Brazilian experimental datasets for multi scale interactions in the critical zone under extreme drought

Abstract

BEMUSED recognizes that a more scale-integrated view of the role of soil moisture in the critical zone (the earth's outer layer from vegetation canopy to the soil and groundwater that sustains life) is of great importance in South America. Soil moisture is a key environmental variable of the hydrological cycle connecting the rapid changes in atmospheric conditions near the surface with slower subsurface processes. However, our understanding of key soil moisture controlling factors has been limited due to a lack of soil moisture measurements directly compatible to so-called "hyper-resolution" hydrological models. Recently, the development of new Cosmic-Ray Sensors (CRS) technology for monitoring soil moisture at unprecedented sub-kilometer scales provides the missing link between traditional point-scale sensors and large-scale satellite remote sensing products. In recent years, networks of CRS have been established worldwide but not yet for tropical hydrological studies (e.g., in South America). In addition, limited representation of key hydrological processes (including subsurface-surface interactions) in current Earth System Models poses extreme challenges for prediction and adaptation strategies. This is important for predicting extreme events such as droughts, especially in data scarce regions such as in tropical areas. The recent (2013-2014) extreme drought event that occurred in southeast Brazil severely affected water resources in the region including the Cantareira Reservoir System (one of the largest in the world) which supplies water to more than 9 million people in Sao Paulo metropolitan area. Lack of accurately representing the role of soil moisture in connecting the subsurface to surface water dynamics will continue to undermine our predictability skills, consequently providing sub-optimal information for adaptation strategies in important economic-social region in South America and globally. (AU)