A Joint Soil‐Vegetation‐Atmospheric Water Tagging Procedure With WRF‐Hydro: Implementation and Application to the Case of Precipitation Partitioning in the Upper Danube River Basin

Abstract

Atmospheric models such as the Weather Research and Forecasting (WRF) model provide a tool to evaluate the behavior of regional hydrological cycle components, including precipitation, evapotranspiration, soil water storage, and runoff. Recent model developments have focused on coupled atmospheric‐hydrological modeling systems, such as WRF‐Hydro, in order to account for subsurface, overland, and river flow and potentially improve the representation of land‐atmosphere interactions. The aim of this study is to investigate the contribution of lateral terrestrial water flow to the regional hydrological cycle, with the help of a joint soil‐vegetation‐atmospheric water tagging procedure newly developed in the so‐called WRF‐tag and WRF‐Hydro‐tag models. An application of both models for the high precipitation event on 15 August 2008 in the German and Austrian parts of the upper Danube river basin (94,100 km2) is presented. The precipitation that fell in the basin during this event is considered as a water source, is tagged, and subsequently tracked for a 40‐month period until December 2011. At the end of the study period, in both simulations, approximately 57% of the tagged water has run off, while 41% has evaporated back to the atmosphere, including 2% that has recycled in the upper Danube river basin as precipitation. In WRF‐Hydro‐tag, the surface evaporation of tagged water is slightly enhanced by surface flow infiltration and slightly reduced by subsurface lateral water flow in areas with low topography gradients. This affects the source precipitation recycling only in a negligible amount.

High-resolution fully-coupled atmospheric–hydrological modeling: a cross-compartment regional water and energy cycle evaluation

“…It should be noted that, however, the impact of the lateral water transport modeling on average precipitation amounts may be much less important than, e.g., the selection of the PBL scheme (Arnault et al, 2018). The findings are also corroborated by water vapor tagging studies that conclude that regional precipitation recycling is largest during weak synoptic forcing and that variations on larger scales are rather small (Wei et al, 2015;Arnault et al, 2019). Nevertheless, for larger regions the impact may be considerable.…”

Simulation of extreme rainfall and streamflow events in small Mediterranean watersheds with a one-way-coupled atmospheric–hydrologic modelling system

“…The implementation of rainfall data correction or assimilation schemes could improve the forecasts of the atmospheric-hydrologic modelling chain, as demonstrated and discussed by previous studies (e.g. Avolio et al, 2019;Verri et al, 2017;Yucel et al, 2015). Recently, increasing efforts have been made to implement two-waycoupled modelling systems, which were found to improve the overall skills of the modelling system (e.g.…”

Impact of Lateral Terrestrial Water Flow on Land‐Atmosphere Interactions in the Heihe River Basin in China: Fully Coupled Modeling and Precipitation Recycling Analysis

“…The focus is on the analysis of the water cycle differences between coupled WRF‐Hydro and WRF with a joint atmospheric‐terrestrial water budget, especially in the upper HRB where most of the water is produced. Differences in land‐atmosphere interactions caused by the consideration of lateral terrestrial water flow are quantified with a bulk‐type precipitation recycling analysis (Eltahir & Bras, ; Schär et al, ) and a fully three‐dimensional atmospheric moisture tracing method (e.g., Arnault, Knoche, et al, ; Arnault et al, ; Wei et al, ).…”