The importance of aspect for modelling the hydrological response in a glacier catchment in Central Asia

Abstract

Understanding how explicit consideration of topographic information influences hydrological model performance and upscaling in glacier dominated catchments remains underexplored. In this study, the Urumqi glacier no. 1 catchment in northwest China, with 52% of the area covered by glaciers, was selected as study site. A conceptual glacier‐hydrological model was developed and tested to systematically, simultaneously, and robustly reproduce the hydrograph, separate the discharge into contributions from glacier and nonglacier parts of the catchment, and establish estimates of the annual glacier mass balance, the annual equilibrium line altitude, and the daily catchment snow water equivalent. This was done by extending and adapting a recently proposed landscape‐based semidistributed conceptual hydrological model (FLEX‐Topo) to represent glacier and snowmelt processes. The adapted model, FLEXG, allows to explicitly account for the influence of topography, that is, elevation and aspect, on the distribution of temperature and precipitation and thus on melt dynamics. It is shown that the model can not only reproduce long‐term runoff observations but also variations in glacier and snow cover. Furthermore, FLEXG was successfully transferred and up‐scaled to a larger catchment exclusively by adjusting the areal proportions of elevation and aspect without the need for further calibration. This underlines the value of topographic information to meaningfully represent the dominant hydrological processes in the region and is further exacerbated by comparing the model to a model formulation that does not account for differences in aspect (FLEXG,nA) and which, in spite of satisfactorily reproducing the observed hydrograph, does not capture the influence of spatial variability of snow and ice, which as a consequence reduces model transferability. This highlights the importance of accounting for topography and landscape heterogeneity in conceptual hydrological models in mountainous and snow‐, and glacier‐dominated regions.

Understanding changes in the water budget driven by climate change in cryospheric‐dominated watershed of the northeast Tibetan Plateau, China

“…Because of the shrinking cryosphere over the past decades (Kang et al, , ; S. Liu et al, ; Wu & Zhang, ; T. Yao et al, ), the Tibetan Plateau is considered to be one of the most sensitive indicators of climate change in China (K. Yang et al, ). Changes in temperature and precipitation over the past decades were expected to significantly affect the cryospheric balances and the hydrology of headwater catchments on the Tibetan Plateau (Duethmann, Peters, Blume, Vorogushyn, & Güntner, ; H. Gao, Ding, Zhao, Hrachowitz, & Savenije, ; T. Gao, Zhang, Lin, Kang, & Sillanpää, ; K. Yang et al, ; W. Zhang, Yi, Song, Kimball, & Lu, ). Therefore, systematic understanding of implications for the water budget in cryospheric watersheds is a key issue.…”

Assessing Green and Blue Water: Understanding Interactions and Making Balance between Human and Nature

“…Different ecosystems have different hydrological processing mechanisms, thus the philosophy of water use for different ecosystems might also be different (Gao et al, 2017;Savenije and Hrachowitz, 2017). In addition, the spatial and temporal heterogeneity which is shown in previous analyses will also effect the water use by different ecosystems.…”

Impacts of climate change on the discharge and glacier mass balance of the different glacierized watersheds in the Tianshan Mountains, Central Asia

“…Even glacier area is less than 5% in watershed, meltwater can provide significant contributions to discharge (Hagg, Braun, Kuhn, & Nesgaard, ). Researchers have been paying increased attention to the changes in regional hydrological regimes associated with climate change (Chen et al, ; Gao, Ye, Zhang, Qiao, & Zhang, ; Zhang, Hua, Meng, & Zhang, ; Li, Chen, Chen, & Li, ; He, Tian, Gupta, HC, & HP, , Zhao et al, ; Gao, Han, Zhao, & Liu, , Gao, Ding, Zhao, Hrachowitz, & Savenije, ). Changes in temperature and precipitation not only influence water cycle processes and cause spatiotemporal redistributions of water resources but also affect the hydrological regimes of rivers (Nijssen, O'Donnell, Hamlet, & Lettenmaier, ; Chen et al, ; Ling, Xu, & Fu, , ; Deng, Chen, Wang, & Zhang, , Mao, Wang, & Zhang, ).…”