The development of mankind goes hand in hand with ever-increasing requirements for nature and natural resources, and for landscape space, which in turn result in appreciable damage to the soil and, ultimately, in soil loss, water pollution, modification of natural ecosystems and general deterioration of the environment. On extensive areas of the continents the balanced interrelationships of living organisms to one another, man included, and their environment are now facing the threat of serious interference. Recently, ecologists have been increasingly emphasizing this dangerous situation, which is indicative of the hegemony of engineering, industry, and chemistry in our present civilization. The rising economic and cultural requirements of mankind, whose settlement of this planet features ever faster progress resulting in increased population densities, tend to promote activities which are distinguished by dynamical transformations of the countryside, with but relatively little conservation of outstanding and endangered areas and special ecosystems. Notwithstanding this, the various activities aimed at a metamorphosis of the landscape need to be developed further, with regard to the requirements of society. However, activities of that kind must be based on ecological principles, i.e. approached not only from the position of maximal economic efficiency which, frequently, may be of only a temporary nature; for it is imperative that integrity, viability, and productivity of a landscape environment be maintained to serve the generations to come. In this treatise, reasons have therefore been given for the need for a scientific and practical field referred to as ‘eco-engineering’. Eco-engineering is conceived as a direct continuation of the existing science of ‘land reclamation and improvement’ because of its constructional-engineering approach to the management of a countryside's natural resources; in addition, it involves ecological knowledge inasmuch as this relates to the theory of scientific recognition of the environment, and also to the practical aspects of realizing particular projects. From what has been said above the term ‘eco-engineering’ suggested by us may be defined as the art, science, and practice through which nature, landscape space, and natural resources — these including soil, water, and biocoenoses above all — are made more beneficial to man. It is a continuous process which involves a rational and beneficial management of flow energy, properties of matter, and the sources of power in nature toward biomass production, and toward implementation of engineering works in the countryside and modifications of the same while, simultaneously, conserving its environment and maintaining its diversity, ecological equilibrium, and vital integrity.