坦桑尼亚公路项目冲沟形成研究分析及危害处理措施

冲沟侵蚀是一种非常常见的土壤侵蚀形式,严重影响了土地的使用,并可能对基础设施造成很大威胁。论文通过采集现场土样,分析其塑性性能、内摩擦角和黏聚力,并基于可蚀性因子公式研究其可蚀性等级;通过现场测绘和分水岭模型研究其地表水流向和径流量,以此明确地表水径流量与冲沟形成关系。最终得出结论:冲沟的侵蚀是由于地表雨水不断对研究区域的土壤进行冲刷形成。由此提出阻止冲沟的进一步侵蚀的措施,旨在保护公路路基安全。

Effectiveness of Soil Conservation Methods in Preventing Red Soil Erosion in Southern China

Rainfall, runoff(surface runoff and interflow) and soil loss were recorded from 2002 to2005 in an experiment with four treatments on sloping red soil land in southern China. Treatments consisted of bare sloping ground(control check, CK),interplanting with soybean in spring or radish in autumn(I), level terrace(i.e., grass planted on the riser and bunds built at the edge of a bench terrace)(II), and level terraces of orchards with Bahia grass planted on the riser(III). The surface runoff and erosion in treatment II and III during the four years were low despite the occurrence of potentially erosive rains. By contrast, the CK plot had both the highest surface runoff coefficient and the highest sediment yield among all the plots. The surface runoff and soil erosion of the CK plot significantly differed from that of the treatment plots(p < 0.05). Additionally,Significant differences between the interflow of the CK plot and that of the treatment plots was found from April to August(p < 0.05). However, no significant differences between the CK and treatment plots were found from January to March and September to December. The order of the plots in terms of surface runoff coefficients and soil losses was: CK > I > III > II, whereas their order in terms of interflow was II > III > I > CK. The effects of treatment II were excellent, indicating that level terrace(i.e., grass planted on the riser and bunds built at the edge of a bench terrace) can be an excellent practice for soil and water conservation on sloping red soil land. Soil loss in southern China can be reduced through the widespread use of this approach.

Analysis of Surface and Ground Water Exchange in Two Different Watersheds

Water regime of Albanian rivers is a Mediterranean typical one. During the wet period, it flows 85%-90% of the annual flow and the dry period represents only 10%-15% of the annual amount. In this paper the water regime of the Semani and Vjosa River is analyzed. These are two rivers with total different hydro-geological characteristics. Vjosa river watershed is mainly composed of massif calcareous rocks that are streaky and karstifled. A totally different view is in the other river, in Seman where the impermeable rocks dominate. Even the distribution of the precipitation is quite different. In the Vjosa River the amount of the precipitation varies from 1,500 mm to 2,500 mm per year and in Semani River only 1,100 mm per year. The flow in the wet period is mainly a result of the precipitation and the minimum discharge occurs during the dry period representing the base flow that is the contribution from the groundwater. In this point of view the flow in the dry period is also an indicator of the underground water resource. During the dry period the watershed gives what it received and what has cumulated during the wet period. This is more evident in the case of a karstic watershed. The recession curves were analysed for all the hydrometric stations in both river basins and the parameters of these curves are evaluated. These results are analyzed and compared between the two different watersheds reflecting the differences on water exchange of surface and ground water. Finally, an assessment of groundwater resources in both hydro geological basins is worked out.

Climate Change and Water Resources： Strategies and Practices for Improved Water Management in Arid Countries

Assessment report of the Intergovernmental Panel on Climate Change （IPCC） highlighted the complex linkages between climate change and water. The likely warmer climate induced by the climate change is set to alter hydrological cycle and the shifting pattern of the rainfall would affect the spatial and temporal distribution of runoff, soil moisture, and surface and groundwater reserves. Therefore, there is an urgent need to assess the impacts of climate change on water and devise adaptation measures including management structures and processes by which one can deal with this challenge. The paper highlights with the global overview of climate change impacts on water in the arid region, supported and substantiated through scientific evidence drawn from IPCC reports and other relevant documents. This paper provides an overview of water resource management challenges including transboundary geopolitical concerns documented across the world and emphasizes the importance of an integrated framework for adaptive policy making. Further, it examines the viable water resource management options for various sectors and regions and showcases some of the international best practices in adaptation and mitigation. The paper also explains the complementary role of traditional knowledge in coping with climate change risks and uncertainties and the need for a balanced view in designing adaptation and mitigation strategies.

The discovery of surface runoff in the megadunes of Badain Jaran Desert,China,and its significance

The Badain Jaran Desert exhibits the greatest difference in altitude of all of the world's deserts.On the slopes of megadunes in the desert,there are physical and chemical deposits produced by surface runoff.In addition,we have observed rarely-seen infiltration-excess surface runoff in the megadune depressions as well as spring streams at the base of megadunes.We used electron microscopy,energy spectrum analysis,infiltration experiments,moisture content determinations and grain-size analysis to study the mineral and chemical composition of the runoff precipitates,and grain-size of the deposits associated with the runoff,together with the hydrological balance in the megadune area,and the atmospheric precipitation mechanism responsible for groundwater recharge and for supplying water to lakes.The observations of shallow runoff and infiltration-excess surface runoff indicate the occurrence of strong and effective precipitation in summer,which would provide an important source for groundwater recharge.Several lines of evidence,such as the physical and chemical deposits resulting from shallow subsurface runoff,spring streams,infiltration-excess runoff,and gravity capillary water with a moisture content of 3-6%,demonstrate that precipitation reaches the base of the megadunes through infiltration and subsequently becomes groundwater.The chemical deposits,such as newly-formed calcite and gypsum,and gray-black physical deposits,as well as different stages in the development of fan-shaped landforms resulting from shallow subsurface runoff,indicate that groundwater recharge in the area is the result of long-term precipitation,rather than intermittent individual major rainfall events.Fine sand layers with a low infiltration capacity lead to subsurface runoff emerging at the ground surface.Five factors play an important role in maintaining a positive water balance and in replenishing groundwater via rainfall:effective rainfall as a water source,the high infiltration capacity of the sands enabling rainfall to rapidly become capillary water in the dunes,low evapotranspiration rates due to the sparse vegetation,the fact that the depth of the sand layer influenced by evaporation is shallow enough to maximize the deep infiltration of rainfall,and rapidly-moving gravity capillary water in the sandy dunes.These five factors together constitute a mechanism for groundwater recharge from rainfall,and explain the origin of the groundwater and lakes in the area.Our findings represent a significant advance in research on the hydrological cycle,including groundwater recharge conditions and recharge mechanisms,in this desert region.