SMAP observes flooding from land to sea: The Texas event of 2015

Floods can have damaging impacts on both land and sea, yet studies of flooding events tend to focus on only one side of the land/sea continuum. Here we present the first two-sided analysis, focusing on the May 2015 severe flooding in Texas. Our investigation benefits from simultaneous measurements of land surface soil moisture and sea surface salinity from NASA's recent Soil Moisture Active Passive (SMAP) mission as well as ancillary data. We report the comprehensive chronology of the flooding: above average rainfall preceding the flood caused soils to saturate; record rainfall then generated record river discharge; and subsequently, an unusual freshwater plume associated with anomalous ocean currents formed in the north central Gulf of Mexico. Together with the Mississippi River plume, a rare horseshoe pattern was created that may have significant biogeochemical implications. Such integrated land/sea analysis of flood evolution can improve impact assessments of future extreme flooding events.