Investigating Snow Cover and Hydrometeorological Trends in Contrasting Hydrological Regimes of the Upper Indus Basin

Abstract

Abstract:The Upper Indus basin (UIB) is characterized by contrasting hydrometeorological behaviors; therefore, it has become pertinent to understand hydrometeorological trends at the sub-watershed level. Many studies have investigated the snow cover and hydrometeorological modeling at basin level but none have reported the spatial variability of trends and their magnitude at a sub-basin level. This study was conducted to analyze the trends in the contrasting hydrological regimes of the snow and glacier-fed river catchments of the Hunza and Astore sub-basins of the UIB. Mann-Kendall and Sen's slope methods were used to study the main trends and their magnitude using MODIS snow cover information (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) and hydrometeorological data. The results showed that in the Hunza basin, the river discharge and temperature were significantly (p ≤ 0.05) decreased with a Sen's slope value of −2.541 m 3 ·s −1 ·year −1 and −0.034 • C·year −1 , respectively, while precipitation data showed a non-significant (p ≥ 0.05) increasing trend with a Sen's slope value of 0.023 mm·year −1 . In the Astore basin, the river discharge and precipitation are increasing significantly (p ≤ 0.05) with a Sen's slope value of 1.039 m 3 ·s −1 ·year −1 and 0.192 mm·year −1 , respectively. The snow cover analysis results suggest that the Western Himalayas (the Astore basin) had a stable trend with a Sen's slope of 0.07% year −1 and the Central Karakoram region (the Hunza River basin) shows a slightly increasing trend with a Sen's slope of 0.394% year −1 . Based on the results of this study it can be concluded that since both sub-basins are influenced by different climatological systems (monsoon and westerly), the results of those studies that treat the Upper Indus basin as one unit in hydrometeorological modeling should be used with caution. Furthermore, it is suggested that similar studies at the sub-basin level of the UIB will help in a better understanding of the Karakoram anomaly.

Modeling Hydrological Response to Climate Change in a Data-Scarce Glacierized High Mountain Astore Basin Using a Fully Distributed TOPKAPI Model

“…The other significant output of the TOPKAPI model is snow cover extent; the results indicate that the average snow-covered in two seasons, i.e., in winter (November to April) and summer (May to October) was 91 % and 11% respectively. A similar snow cover trend was reported by Atif, Iqbal, and Mahboob [78], they reported that the snow cover in the Astore basin varies from 92% during winter to 15% in summer seasons.…”

“…Additionally, the higher temperature 12 • C than the average temperature in the basin during the summer season caused increased melting of snow/glaciers resulting in peak discharges of Astore basin. Several research studies also reported a similar trend in hydro-meteorological data [77][78][79]. Whereas, moderate river flow was observed in the late summer (model 81 m 3 .s −1 , observed 85 m 3 .s −1 ) with a decrease in discharge started in late August till mid of October.…”

Trends in Snow Cover Duration Across River Basins in High Mountain Asia From Daily Gap-Filled MODIS Fractional Snow Covered Area

“…The 30-m ASTER GDEM V2 dataset was used to classify and assess data within specific elevation bands, an approach that has also been used by other studies in this region (Mishra et al, 2014;Tahir et al, 2016;Atif et al, 2018). The DEM was bilinearly resampled to align with the 500 m spatial resolution of MODIS.…”

“…The Mann-Kendall test is also commonly used with small sample size datasets in the earth sciences (Hipel and McLeod, 2005). Both the Mann-Kendall test and Sen's slope have been previously used in monitoring snow cover trends across HMA (Mishra et al, 2014;Tahir et al, 2016;Atif et al, 2018;Negi et al, 2018) and allowed a direct comparison of this work.…”

A time series assessment of terrestrial water storage and its relationship with hydro-meteorological factors in Gilgit-Baltistan region using GRACE observation and GLDAS-Noah model

“…In GB, Pakistan, except traditional hydrological studies [4,6,7,15], TWS is not considered at a regional scale with the GRACE observation data and technologies. In GB, the previous studies using traditional remote sensing technologies about water resources, i.e., glaciers and snow have contrasting results, few authors have concluded expansion and increase in glaciers and snow cover areas, whereas other contradicted their results [6,15,18].…”