牧马河灌区灌溉制度探讨

从农作物生长过程所需要的水量、灌溉水利用系数、有效降雨量等因素入手,并结合当地实际情况确定灌溉制度。

Probability Prediction Model for Landslide Occurrences in Xi'an, Shaanxi Province, China

Landslides are increasing since the 1980s in Xi'an, Shaanxi Province, China. This is due to the increase of the frequency and intensity of precipitation caused by complex geological structures, the presence of steep landforms, seasonal heavy rainfall, and the intensifcation of human activities. In this study, we propose a landslide prediction model based on the analysis of intraday rainfall(IR) and antecedent effective rainfall(AER). Primarily, the number of days and degressive index of the antecedent effective rainfall which affected landslide occurrences in the areas around Qin Mountains, Li Mountains and Loess Tableland was established. Secondly, the antecedent effective rainfall and intraday rainfall were calculated from weather data which were used to construct critical thresholds for the 10%, 50% and 90% probabilities for future landslide occurrences in Qin Mountain, Li Mountain and Loess Tableland. Finally, the regions corresponding to different warning levels were identified based on the relationship between precipitation and the threshold, that is; "A" region is safe, "B" region is on watch alert, "C" region is on warning alert and "D" region is on severe warning alert. Using this model, a warning program is proposed which can predict rainfall-induced landslides by means of real-time rain gauge data and real-time geo-hazard alert and disaster response programs. Sixteen rain gauges were installed in the Xi'an region by keeping in accordance with the regional geology and landslide risks. Based on the data from gauges, this model accurately achieves the objectives of conducting real-time monitoring as well as providing early warnings of landslides in the Xi'an region.

Optimal Management Helps Reducing Risks for Potable-Water Resources in Albania

Albania is located on the eastern shore of the Adriatic and Jon Sea, south of former Yugoslavia, north of Greece, and west of Macedonia. It is divided into three agro-ecological zones based on climate, soils and vegetation： the fertile coastal plains, the intermediate hilly region, and the non-arable mountain zones. Annual rainfall varies from 800 to 2,000 mm in coastal areas to 1,600 to 2,000 mm in the hilly regions and up to 3,000 mm in the mountains. Rainfall is concentrated mainly in the winter, and less than 20 percent of annual rainfall occurs in the six-month period between April and September. Studies indicate that available sources of supply could provide more than enough to satisfy the country＇s overall water demand. In many cities, water availability at the source is about 500-700 litres per capita per day, but leaks and waste mean that only a small fraction of water produced is consumed. The paper research concludes that the Albanian government should： （1） Introduce and implement new anti-corruption laws to increase the market transparency; （2） Continue the ongoing institutional and economical reform to deliver better legal institutions and market efficiency; （3） Reduce anti-competitive practices such as government monopoly in some sectors and privatize all the strategic sectors; and （4） Urgently develop with the help of International Monetary Fund, new projects regarding infrastructure with clear the National Investment Promotion Agency from the bureaucratic procedures and further increase the budget to improve the whole internal infrastructure.

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.