Advanced Materials Research Vols. 1092-1093

Abstract: With the accelerated development of land desertification, sudden wind sand disaster, strong dust storm occurrence frequency more and more high.In the desert area where the alkali content in soil is low and there is existence of quicksand, the sand brick was prepared by using sodium silicate as chemical sand fixation adhesive materials and sodium fluosilicate as hardening agent, in order to improve the surface properties of desert land, control the spread of deserts and improve the environment of desert. In this paper, the suitable dosage of sodium fluosilicate and sodium silicate were studied,which have an important effect on compressive strength, flexural strength, block antifreeze and water absorption properties of the mortar test block.

Abstract: Due to the disorder development of Beihai Silver Beach and the effects of the climate,there has been a serious phenomenon of beach erosion at Beihai Silver Beach,so to put forward effective and feasible maintenance methods of Silver Beach has the great significance.Through the sediment numerical simulation of the waters near the Silver Beach and analysis of the results and to conclude the law of sediment transport both in typhoon and normal wind and the sediment recovery mechanism of the Silver Beach.After a typhoon,the nearshore is scoured and the far offshore is deposited.The average scour depth is around 4cm and the average deposited height is around 2cm.The normal wind period is the sediment recovery period.After a year of normal wind,the nearshore and the far offshore is deposited,between them is a scouring area.The average scour depth is around 3cm and the average deposited height at the nearshore is around 4cm.The sediment recovery mechanism is that ,due to the dynamic action of the water in the normal wind period,it transports the deposition of sediment at the far offshore to the nearshore so as to make it recovered and gradually deposited.Based on the above regularity and mechanism,measures can be taken like that,to fill a sediment barrier parallel to the shoreline,which can make the water carry more sediment to the nearshore so as to speed up the recovery at Silver Beach.The sediment can be got from Baihutou and Yingpan Town.

Abstract: In order to study the effect of adding substrates on soil seed banks (SSBs) germination characteristics, vermiculite (inorganic substrates), rice husk char (organic substrates) and their mixed substrates were selected to be added to SSBs by different ratios. After the germination test, the results show that SSBs in different treatments present different germination characteristics. In this test, the nutrition of organic substrates is more important for promoting the rate of seeding emergence, while the inorganic substrates is better for greater density and seeding community diversity. T1(rice husk char: soil=1:9), T5(rice husk char: vermiculite: soil=2:1:7) and T4(vermiculite: soil=3:7) correspond the best promoting effect on these three aspects. Thus the substrates selection should be determined according to specific objectives during vegetation restoration. Mixed substrates combine the advantages of organic and inorganic substrates, which leads to comparative advantages in all aspects.

Abstract: The soil column was structured to simulate the sunken lawn and three processes were simulated, including rainfall and runoff process, surface erosion and vertical infiltration process, pollutant migration and transformation process. Results show that sunken lawn is a sink and has significant effects for stormwater pollution. The overall reduction rates of COD_Cr, TN and ammonia is 71.01±1.75%, 69.00±1.78%, and 64.39±1.84% respectively. The reduction effect is related to the pollution load, hydraulic loading and antecedent dry period.

Abstract: Flooding disasters not only threat the people's life and property, also affect the safety of environment resources ecosystem, which could make the destructive damage to the cultivated land resources both at quantity and quality. The cultivated land, once damaged, need to invest huge human, material and financial resources to restore its agricultural productivity. Based on analyst the formative factors of cultivated land damaged by flooding disasters, this paper selecting the restrictive factors such as, rainfall, relief amplitude, flooding disasters frequency and water system (including rivers and lakes),combing with the comprehensive evaluation method and putting forward the corresponding countermeasures. The risk of cultivated land damaged by flooding disasters in China is divided into severe risk, moderate risk and light risk level three class and nine subclasses totally. The result shows that: severe risk class covers an area of 194400 km², accounting for 15.13% of the cultivated land; Moderate risk class covers an area of 407400 km², accounting for 31.71% of the cultivated land area; Mild risk class covers an area of 682900 km², accounting for 53.16% of the cultivated land area. Making a risk grading evaluation to the cultivated land damaged by flooding disasters provides the basic theory basis for flooding disaster prevention, disaster relief, land consolidation planning and the establishment of basic farmland construction standards.

Abstract: Nebkha plays a major role in the ecological and environmental stabilization by accumulating wind-blown sediments around shrubs. Grain-size characteristics of different positions on nebkha reflect the sorting effect of aeolian dynamics. Based on the collected sand grains of different positions on four types of nebkhas at the southern fringe of Taklimakan Desert, China, this paper provided detailed insight into variability of the grain size of surface sand on nebkhas. The results showed that: a) Grain-size distributions on shield-shaped Karelinia caspica Nebkhas under natural condition had the larger spatial variability in comparison with the others. b) Grain size on nebkhas regularly showed the spatial variation. Grain size was increasingly larger along the windward slope upward, and then became finer along the leeward slope downward. c) The grain-size sortings of different positions on shield-shaped Alhagi sparsifolia Nebkhas under new reclaimed land were the best.

Abstract: The airflow field and sand movement path around fences of 0 and 40% porosity are of numerical calculation by CFD technology and the sand-blocking mechanism of fence is analyzed comprehensively. The results show that the two preconditions for the good sand-blocking performance of fence are to greatly reduce the coming wind velocity and form a large weak wind velocity area, and ensure the sand movement path in the weak wind velocity area. The numerical simulation research of the sand-blocking mechanism of fence is an useful supplement of traditional experimental research and of reference significance in further understanding the dynamic mechanism of fence protection.

Abstract: For the three big problems of water resources supply and demand contradiction, protection of groundwater environment and sediment over long distances in Xiaokai river irrigation area, the model of water utilization benefit maximization, groundwater level optimal control and the goal of sediment transport effect optimization model are established, and coupled into a multi-objective optimization model. The model is solved by using The delaminating sequence method, obtained the rational allocation plan of water resources in water years, and analyzing the rationality of the plan. The results show that, the scheme comprehensively considers the economic and environmental issues and has great reference value to promote sustainable development of irrigation area.

Abstract: Hazard waste has become a big problem to environment and human society. So its supervision and management is becoming a research hotspot in environmental science. This paper adopts open source software PostGIS, GeoServer and OpenLayers to build a hazard waste supervision WebGIS, which has realized online display of hazard waste sources, visualized analysis of hazard waste sources and hazard waste transportation route tracking based on GPS data.

Abstract: Withdrawn be author’s request.