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Hydrogen and oxygen stable isotope in water bodies is a widely used tracer in hydrological process studies. In order to provide a basis for stable isotopic characteristics in different water bodies at the high mountainous area of northwestern Tibetan Plateau, samples for river water, groundwater, soil water, and plant water were collected from 10 sites in the Qilian Mountains during July and August 2015, and then analyzed for δ18O and δD, respectively. Results indicated that the stable isotope values of soil water were mostly plotted below the global meteoric water line (GMWL), which suggested that evaporation made heavy isotope in soil water enriched. The stable isotope values of soil water were quite different in the top soil layer, but tended to be uniform in the deep soil layer. Furthermore, the stable isotope difference of plant water is related to climatic conditions, water isotopes utilized by plant, plant species, growing season, and so on. Additionally, the variation of δ18O values for river water and groundwater relatively coincided with each other, and this showed the recharge sources of above two water bodies may be consistent. The stable isotope values of river water and groundwater were mainly plotted on the upper left of GMWL, and the lower level of isotopic fractionation due to weak evaporation may accountable for this. [ABSTRACT FROM AUTHOR]

Snow cover on glacial surfaces is a sensitive environmental indicator. However, it is difficult to differentiate snow cover from a bare ice surface, and snow cover also changes rapidly during the melt season. Monitoring these dynamics requires sufficient time and spatial resolution; thus, traditional satellite data lack the necessary spatial resolution and rarely used to monitoring snow cover on glacier surface, which induced monitoring of snow dynamics on glacier is more challenging. Time-lapse photography has the advantage of obtaining images with high time and spatial resolution. By using an automated time-lapse digital camera, this paper documents two successive years snow cover dynamics on the Shiyi glacier and compared the meteorological conditions which induced different melt conditions. Monitoring indicate that the 2012 melt season experienced a higher snow cover fraction than the 2013 melt season because of a greater accumulated snow depth, lower air temperature and fewer sunlight hours. Successive photographs also indicate that, on the Shiyi glacier, atmospheric dust accelerates the snow melt speed and attenuates the snow depth. For the bare ice surface, the effects of atmospheric dust were reduced because the dusts were composed of Fine particles and are more easily washed away by melt water or rain. Studies on the Shiyi glacier indicate that the snow cover fraction is a key parameter that indicates the status of glacial accumulation or ablation. [ABSTRACT FROM AUTHOR]

A total of 90 individual precipitation samples have been collected in the central Qilian Mountains from August 2012 to November 2013. All samples were analyzed for major cations (Na, K, Ca and Mg), anions (Cl, NO and SO) and conductivity. Precipitation EC ranged from 2.26 to 482 μc/cm with an average value of 41.9 μs/cm. Precipitation was of SO-Mg-Ca type, and these three ions contributed >70 % to the total ionic concentration. Precipitation events occurred around summer displayed lower concentrations, whiles it had higher concentrations in winter and spring with little precipitation and larger wind speed. The major sources for these ions are regional crustal aerosols and species from central Asia and northwestern China arid regions brought by the westerly, and some aerosols from human pollution are secondary sources. It is also interesting that precipitation chemistry is different under diversely atmospheric circulation in Hulugou basin: the monsoon precipitation, the interaction precipitation influenced both by monsoon and westerly, and the westerly precipitation events. [ABSTRACT FROM AUTHOR]

Isotope geochemistry of precipitation, river water, well water and spring water in the Babao River basin, China, during different seasons showed that regional runoff was dominated by precipitation in summer and autumn and by underground water in winter and spring. The δO and δD values of precipitation and spring water displayed a clear altitude effect. Water from the main stream and tributaries displayed a converse altitude effect in the summer-wet season. The isotopic composition of the various water sources was not well correlated with elevation during the winter-dry season. The spatial distribution of the stable isotope signals of river water demonstrated the influence of rainfall inputs, evaporation and variable flow. An end-member mixing model used for hydrograph separation indicated that in the summer-wet season, the Babao River water was recharged by precipitation (71.9 %), spring water (11.7 %) and well water (16.4 %), whereas the winter-dry season recharge was sourced from spring water (28.2 %) and well water (71.8 %). [ABSTRACT FROM AUTHOR]

Different types of precipitation significantly affect the associated environmental temperature field. Because of its variability at different altitudes, it is very difficult for researchers to obtain precipitation-type information in mountainous regions. A new precipitation observation method based on time-lapse cameras was used to monitor the precipitation type during the warm season (May-September) of 2012 in the Hulugou River Basin (HRB) of the Qilian Mountains. By georeferencing the camera images, the elevation of the rain/snow boundary for 29 precipitation events was obtained. The critical air temperature (critical air temperature was used to differentiate rain and snow) at rain/snow boundary was calculated through interpolation of observed air temperatures in the HRB at six different altitudes (2,980, 3,382, 3,710, 3,839, 4,166 and 4,496 m). The outcome indicates that from April to July, the elevation of the rain/snow boundary increased from 3,000 to 4,000 m above; subsequently, the elevation of the rain/snow boundary decreased to 3,000 m in October. The daily critical air temperature ranged from 0.0−4.1 °C. Based on the observations of the critical air temperature, the amount of solid precipitation was calculated at different elevations. The results indicated that the proportion of solid precipitation increased from 5.7 to 31.9 % at 3,382-4,496 m during the warm season in the HRB. [ABSTRACT FROM AUTHOR]

The Qilian Mountains water conservation forest in Gansu province is an important ecological barrier surrounding the oasis in China's Hexi Corridor. The water they provide is the basis for the existence and sustainable socioeconomic development of those oases. As a result of unsustainable use of the water conservation forest until the 1980s, the oasis ecosystems of the Hexi region were seriously damaged, and the oasis areas experienced deterioration of their ecological environment. In this paper, Landsat images were used to monitor the temporal and spatial changes in area of water conservation in Qilian Mountains of China's Gansu province and to assess the effect on water conservation by analyzed relationship between water conservation forest area, climatic data and hydrological data. The results showed that the forest covered 15.1% of the study area in 2007 and has followed different trends during the study period. From 1978 to 1990, the forest area decreased; however, from 1990 to 2007, the forest area increased, with a faster rate of increase from 1990 to 2000, and the rate of increase averaged 2,733.89 ha per year since 1990. The water conservation forest appears to play an important role in flood control, runoff regulation, the prevention of soil erosion, and water conservation; and these benefits increase with an increasing area of forest. [ABSTRACT FROM AUTHOR]