Analysis of Winter and Summer Glacier Mass Balances

Seasonal mass balance components b_w (winter balance) and b_s (summer balance) as well as c_t (total accumulation) and a_t (total ablation), can be used directly to infer climate variables. In contrast, a_c (net balance of the accumulation area) and a_a (net balance of the ablation area), and b_a or b_n (annual or net balance) can not. The traditional Alpine system of observations of a_c and a_a , however, can be converted to true seasonal values b_w and b_s if both pairs of components are simultaneously observed for some years, because a correlation between the two pairs of components exists. We analyzed b_w and b_s data and their mean, standard deviations and ratios of these to the corresponding net or annual balances for 50 glaciers with relatively long records representing different regions in the northern hemisphere. We also investigated correlations between seasonal components. A negative correlation between b_w and b_s exists at many glaciers. About two-thirds of the glaciers show insignificant correlations (?0.3 < r < 0.3), implying independence of summer and winter balances. In a few unusual cases the correlations are positive. These different correlations, or lack thereof, may offer insight into feedback conditions that must exist in this climate-related system. The correspondence of the b_w and c_t , and b_s and a_t , appears to depend largely on the relative amounts of summer snowfall, a function of their climatic environment expressed as [α = (b_w+b_s)/2]. The contribution of variability of b_s to the net balance increases markedly with decreasing values of α. The variability of b_w and b_s , and therefore the net balance, has been increasing with time; whether this is due to an increase in climate variability or to other causes is not clear. It appears that b_w has been increasing with time at the highest altitudes, but b_s has been increasing more rapidly especially at low altitudes; the many-glacier average net balance is becoming more negative.     

Spatial Variability of Mass Movements in the Satluj Valley,Himachal Pradesh during 1990～2006

Satluj Valley is known to have a history of landslides and related mass movement activities since the geological times. Geological and geomorphological settings combined with anthropogenic activities constitute a propensity towards slope failure. During the last two decades,the area witnessed substantial increase in athropogenic pressure,mainly due to the exploitation of hydropower potential,changing landuse pattern and population growth. In addition,a shift of the climatic patterns in the form of larger area falling under the influence of rains was observed. These natural as well as anthropogenic changes in the area have resulted in increased spatial coverage of landslide in the area. This paper documents these changes during 1990～2006.     

1975年8月河南省特大暴雨雨强极值的重新估算

通过对云中气载液态水含量以及水汽和气载液态水之间的平衡方程的讨论,建立了改进的可降水量Ia公式。按照改进的公式,重新估算了1975年8月河南省特大暴雨7日20时雨强。结果表明,分别以遂平气象站记录的8 m/s和按物象估算的12 m/s地面风速为基础的改进的板桥水库附近8月7日20时雨强估算值Iae1=75.0 mm/h和Iae1=95.8 mm/h很接近实际的雨强极值Ioe=99.7 mm/h。     

太湖生态环境演化及其原因分析

太湖地处长江下游三角洲,水域面积为2338km²,平均水深1.9m,最大水深不足2.6m,为一典型的大型浅水湖泊。太湖流域地势平坦,河网密布,河湖水力关系复杂。其主要补给径流来自西南部的天目山区及西部的宜溧河流域。每年夏天,大部分入湖洪水通过位于东太湖的太浦河及东北部的望虞河分别排入黄浦江与长江,由于出入湖河道的特殊位置,使得太湖南部的换水周期较短而北部较长。近几十年来,太湖由于污染而逐步呈现富营养化特征,污染物主要来自北部的无锡市和常州市,通过河道排入太湖北部的五里湖与梅梁湾,因此上述两地的水质较南部差。在东太湖,水产养殖对水环境的影响很大,亦呈现出富营养化特征,并殃及该地区的供水,加之该地区为太湖主要的泄洪通道,因此泥沙淤积严重,而且水生植物生长旺盛,呈现出明显的沼泽化趋势;在太湖四周地区,由于湖泊围垦和水利工程建设,其污染净化能力将降低,从而加速水环境恶化的趋势。太湖所面临这些问题,有待于强化湖泊科学管理来解决。     

水资源优化配置的研究与展望

目前全国水资源优化配置的研究依然停留在借鉴和摸索阶段,对水资源优化配置的主要任务、遵循的原则、配置方案以及未来的发展方向进行了探讨.     

北半球50条山地冰川近期的物质平衡状况

近期北半球大多数山地冰川的物质平衡为负,冰川普遍退缩,表明北半球气候暖化的趋势.由于区域气候波动和变化的差异性以及冰川对气候变化的敏感性(响应程度)的不同,北半球山地冰川在普遍退缩的背景下具有鲜明的区域特征.     

A laboratory study on groundwater quality and mass movement occurrence

In this study, soil samples collected from the sides of two streams with high debris flow potential at Shenmu and Fengchiou village in Nantou County, Taiwan, were used for seepage tank tests in the laboratory. While the tests were being conducted, observations were made to investigate the relationships among displacement of the slope, quality of the seepage water and occurrence of mass movement. The results showed that according to the change rate, displacement could be divided into two stages, namely, the initial failure displacement stage and primary failure displacement stage. While the displacement of the slope was in primary failure displacement stages, the probability of slope failure became much higher. Before general slope failure, electrical conductivity (EC) and sulfate ion (SO₄ ²⁻) concentration of the seepage water increased significantly. The time when EC of the seepage water started to increase rapidly was much earlier than that when displacement of the slope started to increase significantly. Therefore, from the hazard mitigation view, there will be a longer time for response if EC of the seepage water was monitored.     

Will the river Irtysh survive the year 2030? Impact of long-term unsuitable land use and water management of the upper stretch of the river catchment (North Kazakhstan)

The Irtysh river basin all the way from river spring in China across Kazakhstan as far as the Russian part of Siberia is among the most ecologically endangered and affected regions on our planet. The study provides a summary of the historical reasons for anthropological interventions in this area, which began with the construction of plants of the military—industrial complexes in the forties of the last century during World War II. These plants have a major share in extreme high concentrations of heavy metals in surface as well in groundwaters locally. The Semipalatinsk nuclear polygon plays a specific role as a source of contamination of local waters. The release of top secret data enabled us to gain knowledge about serious problems related to high radioactivity of groundwaters, which should spread uncontrollably through a system of secondary fissures activated by nuclear blasts. Another serious problem in this region is the quantitative aspect of contamination. Model simulations of water balance indicate that large industrial development in the spring area in China and continuously increasing water consumption in Kazakhstan may lead to desiccation of the lower stretch of this large river in Siberia during the summer months of 2030.     

元素分析仪-同位素比值质谱测量碳氮同位素比值最佳反应温度和进样量的确定

沉积有机质的碳氮稳定同位素值是进行古气候、古环境及生态系统研究不可或缺的主要研究手段,目前碳氮同位素主要利用元素分析仪-同位素比值质谱(EA-IRMS)系统来测定。EA-IRMS测定过程中的反应温度及样品进样量直接影响反应物在测试中的燃烧程度,从而影响测试数据的精度。本文利用EA-IRMS技术,以标准样品为参考,在不同转化温度下测试碳氮同位素值,研究保证测试精度的最佳反应温度条件;同时,通过分析不同含氮量样品的检测限,明确了样品含氮量与最低检测限之间的关系,确定了精确测定氮同位素值的最低进样量。结果表明:反应温度对测试精度有显著影响,在碳同位素测定时,将反应温度设定为900℃或以上时测试精度均能达到±0.2‰;氮同位素测定时,反应温度须设定为950℃时测试精度才能达到±0.3‰。实验得出样品含氮量与检测限之间的线性相关性为R2=0.873,开展氮同位素测定时可根据此关系来判断和控制进样量。     

欠平衡钻井技术在煤层气勘探开发中的应用

分析了当前国内外开发利用煤层气的现状；指出中国煤层气气藏具有低压低渗、难脱附、驱动力不足和构造煤发育等重要特殊性，这种特殊性使常规煤层气开发技术有很大的局限性；提出了适合低压低煤层气藏特点的开发技术系列，包括欠平衡钻井与洞穴完井技术和欠平衡钻多分支水平井与洞穴技术。