Hydrochemical and hydrological processes in the different landscape zones of alpine cold region in China

Abstract

Investigation of water sources and flow pathways is crucial to understand and evaluate the characteristics of surface water and groundwater systems. This article aims to identify the hydrochemical and hydrological processes in different landscape zones based on hydrochemical analyses of various samples, including samples from glacier, snow, frozen soil meltwater, surface water, groundwater, and precipitation, in the alpine cold region of China. Hydrochemical tracers indicated that chemical compositions are characterized by the Ca-HCO 3 type in the glacier-snow zone; the Mg-Ca-SO 4 type in the alpine cold desert zone; the Ca-HCO 3 -SO 4 type in the marsh meadow zone; the Ca-Mg-HCO 3 type in the alpine shrub zone; and the Ca-Na-SO 4 type in the mountain grassland zone. An end-member mixing model was used for hydrograph separation. The results showed that the Mafengou River in the wet season was recharged by groundwater in the alpine cold desert and alpine shrub zones (67%), surface runoff in the glacier-snow zone (11%), surface runoff in the alpine cold desert zone (8%), thawed water from frozen soil in the marsh meadow and mountain grassland zones (9%), and direct precipitation on the river channel (5%). This study suggests that precipitation from the whole catchment yielded little direct surface runoff; precipitation was mostly transformed into groundwater or interflow and was then concentrated into the river channel. This study provides a scientific basis for evaluation and management of water resources in the basin.

Soil water migration in the unsaturated zone of semiarid region in China from isotope evidence

“…Isotopic tracers can provide valuable information on complex hydrological problems, such as the runoff processes, residence time, runoff pathway and the origin and contribution of each runoff component (Arny et al, 2013;Ohlanders et al, 2013;Yang et al, 2012a;McInerney et al, 2011;Maurya et al, 2011;Kevin et al, 2010). The isotopes of D and 18 O are conservative and do not react with clay minerals and other soil materials.…”

Temporal and Spatial Variations of Hydrological Processes on the Landscape Zone Scale in an Alpine Cold Region (Mafengou River Basin, China): An Update

“…The isotopic composition of river water was low due to recharge by glacier snow meltwater and thawed frozen soil. It is revealed that river water is recharged by thawed frozen soil, glacier snow meltwater and precipitation in the wet season [3,9,38]. During the dry season, in river water in the lower reaches, δ 18 O ranges from −8.91‰ to −8.84‰, and δD ranges from −52.46‰ to −51.72‰, respectively, between groundwater and meltwater, which indicates that river water is recharged by groundwater and meltwater.…”

“…The lithology is dominated by Paleozoic-Mesozoic and Cenozoic sandstone, conglomerate, shale, limestone and slate, which have degenerated to different degrees [3,9,39]. There is abundant bedrock fissure water, which is characterized by metamorphic and clastic rock dating from the Paleozoic to the Cenozoic [3,9,40].…”

“…There are no obvious altitude effects among the various landscape zones. This is because the river water is recharged by thawed frozen soil water and glacier snow meltwater, and thawed frozen soil water and glacier snow melts water infiltrated and turned into groundwater [3,9,38]. Therefore, the altitude effect cannot be applied to determine the recharged level of groundwater or river water in the Mafengou River Basin.…”

“…Isotopic tracers can provide data and information on the origin of runoff processes and components [1][2][3][4][5][6][7]. It can be used to study the water cycle and origin of atmospheric condensates [8][9][10][11][12][13].…”