Lake Qinghai, the largest saline lake with an area of 4,260 km 2 (2000) and average depth of 21 m (1985) in West China, has experienced severe decline in water level in recent decades. This study aimed to investigate water balance of the lake and identify the causes for the decline in lake level. There was a 3.35-m decline in water level with an average decreasing rate of 8.0 cm year −1 between 1959 and 2000. The lake water balance showed that mean annual precipitation between 1959 and 2000 over the lake was 357± 10 mm, evaporation was 924±10 mm, surface runoff water inflow was 348±21 mm, groundwater inflow was 138 mm±9 and the change in lake level was −80±31 mm. The variation of lake level was highly positively correlated to surface runoff and precipitation and negatively to evaporation, the correlation coefficients were 0.89, 0.81 and −0.66, respectively. Water consumption by human activities accounts for 1% of the evaporation loss of the lake, implying that water consumption by human activities has little effect on lake level decline. Most dramatic decline in lake level occurred in the warm and dry years, and moderate decline in the cold and dry years, and relatively slight decline in the warm and wet years, therefore, the trend of cold/warm and dry climate in recent decades may be the main reasons for the decline in lake level.

The recovery of heavy oil from ultradeep wells is a technical challenge faced by the petroleum industry. One of the key issues is the flow assurance of heavy oil inside the wellbore and through the pipelines, i.e., effectively lifting heavy oil from the wellbore and subsequently transporting it smoothly through the pipelines. Traditional chemical methods for reducing the viscosity of heavy petroleum fluids adopt oil-soluble and water-soluble viscosity reducers, but these methods have their limitations. In this work, we develop a new composite viscosity reducer called SDG-2, which combines the advantages of oilsoluble and water-soluble viscosity reducers. The molecular chain of this viscosity reducer is grafted with a high-carbon lipophilic polar group and a salt-tolerant hydrophilic group, providing the reducer with both dispersion and emulsification capabilities. An experimental test shows that, without water, the viscosity reducer SDG-2 can achieve a 50% degree of viscosity reduction (DVR) for the ultraheavy oils tested. A low oil/water interfacial tension (IFT, 0.41 mN•m −1 ) can be achieved when 0.15 wt % SDG-2 is added into the highly saline (2.26 × 10 5 mg•L −1 ) solution. This IFT is significantly lower than the 13.42 mN•m IFT obtained by a 0.60 wt % oil-soluble viscosity reducer, as well as the 8.21 mN•m IFT achieved by a 0.40 wt % water-soluble viscosity reducer. The emulsification capability of SDG-2 is also superior to that of a water-soluble viscosity reducer; oil-in-water emulsion can be obtained when the oil is mixed with 30% (v/v) water and 0.30 wt % SDG-2. Higher DVR values (99%) can be achieved for the Tahe (China), Canada, and Venezuela heavy oils when emulsification occurs. Field tests of the new composite viscosity reducer are conducted in the Tahe oilfield of Xinjiang Province in China. Results show that considerably less light oil is needed to dilute heavy oil to the desired viscosity when the new viscosity reducer is used. On average, a 22.5% increase in heavy oil production rate can be obtained.

Based on the tree ring width index of Pinus tabulaeformis, precipitation in the last 140 years was reconstructed at south margin of the Tengger Desert. The results indicated that there were obvious fluctuations of dry-wet changes in precipitation: two wet periods occurred during 1868-1876 and 1932-1939, and two dry periods during 1877-1894 and 1924-1932, however, the years 1887 and 1888 were a little wet. There were small changes in precipitation during 1895-1923 and 1940-2000. As compared to the average, the maximum increasing range of precipitation amounted to 56% during the wet periods, and 42% during the dry periods. And the range of variability of precipitation exceeded 30% in 19 years. There was no obvious consistent drying or wetting trend in the last 140 years. But since 1940 fluctuating scope of precipitation tended to be smaller, while the frequency of the fluctuation tended to be larger. Power spectrum analyses suggested that precipitation of south margin of the Tengger Desert had significant periodicities of 2.46-2.64 a and quasi periodicity of 11.67 a.

The morphology and stability of concave surface of the straw checkerboard barriers are the fundamental guiding principles of exploring the mechanism of erosion and deposition, evaluating effectiveness and life period, and optimizing the physical structures of the sand barriers. Especially, in alpine sandy land, characteristics of erosion (deposition) and capacity for anti-erosion and sand burial of straw checkerboard barriers are significantly different from the arid and semi-arid desert regions. Erosion (deposition) measurements and wind-sand observations for different specifications (1 m 9 1 m, 1.5 m 9 1.5 m and 2 m 9 2 m) and slope positions (toe, middle and top of the windward areas) of wheat straw checkerboard barriers were adopted in the eastern shore of the Qinghai Lake study area. The different sizes of straw checkerboards at different windward areas have distinctly erosive and depositional stability and intensity. Including the checkerboards with 1.5 m 9 1.5 m (medium) size at the middle and top, 1 m 9 1 m (small) size at the top and 2 m 9 2 m (large) size at the toe, all the erosion (deposition) coefficients are between 0.09 and 0.11, while their intensities of accumulation are relatively steady (70-90 kg m −2 ), which are the easiest to form stable concaves, and the heights of the barriers change least. Nevertheless, the concaves with small size at the toe are seriously buried, but eroded in the center of some checkerboards with large size at the top, which lead to a short protective period within 3 years and an unbalance between erosion and deposition. Moreover, the transects of erosion (deposition) dominated by southwesterly and northwesterly winds reflect the different intensities of erosion (deposition) at various orientations. On the transect of the NW-SE orientation, at the dune section, each square in the NW direction is strongly accumulated, and the center-SE azimuth is weakly eroded. Usually, deeper accumulation in the center of transects happen in those checkerboards with smaller size and lower terrain slope, which is mainly caused by an obviously positive correlation between the northwest and southwest wind velocity and the erosive depth, and the same is true with the wind frequency (all correlation coefficients are between 0.85 and 0.95). Taking the characteristics of erosion (deposition), sand protection benefits and costs of all types into account, large size at the toe and medium size at the middle of windward slope are the most practical combinations, while small size is suitable to play an emergency treatment role in some extremely serious hazard areas in alpine sandy land.

The planting of sand-binding vegetation in the Qinghai Lake watershed at the northeastern edge of the Qinghai–Tibet Plateau began in 1980. For this paper, we took the desert on the eastern shore of Qinghai Lake as the study area. We analyzed a variety of aged Hippophae rhamnoides communities and aeolian activities, and we discuss the relationship between them. The main conclusions are as follows: (1) With an increasing number of binding years, the species composition became more abundant, natural vegetation began to recover, and biodiversity increased year by year. At the same time, plant height, canopy width, and community coverage increased, but H. rhamnoides coverage was reduced to 36.70% as coverage of Artemisia desertorum increased to 25.67% after 10 years of fixing. The biomass of H. rhamnoides increased significantly, especially the underground biomass. For example, the biomass of area 15a was about 10 to 30 times that of area 1a. (2) Plants are a useful obstacle to aeolian activity. The presence of plants reduced the wind flow in the upper parts of the plants, but it did not have obvious regular characteristics. The longer the fixation term, the lower the surface sediment transport. It is significant that the sediment transport amount in winter was four times that in the summer. After 15 years of binding, H. rhamnoides grows well, and the community is still stable in the study area.