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For example, temperature increase by 1.5–2.1 percent across the Nile Basin over the next 30–40 years could change the region from semi-arid to arid, significantly reducing the land usable for agriculture. In addition, changes in land use can increase demands on soil water and thereby increase aridity. [6]
Aridification is the process of a region becoming increasingly arid, or dry.It refers to long term change, [1] rather than seasonal variation. It is often measured as the reduction of average soil moisture content.
Desertification is a gradual process of increased soil aridity.Desertification has been defined in the text of the United Nations Convention to Combat Desertification (UNCCD) as "land degradation in arid, semi-arid and dry sub-humid regions resulting from various factors, including climatic variations and human activities."
Aridity increased, with the Ghaggar-Hakra River retracting its reach towards the foothills of the Himalayas, [62] [65] [66] leading to erratic and less-extensive floods, which made inundation agriculture less sustainable. Aridification reduced the water supply enough to cause the civilisation's demise, and to scatter its population eastward.
There is a significantly greater proportion of drylands in developing countries (72%), and the proportion increases with aridity: almost 100% of all hyper-arid lands are in the developing world. Nevertheless, the United States , Australia , and several countries in Southern Europe also contain significant dryland areas.
Aridity is different from drought because aridity is permanent whereas drought is temporary. [1] A number of aridity indices have been proposed (see below); these indicators serve to identify, locate or delimit regions that suffer from a deficit of available water, a condition that can severely affect the effective use of the land for such ...
Altitudinal zones of Andes Mountains and corresponding communities of agriculture and livestock raised. Human populations have developed agricultural production strategies to exploit varying characteristics of altitudinal zones. Elevation, climate, and soil fertility set upper limits on types of crops that can reside in each zone.
Dryland farming caused a large dust storm in parts of Eastern Washington on October 4, 2009. Courtesy: NASA/GSFC, MODIS Rapid Response [1]. Dryland farming has evolved as a set of techniques and management practices to adapt to limited availability of water, as in the Western US and other regions affected by climate change for crops such as tomato and maize.