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Highlights: [•] Glacio-hydrometeorological conditions with four flow regimes in Upper Indus Basin. [•] Highest flow regime from July to September carry 53–62% annual flow volumes (m3). [•] Three most glaciated watersheds contribute 48–54% flow to the highest flow regime. [•] Melt water from altitude >3500m constitutes 41–54% of annual flow volumes. [•] Near the outlet, glacial and snow melt components respectively constitute 21% and 49% of annual flows. [Copyright &y& Elsevier]

Highlights: [•] Auto pit-filling applied to DEMs can result in significant errors in catchment areas. [•] Past estimates of the Upper Indus Basin area are ranging between 160,000 and 266,000km2. [•] The best estimate of the Upper Indus Basin (UIB) area is 164,867km2, using SRTM DEM. [•] The Pangong Tso catchment is not part of the UIB, for at least past thousand years. [•] Past studies based on the over-estimated watershed areas of the UIB need revision. [Copyright &y& Elsevier]

Scarcity of in-situ observations coupled with high orographic influences has prevented a comprehensive assessment of precipitation distribution in the high-altitude catchments of Indus basin. Available data are generally fragmented and scattered with different organizations and mostly cover the valleys. Here, we combine most of the available station data with the indirect precipitation estimates at the accumulation zones of major glaciers to analyse altitudinal dependency of precipitation in the high-altitude Indus basin. The available observations signified the importance of orography in each sub-hydrological basin but could not infer an accurate distribution of precipitation with altitude. We used Kriging with External Drift (KED) interpolation scheme with elevation as a predictor to appraise spatiotemporal distribution of mean monthly, seasonal and annual precipitation for the period of 1998–2012. The KED-based annual precipitation estimates are verified by the corresponding basin-wide observed specific runoffs, which show good agreement. In contrast to earlier studies, our estimates reveal substantially higher precipitation in most of the sub-basins indicating two distinct rainfall maxima; 1st along southern and lower most slopes of Chenab, Jhelum, Indus main and Swat basins, and 2nd around north-west corner of Shyok basin in the central Karakoram. The study demonstrated that the selected gridded precipitation products covering this region are prone to significant errors. In terms of quantitative estimates, ERA-Interim is relatively close to the observations followed by WFDEI and TRMM, while APHRODITE gives highly underestimated precipitation estimates in the study area. Basin-wide seasonal and annual correction factors introduced for each gridded dataset can be useful for lumped hydrological modelling studies, while the estimated precipitation distribution can serve as a basis for bias correction of any gridded precipitation products for the study area. [ABSTRACT FROM AUTHOR]