Need for sustainability
The increasing stress put on resources and environmental systems such as water, land and air have been seen as not sustainable, especially as the world's population continues to increase (SD 2007). The goal of sustainable development is therefore to enable all people throughout the world to satisfy their basic needs and enjoy a better quality of life without compromising the quality of life of future generations. Sustainable development means a better quality of life now and for generations to come, that is, development which meets the needs of the present without compromising the ability of future generations to meet their own. It also means not using up resources faster than the planet can replenish, or re-stock them and joining up economic, social and environmental goals. In other words, sustainable development is maintaining a delicate balance between the human need to improve lifestyles and feeling of wellbeing on one hand, and preserving natural resources and ecosystems, on which we and future generations depend (UNCED) 1992. To achieve the desired result of sustainability for the built environment, proper physical development planning is crucial in the human geographic space. This is because physical development often involves huge resources and infrastructures. So to prevent huge wastes for now and the future, it is most instructive that physical development planning is done to produce optimum utility and benefits to the users. When available space is put to its optimum utility, revisions of land use usually become unnecessary and wastages are averted. But when revision becomes inevitable, it would be implemented without significant damage to other socio-economic infrastructures that may exist or that may be in the pipeline. This statement describes the concept of sustainability.