Partitioning of Historical Precipitation Into Evaporation and Runoff Based on Hydrologic Dynamics Identified With Recent SMAP Satellite Measurements

Abstract

Microwave brightness temperature observations from the NASA Soil Moisture Active Passive (SMAP) mission and gauge-based precipitation data over the United States are used to reconstruct the soil water loss function and then historical (1979-2019) hydrological fluxes in the form of evapotranspiration (ET) and drainage (D) are quantified. Over the period of study, with the exception of snowy and hyper-arid regions, we observe a correlation of R 2 > 0.6 between SMAP-precipitation derived drainage estimates and streamflow measurements from the U.S. Geological Survey (USGS). There is a bias between estimated drainage and USGS streamflow with an underestimation of about 1 mm day −1 in southwest United States to 3 mm day −1 in parts of the eastern United States. SMAP-derived sensitivities of drainage and ET partitioning with respect to precipitation anomalies are also calculated. In parts of the Great Plains the drainage partitioning exhibits a near-linear response, while in the southeast United States, the response is nonlinear. Partitioning also is examined for 6 four-digit hydrologic unit basins wherein year-to-year variations in drainage partitioning are shown to be key mediators in translating precipitation anomalies into streamflow anomalies. Observation-driven drainage and ET estimates are obtained without relying on full hydrologic and Land Surface Models (LSMs). This independence (isolation from model parameterization assumptions) provides a path toward using satellite-derived landscape hydrological diagnostics to assess hydrologic models and LSMs as well as to guide their further development.

Remotely Sensed Soil Moisture Can Capture Dynamics Relevant to Plant Water Uptake

“…While soil moisture in the unsaturated zone stores only 0.005% of Earth's water by volume (Bras, 1990), its position at the interface of the land and the atmosphere is of high value for understanding these global cycles (Koster & Suarez, 2001; McColl et al., 2017). As such, satellite‐based soil moisture estimates are increasingly being used in studies of land‐atmosphere interactions, numerical weather prediction, plant function and stress, and land surface response to climate change (Akbar et al., 2020; Dong et al., 2020; Feldman, Akbar, & Entekhabi, 2018; Feldman et al., 2022; Konings et al., 2017; Purdy et al., 2018; Santanello et al., 2019; Short Gianotti et al., 2020; Taylor et al., 2012; Tuttle & Salvucci, 2016).…”

Estimating Reservoir Inflow and Outflow From Water Level Observations Using Expert Knowledge: Dealing With an Ill‐Posed Water Balance Equation in Reservoir Management

“…Hrachowitz et al (2014) demonstrated that an uncalibrated but constrained complex model yielded levels of model performance and uncertainty similar to those of a calibrated but unconstrained standard lumped model. As various types of remotely sensed data emerge (e.g., soil water content and water levels) and hydrological information and knowledge accumulate, soft data is expected to be used to a greater extent to complement hard calibration in hydrological analysis (Akbar et al, 2020;Huang et al, 2020;Mao et al, 2020). Advanced uncertainty and sensitivity analysis methods such as a global sensitivity analysis (Razavi et al, 2021;Sheikholeslami et al, 2019) may help reduce the parameter spaces by identifying a dominant group of parameters that significantly contribute to variability in model outputs (see Figures S2 and S3 in Supporting Information S1 for more information).…”

Can the Accuracy of Fine-Resolution Precipitation Products Be Assessed from the Surrounding Water Balance and Drought Chain (WBDC) in the Qinghai–Tibetan Plateau?

“…The great importance of the water balance equation, which posits that precipitation is equal to runoff plus evaporation and was first suggested by A. Penck in 1896 [12], is well known in hydrological sciences. The partition of precipitation into evapotranspiration and runoff at the land surface plays an important role in the Earth's hydrology and climate system [25,26]. Common precipitation abnormal phenomena are droughts and floods.…”