Short‐term spatial and temporal patterns of suspended sediment transfer in proglacial channels,small River Glacier,Canada     

John F. Orwin  C. C. Smart 《水文研究》2004,18(9):1521-1542

Alpine glacial basins are a significant source and storage area for sediment exposed by glacial retreat. Recent research has indicated that short‐term storage and release of sediment in proglacial channels may control the pattern of suspended sediment transfer from these basins. Custom‐built continuously recording turbidimeters installed on a network of nine gauging sites were used to characterize spatial and temporal variability in suspended sediment transfer patterns for the entire proglacial area at Small River Glacier, British Columbia, Canada. Discharge and suspended sediment concentration were measured at 5 min intervals over the ablation season of 2000. Differences in suspended sediment transfer patterns were then extracted using multivariate statistics (principal component and cluster analysis). Results showed that each gauging station was dominated c. 80% of days by diurnal sediment transfer patterns and ‘low’ suspended sediment concentrations. ‘Irregular’ transfer patterns were generally associated with ‘high’ sediment concentrations during snowmelt and rainfall events, resulting in the transfer of up to 70% of the total seasonal suspended sediment load at some gauging stations. Suspended sediment enrichment of up to 600% from channel storage release and extrachannel inputs occurred between the glacial front and distal proglacial boundary. However, these patterns differed significantly between gauging stations as determined by the location of the gauging station within the catchment and meteorological conditions. Overall, the proglacial area was the source for up to 80% of the total suspended sediment yield transferred from the Small River Glacier basin. These results confirmed that sediment stored and released in the proglacial area, in particular from proglacial channels, was controlling suspended sediment transfer patterns. To characterize this control accurately requires multiple gauging stations with high frequency monitoring of suspended sediment concentration. Accurate characterization of this proglacial control on suspended sediment transfer may therefore aid interpretation of suspended sediment yield patterns from glacierized basins. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

黄河三角洲农牧业生产潜力   总被引：6，自引：0，他引：6  

许学工 《地理学报》1991,(2)

本文从对黄河三角洲的宜农地和宜牧地的分析入手,对该区农作物生产潜力、牧草及载畜量潜力进行了探讨。并针对目前农牧业生产水平和存在的问题,提出了相应的对策。  相似文献   

QUANTITATIVE MODELING OF SUSPENDED SEDIMENT IN MIDDLE CHANGJIANG RIVER FROM MODIS     

LIU Can-de HE Bao-yin LI Mao-tian REN Xian-you 《中国地理科学(英文版)》2006,16(1):79-82

1INTRODUCTIONThe quality of water is traditionally determined by col-lectingwatersamplesandanalyzingthesamplesin a lab-oratory. However, sampling is very much hard sledding,time-consuming, slow and expensive, and easily in thecontrol of weather conditions, and does not include allwater areas. Satellite estimates of water quality havefound widespread application. Remote sensing instru-ments have been applied in water quality monitoringwith varying success (DANA and RICHARD, 1999;RUDD…  相似文献   

Interannual and seasonal variation of the Huanghe (Yellow River) water discharge over the past 50 years: Connections to impacts from ENSO events and dams   总被引：4，自引：2，他引：2  

Houjie Wang  Zuosheng Yang  Yoshiki Saito  J. Paul Liu  Xiaoxia Sun   《Global and Planetary Change》2006,50(3-4):212-225

The Huanghe, the second largest river in China, is now under great pressure as a water resource. Using datasets of river water discharge, water consumption and regional precipitation for the past 50 years, we elucidate some connections between decreasing water discharges, global El Niño/Southern Oscillation (ENSO) events and anthropogenic impacts in the drainage basin. Global ENSO events, which directly affected the regional precipitation in the river basin, resulted in approximately 51% decrease in river water discharge to the sea. The degree of anthropogenic impacts on river water discharge is now as great as that of natural influences, accelerating the water losses in the hydrological cycle. The large dams and reservoirs regulated the water discharge and reduced the peak flows by storing the water in the flood season and releasing it in the dry season as needed for agricultural irrigation. Thus, as a result, large dams and reservoirs have shifted the seasonal distribution patterns of water discharge and water consumption and finally resulted in rapidly increasing water consumption. Meanwhile, the annual distribution pattern of water consumption also changed under the regulation of dams and reservoirs, indicating that the people living in the river basin consume the water more and more to suit actual agricultural schedule rather than depending upon natural pattern of annual precipitation. The combination of the increasing water consumption facilitated by the dams and reservoirs and the decreasing precipitation closely associated with the global ENSO events over the past half century has resulted in water scarcity in this world-famous river, as well as in a number of subsequent serious results for the river, delta and coastal ocean.  相似文献   

Hydrogeologic controls on summer stream temperatures in the McKenzie River basin,Oregon     

Christina Tague  Michael Farrell  Gordon Grant  Sarah Lewis  Serge Rey 《水文研究》2007,21(24):3288-3300

Stream temperature is a complex function of energy inputs including solar radiation and latent and sensible heat transfer. In streams where groundwater inputs are significant, energy input through advection can also be an important control on stream temperature. For an individual stream reach, models of stream temperature can take advantage of direct measurement or estimation of these energy inputs for a given river channel environment. Understanding spatial patterns of stream temperature at a landscape scale requires predicting how this environment varies through space, and under different atmospheric conditions. At the landscape scale, air temperature is often used as a surrogate for the dominant controls on stream temperature. In this study we show that, in regions where groundwater inputs are key controls and the degree of groundwater input varies in space, air temperature alone is unlikely to explain within-landscape stream temperature patterns. We illustrate how a geologic template can offer insight into landscape-scale patterns of stream temperature and its predictability from air temperature relationships. We focus on variation in stream temperature within headwater streams within the McKenzie River basin in western Oregon. In this region, as in other areas of the Pacific Northwest, fish sensitivity to summer stream temperatures continues to be a pressing environmental issue. We show that, within the McKenzie, streams which are sourced from deeper groundwater reservoirs versus shallow subsurface flow systems have distinct summer temperature regimes. Groundwater streams are colder, less variable and less sensitive to air temperature variation. We use these results from the western Oregon Cascade hydroclimatic regime to illustrate a conceptual framework for developing regional-scale indicators of stream temperature variation that considers the underlying geologic controls on spatial variation, and the relative roles played by energy and water inputs. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Reduced rates of primary production in the Columbia River Estuary following the eruption of Mt Saint Helens on 18 May 1980     

Bruce E. Frey  J.Rubén Lara-Lara  Lawrence F. Small 《Estuarine, Coastal and Shelf Science》1983,17(2):213-218

The eruption of Mt Saint Helens on 18 May 1980 resulted in a massive increase in suspended particulate material in the Columbia River Estuary, producing a substantial increase in light attenuation. Since photosynthesis in the estuarine water column is partly controlled by the depth of light penetration in the water, photosynthesis was reduced by about 75% during the period of increased turbidity. It took about five weeks for the estuary to clear. Although primary production within the estuarine water column was greatly diminished during this period, the flux of particulate carbon through the estuary was high, and the total production we estimate to have been lost amounted to only about 2% of the total particulate carbon flux just after the eruption. That the high levels of turbidity in the estuary did not induce a severe fall in the phytoplankton population is evidence that phytoplankton biomass concentrations in the Columbia River Estuary are mostly a function of import from the Columbia River, rather than a function of in situ production.  相似文献   

The spatial division of industries of the pearl river delta in the 1990s: Characteristics and trends     

Yong-jian Xu  Xiao-pei Yan  Xue-qiang Xu 《中国地理科学(英文版)》2001,11(1):63-69

The article analyzed the spatial division of industries of the Pearl River Delta (PRD) in the 1990s, a period that witnessed the deepening of the reform and opening policies and continued rapid development of the region. By adopting the index of specialization, the extent of specialization, its change and its spatial distribution in the region are measured and demonstrated. The research revealed that, despite the trend of more balanced development of the secondary sector between the PRD and the rest of the province, in the PRD, it is the unbalanced development that dominated and the spatial division of the secondary sector has been shaped. The tertiary industry has also been experiencing unbalance development and the spatial division of the tertiary sector has been emerging, its extent of concentration appearing even more evident than that of the secondary sector. The author also discussed the linkage between the spatial division of the two sectors. In the end of the paper, the trends of the spatial division of the industries in the PRD are forecasted. Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 49831030). Biography: XU Yong-jian (1972 – ), female, a native of Changsha City, Ph. D.. Her research interest includes urban geography.  相似文献   

PROBLEMS　OF　THE　AQUATIC　ENVIRONMENT　AND　COUNTERMEASURES　IN　RAPID　ECONOMIC　DEVELOPMENT　IN　THE　ZHUJIANG　RIVER　DELTA     

温琰茂  程国佩 《中国地理科学(英文版)》1995,(1)

ＰＲＯＢＬＥＭＳＯＦＴＨＥＡＱＵＡＴＩＣＥＮＶＩＲＯＮＭＥＮＴＡＮＤＣＯＵＮＴＥＲＭＥＡＳＵＲＥＳＩＮＲＡＰＩＤＥＣＯＮＯＭＩＣＤＥＶＥＬＯＰＭＥＮＴＩＮＴＨＥＺＨＵＪＩＡＮＧＲＩＶＥＲＤＥＬＴＡ￥ＷｅｎＹａｎｍａｏ（温琰茂）；ＣｈｅｎｇＧｕｏｐｅｉ...  相似文献   

长江上游防护林体系建设要点     

钟祥浩  程根伟  杨定国  陶和平 《山地学报》1991,(2)

本区防护林体系的建设目标是:改善生态环境,发展山区经济。人口稠密区防护林体系建设成败的关健在于:能否掌握生态生产双重功能,是否具有生态社会经济三大效益。为此进行了防护林体系分类,提出了林种的生态功能指标和生产功能指标。防护林体系的生态经济分区要研究生态经济系绽的地域差异,有助于发挥各个林种的生态生产双重功能,是建设防护林体系的重要途径,为合理布局提供科学依据。  相似文献   

THE DISCOVERED DEEP BURIED LAKE ICE IN SOURCE REGION OF THE HUANGHE RIVER     

王绍令  李位乾 《中国地理科学(英文版)》1993,3(3):247-254

The 4.45 m-thick pure ice lens have been discovered firstly at depth from 19.81 -24.26 m in the bore No.6, which locates in north bank of the Ngoring Lake. In source region of the Huanghe (Yellow) River, 14C dating, X -ray diffraction, pollen analysis, micropalaeontology, chemical components, environmental isotope 2H, 3H, 18O and freezing point of the ice and water samples from the bore have been tested and microorganism in the ice have been also appraised with microscope. Combined with the research on geomorphy and Quaternary around the lake, the ice lens are determined as a kind of deep-buried lake ice, formed in 35,030-45,209 yr.B.P., and annual mean air temperature was about -10℃ during that time.  相似文献