How unprecedented is the current Colorado River drought? - a paleo perspective
Abstract
The on-going ~20-year long drought in the Colorado River Basin (CRB) has gained notoriety as the worst drought since modern record-keeping began over 100 years ago. Historically low reservoir levels, due to a lack of reservoir replenishing high-flow years and greater losses induced by increased temperature across the basin, the so-called Millennium Drought has precipitated unprecedented cutbacks to water use in the seven southwestern US states. The question on everyones minds is how unprecedented is the current drought? To answer this, we seek insights from long records of paleo-flow reconstructions, which have shown that multi-decadal droughts have occurred in the CRB periodically over the last 1000 years. Some of these mega-droughts are estimated to be worse than the current drought in terms of both flow volume deficit and drought duration. To answer the posed question, in this study, we assess the return period of two decade long droughts in the CRB based on the paleo and modern observational record spanning over 1000 years and slightly more than 100 years, respectively. We fit Hidden Markov Models (HMM) to these two data sets separately and generate long sequences of flow simulations. From these simulations, the return periods of multidecadal drought attributes duration and magnitude - will be computed and compared. We will also compare them with projections of drought attributes in the basin under warmer climate. The estimates of relative frequency of drought duration and magnitude will help place the current drought in a broader context paleo, modern and future. This will be of great help to all stakeholders in the basin to devise efficient water management strategies.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMGC23A..03R