Onset and Propagation of the 2012-2016 Drought in Southern California
Abstract
The 2012-2016 drought in California had a strong impact on soil moisture and vegetation. Despite a clear signal of overall impacts, we have limited understanding of the onset, development and propagation of drought, which greatly influences our ability to predict its dynamics at longer timescales. We used high-resolution (15-min) climate and soil moisture data from two contrasting sites in southern California in conjunction with a parsimonious soil moisture balance model to analyze the onset and propagation of the 2012- 2016 drought within the shallow rooting zone, including the feedbacks between vegetation health (i.e., Normalized Difference Vegetation Index from Landsat), and soil moisture. Retrospective analysis of the climate and soil moisture data showed that coastal areas were less affected by the drought, as higher humidity and moderate temperatures buffered the negative impacts of prolonged soil moisture deficit on vegetation. Further inland, vegetation health and soil moisture repeatedly reached a critical state of plant water availability in 2013, 2014 and 2016 after 156, 188, 161 days of no rain respectively, indicating plants' dependence on soil moisture and their vulnerability to prolonged periods of high evaporative demand. Analysis of precipitation data showed that storm intensity declined during the drought at both sites while the time interval between storms increased, resulting in lower overall seasonal soil moisture in the shallow surface during the drought. The coupled vegetation-soil moisture model captured the soil moisture dynamics well, making it a valuable tool to explore the linkage between water and vegetation under a changing climate at different locations. The results further highlight the value and need for more accurate characterization of the onset and propagation of drought to manage water resources under climate change and mitigate negative drought impacts on vegetation health.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H12G..05W
- Keywords:
-
- 1812 Drought;
- HYDROLOGY;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1833 Hydroclimatology;
- HYDROLOGY;
- 1834 Human impacts;
- HYDROLOGY