Development of an Evapotranspiration Data Assimilation Technique for Streamflow Estimates: A Case Study in a Semi-Arid Region

Abstract

Streamflow estimates are substantially important as fresh water shortages increase in arid and semi-arid regions where evapotranspiration (ET) is a significant contribution to the water balance. In this regard, evapotranspiration data can be assimilated into a distributed hydrological model (SWAT, Soil and Water Assessment Tool) for improving streamflow estimates. The SWAT model has been widely used for streamflow estimations, but the applications combining SWAT and ET products were rare. Thus, this study aims to develop a SWAT-based evapotranspiration data assimilation system. In particular, SWAT is gridded at Hydrologic Response Unit (HRU) level to incorporate gridded ET products acquired from the remote sensing-based ETMonitor model. In the modeling case, Gridded SWAT (GSWAT) shows a good agreement of streamflow modeling with the original SWAT. Such a scant margin between them is due to the modeling domain mismatch caused by different HRU delineations. In the ET assimilation case, we carry out a synthetic data experiment to illustrate the state augmentation Direct Insertion (DI) method and a real data experiment for the upper Heihe River Basin. The results demonstrate the benefits of the ET assimilation for improving hydrologic processes representations. In the future, more remotely sensed data can be assimilated into the data assimilation system to provide more reliable hydrological predictions.

Application of SEBAL and Ts/VI Trapezoid Models for Estimating Actual Evapotranspiration in the Algerian Semi-Arid Environment to Improve Agricultural Water Management

“…Conventional methods (such as Bowen ratio system, eddy covariance system, or weighting lysimeters) that use point measurements to estimate ET are representative only of local areas and cannot be extended to large areas because of heterogeneity of landscape (Liu and Xu, 2019). Remote sensing-based energy balance models are presently best alternatives for estimating ET at both field and regional scales where ground measurements are not feasible and reliable estimates of ET are needed (Yang et al, 2019;Zhang et al, 2016).…”

“…This proportion may be higher in dry regions, such as the Mediterranean basin (Boulet et al, 2020). Inaccurate estimates of ET in these regions can cause large errors in the hydrological components prediction such as runoff and recharge, and in the associated water balance and water resources availability (Zhang et al, 2017).…”

Sensitivity‐Based Soil Moisture Assimilation for Improved Streamflow Forecast Using a Novel Forward Sensitivity Method (FSM) Approach

“…Various variables including soil moisture (Alvarez‐Garreton et al., 2015; Gevaert et al., 2018; Lü et al., 2011; Massari et al., 2015), streamflow (Mazzoleni et al., 2015; Rupp et al., 2008; Trudel et al., 2014), soil temperature (Huang et al., 2008; Meng et al., 2009; Reichle et al., 2010), evapotranspiration (Hartanto et al., 2017; Irmak & Kamble, 2009; Zhang, 2017; Zou et al., 2017), and snow cover (Andreadis & Lettenmaier, 2006; De Lannoy et al., 2012; Sun et al., 2004) are assimilated into the hydrological models to improve the streamflow forecast. Among the other variables, soil moisture is preferred because it performs an important role in the partitioning of precipitation into overland and underground flows.…”

Integration of Satellite-Derived and Ground-Based Soil Moisture Observations for a Precipitation Product over the Upper Heihe River Basin, China

“…Precipitation can be derived from gauge stations, ground-based weather radars, and satellite radars and radiometers [1]. With the steady development of remote sensing, rainfall retrievals from satellite have proven successful and become increasingly important in various applications globally [2], e.g., meteorology, hydrology, agricultural applications, drought monitoring, flood forecasting, and water resources management [3][4][5].…”