Technology is an essential instrument for the achievement of sustainable and environmentally sound development. But it is also through the application of such technology that Man has most impact on the environment.

With an ever-increasing world population and the resultant pressure to grow more and more food, marginal areas in many Third World and other countries are coming under intensive pressure towards expanding agricultural production. The ecosystems of marginal areas are often fragile, and thus particular care has to be taken in developing such lands for farming or grazing.

On the basis of published information and the Authors' own experience in the field, a schema of land deterioration in 5 major sub-areas of Central Chile is proposed. The 5 sub-areas are: 1. Coastal Marine terraces; 2. Coastal ranges; 3. Andean foothills; 4. Central valley and river valleys; and 5. Norte Chico.

Land erosion in wilderness, conservation, and recreational, areas may be accelerated by certain non-agricultural land management practices. Examples from the Natal Drakensberg are used to demonstrate how certain types of land modification—such as burning, the construction of unpaved access roads, and the creation of paths and tracks—may result in rapid acceleration of erosion rates.

Two major development projects in Papua New Guinea, while still in the planning stage, are being approached with full awareness of their possible impact on the environment. A copper-mine high up in the catchment of a large river, the Fly, and a large hydroelectric dam on another sizeable river, the Purari, raise a number of questions. The extremely high rainfall in the area of the proposed copper-mine precludes the use of standard methods of tailings disposal. Thus if the tailings were stored behind a dam, it would frequently overflow; alternatively, they could be discharged directly into a stream. Both alternatives would have a negative environmental impact. Downstream dilution by tributaries would, however, be an important mitigating factor of tailing disposal. At present, frequent, naturally-occuring landslides in the upper catchment result in a very high input of sediments, with a disastrous impact on the aquatic life.

The machair coastal areas of the Outer Hebrides form one of the more distinctive coastal environments in Britain and owe their origin to an apparently unique, as yet not clearly understood, combination of factors which operated in the late postglacial period. A further distinguishing characteristic is the often quite extensive level machair grassland plain, which is suggested here as being the last of a series of evolutionary phases which took place from the time of initial sand deposition (ca 6000 B.P.) until ca 2000 B.P. There is evidence that, in a modified form, these processes may have continued right through to the present time.

The term ecosystem integrity may be defined as the maintenance of the community structure and function that is characteristic of a particular locality or habitat. The study of aquatic ecosystem integrity in the rivers and lakes of India holds a bright prospect for the evaluation and management of the quality of our water.