焉耆盆地绿洲区近50年地下水文时空变异及水盐演变   总被引：4，自引：0，他引：4  

王水献  董新光  刘延峰 《地质科技情报》2009,28(5)

以地统计学理论和焉耆盆地绿洲区浅层地下水矿化度不同时期(1960年和2005年)的实测数据为基础,对取得的实测数据进行了半方差函数分析,结果表明:焉耆盆地绿洲区地下水矿化度和埋深在时间和空间上都存在明显的时空变异性.在空间尺度上,地下水矿化度在开都河中下游地区及其两岸灌区有增大的趋势;在时间尺度上,地下水随时间推移向盐化加重方向发展.近50年水盐动态表明焉耆盆地一直处于积盐过程,而绿洲区则处于脱盐过程,盐分都积累在博斯腾湖区,在1982年后转移至孔雀河流域.焉耆盆地地下水盐化态势表明,近年来地下水各项离子质量浓度都在积聚.绿洲区水土资源开发不仅改变了水盐分布,而且也深刻影响了地下水水体.  相似文献   

Relationship between the variation of water quality in rivers and the characteristics of watershed at Miyun,Beijing, China     

Xiaoyan Wang  Yang Ou  Peiqian Dou  Xiaoduo Fang 《中国地球化学学报》2009,28(1):112-118

Based on the characteristics of land use and drainage network of the upper watershed of the Miyun Res-ervoir, Beijing, 26 monitoring and sampling sites were selected in different sub-catchments. Temporal and spatial variations in nutrient loss were dealt with in this paper in terms of the monitoring data on the water quality of the main tributaries flowing into the Miyun Reservoir. In combination with the monitoring data on water quality, the impacts of watershed characteristics including land-use type, landscape pattern, and drainage density were assessed, The concentrations of nutrients in the rainy season are higher than those in other seasons, and the concentrations of NO3--N are linearly related to those of total N which is the main form of nitrogen present in the fiver water. The concentrations of nitrogen become higher toward the reservoir along the main rivers. The seasonal variation of ni-trogen in the watershed affected by intensive human activities is very obvious; in the watershed with steady or low water flow, the seasonal variation of nitrogen is less obvious. Forest land and grassland can trap and filter nitrogen effectively. Land-use pattern also has important impacts on the loss of nitrogen. The concentrations of nitrogen and phosphorus in the water bodies show great temporal and spatial variations. On a temporal scale, the concentrations of TN and TP in the rainy reason are higher than those in other seasons. On a spatial scale, the concentrations of TN and NO3--N in the Qingshui River and Chaohe River are highest all the time. The spatial variation of TP is distinct, being obvious at sampling sites near villages. The form of nitrogen and phosphorus loss varies in different hydrological seasons. Dissolved nitrogen and phosphorus are the main forms in streams in non-rainy seasons, the dissolved nitro-gen and total nitrogen decrease in percentage in the rainy season. Particulate nitrogen and phosphorus are the main forms in some rivers. The concentrations of TN and NO3--N from orchards and villages are high whereas those from forest land are lowest. Land-use pattern has impacts on TN and NO3--N losses, at the sampling sites near the source landscape, the concentrations are higher than those at the sampling sites near the sink landscape. Water quality of the rivers which flow into the Miyuan Reservior is influenced by the composition of adjacent soils.  相似文献   

Seasonal diet of black-backed jackal in the Eastern Karoo,South Africa     

《Journal of Arid Environments》2013

The ability of small canids to consume a variety of resources in an opportunistic manner has been cited as a reason for their wide distribution across many habitats. Black-backed jackals Canis mesomelas have varied diets that reflect changes in food availability as a result of seasonal fluctuations in resources. Seasonal fluctuations can include variations in food type availability, as well as variations in the phenology of food resources (i.e. ungulate birth peaks). Additionally, the presence of apex predators can affect opportunistic predator diets through the provision of carrion. We investigated the diet of black-backed jackals on a reserve in the semi-arid Karoo, South Africa. Ungulates (>5 kg) were the dominant prey item across all seasons, reflecting either active predation or scavenging. Most seasonal comparisons in percent occurrence of prey groups revealed significant seasonal fluctuations in black-backed jackal diet. However, in terms of biomass consumed, the diet remained stable, dominated by small ungulates across all seasons with no clear seasonal change in ungulate composition. These results suggest that in this study black-backed jackals, although being opportunistic in terms of diet composition, had a seasonally stable food resource, most likely facilitated by the presence of cheetahs Acinonyx jubatus providing scavenging opportunities.  相似文献   

准噶尔盆地南缘荒漠区梭梭维持水源初步研究   总被引：2，自引：0，他引：2  

吕金岭  张希明  吕朝燕  刘国军 《中国沙漠》2013,33(1):110-117

为了了解沙漠植物梭梭维持水源的利用情况,探明其对水源的利用策略,利用稳定性同位素技术定位取样,对准噶尔盆地南缘荒漠区梭梭进行了研究.结果表明,冬季,梭梭基本没有直接利用降雪;随着融雪后浅层土壤含水率的上升,梭梭明显利用浅层土壤水;梭梭利用水源中,地下水占有很大比例,这种比例在冬季和夏季最高,最高幅度可达到80％,平均占到30％左右;降雨也是梭梭利用的水源之一,在降雨后的3～5 d内,梭梭木质部δ18O值有明显趋近降雨δ18O值的趋势.因此,本研究区的梭梭维持水源有多个途径,地下水、融雪形成的浅层土壤水是其主要水源,中、大量降雨也是其利用的水源之一.  相似文献   

甘肃河东地区近30年季节极端气温指数变化与环流影响     

黄浩  张勃  马尚谦  黄涛  马彬  崔艳强  王晓丹 《高原气象》2021,40(1):133-144

基于1988-2017年61个气象站点逐日气温数据,分析了甘肃河东地区近30年各季节极端气温指数的时空变化特征,并分析了ENSO和AO对河东地区极端气温指数的影响。结果表明:近30年河东地区处于变暖态势中,各季节气温日较差(DTR)、暖夜日数(TN90p)、暖昼日数(TX90p)均呈增加趋势,冷夜日数(TN10p)、冷昼日数(TX10p)均呈减少趋势。甘南高原极端气温指数在各区中变化最显著,春季是各极端指数变化最显著的季节,也是河东地区DTR变化趋势不同于全国的影响因素。DTR于1992年突变后增加,平均气温于1996-1997年发生突变,其余极端气温指数于1997年突变,极端气温指数在其自身以及平均气温突变年份前后的变化反映了区域变暖的态势。El Ni?o影响河东地区冬季DTR的增加,La Ni?a影响冬季TX10p日数增加,AO正相位时河东地区夏季高温事件更易发生。  相似文献   

基于CRU资料的山西百年气温时空演变特征     

杜泽玉  曹富强  杨荣 《高原气象》2021,40(1):123-132

全球变暖的背景下,百年尺度上的区域气温变化规律,近年来已成为气候变化研究的热点。本文基于1901-2016年英国东英吉利(East Anglia)大学气候研究中心(Climatic Research Unit,CRU)提供的高分辨率、逐月气温数据集,采用一元线性回归法、滑动平均法和Mann-Kendall突变检验法分析了116年来山西气温的时空分布特征。结果表明:百年来山西年平均气温和各季节气温均呈波动上升趋势,年均和各季节气温倾向率分别为0.13℃·(10a)-1(年平均)、0.16℃·(10a)-1(春季)、0.05℃·(10a)-1(夏季)、0.09℃·(10a)-1(秋季)、0.22℃·(10a)-1(冬季),其中冬季气温增幅最大,对年均温增长的贡献最大,贡献率为42.31%,夏季气温增幅最小,贡献率也最小(9.62%)。研究时段内,山西各季节气温均发生突变,春季季均温突变开始于1993年,夏季在1917年和1996年都发生了气温突变,秋季、冬季出现突变的年份分别为2001年、1984年。空间上,山西多年平均气温和季均温均以南高北低的纬度变化规律为主,同时受到地形的影响,分别形成不同气温中心,其中冬季受地形影响最小,尤其是最冷月。  相似文献   

2007～2010年云南GPS观测大气可降水量特征分析   总被引：2，自引：0，他引：2  

海云莎  孙绩华  陈新梅 《云南地理环境研究》2011,23(2):78-84

利用最新云南地基GPS站观测和探空观测资料分析表明:GPS/PWV和探空大气可降水量变化趋势一致,相关性好;云南省GPS/PWV年内干湿季气候特征分明,湿季开始前GPS/PWV月变率小于干季开始前的月变率;全省GPS/PWV年平均日变化峰值和谷值出现时间一致,勐腊、蒙自和昆明具有准双峰型特征;勐腊站干季、湿季日变化明显不同,其余测站干季和湿季的PWV日变化特征与全年平均日变化特征基本一致。GPS/PWV资料能够反应云南雨季开始期时空演变趋势。  相似文献   

华北时变重力场离散小波多尺度分解   总被引：3，自引：2，他引：1  

刘芳  祝意青  陈石 《中国地震》2013,29(1):124-131

利用华北地区地震重力监测网的绝对重力与相对重力多期重复观测资料,处理获取不同时空尺度的华北区域重力场动态变化图像.利用二维小波分解技术,将不同场源深度异常进行了分离,并对不同时空尺度的重力变化给出了解释,提高了对华北地区重力场变化趋势的认识水平.在此基础上,通过对小波细节的功率谱分析,可以获得各阶小波变换逼近及小波细节分析图所对应的场源深度.研究结果表明,不同时空尺度的重力场变化对于深入认识华北地区潜在地震危险性具有一定的科学意义.  相似文献   

关中地区3次中小地震前后的重力变化   总被引：1，自引：1，他引：0  

高好林 《中国地震》2013,29(3):367-376

采用拟稳平差方法对关中地区近20 年流动重力观测资料重新进行了处理,并结合其它观测资料和研究结果,对区域内重力场变化过程、3次中小地震前后重力场变化机理、构造活动以及区内外地震间的关系等进行了较深入地分析和研究。  相似文献   

Application of Fourier series in managing the seasonality of convective and monsoon rainfall     

Abas Norzaida  Mohd Daud Zalina  Yusof Fadhilah 《水文科学杂志》2013,58(10):1967-1980

ABSTRACT

This study assesses the performance of Fourier series in representing seasonal variations of the tropical rainfall process in Malaysia. Fourier series are incorporated into a spatial-temporal stochastic model in an attempt to make the model parsimonious and, at the same time, capture the annual variation of rainfall distribution. In view of Malaysia’s main rainfall regime, the model is individually fitted for two regions with distinctive rainfall profiles: one being an urban area receiving rainfall from convective activities whilst the other receives rainfall from monsoonal activities. Since both regions are susceptible to floods, the study focuses on the rainfall process at fine resolution. Fourier series equations are developed to represent the model’s parameters to describe their annual periodicity. The number of significant harmonics for each parameter is determined by inspecting the cumulative fraction of total variance explained by the significant harmonics. Results reveal that the number of significant harmonics assigned for the parameters is slightly higher in the region with monsoonal rains. The overall simulation results show that the proposed model is capable of generating tropical rainfall series from convective and monsoonal activities.