Since the 1950s, China has been persistently conducting research on wind-sand disasters and implementing control projects at the regional level and for major engineering facilities for a long time, and has achieved a series of results. Although these regional wind-sand disaster prevention and control projects were not explicitly targeted at towns and cities, objectively, they have had a good effect on sand control in towns and cities. The existing research achievements in sand control theories and technologies have laid a solid theoretical foundation for the research on sand control in towns and cities. With the improvement of the urbanization level in arid regions of China, as well as the increasingly prominent needs for regional economic and social sustainable development and ecological security due to wind-sand disasters in towns and cities, during the later period of the "10th Five-Year Plan" and the "11th Five-Year Plan", the National Science and Technology Support Program officially approved research projects related to sand control in towns and cities. These projects have played an important role in promoting in-depth research on the theories and technologies of sand control in towns and cities and have achieved some targeted results. However, compared with the current situation of sand control against disasters in Chinese towns and cities, the above-mentioned achievements are too scattered to form a system, and far from meeting the rapidly growing technical requirements for sand control in towns and cities.

      The book "The Theory and Engineering of Sand Control in Towns and Cities" written by Professor Zou Xueyong and others comes at the right time. The book was recently published by Science Press. Thanks to the authors' solid theoretical foundation, unyielding scientific spirit, down-to-earth work style, and rigorous scientific attitude, as well as their long-term and rich accumulation of combining theory with practice, the book is rich in content and organically combines theory and practice. Supported by the theoretical achievements of field observations, wind tunnel simulation experiments, and numerical simulations, it deeply expounds the engineering technical principles of various individual sand control technologies and the optimized allocation of multiple technologies. It summarizes the comprehensive technical system models for sand control in towns and cities in different bioclimatic regions, which has important scientific theoretical and engineering practical values for guiding sand control in towns and cities along the "Land Silk Road", in towns and cities on the Qinghai-Tibet Plateau, and even in towns and cities of other countries.

      The book comprehensively summarizes the engineering technical principles of sand control in towns and cities, establishes a theoretical framework for sand control in towns and cities, proposes an innovative model for sand control in towns and cities with a solid theoretical foundation, and provides a series of successful cases of sand control projects in towns and cities. With comprehensive and rich content, covering the basic theories and engineering practices of sand control in towns and cities, the book has high scientific and technical value.

      (1) Constructed a theoretical system for sand control in towns and cities. As an important field in the research of wind-sand engineering, although the research on sand control in towns and cities started late, the publication of the book "The Theory and Engineering of Sand Control in Towns and Cities" took the lead in establishing a relatively complete special theoretical system for sand control. Its core idea is to take towns and cities as the center. Based on in-depth research on the causes of wind-sand disasters and the characteristics of the regional wind-sand flow field, it optimizes the spatial pattern of land use around towns and cities and establishes an optimized sand control engineering system to prevent the invasion of wind and sand, improve the quality of the atmospheric environment, and maintain the coordinated and sustainable development of the urban economy and society and the regional resources and environment. This is not only an important contribution to the research of wind-sand engineering but also provides a reference for the construction of theoretical systems for sand control of other protected objects such as roads and oases.

      (2) Proposed innovative models for sand control in towns and cities. Sand control in towns and cities has significant regional, complex, and comprehensive characteristics, which are determined by the regional and complex nature of the wind-sand environment, the forms of wind-sand hazards, the prevention and control conditions in towns and cities, as well as the comprehensiveness of the prevention and control engineering technical measures. In response to the above attributes and engineering practice explorations, the authors have developed and summarized several representative engineering technical models for sand control in towns and cities: ① The sand control technical model for towns and cities in the semi-humid region of northern China. It is divided into the "four-circle model" for towns and cities on the edge of the sand source area (from the urban center to the periphery, there are a green landscape belt with the built-up urban area as the core, an area for efficient agricultural and pastoral production, an ecological conservation circle, and a closed protection circle in sequence) and the "three-circle model" for towns and cities within the sand source area (in sequence, there are a green landscape belt with the built-up urban area as the core, an area for agricultural and pastoral production and dune closure, and a closed protection circle). ② The sand control technical model for towns and cities in the semi-arid region of northern China. It can be summarized as the "three-circle model" composed of a green landscape belt with the built-up urban area as the core, an area for agricultural and pastoral production and sand land (dune) closure, and a sand land (dune) closed protection circle. ③ The sand control technical model for towns and cities in the arid region of northern China. It can be summarized as the "four-circle model" composed of a green landscape belt with the built-up urban area as the core, a water-saving irrigation agricultural area, an outer protection belt, and a closed protection belt. ④ The sand control technical model for towns and cities in the intermontane basins of the Qinghai-Tibet Plateau. It is summarized as the "four-in-one" engineering system of "sand barriers + shelterbelts + artificial grasslands + irrigation systems", with no obvious zonal structure, highlighting the reasonable allocation of various sand control engineering technologies within the region. ⑤ The sand control technical model for towns and cities in the wide river valleys of the Qinghai-Tibet Plateau. This model can be summarized as gradually treating the sand sources upwind of the towns and cities by combining river channel regulation and sand control projects from near to far. The above models are all the integration of various individual technologies, achieving the goal of optimized allocation of multiple technologies. They are the integrated results of accurately calculating the wind-sand flow field in the region where the towns and cities are located, optimizing the spatial pattern of land use, optimizing the parameters of individual technologies, simulating the functions of the engineering system (model simulation and numerical simulation), and comparing multiple schemes. The scientificity and advancement of these models have been verified by the practice of sand control in towns and cities.

      (3) Systematically summarized the engineering technical principles of sand control in towns and cities. The principles of wind prevention, sand fixation, and sand blocking have always been the core content of the research on wind-sand engineering, and there have been abundant research achievements in field observations, wind tunnel simulations, and numerical simulations of individual technologies. This book systematically combs the classification of sand control engineering technologies, summarizes the principles of wind prevention and sand fixation of various technical measures, and expounds their application scopes and applicable objects respectively. It includes many of the authors' latest research achievements. The summary and supplementation of these achievements have improved the scientific level of sand control engineering technologies in towns and cities. At the same time, the book also highlights the flexibility of various sand control engineering technologies and their configurations, that is, on the basis of the basic configuration, according to the differences in the protected objects and the wind-sand environment, other individual sand control technologies can be added or the spatial positional relationships of different technical measures can be changed to improve the overall sand control function of the engineering technical system, which provides conditions for the extended application of the innovative models for sand control in towns and cities proposed by the authors.

      (4) Vividly presented excellent cases of combining the theory and practice of sand control in towns and cities. There are numerous towns and cities in the sandy areas of northern China, and the urban residents have accumulated rich sand control experience in the long-term struggle against wind and sand. However, in the frigid sandy areas of the Qinghai-Tibet Plateau, due to the extremely harsh natural conditions, the affected towns and cities are helpless in the face of the strong invasion of wind and sand. Shiquanhe Town in the Tibet Autonomous Region once faced the desperate situation of being buried by wind and sand. Given its crucial national defense status and the high cost of relocation, proactive sand control became the only choice. The authors of "The Theory and Engineering of Sand Control in Towns and Cities" and their colleagues carried out arduous research work in the absence of experiences to draw on. After continuously overcoming difficulties and going through nearly 20 years of painstaking exploration, they developed an effective and highly functional "four-in-one" comprehensive sand control engineering technical system of "gravel sand barriers + shelterbelts + artificial grasslands + irrigation systems". Through large-scale engineering practice, the sand control effect far exceeded expectations. The former vast Gobi Desert has now become the largest and most functional greening base in Shiquanhe Town. The ecological environment has been completely renewed, and the town has regained its new look as the "Pearl on the Plateau". The sand control project in Shiquanhe Town has set an international precedent for sand control in towns and cities in extremely cold and arid environments and has become a milestone in the history of sand control research in Chinese towns and cities.

      This book constructs a theoretical system for sand control in towns and cities, explores sand control models suitable for different wind-sand environments in towns and cities, and discusses the relationship between sand control in towns and cities and new urbanization. It re-combs the technical type system of wind-sand engineering, supplements a large number of the latest research achievements in the technical principles of wind-sand engineering, and proposes a series of technical configuration models for wind and sand with different applicability. It lists typical cases of sand control in towns and cities under different wind-sand environments and summarizes the specific contents that need to be considered in engineering design, such as the design principles of sand control projects in towns and cities, benefit evaluation, environmental impact assessment, and guarantee measures. With rich content and a complete structure, the book has a high theoretical level and academic value. It can provide a reference for the construction of theoretical systems for sand control of specific objects such as roads, oases, lakes, and reservoirs. It is worthy of being read and referred to by teachers and students engaged in the research of wind-sand engineering, theories, and technologies for desertification prevention and control in universities and scientific research institutions, as well as professional engineering and technical personnel in the fields of forestry, soil and water conservation, and environmental protection in sandy areas.

Ci Longjun, Chinese Academy of Forestry