Dr. Tewari, it is a good question. I think, it leads to decrease in soil/ambient temperature specially during summer season as well as diurnal variation. Helps to increase in humidity. Soil surface may stabilize which become suitable for the cultivation and growth of trees which leads to development of environment as well as improve the soil properties. It helps to improvement in soil organic matter and microbial and enzymatic activities. Although it may have some adverse effect on desert plants and animals as well as may invite more diseases and pests.

Thank you very much Dr. Tarafdar for your views on loss of sand dunes . Regards .

Dr Tewari, my opinion wrt your question is little different than Dr Tarafdar.No doubt there shall be certain changes with spatio temporal abbrasions caused due to sand dunes but one thing is sure that this shall prevail only till the water for irrigation is available.The day water becomes limited or even gets vanished for agararian usage in those araeas, nature will again leadto sand dune development within a very short span of period.One thing is for sure that soil texture and soil structure can not be changed by human interventions and by the time, water elopes from the scene,every thing will be on the mercy of mother nature as at that point of time say 50-100 years from now, managing water for agaraian purposes will be the greatest issue.Rest assured if water or rainfall becomes ample,then i shall be endorsing the response of Dr Tarafdar.

Dear Dr. Tewari,

Disappearance of sand dunes in many parts of That (Thal/Thar) desert due to availability of water from canal irrigation system is a sure sign of ecosystem mis-balance.

In the following Paper I have tried to suggest:

It is a matter of fact that the dams and barrages were constructed to harness hydroelectricity and to irrigate the land. The benefits were realized in no time and soon enough electricity was available in the remotest villages while the land in the irrigation canal command area was able to produce at least 3 times as much.

The benefit was at the cost of the forested area that had to be cleared; the land area that was submerged and the Project Affected Persons who were forced to abandon their hearth and home.

The dams when commissioned had to face the problem of silting up and only after a few years their capacity was invariably reduced by one third. The silt having been retained at the dam sites was not available downstream, and thus the water made available for irrigation did not have the nutrients available earlier. No wonder the high dams are not being favoured in the countries which introduced them.

The irrigation system has likewise had its days and has in most cases outlived its age. The valuable land has lost its productivity while only halfway through i.e. in about 7 to 10 years since signs of salinization and waterlogging due to seepage started appearing in just as much time. The land was salinized by the accumulation of salts brought by the rivers.

Sand dunes were partially stabilized due to increase in humidity and also appearance of saline lakes resulting from seepage from canals.

Diversion of river water into the irrigation fields deprived the rivers of freshwater in the delta areas. Freshwater stopped flowing for almost ten months in the downstream areas, while seepage from the unlined canals and irrigated land accumulated and waterlogged the adjacent land.

The lower deltaic plain in the area lying in the deltaic floodplain being no longer an active flood plain was subjected to extensive erosive action of the sea waves particularly during stormy conditions. This led to submergence of a number of islands. The erosive action of flood flow over the dry river bed of the rivers e.g. the Indus and of flash floods over other rivers in Sindh East has exposed the river bed of the concerned rivers to the rock bottom. The rock bottom in the case of River Indus is only 3 meter above sea level at Kotri Railway Bridge about 170 km from the sea coast, and is now exposed to intrusion of seawater during high tides.

Flooding in the lower deltaic plain used to restrain the seawater salinity from intruding into the mainland, but flooding has ceased to occur and hence the potential gradient is reduced to the extent that seepage potential has overwhelmed the stream flow. The canal command boundary has, during the course of time, become wet with seawater reaching upland during high tides. The ecology of the entire Indus Basin has changed as a consequence of diversion and distribution of the water resources thinly over accessible and inaccessible areas of the country. ........more.

It is a long story of Disaster entailed by development process. You may read the paper; it is worth reading.

Research Dam The Rivers & Damn the Land-Seas-Ocean Ecosystems

Many disadvantages have been mentioned by Dr. Arshad. Developed countries have replaced dams by other power generating technology, but poor countries have little options for low cost electricity generation

Thank you Dr.Beg for your valuable comments on the issue . Regards !

Thank you Dr. Mushtaq for expressing your interesting comments on the issue .

extremely low and high temperature of that area may affect due to disappearing of sand dunes as well as burning of carbon may decrease due to decrease in temperature during summer.

Dr.Mukesh , Thank you very much for your views on the issue . Regards!

Sir,

This will have very notable adverse impact on the Thar Desert Ecosystem and imbalance the Ecosystem productivity and loss of Biodiversity. Simply, there are many endemic, threatened and rare plant and animal species found in this ecosystem will note accept the sudden change. Furthermore In the world very few Great Indian Bustard (Godavan) are exist and they are on critically engendered.

Dr. Rohit , you are absolutely right ! I always used to think what would be the consequences of loss of sand dunes in ecological terms . Agriculture scientists ( I m not blaming any one ) have one problem , though they often use term ecology , ecosystem , biodiversity , ecosystem functioning , etc.but , in my opinion they never think of futuristic scenario of environmental impacts of certain major happenings like , loss of sand dunes in present case . They are always concerned with arable crops and their production enhancement ,etc . Okay, with canal irrigation , you will bring dessert landscapes into production system , but at what environmental cost ? If sand dunes disappear , you are going to loose tremendous amount of biodiversity. This is just only one example . There are many more issues , situation is very complex. Unfortunately in India , no work is available on these lines . Regards !

Dr. Tewari,

I have already touched on your observation: "Okay, with canal irrigation , you will bring dessert landscapes into production system , but at what environmental cost ? If sand dunes disappear , you are going to loose tremendous amount of biodiversity. This is just only one example . There are many more issues , situation is very complex. Unfortunately in India , no work is available on these lines ."

Perhaps you did not read the Paper. I will strongly advise you to read the Paper, since the last few lines of its abstract read:

"I would suggest and strongly appeal to the intellectuals to stop their governing hierarchies from the nonsense of rapid growth of their economy, it would be much better to adopt a sustainable rate and plan not to impoverish the resources in one go."

"The Himalayas are littered with dams on the east west south and north. India has not learnt any lesson from the Uttarkhand disaster nor from the destructive earthquake in Nepal, but is going full steam for construction of dams. Any restraint on the ecosystem is at the cost of precious ecology or enthalpy in Socio-physicochemical sense."

"This in turn implies increase in entropy or degradation of the environment. The Socio-physicochemical theory therefore holds that construction relating to damming the rivers leads to extensive degradation of the ecosystem and is therefore not sustainable."

This is not all Dr. Tewari, degradation of the environment is on leaps and bounds. The recent description of Mt. Everest by the mountain climbers and of the Sadhu on the Gangotri glacier, which feeds the Ganga, should be an eye opener. But India is too ambitious to pay heed to the impending disaster: The impending disaster is likely to lead to much reduced flow of snow-melt and ultimately low flow in the Holy Ganges.

That futuristic estimate places the disaster to be incident in just within the next decade. I can only wish the estimates are all wrong.

Mirza Arshad Ali Beg

Dear Dr . Beg , I have gone through your observations . You have highlighted the issue very well . I strongly endorse your views . In fact , you educated me in this context . With regards !

Now the debate on the issue has been set in. My personal view is that government agencies should strictly follow sand dune stabilization programme through vegetative means rather promoting agricultural activities in duny landscapes. There should be policy to protect the dunes.In my view ecosystems in Thar desert , India are perturbation dependent , not very fragile as often termed . I have very good experience of that - in certain areas where biotic disturbances were completely checked , those areas accumulated tremendous biomass in form of perrenial grasses , shrubs of different kinds , under canopy and as well as canopy tree species without any plantation programmes of any kind. If the lands have such tremendous regeneration potential , why are we doing so much interfarance in ecosystem functioning by way of turning natural desertic landscapes into agricultural production systems because India has enough food reserve to feed her population. I don't know to what extent my thinking is right ??It was batter to practice subsistence agriculture as people were doing earlier in this part of the country . As agriculture in the region is still default organic in larger parts , let's give total emphasis to organic agriculture with agroforestry in central theme + animal husbandry ( it is age old tradition of income of farmers ). That would be sufficient to provide the income which farmers are getting in recent times.

Dear. Dr. Tewari,

It is good to find some body listening to you. But you will hardly find a majority favouring subsistence / organic agriculture in a world studded with industries producing fertilizers, pesticides, genetically modified seeds and supplements; irrigation network that brings water to the door step of the farmer, or the rich enjoying their richness. The irrigation canals have brought in prosperity for the land owners, but have caused irreversible damage to the ecosystem, disappearance of sand dunes, as you have identified is a sure sign thereof. Time now is to face reality. We, in South Asia just cannot afford to spread the dwindling resources too thin, knowing fully well that they are not renewable.

In an earlier post I have described the water availability situation from the Gangotri glacier that feeds the sacred Ganga. Ravi, Beas, Sutluj Jamuna and Ganga have all been dammed while their East Himalayan glacial melt is getting reduced year after year.

That only suggests a return ticket to following the sustainability principles.

Good Luck

Mirza Arshad Ali Beg

Thank you Dr. Beg for responding to my observation . If we want sustainable development in south Asia , it requires some thing above than the principles of so called economic development which is taking big tool of environment . Ecosystems are damaging very fast in Tar / Thal deserts , but big question in my mind is why intellectuals are silent , leave politicians.Those few who voice concerns are often find no takers of their views. Any way , your observations really educated me . With warm regards , J. C. Tewari.

Disappearing sand dunes are important issue from ecological view point . There are many outstanding ecologists are members of RG , I sincerely request to them , please debate on the issue so that we could reach in a logical conclusion . Regards to one and all .

Great Discussion!

I recently visited Jaisalmer for the second time in 2 years and was appalled to see so much vegetation in the region. The sand dunes surrounding Sam, Jaisalmer had shrunk so much and even in non-irrigated lands the amount of vegetation has increased drastically. Before studying long-term impacts of such changes to the ecosystem, I believe it is necessary to address the basic parameters that should be observed. The first and foremost impact will be on the radiation budget of the region. Increase in vegetation cover implies reduced albedo (compared to sand) and more shortwave radiation being absorbed. This can have major impact on the regional hydrologic and carbon cycle.