6 (ii) ‘Analyse the measurements of desertification’
“Drought and desertification threaten the livelihood of over one billion people in more than 110 countries” warned general Kofi in 2001 (Kovach,2003). Desertifications definition is highly disputed but it is generally the shift of arid or semi-arid regions to desert-like conditions, which support: little vegetation, a low soil fertility and high evaporation rates (Haggett, 2001). This work will overlook how deserts are measured by a variety of different means.
To measure the growth of deserts characteristics need to be obtained. By creating set indicators for deserts the spread of desertification can be gauged. Climate (Anderson,2001) is one of the larger indicators of the spread of deserts: as you can see from appendix 1B, the worlds deserts are in general located in and around the equatorial region and the tropics. Due to this they are influenced heavily by the movements of the inter-continental convergence zone (ITCZ) which generates areas of high pressure over deserts such as the Sahara desert and due to this there is little precipitation for the whole year (below 25mm) (Berrahmouni, 2001). Desert zones receive little rain during a year but when they do it is heavy and sporadic and causes much soil erosion (Sharma1997). So by gauging precipitation levels around arid and semi-arid regions meteorologists can approximate as to how ‘at risk’ the area is. As without a decent supply of precipitation, soil infrastructure and fertility will decline due to a lack of moisture and the denaturing of the surrounding biota i.e. roots and nutrient cycles (Sharma1997). National monthly rainfall index (NMRI) (UN) is used to measure monthly changes in precipiatation, weighjted against the yearly averages (UN, 2004).
