Flow Analysis at the Snow Covered High Altitude Catchment via Distributed Energy Balance Modeling

Abdul Shakoor,Naeem Ejaz

doi:10.1038/s41598-019-39446-1

Abdul Shakoor, Naeem Ejaz

Open Access

https://doi.org/10.1038/s41598-019-39446-1

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Abstract

Energy budget-based distributed modeling at high-altitude glacio-nival watersheds is essential to accurately describe hydrological processes and quantify the flow rates. In this study, SNOWPACK model and its distributed version Alpine3D are applied for the first time in Pakistan to simulate the runoff response of a high altitude glaciated catchment. The basic aim was to explore the feasibility of this modeling system and its future applications in the region. Final results demonstrated satisfactory performance of the model between measured and modeled discharges with Nash-Sutcliff Efficiency of 0.54. However, total simulated flow volume differs only 1.3 times as compared to measured discharge of the lake, located at the glacier snout. Flow composition analysis revealed that the runoff regime of the study site is strongly influenced by the snow and glacier melt runoff representing 53% snowmelt and 38% glacier melt contribution. Low model efficiency has been observed during glacier melting season due to inaccurate wind speed distribution and biased input met-data. It is concluded that high performance of this model can be achieved if the model is optimized over the catchment similar to the study site provided with long term data sets. This study leaves a firm foundation for the potential application of a highly accurate distributed energy balance model in the entire Karakoram and Himalaya region to understand the melt dynamics of such a rugged terrain glacier rich mountains.

Highlights

SNOWPACK and ALPINE3D energy balance models have been applied for the first time in Pakistan to assess the hydrology of Passu catchment located in Hunza Watershed, Pakistan
The aim was to test the performance and feasibility of these models in order to quantify the hydrological discharge in high altitude mountainous catchments of Pakistan
The results demonstrate temporal scatter between measured and modeled flow rates with Nash-suttcliff effeciency (NSE) of 0.54 and just meet the satisfactory performance threshold

Summary

Introduction

Present research uses point scale simulations to assess melt with a highly accurate energy balance model in order to compute the parameters of distributed hydrological model This technique works by the concept that simulated melt rates with a physics based energy balance model are very precise at the location of Automatic Weather Stations due to the use of available high-quality meteorological measurements. Such simulation outputs can be used as a replacement of high-resolution ablation data and can be used to optimize parameters in the distributed hydrological model.

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