No abstract

Two approaches to biomass mapping of shrublands across sub-humid and arid transition zones are integrated. The first generalizes relationships between biomass and precipitation from sites in the Mediterranean Basin, California, Namibia and Mongolia. The second represents existing Normalized Difference Vegetation Index (NDVI)-based models for biomass estimation on a regional scale. A new modified NDVI-based model is presented that uses relative rain availability as the ratio between the mean annual precipitation and the threshold rain level representing the transition from herbaceous growth to shrub dominance. While the data accounts for the actual vegetation cover, the relative rain parameter accounts for the potential biomass production. Implementation of the modified relative rain model with Landsat imagery of climatic gradients (the east-west gradient between the Judean Mountains and the Judean desert and the north-south gradient between the Judean Mountains and the Negev Desert) yielded realistic estimates of biomass in areas of high human disturbance to the natural ecosystems. These results support the possibility that the modified model can be used to map biomass across wide Mediterranean and desert-fringe ecosystems.

Recent climate studies of the South-Eastern Mediterranean indicate an increase in drought frequencies and decreasing water resources since the turn of the century. A four-phase methodology was developed for assessing above-ground biomass changes in shrublands caused by these recent trends. Firstly, we generalized the function SB = 0.008MAP 1.54 describing the shrublands above-ground biomass (SB) dependence on mean annual precipitation (MAP) for areas of full shrub cover. Secondly, relationships between MAP and NDVI were formalized, allowing an estimation of precipitation levels from observed NDVI values (MAPNDVI). Thirdly, relative water-use efficiency (RWUE) was defined as the ratio between MAPNDVI and MAP. Finally, the function SBRWUE = 0.008MAP 0.54 + RWUE was formalized, utilizing RWUE in estimating shrublands biomass. This methodology was implemented using Landsat TM images (1994 to 2011) for an area between the Judean Mountains and the deserts bordering them to the east and south. More than 50% of the study area revealed low biomass change (±0.2 kg/m

This paper describes the relationship between urban road network density and urban runoff coefficient in the coastal plain of Israel. The study assessed 30 years of recorded changes in rainfall-runoff coefficient in an urban catchment in the coastal plain of Israel. Rain and runoff were measured and sampled at measurement stations. Insight into the factors affecting urban runoff was gained by applying GIS and remote-sensing analysis, including street network density assessment and urban impermeable area recognition. Street network density was found to be a reliable indicator for both urban impermeability (R 2 ¼ 0.83) and runoff (R 2 ¼ 0.92) change dynamics, showing a strong linear correlation. Thus the urban street drainage network can help explain the dynamics of change in urban runoff. To prevent urban flooding hazards, and to help conserve water resources, regional planners should take into consideration road network density in built-up areas.