Diaz, H. F., 2003: Biomes, river basins, and climate regions: Rational tools for water resource management. In Climate and Water: Transboundary Challenges in the Americas, H. F. Diaz and B. J. Morehouse (Eds.), Kluwer Academic Publishers, 221-235.


This chapter makes a case for the use of climate-based boundary definitions for regions where the management of water and biotic resources is of great concern, using as examples the Colorado River system and the southwestern U.S. desert biomes. Dam construction in the U.S. portion of the Colorado River beginning in about 1930 reduced natural flows to the Colorado River Delta to nearly zero by the late 1960s. A delta ecosystem encompassing nearly 2 million acres was nearly extinguished; today it exists within fewer than 200,000 acres. It is suggested that impacts of such magnitude to a major continental river system occurred because of the presence of an international political boundary, and also due to the absence of a decision-making framework for water resources management that takes into account ecological values. Incorporation of data and information regarding possible climatic variations in the future is also emphasized.