Desert greening

• Planting trees (pioneer species) and salt-loving plants (halophytes), such as Salicornia
• Planting trees augmented by dew and rain harvesting technologies like the Groasis Waterboxx
• Regeneration of salty, polluted, or degenerated soils

• Ecoscaping; landscaping methods which reduce evaporation, erosion, consolidation of topsoil, sandstorms, and high temperatures
• Floodwater retention and infiltration (flood control)[3]

• Desert farming based on fossil groundwater, although not being sustainable
• Farmer-managed natural regeneration
• Greenhouse agriculture
• Holistic management
• Inland mariculture[4]
• Managed intensive rotational grazing
• Permaculture in general – harvesting runoff rainwater to grow plant communities polyculture, composting or multitrophic agriculture
• Prevention of overgrazing
• Regenerative agriculture
• Seawater greenhouses and farming, for example, Seawater Foundation or the IBTS Greenhouse

• Prevention of firewood or charcoal use, respectively providing electricity for cooking

Once the fresh water or seawater has been attained in centralized systems it must be distributed. This can be done using dug canals or in some instances aqueducts (which are both the least attractive option since they allow much water to be evaporated), troughs (as used in the Keita Project[5]), earthenware piping (semi-open or closed) or even underground systems i.e. qanāt.

Depending on the method of distribution of the water, it can then be provided on different methods to the plants. A costly solution (used only on pipes) is drip irrigation. Other methods are the use of wadis (basically V-shaped ponds dug in the earth) or by simply planting the trees in holes inside/over the water pipe itself. The tree's roots can then suck the water straight from the water pipe (used in qanāt, hydroponics, ...) A similar technique can be done with semi-open pipes (i.e. dug throughs in the Keita Project).

The use of water is, however, not always without problems. Desert greening by the Helmand and Arghandab Valley Authority irrigation scheme in Afghanistan significantly reduced the water flowing from the Helmand River into Lake Hamun and this, together with drought, was cited as a key reason for the severe damage to the ecology of Lake Hamun, much of which has degenerated since 1999 from a wetland of international importance into salt flats.[6]

Reversing desertification of Mu Us Desert west of Yulin, Shaanxi. 1985 (above) and 2021 situation.

The Three-North Shelter Forest Program, also nicknamed the "Great Green Wall", is a series of windbreaking forests in China designed to hold back the expansion of the Gobi Desert[8][9] and reduce the incidence of dust storms that have long caused problems for northern China,[10] as well as also providing timber to the local population.[11] The program started in 1978 with the proposed end result of raising northern China's forested area from 5 to 15 percent,[12] and is planned to be completed around 2050,[13] at which point it will be 4,500 km (2,800 mi) long. The fourth phase of the project started in 2003 and has two parts: the use of aerial seeding to cover wide swathes of land where the soil is less arid, and the offering of cash incentives to farmers to plant trees and shrubs in more arid areas.[14] A $1.2 billion oversight system (including mapping and surveillance databases) is also to be implemented.[14] A belt of sand-tolerant vegetation arranged in checkerboard patterns are planted to stabilize the sand dunes, and a gravel platform will be next to the vegetation to hold down sand and encourage a soil crust to form.[14] In 2008, winter storms destroyed 10% of the new forest stock, causing the World Bank to advise China to focus more on quality rather than quantity in its stock species.[15]

As of 2009, China's planted forest covered more than 500,000 km² (190,000 sq mi), increasing tree coverage from 12% to 18%. It is the largest artificial forest in the world.[15] According to Foreign Affairs, the program successfully transitioned the economic model in the Gobi Desert region from ecologically harmful industrial farming and pastoralism to beneficial ecotourism, fruticulture and forestry.[16] In 2018, United States' National Oceanic and Atmospheric Administration found the increase in forest coverage observed by satellites is consistent with the Chinese government data.[17] According to Shixiong Cao, an ecologist at Beijing Forestry University, the Chinese Government recognized the water shortage problems in arid regions and changed the approach towards vegetation with lower water requirements.[17] Zhang Jianlong, head of the Forestry Department, told the media that the goal was to sustain the health of vegetation and choose suitable plant species and irrigation techniques.[17]

According to BBC News report in 2020, China's tree plantation programs resulted in significant carbon fixation and helped mitigated climate change, and the benefit was underestimated by previous research.[18] The program also reversed the desertification of the Gobi desert, which grew 10,000 km² (3,900 sq mi) per year in the 1980s, but had shrunk by more than 2,000 km² (770 sq mi) in 2022.[19]

The soil of the Thar Desert in India remains dry for much of the year and is prone to soil erosion. High speed winds blow soil from the desert, depositing some on neighboring fertile lands, and causing shifting sand dunes within the desert, which buries fences and blocks roads and railway tracks. A permanent solution to this problem of shifting sand dunes can be provided by planting appropriate species on the dunes to prevent further shifting and planting windbreaks and shelterbelts. These solutions also provide protection from hot or cold and desiccating winds and the invasion of sand. The Rajasthan Canal system in India is the major irrigation scheme of the Thar Desert and is intended to reclaim it and to check spreading of the desert to fertile areas.

Prevention of shifting sand dunes is accomplished through plantations of Vachellia tortilis near Laxmangarh town. There are few local tree species suitable for planting in the desert region and these are slow growing. The introduction of exotic tree species in the desert for plantation has become necessary. Many species of Eucalyptus, Acacia, Cassia and other genera from Israel, Australia, US, Russia, Zimbabwe, Chile, Peru, and Sudan have been tried in the Thar Desert. Vachellia tortilis has proved to be the most promising species for desert greening. The jojoba is another promising species of economic value which has been found suitable for planting in these areas.

The "Great Green Wall of the Sahara and the Sahel" is a project adopted by the African Union in 2007, initially conceived as a way to combat desertification in the Sahel region and hold back expansion of the Sahara Desert by planting a wall of trees stretching across the entire Sahel from Djibouti City to Dakar. The original dimensions of the "wall" were slated to be 15 km (9.3 mi) wide and 7,775 km (4,831 mi) long, but the program has expanded to encompass nations in both North and West Africa.[20] The modern green wall has since evolved into a program promoting water harvesting techniques, greenery protection and improving indigenous land use techniques, aimed at creating a mosaic of green and productive landscapes across North Africa.[21] The ongoing goal of the project is to restore 100 million hectares of degraded land and capture 250 million tonnes of carbon dioxide, and create 10 million jobs in the process all by 2030.

As of March 2019, 15 per cent of the wall was complete with significant gains made in Nigeria, Senegal and Ethiopia.[22] In Senegal, over 11 million trees had been planted. Nigeria has restored 4,900,000 ha (12,000,000 acres; 49,000 km²) of degraded land, and Ethiopia has reclaimed 15,000,000 ha (37,000,000 acres; 150,000 km²).[20] A report commissioned by the United Nations Convention to Combat Desertification (UNCCD) was published on September 7, 2020,[23] that the Great Green Wall had only covered 4% of the planned area, with only 4,000,000 ha (9,900,000 acres; 40,000 km²) planted. Ethiopia has had the most success with 5.5 billion seedlings planted, but Chad has only planted 1.1 million. Doubt was also raised over the survival rate of the 12 million trees planted in Senegal.[24]

In January 2021, the project received a boost at the One Planet Summit, where its partners pledged 14.3 billion USD to launch the Great Green Wall Accelerator, aimed at facilitating the collaboration and coordination among donors and involved stakeholders across 11 countries.[25] In September 2021, the French Development Agency estimated that 20 million hectares have been restored and 350,000 jobs have been created.[26] According to the second edition of the Global Land Outlook' published by the UNCCD in April of 2022, one reason the project has experienced implementation challenges is the political risk associated with investing in more fragile nations as well as the fact that many "GGW projects generate low economic returns compared to the significant environmental and social benefits accrued that often have little or no market value". Furthermore, international donors seem to favor investing in more stable nations, picking and choosing which projects they will fund, and leaving nations with less stable governments behind.[27]

Sundrop Farms launched a greenhouse in 2016 to produce 15,000 tonnes of tomatoes using only desert soil and desalinated water piped from Spencer Gulf.[28]