The impacts of climate change on hydrology in a typical glacier region A case study in Hailuo Creek watershed of Mt.Gongga in China

The glaciers of the Hengduan Mountains play an important role in the hydrology processes of this region. In this study, the HBV Light model, which relies on a degree-day model to simulate glacier melting, was employed to simulate both glacier runoffand total runoff. The daily temperature and precipitation at the Hailuo Creek No. 1 Glacier from 1952 to 2009 were obtained from daily meteorological observed data at the glacier and from six national meteorological stations near the Hailuo Creek Basin. The daily air temperature, precipitation, runoff depth, and monthly potential evaporation in 1995, 1996, and 2002 were used to obtain a set of optimal parameters, and the annual total runoff and glacier runoff of the Hailuo Creek Glacier （1952--2009） were calculated using the HBV Light model. Results showed the average annual runoff in the Hailuo Creek Basin was 2,114 mm from 1952 to 2009, of which glacial melting accounted for about 1,078 mm. The river runoff in the Hailuo Creek catchment increased as a result of increased glacier runoff. Glacier runoff accounted for 51.1% of the Hailuo Creek stream flow in 1994 and increased to 72.6% in 2006. About 95% of the increased stream flow derived from the increased ~lacier runoff.

Chemical Characteristics and Environmental Significance of Fresh Snow Deposition on Urumqi Glacier No.1 of Tianshan Mountains, China

Ice and snow chemistry of alpine glaciers is crucial for the research of regional atmospheric environment change. Fresh snow samples were weekly collected from Urumqi Glacier No.1 in the Tianshan Mountains, Xin- jiang, China, and the chemical characteristics and seasonal variations of major ions, mineral dust, δ18O and trace metals were measured. Results show that the concentrations of major ions in the snow are Ca2+ > SO42-> NH4+ > NO3-> Cl-> Na+ > Mg2+ > K+, in which Ca2+ is the dominant cation, and SO42-is the dominant anion. All major ions have close positive correlations with each other except NO3-. δ18O shows positive correlation with air temperature change during the study period. Mineral dust particle and major ionic concentrations in fresh snow have obvious seasonal change, with high concentration in spring but low concentration in summer and autumn, which indicates that the chemical mass input from Asian dust activity to snow is very significant. Temporal changes of trace metals in fresh snow, e.g., Cd, Pb, Zn, Al, Fe, have shown that human-induced pollution of central Asian region also has large contribution to the snow chemistry on alpine glaciers of the Tianshan Mountains.

Contributions of climate and human activities to changes in runoff of the Yellow and Yangtze rivers from 1950 to 2008

Runoffs in the Yellow River and Yangtze River basins, China, have been changing constantly during the last half century. In this paper, data from eight river gauging stations and 529 meteorological stations, inside and adjacent to the study basins, were analyzed and compared to quantify the hydrological processes involved, and to evaluate the role of human activities in chang- ing river discharges. The Inverse Distance Weighted （IDW） interpolation method was used to obtain climatic data coverage from station observations. According to the runoff coefficient equation, the effect of human activities and climate can be ex- pressed by changes in runoff coefficients and changes in precipitation, respectively. Annual runoff coefficients were calculated for the period 1950-2008, according to the correlation between respective hydrological series and regional precipitation. An- nual precipitation showed no obvious trend in the upper reaches of the Yellow River but a marked downward trend in the mid- dle and downstream reaches, with declines of 8.8 and 9.8 ram/10 a, respectively. All annual runoff series for the Yellow River basin showed a significant downward trend. Runoff declined by about 7.8 mm/10 a at Sanmenxia and 10.8 ram/10 a at Lijin. The series results indicated that an abrupt change occurred in the late 1980s to early 1990s. The trend of correlations between annual runoff and precipitation decreased significantly at the Yellow River stations, with rates ranging from 0.013/10 a to 0.019/10 a. For the hydrologic series, all precipitation series showed a downward trend in the Yangtze River basin with de- clines ranging from about 24.7 mm/10 a at Cuntan to 18.2 mm/10 a at Datong. Annual runoff series for the upper reaches of the Yangtze River decreased significantly, at rates ranging from 9.9 to 7.2 mm/10 a. In the middle and lower reaches, the run- off series showed no significant trend, with rates of change ranging from 2.1 to 2.9 ram/10 a. Human activities had the greatest influence on changes in the hydrological series of runoff, regardless of whether the effect was negative or positive. During 1970-2008, human activities contributed to 83% of the reduction in runoff in the Yellow River basin, and to 71% of the in- crease in runoff in the Yangtze River basin. Moreover, the impacts of human activities across the entire basin increased over time. In the 2000s, the impact of human activities exceeded that of climate change and was responsible for 84% of the decrease and 73% of the increase in runoff in the Yellow River and Yangtze River basins, respectively. The average annual runoff from 1980 to 2008 fell by about 97%, 83%, 83%, and 91%, compared with 1951-1969, at the Yellow River stations Lanzhou, San- menxia, Huayuankou and Lijin, respectively. Most of the reduction in runoff was caused by human activities. Changes in pre- cipitation also caused reductions in runoff of about 3%, 17%, 17%, and 9% at these four stations, respectively. Falling precipi- tation rates were the main explanation for runoff changes at the Yangtze River stations Cuntan, Yichang, Hankou, and Datong, causing reductions in runoff of 89%, 74%, 43%, and 35%, respectively. Underlying surface changes caused decreases in runoff in the Yellow River basin and increases in runoff in the Yangtze River basin. Runoff decreased in arid areas as a result of in- creased water usage, but increased in humid and sub-humid areas as a result of land reclamation and mass urbanization leading to decreases in evaporation and infiltration.

Mercury speciation and spatial distribution in surface waters of the Yarlung Zangbo River,Tibet

The Yarlung Zangbo River is the highest river in the world.It flows from west to east through the southern part of Tibet.The mercury(Hg)speciation and distribution in surface waters and soils near the bank of the Yarlung Zangbo River and its two tributaries,the Lhasa and Niyang Rivers,were investigated in June 2007.Simultaneously,major water quality parameters were also measured at the same stations.Total Hg(THg)and total methylmercury(TMeHg)concentrations in surface waters of the Yarlung Zangbo River ranged from 1.46 to 4.99 ng/L and from 0.06 to 0.29 ng/L,respectively,representing the background levels in river systems of the Tibetan Plateau.Particulate Hg(PHg)accounted for 69%of the THg,and the two Hg species had a significant relationship(r=0.990,P<0.01).Approximately 61%of the spatial distribution of THg was controlled by the concentrations of total suspended particles(TSP).Reactive Hg(RHg)concentrations ranged from 0.10 to 0.36 ng/L,and this fraction may play a weak role in terms of the transport and fate of Hg in surface waters.Dissolved methylmercury(DMeHg)constituted 71%of the TMeHg and was significantly correlated with TMeHg(r=0.746,P<0.01).The spatial distribution of TMeHg is not strongly affected by environmental factors such as THg,RHg,temperature,pH,dissolved organic carbon(DOC),and TSP.In addition,the inflow of both the Lhasa and Niyang Rivers probably influences the concentrations of THg in surface waters of the mainstream, but such an effect is not obvious for TMeHg.