and ecosystem structure. In both areas considered the increase in the average annual rainfall had negative effects on the water resources and related ecological properties.