Climatic fluctuations, drought, and flow in the Colorado River

The purpose of this Fact Sheet is to discuss the causes of drought in the Colorado River basin and the predictability of river flows using global climate indices... INTRODUCTION Climatic fluctuations have profound effects on water resources in the western United States (Fig. 1). In the arid and semiarid parts of the Southwest, climatic fluctuations affect many hydrologic characteristics of watersheds, including the quantity of base flow, the occurrence of large floods, and the timing of snowmelt runoff (Cayan and others, 1999; Stewart and others, 2004). Since the start of a persistent drought in about the year 2000, inflows to Lake Powell on the Colorado River have been below average, leading to drawdown of both Lakes Mead and Powell, the primary flow-regulation structures on the river (Fig. 2). The recent drought, referred to here as the early 21st century drought, has its origins in several global-scale atmospheric and oceanic processes that reduce delivery of atmospheric moisture to the Colorado River basin. The purpose of this Fact Sheet is to discuss the causes of drought in the Colorado River basin and the predictability of river flows using global climate indices.

Climatic fluctuations, drought, and flow in the Colorado River

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