Hi Munirul,

The term desertification has been highly contentious as it encompasses multiple disciplines and have been applied to non-equilibrium ecosystems that do not behave linearly (become 'desert'). Some remote sensing scientists have attempted to define 'desertification' as the inability of a region to reach its potential productivity as indicated by its biome (rainfall, temperature, vegetation types). This enables a quantitative estimation of land degradation across space and time. What they find is that land degradation is a local event that is harder to detect on continental scales, since at these scales climate has a greater influence. Land cover change and agriculturally caused soil erosion are more specific processes that are usually not described by 'desertification'. Some references on these quantitative approaches are below:

Wessels, K.J., Prince, S.D., Frost, P.E., & van Zyl, D. (2004). Assessing the effects of human-induced land degradation in the former homelands of northern South Africa with a 1 km AVHRR NDVI time-series. Remote Sensing of Environment, 91, 47-67

Prince, S.D. (2004). Mapping desertification in southern Africa. In G. Gutman, A. Janetos & C.O. Justice (Eds.), Land Change Science: Observing, Monitoring, and Understanding Trajectories of Change on the Earth's Surface (pp. 163-184.). Dordrecht, NL: Kluwer

Thank you very much Molly

Desertification is considered as a process which is considered both as a onward marching front of deserts. There was a controversy in India during PM Rajiv Gandhi's regime that Indian deserts through certain corridors is invading or marching into more productive areas including plains of Bihar. It was Dr. Survinder Singh, then Head of Geomorphology Division of Central Arid Zone Research Institute (CAZRI) who put to rest the controversy and savied much of burden on the country's financial resources. However, there is some truth in it that sometimes deserts in this way particularly in adjoining semi-arid and sub-humid areas as strong winds from deserts bring with them sharp tools of erosion and upper layer of productive soils is not only eroded but sand is also deposited in the process. It is also true that desertification takes place spontaneously in certain locale due to faulty land use as pushing crops taxing on soil resources in fragile or unlikely areas and over use of fertilisers or in other modern inputs, dust bowl of the US is an example of intensive use of land using modern agricultural technology is one example. basically desert means to leave or an area uninhabited mostly due to constraint of water and by extension an area that becomes unproductive due to some reasons. However, scientists for their convenience to the effect of quantification may have defined a a region or area as desert due to its "inability ... to reach its potential productivity as indicated by its biome (rainfall, temperature, vegetation types)." If the word vegetation has not been incorporated then I have considered this definition referring to productivity of an ecosystem, But use of vegetation in the context of potential of productivity means it refers to agricultural productivity. As a student of geography, ecology and environment, I would like to differ. Like carrying capacity, to determine agricultural production or assess it is very very hard as you will find out that different scholars have give quite wide ranging values of biophysical potential of the planet to support population, Further, realisation of productivity of a region not only depends on its climatic energy and capacity to have dense vegetation, type of technology and innovativeness of farmers and their managerial skills and financial status also contribute significantly to this effect. Therefore, this measure of desertification is theoretically untenable.

It is true in view of climate change and intensification of agriculture may intensify this process. But, dry lands, in view of increasing population pressure and competitive land uses whereby more and more productive land and environmentally/ecologically sensitive or desirable land is being diverted to other development activities, are future hope mankind.

tt requires urgent measures to turn dry lands into green and productive areas as to enhance fertility of minerals rich dry land soils a green cover is needed to gradually make it more productive. However, in these water scarce or water stressed areas it seems quite unlikely. However, at community levels sporadic extreme water may be harvested into tanks or ephemeral and seasonal streams may be diverted towards large depression which by traditional knowledge or due to geophysical data are considered have an underlying aquifer geochemistry that has little or less probability to make recharge water unusably saline. On the other hand, at governmental levels steps may be taken to divert excess flood water in in distant places to store it in fresh but exhausted aquifers of these lands.

This water may be used for agricultural purposes, tree linings and vegetation breaks nearby deserts and also to grow grass cover.

These steps not only help in carrying out a commercial (non-subsistence) agriculture but also minimise soil erosion and slowdown expansion of desert in these dry lands.