The formation age and evolution of Kumtagh Desert

The ancient aeolian sand has been regarded as an indicator for the formation and evolution of a desert in the past.Kumtagh Desert is located at the northern fringe of Qinghai-Tibet Plateau.The first integrated scientific investigation to the desert was carried out during the period of 2004-2006.Kumtagh Desert is an ideal natural model for studying the formation and evolution of the desert because the Quaternary strata containing ancient aeolian sands are widely distributed.The integrated field investigation and studies on sedimentary,chronology and palynology of typical profiles named Suosuo gully,Xiaoquan gully and gravel body with ancient aeolian sand layers showed that Kumtagh Desert was probably formed as early as 2,097.7±314.7 ka BP.During the period of 386.9±58.0 ka BP to 285.9±42.9 ka BP,the desert largely expanded and formed its modern distribution pattern.The desert was originally developed in the southwest,subsequently,expanded to the north and northeast.The sedimentary facies of Suosuo gully profile revealed that the desert experienced at least 19 cycles of advance and inverse processes of desertification with an average period of 110 ka in the Quaternary.The neotectonic movements played an important role in the formation,development and geomorphology of the desert.On one hand,the movements caused the formation of intermontane fault basin,which was further developed towards the closed drought basin,and caused the formation of natural environment.On the other hand,under the control of surrounding faults,the unique broom-shaped desert landscape was formed,and the gullies and sand ridges in this region experienced an abrupt directional change from north by west to north by east at the location of 39°45＇-39°55＇N.The unique landscape of gravel body that occurred widely in the northern desert was formed after 285.9±42.9 ka BP.The results in this paper provide the scientific basis for studying the formation age and evolutionary process under the dry climate and environment in the northwestern China,and the uplifting of Qinghai-Tibet Plateau as well as its responses to the global climate changes.

Shiyang River ecosystem problems and countermeasures

With the increase of population and the development of social economy, contradiction between water supply and demand of Shiyang River Basin become more outstanding. Unreasonable exploitation and utilization of water resources cause the serious deterioration of ecological environment. According to the present ecoligical situation, by analyzing some actual problems of the ecosystem of Shiyang River Basin, a series of feasible control countermeasures are proposed. The article provide theoretical basis for the treatment and recovery of the degradation of ecological environment of Shiyang Rive Basin.

Effects of separate and mutual application of Na and Si on drought resistance of Haloxylon ammodendron

We studied pot cultivated Haloxylon ammodendron＇s growth, physiological changes and drought resistance under NaC1, H2SiO3, and NaCl＋H2SiO3 treatments. Results show that 0.3 g/kg NaC1, 0.2 g/kg HzSiO3 or 0.3 g/kg NaCI＋0.1 g/kg H2SiO3 treatments can effectively promote growth and improve the drought resistance of/-L, ammodendron. Compared with that without NaCI treatment, H. ammodendron＇s height, crown diameter and fresh weight increased by 42%, 91% and 62% respectively under 0.3 g/kg NaC1 treatment, and its main stem diameter, main root diameter and main root length increased by 40%, 39% and 23%, respectively. Compared with that without H2SiO3 treatments, H. ammodendron＇s height, crown diameter and flesh weight increased by 36%, 45% and 27% respectively under 0.2 g/kg HeSiO3 treatment, and its main stem diameter, main root diameter and main root length increased by 23%, 23% and 20%, respectively. Compared with that under 0.3 g/kg NaC1 treatment, H. ammodendron＇s height, crown diameter and fresh weight and main root length increased by 9%, 10%, 17% and 12% respectively under 0.3 g/kg NaCI＋0.1 g/kg H2SiO3 treatment. Compared with that under 0.1 g/kg H2SiO3 treatment, H. ammodendron＇s height, crown diame- ter and fresh weight increased by 28%, 76% and 68% respectively under 0.3 g/kg NaCI＋0.1 g/kg H2SiO3 treatment, and its main stem diameter, main root diameter and main root length increased by 30%, 32% and 27%, respectively. This suggests that moder- ate levels of NaCI＋H2SiO3 interaction can effectively promote growth and improve drought resistance of/-L, ammodendron than separate applications of NaC1 or H2SiO3.

The Process of Cultivated Land and Water Resource Distribution Changing in Recent Decades in Upstream and Downstream in Shiyang Inland River Basin in Arid Area of Northwest China

Last century 50 - 70 years, the dam construction of Shiyang Inland River Basin (SIRB) profound impact on the distribution of water resources and arable land in the basin. Through data collection, field surveys and remote sensing image interpretation, we analysis the use of land and water resources change process in the middle and lower reaches of SIRB in recent decades. The results show: (1) The cultivated area of SIRB has been an upward trend in recent decades, The whole basin cultivated area has increased total 229,000 hm2 from 1973 to 2010 and mainly in the middle and lower reaches. Midstream increased by 149,700 hm2 accounting for 65.36 percent of total, downstream increased by 70,000 hm2 accounting for 30.70 percent of total. (2) The amount of surface water resources of downstream reduce significantly gradually since dam construction, and the water table sharp decline. While the volume of surface water resources come downstream from the 1950s accounted for 30 to 40 percent of the total gradually reduced to less than 10% in 2012;(3) since the arable land area of middle and lower reaches of SIRB basin substantial increase, so the surface water resource does not meet irrigation needs. Agricultural irrigation relies heavily on exploitation of groundwater to supplement, resulting in Regional Groundwater Depth dropped rapidly, and forming several huge funnel groundwater settlements. 20 years from 1981 to 2001 the groundwater level of midstream dropped from around 5m to around 10m in Wuwei, and in Minqin dam-region of downstream along faster rate of decline in 20 years fell from 8.52 m to 22.68 m. Dam construction project has changed the pattern of the basin water cycle, the middle reaches closure a large number of surface water resources led to downstream sharp decline. Downstream continued exploitation of groundwater formed a few huge funnel groundwater settlements, it caused serious ecological problems. The basin should adjust the industrial structure and develop water saving irrigation, promote a virtuous cycle of water resources, to achieve sustainable development, seek a sustainable development ways conversion natural oasis to artificial oasis efficiency in arid zone.