China is one of countries with largest area of desertification in world. At present, China's total desert area is 700,000 square kilometers, and including Gobi area, it will reach 1.28 million square kilometers, which is 13% of country's total area. Turning deserts into oases and farmland has always been a dream of Chinese. Since founding of new China, Chinese have tried to control desert and have made great strides. So can China turn all deserts into oases?
First, we need to understand how deserts form. The climate of China is mainly divided into two types of climate: monsoonal in east and continental in northwest. China is located in eastern part of Eurasian continent, and its southeastern part is affected by southeast monsoon and southwest monsoon and has abundant rainfall, so ecological environment is relatively better. It is difficult for monsoon to reach northwest region, so rainfall in northwest region is low and evaporation is high, so many deserts form.
In highlands of Northwest China, mountains block water vapor, which can form a certain amount of precipitation, ice and snow. These large mountains are source of oases. For example, area with best climate in northwest is Ili River basin, where a spur of Tien Shan Mountains blocks water vapor from westerly winds, producing relatively abundant precipitation. These mountains are home to many rivers in Northwest and cradle of historical nomadic peoples. The wider basin has no water vapor replenishment and can only become a desert.
For example, Taklamakan Desert is located in Tarim Basin, Gurbantunggut Desert is in Junggar Basin, Badain Jaran Desert and Gobi Desert are in low-lying areas in middle of Mongolian Highlands, and Qinghai Desert is mainly located in Qaidam Basin Desert.
In history, area of the desert was not as large as it is today. During ice age, glaciers were widespread in north of Eurasian continent. After end of ice age, large lakes were widespread on Eurasian continent, which provided North-West with water resources. Because of large lakes, climate in northwest is not as dry as it is now. But later, lakes in northwest shrank, and climate in northwest became drier.
The main reason for reduction of lakes in Northwest is that fresh water entering lakes has decreased. Northwest China is one of areas where civilization used to be born. People built cities along rivers. Many city-states in western regions were built on tributaries of Tarim River. The growth of cities has led to an increase in water consumption, and river water has been intercepted. Combined with increase in number of people, scale of agriculture and grazing also expanded, and many pastures turned into deserts, so climate in northwest became harsh.
Loulan Ancient City: a city that disappeared due to depletion of water sources
Obviously, areas that were originally deserts are difficult to manage, while areas that were originally grasslands are relatively easier to manage. For decades, China has continuously planted trees in surrounding desert areas, and many deserts have been restored to pastures and even forests, which were originally pastures and forests in history but were later destroyed by humans. But if you want to control more than 1.2 million square kilometers of China's deserts and Gobi, can you do it?
Since deserts in northwest are mostly caused by drought, main measure to combat deserts is to increase water resources in northwest. In order to control desert, we have envisaged large-scale water conservation projects, such as diverting Tibetan waters to north and injecting sea water into Xinjiang. If water resources flowing from Qinghai-Tibet can be mobilized to Qinghai, Xinjiang and Inner Mongolia, water situation in northwest will improve significantly.
How to transform desert with water resources? Could it be that pumped water is directly pumped into rivers and lakes? This is definitely not best solution. Water resources are precious and pumped water must be carefully planned and distributed. As far as we know, basins in northwest are mostly very flat, and if these basins were turned into cultivated land, it would greatly increase China's grain production and ensure food security. Therefore, it is possible to lay pipelines widely in desert, and then transport water to various places in desert for implementation of drip irrigation and development of drip irrigation in agriculture.
Compared to afforestation, effect of agricultural development with drip irrigation is faster, and economic benefits are higher. The economic value created by development of agriculture with drip irrigation must be much greater than money spent on pumping water. After increase in water resources in northwest, amount of water entering lakes from rivers will increase, and large lakes such as Lob Nur will be restored. After total amount of water resources in northwest increases, it will form a large-scale climate effect: increase in water vapor will form a certain internal circulation and increase precipitation in northwest, thereby accelerating transformation of natural environment to northwest.
When developing agriculture with drip irrigation, select multiple afforestation sites, increase forest area in northwest, and improve soil water holding capacity. Only in this way can a virtuous circle be reached.
However, project for a large-scale transfer of water from Qinghai-Tibet Plateau is still far away. I don't know when it will be implemented. We can't wait for water transfer project to be implemented. be completed before we start marching into desert on a grand scale. So what can we do to transform desert before large-scale water resources are available?
Answer: yes, this is photovoltaic energy. The production of photovoltaic energy for desert control is best solution obtained after decades of desert control research in China. This solution can take into account both environmental and economic benefits, killing two birds with one stone. The climate in Northwest is arid, so there is a lot of sunshine. If these solar energy resources can be harnessed, economic value created will far exceed our expectations.
Map of distribution of solar radiation in China
Researching relevant materials, some scholars have calculated that if we call Taklamakan Desert a base for photovoltaic power production, power generation here can provide electricity consumption in 4 China. So our energy problem in China is basically solved. At present, Chinese photovoltaic power generation projects are being promoted in many provinces of Northwest China, and photovoltaic power generation is growing at an alarming rate. In 2022, China's photovoltaic power generation will largely equal hydropower generation, and by 2023, photovoltaic power generation will exceed that of hydropower. In future, photovoltaic energy production will continue to grow dramatically and it is quite possible that it will become largest source of energy in country.
At same time, after installing photovoltaic panels, evaporation on ground will be reduced by 20%-30%, which reduces waste of water resources and helps to restore ecological environment in desert areas. After construction of many photovoltaic bases, grass began to grow under photovoltaic panels. To prevent grass growth from affecting electricity generation, people lift up PV panels and drive sheep under PV panels. This not only restores environment, but also contributes to development of animal husbandry.
If all deserts in China are covered with photovoltaic panels, there will be enough electricity generation for global use, and many deserts will turn into pastures and even farmland. According to statistics, once China's deserts are under control, arable land area will be 500,000 square kilometers, thus northwest will become an important grain production area in China, and grain production will increase significantly. and problem of food security will naturally be solved.
Therefore, China is currently actively promoting construction of sand control photovoltaic projects. At present, installed capacity of China's photovoltaic systems is one third of world's. Photovoltaic power plants are being built on a large scale in large deserts of China and even in some rocky desertification areas in southwest. Many power generation projects have begun to be introduced into Takla Makan desert. In ten years, installed capacity of photovoltaic generation in Xinjiang has exceeded 13 million kilowatts, an increase of 72 times. This is a terrible figure. The world's largest Three Gorges Hydropower Plant has an installed capacity of 22.5 million kilowatts, and Xinjiang's photovoltaic power generation capacity will soon exceed that of Three Gorges Hydropower Plant. In this process, Xinjiang does not know how many deserts will be transformed.
Therefore, all deserts in China will become oases. It's just that people in past have always believed that afforestation has transformed desert, and suddenly photovoltaic power has become biggest driving force and factor in transforming the desert.