It is the policy of the state and the intent of the Legislature to assure orderly planning for specific functions such as water development, transportation, natural resources, economic development and human resources by units of state government who exercise management responsibility for these functions. It is further the intent of the Legislature to provide, as part of the state planning process, that state functional plans proceed from common assumptions and forecasts of statewide growth and development, including those set forth in Section 21001 of the Public Resources Code.