At the beginning of the 21st century, the increasing human population and its development aspirations has become a major factor in progressive environmental degradation on the global scale.
Degradation of biological structures and ecological processes means a reduction in an ecosystem's carrying capacity. As a consequence, during the next 30 to 60 years, human imperatives may clash with the carrying capacity of global environment. Such a clash would be nothing less than catastrophic for humanity.
One of the fundamental tenets of the sustainable development concept is the maintenance of an homeostatic equilibrium within an ecosystem. Degradation of biotic structure degradation alters ecosystem processes to the point where their ability to produce desired resources is seriously diminished. A decline in water quality and biodiversity, observed at the global scale in both developed and developing countries, has provided sobering evidence that a purely technical approach to water resources management has been less than successful.
Human survival and the preservation of biodiversity on the Earth is dependent on our ability to maintain the integrity of ecological processes. These have developed over the course of biogeochemical evolution and are expressed and measurable as energy, volume of water, and nutrient mass dynamics at the basin scale.
Environmentally Sound Technologies (ESTs) are technologies that have the potential for significantly improving environmental performance, in relation to other technologies. ESTs protect the environment, are less polluting, use resources in a sustainable manner, recycle more of their wastes and products, and handle all residual wastes in an environmentally acceptable way. ESTs are not just individual technologies. They can also be defined as total systems that include know-how, procedures, goods and services, and equipment, as well as organizational and managerial procedures for promoting environmental sustainability.