Snow Cover Variations and Controlling Factors at Upper Heihe River Basin, Northwestern China

Abstract

Snow is an important water resource and greatly influences water availability in the downstream areas. In this study, snow cover variations of the Upper Heihe River Basin (UHRB) during hydrological years (HY) 2003-2013 (September through August) is examined using the flexible multiday-combined MODIS snow cover products. Spatial distribution and pattern of snow cover from year to year for the basin is found to be relatively stable, with maximum snow cover area (SCA) and snow cover days occurring in HY2004, HY2008 and HY2012. A method, based on correlation coefficients between SCA and climate factors (mainly air temperature and precipitation), is presented to identify the threshold altitude that determines contributions of climate factors to SCA. A threshold altitude of 3650 ± 150 m is found for the UHRB, where below this altitude, both air temperature (Tair) and precipitation are negative factors on SCA, except in the winter season when both are positive factors. Above the threshold altitude, precipitation acts as a positive factor except in summer, while Tair is a negative factor except in autumn. Overall, Tair is the primary controlling factor on SCA below the threshold altitude, while precipitation is the primary controlling factor on SCA above the threshold altitude.

Spatiotemporal Variation of Snow Cover in Tianshan Mountains, Central Asia, Based on Cloud-Free MODIS Fractional Snow Cover Product, 2001–2015

“…First, the other climate factors such as sunshine duration, vapor pressure, wind velocity, and their synergistic effect also give rise to snow cover variation, which should not be ignored. Second, climate changes and their effect on snow cover vary with geographical environment, especially the elevations [16,56]. Furthermore, the period of 15 years, which is a long time considering available MODIS information, is not sufficient for statements about climate change.…”

The vertical influence of temperature and precipitation on snow cover variability in the Central Tianshan Mountains, Northwest China

“…Due to the lack of meteorological stations in this area, remote sensing data are often used. For example, Bi, Xie, Huang, and Ke (2015) used remote sensing data to perform a correlation analysis between snow cover area (SCA) and temperature/precipitation in the Upper Heihe River Basin, where the highest elevation is over 5,000 m. They found the threshold elevation to be 3,650 ± 150 m, below which temperature is the primary controlling factor on SCA, whereas above which precipitation dominates.…”

“…For example, Bi, Xie, Huang, and Ke () used remote sensing data to perform a correlation analysis between snow cover area (SCA) and temperature/precipitation in the Upper Heihe River Basin, where the highest elevation is over 5,000 m. They found the threshold elevation to be 3,650 ± 150 m, below which temperature is the primary controlling factor on SCA, whereas above which precipitation dominates. Because of the different snow indices and different data sources, we compared the result of this study (Bi, Xie, Huang, & Ke, ) with others that mentioned above (Morán‐Tejeda et al, ; Scalzitti et al, ; Sospedra‐Alfonso et al, ) and noticed that in Upper Heihe River Basin, instead of constantly positive/negative correlation with precipitation/temperature, the temperature does not keep negative correlation to SCA, and precipitation also has negative correlation to SCA at some elevations. But it is not clear where and when temperature/precipitation will have positive or negative correlation to SCA from the result by Bi et al ().…”

An Effective Method for Snow-Cover Mapping of Dense Coniferous Forests in the Upper Heihe River Basin Using Landsat Operational Land Imager Data

“…The Upper HRB (UHRB) is rich in water resources in the form of snow, which represents the majority of the water resources for the entire HRB [22]. A slight change in snow cover in the UHRB would greatly affect the water budget of the Heihe River, thus triggering a chain reaction that would affect agriculture and vegetation in the entire basin area [23]. So, the accuracy of snow-cover mapping is very important to the Heihe River hydrological process.…”