Physicochemical Characterization of the High-Altitude Lakes in Northern Pakistan: Implications for Water Resource Management

Abstract

Lakes provide a wide range of ecological, cultural, and economic benefits and prime opportunities for recreation, tourism, and livelihoods in the Upper Indus Basin (UIB). In the wake of growing anthropogenic actions and climate change impacts, an appraisal of the lake water quality is essential to determine the health of the ecosystem and assist resource conservation initiatives in the region. An attempt has been made to establish a preliminary physicochemical baseline for eight high-altitude lakes in the UIB, Pakistan, to characterize their spatial hydrochemical variability and identify potential water quality concerns in the region. At the time of sampling, the lakes exhibited a slightly alkaline condition with pH ranging between 7.7 and 8.2 (mean 8.0). The lower alkalinity detected in the lakes, like Sheosar (42 mg/L), may indicate limited buffering capacity and more sensitivity to nutrient pulses or potential acidification. Nitrate-N concentration was low in most lakes, with many below detection limits. The Gibbs diagram indicated seven samples in the rock dominance zone, i.e., chemical weathering of rocks as the major factor contributing ions to the lake water, while in one sample, i.e., Borith Lake, evaporation-crystallization was the main source of dissolved chemical ingredients. The Spearman correlation analysis indicated a higher positive relationship (r > 0.9) between Ca and Mg, likely due to carbonate rock weathering. The observed variations in the water quality parameters may have significant effects on both the ecosystem and human health, necessitating further research and future attention. In-depth research on glacio-hydrological dynamics and limnology can support sustainable management and conservation of the freshwater ecosystems in the region.

Keywords

Hydrochemistry / Karakoram / Lake ecosystem / Water quality / Upper Indus Basin

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