VARIABILITY OF MELTWATER AND SOLUTE FLUXES FROM HOMOGENEOUS MELTING SNOW AT THE LABORATORY SCALE

Four experiments were performed to examine the relationship between the meltwater flow field and ion release from melting snow. A 0.4 m³ volume of snow was placed in a Plexiglass box and melted from above using a heating plate. The meltwater and solute fluxes issuing from the bottom of the snow were monitored. In experiments with NaCl tracer added to the snow, the solute concentrations were generally lower in the flow fingers than in the background wetting front. Dye tracer experiments revealed contemporaneous areas of concentrated dye and dilute meltwater in flow fingers. This suggests that the meltwater in flow fingers is diluted by low concentration water from the top of the snowpack. Flow fingers contribute more meltwater flux primarily because the flow is maintained for a longer period of time than in the non-finger areas; however, the relative contribution of flow fingers to solute flux was apparently not as great as that of the background wetting front because of dilution of solute in the flow finger areas.     

THE CONTRASTING EFFECTS OF WILDFIRE AND CLEARFELLING ON THE HYDROLOGY OF A SMALL CATCHMENT

A wildfire in an afforested research catchment presented the rare opportunity to compare the hydrological effects of wildfire with the effects of clearfelling in the same catchment in the Jonkershoek Valley, in the south-western Western Cape Province of South Africa. The timber plantation, which occupies 57% of the 2 km² catchment, had been clearfelled and re-planted to Pinus radiata roughly five years before the fire. The effects of the two treatments on total flow, storm-flow and quick-flow volumes, peak discharge and storm response ratio were determined by means of multiple regression analysis, employing the dummy variable method to test for the significance of treatments. Both clearfelling and wildfire caused significant increases in all the stream-flow variables analysed. But the clearfelling effect was dominated by large increases in total flow (96% over three years), of which storm-flow and quick-flow volumes formed only minor parts. After the wildfire, by contrast, increases in total flow were small (12%) but the storm flow increases were three- to four-fold in the first year and roughly double in the second year. The wildfire caused fire-induced water repellency in the soils which led to overland flow on mid-slope sites, where soil infiltrability normally far exceeds local rainfall intensities. It is argued that these results support the hypothesis that stream-flow generation processes were changed by the wildfire in that overland flow made a direct contribution to storm flows, but that clearfelling had no such effect. © 1997 by John Wiley & Sons, Ltd.     

HYDROLOGICAL CYCLES ON THE NORTH AND SOUTH PERIPHERIES OF MOUNTAIN–GLACIAL BASINS OF CENTRAL ASIA

Four high mountain glacial basins of the northern and southern periphery of central Asia were studied to determine their interaction with the external hydrological cycle over the Eurasian continent. Two of them located in the northern periphery are closed drainage basins with continental climate and the other two are open basins located in the southern periphery. Calculations of mass energy exchange, glacial runoff and components of the hydrological cycles were conducted. For glaciers with a continental climate, the calculations of snow–ice melt and runoff were based on solar parameters. For glaciers with a marine climate regime, glacier melt and runoff were based on air temperature. The relative errors of simulated annual flows were, on average, 8–14%. The components of the regional hydrological cycles (precipitation, condensation, runoff and evaporation) were quantified for each glacial system and their share in total atmospheric moisture was determined. The closed basins of the northern periphery in central Asia stored annually about 0·1–2·4% of the total external atmospheric moisture in the Aralo-Caspian and Tarim hydrographic systems. About 0·22–0·24% of the external water cycle is transferred annually in open glacial basins of the southern periphery. The glaciers of these regions return 0·25–0·30% of the external water cycle per year to the Pacific and Indian oceans, 0·03% and 0·06% of this external moisture is taken from the glacial resources of the Gongga and Xixibangma glaciers. © 1997 by John Wiley & Sons, Ltd.     

CHANGES IN GLACIER AND ALPINE RUNOFF IN THE NORTH CASCADE RANGE,WASHINGTON, USA 1985–1993

From 1985 to 1993, the mean summer temperature was 1.1°C above the long-term mean and the mean winter precipitation was 11% below the long-term mean at the eight Washington State Cascade Mountain weather stations. The effect of this climate fluctuation on glacier and alpine runoff has been examined in five North Cascade basins. From 1985 to 1993 the two basins with less than 1% glacier-covered area experienced mean 1 July to 30 September (late summer) runoff 36% below the long-term mean. The three moderately glaciated basins (3, 6 and 14% glaciated, respectively) experienced a 13% decline in late summer runoff for the same period. A significant change in late summer runoff has occurred in the North Cascades and this change is less pronounced in glacier basins. The cause of the change is decreased winter precipitation and earlier onset of spring melting of the alpine snowpack, followed by above average summer temperatures and an earlier summer melt of alpine snowpack. The smaller decrease in runoff in glacial basins is due to increased ablation and consequent glacier runoff due to high summer temperatures. However, glacier retreat is also reducing glacier runoff.     

EFFECTS OF FOREST ON THE SNOW PARAMETERS DERIVED FROM MICROWAVE MEASUREMENTS DURING THE BOREAS WINTER FIELD CAMPAIGN

Passive microwave data have been used to infer the areal snow water equivalent (SWE) with some success. However, the accuracy of these retrieved SWE values have not been well determined for heterogeneous vegetated regions. The Boreal Ecosystem–Atmosphere Study (BOREAS) Winter Field Campaign (WFC), which took place in February 1994, provided the opportunity to study in detail the effects of boreal forests on snow parameter retrievals. Preliminary results reconfirmed the relationship between microwave brightness temperature and snow water equivalent. The pronounced effect of forest cover on SWE retrieval was studied. A modified vegetation mixing algorithm is proposed to account for the forest cover. The relationship between the microwave signature and observed snowpack parameters matches results from this model.     

地下气体运移变化的物理化学机制研究

在河北省怀来县后郝窑地区，对地下气体运移变化的影响因素进行了野外模拟实验研究。选择３个试验点，对地下气体的扩散作用，物理化学影响因素及水压效应等进行了模拟实验，主要研究Ｈ２，ＣＯ２气体运移变化机制。实验研究表明，Ｈ２，ＣＯ２气体运移变化机制不尽相同，水压效应对Ｈ２，ＣＯ２等地下气体运移影响相当明显     

CHARACTERIZATION AND CAUSATION OF RUNOFF AND SEDIMENT VARIATION IN THE JIALINGJIANG RIVER BASIN

The Jialingjiang River basin is one of the main sediment contributing areas in the upper reaches of the Changjiang River. Great changes have taken place in the runoff and sediment discharge in recent years. Comparing the data of 1991-2003 with the data of 1954-1990, the annual runoff of the Jialingjiang River basin decreased by 23 %, and the suspended sediment transport decreased by 74% or 105 million tons. The main factors affecting the reduction include a decrease in rainfall, sediment detention of hydraulic structures, soil and water conservation activities, sedimentation and sand dredging in the river channel. Thorough investigation and analysis of the contribution of each factor to the sediment decrease at Beibei Station was determined for the first time. The following are the contributing percentages for each factor: a decrease in runoff accounted for 32.9%; soil and water conservation measures accounted for 16.4%; sediment detention of hydraulic structures accounted for 30.5%; sedimentation, river channel sand dredging, and other factors accounted for 20.2%. These findings are very important for forecasting the trend of inflow sediment discharge variation.     

汶川地震的异常及其震后效应特征分析

分析了2008年5月12日四川汶川地震前甘肃地区、四川和青海部分地区的水氡（气氡）资料,甘肃地区数字化改造后的水位和地温资料的变化情况,结果发现在这次地震前有部分水氡测点的资料存在明显的震前异常,而且变化时间早,持续时间长,同步性很好。这些异常在恢复时间上无明显的规律。水位测点震后效应非常明显,部分水氡和地温测点也有不同程度的震后效应。     

EFFECT OF ANNUAL RAINFALL AND RUNOFF COMPOSITION ON SEDIMENT YIELD IN SMALL WATERSHEDS

ＥＦＦＥＣＴＯＦＡＮＮＵＡＬＲＡＩＮＦＡＬＬＡＮＤＲＵＮＯＦＦＣＯＭＰＯＳＩＴＩＯＮＯＮＳＥＤＩＭＥＮＴＹＩＥＬＤＩＮＳＭＡＬＬＷＡＴＥＲＳＨＥＤＳＳｌｏｂｏｄａｎＰＥＴＫＯＶＩＣａｎｄＪｏｖａｎＳＴＥＦＡＮＯＶＩＣ（ＰｒｏｆｅｓｓｏｒｏｆＨｙｄｒａ...     

岩石综合物性差异与变化的特征

从岩石物性与化学元素原子结构的关系出发，从密度、弹性、电性和放射性等诸方面，论述了岩石综合物性差异与变化的特征；并结合实例，得出岩石综合物性参数发生变化反映了组成岩石的原子、分子、矿物和结构发生了变化，且各参数之间具有某种相关性的结果．      

零或负有效应力及其对岩体物性影响的野外证据

本文列举了许多野外观测证据,表明向地下岩体中高压注水可以使其內的有效压力变为零或为负值,并指出在上述压力状态下的岩体的某些特性与常压下时相比,其主要变化是,渗透性明显增强,地表的垂直位移率显著增大和岩体的稳定性明显变差。本文还对这些特性变化的原因进行了讨论。     

海原活动断裂中断层泥的特征、成因及其对断层滑动性能的影响

本文对海原断裂的断层泥的各类特征进行了系统的研究,分析了断层泥带内部的小型断裂类型,探讨了断层泥组分的有机地球化学意义。通过对比,确立了石英碎屑表面机械作用成因的电子显微构造特征组合为活断层的判别标志。本文将石英碎屑表面电子显微溶蚀构造分为五类,据此分析了断层活动时期和状态。研究中还发现了断层泥带内部电子显微结构类型,进而分析了断层活动与微结构、粒度分布间的关系。最后还讨论了断层泥形成演化过程以及断层泥对全新世以来断层滑动性能影响及其与地震活动的关系     

EFFECTS OF WATERSHED MANAGEMENT ON THE REDUCTION OF SEDIMENT AND RUNOFF IN THE JIALING RIVER,CHINA

The Three Gorges Project is one of the largest hydro-projects in the world and has drawn many debates inside China and abroad. The major concern is that sediment load from the river basin may eventually fail the functions of the project for flood control and power generation. To reduce sedimentation in the reservoir, watershed management has been adopted. However, there is limited information regarding the effectiveness of various control measures such as terracing and afforestation on a watershed scale. The Jialing River, a main tributary of the Yangtze River, contributes approximately 25% of the total sediment load in the main river but only represents 8% of the whole basin area. There have been various land use patterns and extensive human activities for thousands of years in the Jialing River watershed. Based on analysis of the major factors affecting erosion in the Jialing River watershed, the main watershed management strategies (afforestation, farming and engineering practice) are illustrated, and their effects on the reduction of sediment and runoff are studied in detail. The sediment budget of the watershed shows that 1/3 of the sediment yield is trapped by the erosion control measures (afforestation and farming) on the slope, 1/3 is trapped by the reservoirs, ponds and dams within the watershed, and only about 1/3 is transported into the Yangtze River, which will affect the Three Gorges Project.     

浅谈地震保险的必要性及其作用

以防震减灾为视角，针对地震灾害对社会发展及人民生活造成的重大损失，从强化地震保险意识的角度，论述地震保险的必要性和重大意义。同时对地震保险在心理、补偿、救灾、缓冲、防灾及附带等方面的作用加以阐述，从而证明要减少地震灾害的损失，充分认识地震保险的必要性及其作用，建立和完善有效的保险机制，对于减轻地震灾害，促进社会发展和人民安居乐业是一项必要的基础性工作。     

前震活动特征及其识别的研究（Ⅰ）

分析了近２０年来中国大陆强震（Ｍ≥７．０）和华北地区中强地震前广义前震序列时间和空间分布的多分形特征，计算其广义分维谱Ｄｑ和标度指数谱Ｆ（α），并探讨了它们随时间的变化．结果表明：（１）对广义前震活动，在所研究地区的时、空分布，均呈现多分形结构；（２）大地震发生前半年至一年，地震活动时、空分布的高次分维Ｄ∞呈下降趋势．这种降维特征，亦在实验室含水大样本岩石破坏前，声发射序列Ｄ∞的变化中观测到；（３）与中强地震相比，大地震孕育区地震活动的空间高次分维偏低，表明地壳应力分布的高度不均匀性，是板内大地震孕育环境中的本质因素之一．     

前震活动特征及其识别的研究（Ⅰ）

分析了近２０年来中国大陆强震（Ｍ≥７．０）和华北地区中强地震前广义前震序列时间和空间分布的多分形特征，计算其广义分维谱Ｄ_ｑ和标度指数谱Ｆ（α），并探讨了它们随时间的变化．结果表明：（１）对广义前震活动，在所研究地区的时、空分布，均呈现多分形结构；（２）大地震发生前半年至一年，地震活动时、空分布的高次分维Ｄ_∞呈下降趋势．这种降维特征，亦在实验室含水大样本岩石破坏前，声发射序列Ｄ_∞的变化中观测到；（３）与中强地震相比，大地震孕育区地震活动的空间高次分维偏低，表明地壳应力分布的高度不均匀性，是板内大地震孕育环境中的本质因素之一．     

腾冲热海温泉群化学特征与形成机理研究

本文系统研究了腾冲热海温泉群１１个泉点的化学组分特征,并据此探讨了温泉群的形成机理,用回归统计法计算了地下冷热水混合方程,根据这些混合方程进一步估算出混合前原始热水的温度和部分相关化学组分的浓度。用Ｒ型群分析法计算出了温泉群各化学组分之间的相关系数,得出了各化学组分的相关谱系图,并据此探讨了温泉化学组分的来源。     

前震活动特征及其识别的研究（Ⅰ）

分析了近２０年来中国大陆强震（Ｍ≥７．０）和华北地区中强地震前广义前震序列时间和空间分布的多分形特征,计算其广义分维谱Ｄｑ和标度指数谱Ｆ（α）,并探讨了它们随时间的变化．结果表明：（１）对广义前震活动,在所研究地区的时、空分布,均呈现多分形结构;（２）大地震发生前半年至一年,地震活动时、空分布的高次分维Ｄ∞呈下降趋势．这种降维特征,亦在实验室含水大样本岩石破坏前,声发射序列Ｄ∞的变化中观测到;（３）与中强地震相比,大地震孕育区地震活动的空间高次分维偏低,表明地壳应力分布的高度不均匀性,是板内大地震孕育环境中的本质因素之一．     

后续地震类型及其特征分析

对中国大陆５．０级以上强震的后续地震进行了分析,按成因将其划分为剩余型、诱导型和后生型３类。讨论了３种后续地震的主要特征及其在大震震源机理研究和地震预报中的意义。