The 2015-16 El Nino had a record-breaking impact on the Amazon rainforest, with the region experiencing extremes of heat and drought. We study the impact of the 2015 drought on the water dynamics in a central Amazonian tropical rainforest using field observations of soil moisture, sap flow, and net radiation among other micrometeorological variables collected at the BR-Ma2 tower (Manaus - ZF2 K34 tower) site. We use these data to look for quantitative and mechanistic relationships between soil moisture, plant transpiration, and precipitation over tropical rainforest. We further study the physiological drivers that control plant transpiration during the drought and in a normal year. Here we present quantifications of precipitation, soil water usage, and plant transpiration during and after the 2015 drought, and characterizations of the impacts of the 2015 drought on ecosystem water processes such as plant transpiration and soil water usage.