Abstract
Hydrological models, with different levels of complexity, have become inherent tools in water resource management. Conceptual models with low input data requirements are preferred for streamflow modeling, particularly in poorly gauged watersheds. However, the inadequacy of model structures in the hydrologic regime of a given watershed can lead to uncertain parameter estimation. Therefore, an understanding of the model parameters’ behavior with respect to the dominant hydrologic responses is of high necessity. In this study, we aim to investigate the parameterization of the HBV (Hydrologiska Byråns Vattenbalansavedelning) conceptual model and its influence on the model response in a semi-arid context. To this end, the capability of the model to simulate the daily streamflow was evaluated. Then, sensitivity and interdependency analyses were carried out to identify the most influential model parameters and emphasize how these parameters interact to fit the observed streamflow under contrasted hydroclimatic conditions. The results show that the HBV model can fairly reproduce the observed daily streamflow in the watershed of interest. However, the reliability of the model simulations varies from one year to another. The sensitivity analysis showed that each of the model parameters has a certain degree of influence on model behavior. The temperature correction factor (ETF) showed the lowest effect on the model response, while the sensitivity to the degree-day factor (DDF) highly depends on the availability of snow cover. Overall, the changes in hydroclimatic conditions were found to be mostly responsible for the annual variability of the optimal parameter values. Additionally, these changes seem to actuate the interdependency between the parameters of the soil moisture and the response routines, particularly Field Capacity (FC), the recession coefficient K0, the percolation coefficient (KPERC), and the upper reservoir threshold (UZL). The latter combines either to shrink the storage capacity of the model’s reservoirs under extremely high peak flows or to enlarge them under overestimated water supply, mainly provoked by abundant snow cover.
Highlights
Mathematical models have been widely used in water resource-related applications, and they have become essential tools for management and planning purposes [1]
The statistics of simulations corresponding to Nash Sutcliff Efficiency (NSE) above the 99.5th percentile and the streamflow simulations obtained based on the parameter sets that maximize the NSE during calibration are shown in Figures 3 and 4, respectively
The present study was performed to investigate the potential influence of the HBV model parameters on the streamflow simulation over a semi-arid watershed characterized by heterogenous hydroclimatic conditions
Summary
Mathematical models have been widely used in water resource-related applications, and they have become essential tools for management and planning purposes [1]. Various structures are available with different degrees of complexity from simple conceptual lumped models to more physically-based distributed ones [2,3,4,5,6,7,8]. Conceptual models based on physical concepts have been more attractive to the hydrological community due to their low requirements of input data and flexibility in application. Many discussions have been conducted on whether simple structures or more complex models provide optimal estimations of streamflow [9,10,11,12]. Some studies have reported that models with complex structures do not always implicate superior performance compared to simple ones [1,13,14]
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