Coevolution of Climate Change, Surface Properties, Vegetation Cover, and Drainage Network in a Loess Covered Area.

Arid and semi-arid areas are often regarded as highly sensitive to climate change. Average annual rainfall is usually regarded as the most important factor controlling soil moisture regime, water availability, and therefore various environmental variables. The present study deals with the ecology of an area located in the semi-arid area of Israel, where average annual rainfall is ~280 mm. The area is located in a loess covered area. The loess cover was deposited during a wet climatic phase. However, pedological and ecological data point to a desertification effect. Data obtained show that non-climatic factors, such as local surface properties, can exert a strong influence on the environment. In addition, the global models disregard the characteristics of the local rainfall regime, such as the distribution of rain intensities, and the duration of individual rain-showers during a rainstorm. Under the present rainfall regime about 85% of the rains are below 5 mm/hr,1, rainfall is also highly intermittent, limiting runoff generation, and infiltration depth. Under such conditions, a high evaporation rate leads to a soil salinization process.