Brazilian Experimental datasets for MUlti-Scale interactions in the critical zone under Extreme Drought (BEMUSED)

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This IOF proposal, entitled "Brazilian Experimental datasets for MUlti-Scale interactions in the critical zone under Extreme Drought" (BEMUSED), is a partnership between the University of Bristol (UoB) and University of Sao Paulo (USP) [RCUK-FAPESP Lead Agency Agreement is applied]. 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.This opportunity is very timely because it will allow both groups to mutually exploit the hydrological model developments from our current NERC New Investigator "A MUlti-scale Soil moisture - Evapotranspiration Dynamics study" (AMUSED) project using locally available data from an experimental catchment in southeast Brazil which has recently experienced an extreme drought event. This provides a unique opportunity to further evaluate our current model developments (i.e., preferential water flow in soils, and groundwater dynamics) in a challenging tropical region. Also importantly, BEMUSED will allow the UoB to engage in knowledge and skills transfer associated with the use of CRS particularly in a tropical South America region where it has never been tested. A CRS is scheduled to be installed at the experimental catchment in 2018, hence we propose to test our CRS deployment/calibration guidelines and data processing approaches, developed under AMUSED, in tropical South America for the first time, and further engage with AMUSED's original Pathways to Impact activities in promoting knowledge transfer and dissemination of new measurement technology by offering a short-course on "Soil Moisture Measurements using Cosmic-Ray Sensors" in Brazil. Finally, a workshop will be held in Brazil to discuss on strategies for improvement of Brazil's national capability for large-scale hydrometeorological monitoring and modeling with the aim to enhance response to future hydroclimatic variability and natural hazards.