Hydrological hysteresis and its value for assessing process consistency in catchment conceptual models

Abstract

Abstract. While most hydrological models reproduce the general flow dynamics, they frequently fail to adequately mimic system-internal processes. In particular, the relationship between storage and discharge, which often follows annual hysteretic patterns in shallow hard-rock aquifers, is rarely considered in modelling studies. One main reason is that catchment storage is difficult to measure, and another one is that objective functions are usually based on individual variables time series (e.g. the discharge). This reduces the ability of classical procedures to assess the relevance of the conceptual hypotheses associated with models.We analysed the annual hysteric patterns observed between stream flow and water storage both in the saturated and unsaturated zones of the hillslope and the riparian zone of a headwater catchment in French Brittany (Environmental Research Observatory ERO AgrHys (ORE AgrHys)). The saturated-zone storage was estimated using distributed shallow groundwater levels and the unsaturated-zone storage using several moisture profiles. All hysteretic loops were characterized by a hysteresis index. Four conceptual models, previously calibrated and evaluated for the same catchment, were assessed with respect to their ability to reproduce the hysteretic patterns.The observed relationship between stream flow and saturated, and unsaturated storages led us to identify four hydrological periods and emphasized a clearly distinct behaviour between riparian and hillslope groundwaters. Although all the tested models were able to produce an annual hysteresis loop between discharge and both saturated and unsaturated storage, the integration of a riparian component led to overall improved hysteretic signatures, even if some misrepresentation remained. Such a system-like approach is likely to improve model selection.

Quantification of the seasonal hillslope water storage that does not drive streamflow

“…Interpretations of direct and indirect storages also raise the question of appropriate representation of storage dynamics in conceptual hydrologic models. The Elder Creek interpretation aligns with common perceptual understanding of catchment run‐off generation: Unsaturated and saturated moisture dynamics can be treated separately (e.g., Bardossy & Singh, ; Botter et al, ; Fovet et al, ) due to a distinct hydrologic zonation between the dynamic unsaturated zone and hillslope water tables. Interpretation of discharge generation and direct/indirect storage dynamics at Dry Creek, however, presents a more significant challenge for the conceptual hydrologic modeller.…”

“…Non‐linear, hysteretic storage–discharge mechanisms are associated with time lags in the transfer of mass or information through a watershed, suggesting that the volume and physical attributes (e.g., saturated vs. unsaturated) of decoupled storage affect catchment transport timescales, hydraulic response to external fluxes, and the sensitivity of evapotranspiration to climate variations (e.g., Nippgen, McGlynn, Emanuel, & Vose, ; Riegger & Tourian, ; Tani, ; Torres et al, ). Conceptual hydrologic models often feature decoupled storage elements (Birkel, Soulsby, & Tetzlaff, ; Botter, Porporato, Rodriguez‐Itubre, & Rinaldo, ; Lehmann, Hinz, McGrath, Tromp van Meerveld, & McDonnell, ), whose process representations are strong determinants of catchment discharge response and the emergent, hysteretic features of modelled storage–discharge relationships (Fovet, Ruiz, Hrachowitz, Faucheux, & Gascuel‐Odoux, ). Thus, estimating the volumes and temporal dynamics of hydraulically decoupled catchment storage could provide important new insights into catchment processes and improve hydrological modelling frameworks.…”

The importance of topography-controlled sub-grid process heterogeneity and semi-quantitative prior constraints in distributed hydrological models

“…Refsgaard and Knudsen, 1996;Booij, 2005). Nevertheless, in many cases these models may remain serious over-simplifications of the different combinations of the dominant processes underlying the observed response patterns as argued by, among others, Young (1992), Reichert and Omlin (1997), Perrin et al (2001), Wagener and Gupta (2005), Gupta et al (2012), Zehe et al (2014), Hrachowitz et al (2014) and Fovet et al (2015). In addition, the transferability of these simple models to other (ungauged) basins is limited.…”

Evaluation of storage–discharge relationships and recession analysis-based distributed hourly runoff simulation in large-scale, mountainous and snow-influenced catchment

“…Several studies also illustrated the non-uniqueness of the response of discharge to storage. For instance, Clark et al (2009) illustrated for a mountain watershed in Georgia (USA) that the recession relationships of (dQ/dt) and Q is approximately consistent with a linear reservoir at a hillslope scale and deviation from linearity becomes progressively larger with increasing spatial scale, and Myrabø (1997), Beven (2006), Ewen and Birkinshaw (2007), Spence et al (2010), Martina et al (2011) and Fovet et al (2015 reported hysteresis in discharge-storage relationships. Furthermore, Teuling et al…”