Misrepresentation and amendment of soil moisture in conceptual hydrological modelling

Abstract

Although many conceptual models are very effective in simulating river runoff, their soil moisture schemes are generally not realistic in comparison with the reality (i.e., getting the right answers for the wrong reasons). This study reveals two significant misrepresentations in those models through a case study using the Xinanjiang model which is representative of many well-known conceptual hydrological models. The first is the setting of the upper limit of its soil moisture at the field capacity, due to the 'holding excess runoff' concept (i.e., runoff begins on repletion of its storage to the field capacity). The second is neglect of capillary rise of water movement. A new scheme is therefore proposed to overcome those two issues. The amended model is as effective as its original form in flow modelling, but represents more logically realistic soil water processes. The purpose of the study is to enable the hydrological model to get the right answers for the right reasons. Therefore, the new model structure has a better capability in potentially assimilating soil moisture observations to enhance its real-time flood

Hydrological Evaluation of Satellite Soil Moisture Data in Two Basins of Different Climate and Vegetation Density Conditions

“…It has been shown that the three-layer XAJ model is very useful in modelling SMD from the hydrological data [47][48][49][50][51]. There are some alternative XAJ formats [52][53][54], but this paper uses its original form because it is the most commonly used format. The XAJ model is a relatively simple operational lumped rainfall-runoff model; its main concept is the runoff generation on repletion of storage, which means that runoff is not generated until the soil water content of its aeration zone reaches the field capacity.…”

Multisource remote sensing data facilitate ecohydrological simulations without runoff calibration

“…They are usually calibrated with gauged runoff data, which is the most important and readily observed and simulated hydrological component (Bai et al, 2018; Duan et al, 2006). However, models are calibrated with only runoff data, which may hamper predictions in catchments with limited observation data and cannot guarantee the reliable simulation of other major hydrological components (e.g., ET, TWSC, root‐zone water storage, and groundwater storage) (Girotto et al, 2016; Li, Rodell, et al, 2019; Maxwell & Condon, 2016; Rakovec et al, 2016; Zhuo & Han, 2016). In general, calibration with multiple objectives (i.e., using more than one hydrological component instead of only runoff data.)…”

Evaluation of Remotely Sensed Soil Moisture for Landslide Hazard Assessment

“…However, such an approach is not recommended by many studies due to the weak relationships found between the antecedent precipitation and the real soil moisture variations [17][18][19]. This is due to not all precipitation enters the soil layer when reaching the earth surface, instead, parts of them become direct runoff [20,21]. In addition, evapotranspiration plays an important role in the soil moisture temporal evolution, which also leads to the weak relationships as aforementioned.…”