. Difficulties in systematic environmental assessment
It is important to be able to predict the likely environmental effects of plans, programs, and projects in order to promote environmentally sustainable development (Sheate et al., 2001; Jones et al., 2005). Since it assesses the environmental effects of plans and programs affecting the initial stages of a development project, PERS can act as a means to create sustainable development. However, systematic approaches to environmental assessment for high-level administrative plans could not proceed because the PERS systemwas conducted on a too restricted set of plans and programs. For example, in the area of urban development, there is a hierarchy of administrative plans; each has a role and scope stipulated in law. Generally the higher level of plan has a wider scope than the lower level of plan.