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1.
Precipitation cycles in the middle and lower reaches of the Yellow River (1736-2000) 总被引:2,自引:1,他引:1
Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736-2000 reconstructed from the rainfall and snowfall archives of the Qing Dynasty, the precipitation cycles are analyzed by wavelet analysis and the possible climate forcings, which drive the precipitation changes, are explored. The results show that: the precipitation in the middle and lower reaches of the Yellow River has inter-annual and inter-decadal oscillations like 2-4a, quasi-22a and 70-80a. The 2-4a cycle is linked with El Nino events, and the precipitation is lower than normal year in the occurrence of the El Nino year or the next year; for the quasi-22a and the 70-80a cycles, Wolf Sun Spot Numbers and Pacific Decadal Oscillation (PDO) coincide with the two cycle signals. However, on a 70-80a time scale, the coincidence between solar activity and precipitation is identified before 1830, and strong (weak) solar activity is generally correlated to the dry (wet) periods; after 1830, the solar activity changes to 80-100a quasi-century long oscillation, and the adjusting action to the precipitation is becoming weaker and weaker; the coincidence between PDO and precipitation is shown in the whole time series. Moreover, in recent 100 years, PDO is becoming a pace-maker of the precipitation on the 70-80a time scale. 相似文献
2.
1IntroductionThe river deltas are generally those areas with a wealth of natural resources, and lots of ports, moreover they are important locations of human activity. Therefore, deltaic areas around the world, such as the Mississippi River delta, the Nile River delta, and the Yangtze River delta, have attracted the attentions of governments, scientists and common people. There are three big deltas in China, i.e., the Yangtze River, the Zhujiang River and the Yellow River deltas. The for… 相似文献
3.
Runoff of the upper Yellow River above Tangnag: characteristics, evolution and changing trends 总被引:2,自引:0,他引:2
1 IntroductionThe basin above Tangnag is the principal area for runoff formation in the upper reaches of the Yellow River. For example, the runoff from the Tangnag Station occupies 95% of the inflow into the Longyangxia Reservoir, the largest reservoir on the upper Yellow River. So variations on runoff in the upper Yellow River above Tangnag have been very important for the utilization of the water resources in the entire Yellow River Basin. However, the runoff in the upper Yellow River… 相似文献
4.
Climate change and human activities have profoundly altered ecosystem services in the Yellow River Basin(YRB) since the Grain for Green project was implemented, but have not been accurately revealed on a year-by-year scale. This study combined the InVEST model to reveal the year-by-year changes in the water-related ecosystem services(WRESs)in YRB during 1990–2020, including water yield, soil conservation and water purification services. The trade-off/synergy of WRESs and impacts of land manageme... 相似文献
5.
During the first Chinese Scientific Expedition to the Arctic in July - September 1999, cyanobacteria in the Bering Sea were measured by epifluorescence microscopy. Cyanobacterial abundance varied from 0 to 7. 93 × 103 cell/ml and decreased along a northerly directed latitudinal gradient in horizontal distribution. Cyanobacteria did not occur at station Bl - 12 (north of 60 °N). Vertically, high cya-nobacterial abundance appeared in the upper 25 - 50 m and decreased rapidly below 50 m. There were no cyanobacteria at the 150 m. Seawater temperature and NH4+ -N are suggested to affect the distribution of cyanobacteria. 相似文献
6.
Zanying Sun Wanzhan Wang Yong Li Mingwu Zhang Hongxia Shang Fangxiu Zhang 《地理学报(英文版)》2016,26(9):1337-1348
This study considered whether the narrowing of the upper (broad and wandering) reaches of the Lower Yellow River could result in a reduction in sedimentation and even an increase in channel erosion in both the upper and the lower (narrow and meandering) reaches. Analysis of field data and numerical modeling results both justify the proposal to narrow the channel. A positive correlation was found between channel eroded-area and the channel width. Therefore narrowing under conditions of low flow will reduce the amount of erosion in the reach, which, in turn, will reduce the amount of sediment transported into the lower channel. This will reduce the amount of siltation in the lower reaches of the river. However, narrowing under conditions of high flow with a low concentration of sediment will reduce both the extent of flood attenuation along the narrowed channel and the amount of lateral channel bank collapse, which results in increased flows and less sedimentation in the lower channel, leading to increased erosion. When flows with a high concentration of sediment are released from the Xiaolangdi Reservoir, both the lower narrow channel and the upper channel can transport a large amount of the sediment load. It is concluded that the narrowing of the upper broad channel will result in a reduction in sedimentation, or even in channel erosion, in both the upper and the lower channels if the reservoir is operated such that the volume of sediment added during low flows is balanced by the volume eroded during high flows with a low concentration of sediment. 相似文献
7.
IntroductionFlood disasters have been serious since the ancient bines. AJthough we have Strengthened the harnessingofbig rivers since the founding of new Chin4 the threat still edeStS (see FigUre l). The Yellow myer hasbeen well known for its flood disasters since long time %o in China. There more than 1500 river burstShappened to the Yellow hiver in the paSt 2000 or 3000 years. Whereas floods of the Changjiang caverwere comparatively not serious in history, but its flood disasters have … 相似文献
8.
Siyuan Wang Bing Zhang Cunjian Yang Yan Zhao Hui Wang 《International journal of geographical information science》2013,27(3):519-539
Rapid landscape pattern change has taken place in many arid and semi-arid regions of China such as Yellow River Basin over the past decade. In this article, the physical suitability of cropland and its change were evaluated and analyzed by the combined use of satellite remote sensing, geographical information system, and landscape modeling technologies. The aim was to improve our understanding of cropland change so that sustainable cropland utilization could be established. First, the spatial pattern change of cropland was analyzed using the 1-km2 area percentage model; second, the numerical model for cropland suitability assessment was explored and developed using analytical hierarchy process analysis method. Using this model, cropland suitability index was computed for the whole of the basin from 1990 to 2005. The cropland suitability index was classified into five levels: better, good, middle, bad, and worse, following the natural breaks classification. The spatial distribution of cropland suitability level and its changes over the 15 years from 1990 to 2005 were analyzed and the driving factors of cropland change were investigated. The results showed that the cropland suitability in the study area was at good level, and the cropland quality had been gradually improved on the whole. However, the cropland quality had become worse over the 15 years in some regions. In the study area, governmental policies for eco-environmental protection and population growth were found to be the major factors that caused the cropland change over the past 15 years. 相似文献
9.
High-quality industrial development (HID) is a requirement of the modern economy and regional development. This paper designed a four-dimensional HID evaluation framework according to the logic of “development foundation-development theme-development subject-development guarantee.” Specifically, momentum cultivation as the foundation, efficiency improvement as the theme, and quality promotion as the subject are the three pivots driving the industrial transformation from high-speed development to high-quality development. A stable economic environment and a harmonious social environment are the guarantees of HID. Choosing the π-shaped Curve Area of the Yellow River basin in China as the study area, this paper measured the spatiotemporal pattern of HID and its four dimensions using the entropy-weighted TOPSIS method based on relevant economic indicators. Besides, the obstacle recognition model was adopted to identify the obstacles to HID. Findings include: From 2005 to 2019, the HID in the Curve Area was characterized by spatial unevenness and relative stability. The industrial structure and industrial layout were more rational in provincial capitals and large cities than in other cities. The spatial organization of the industrial economy presented an incompact polycentric structure, and the industrial association was relatively weak in the curve’s upper reaches. Almost all cities have experienced an increase in single-factor productivity, and technological progress contributed most to the total factor productivity growth. During the study period, the development momentum stabilized at high levels in Inner Mongolia while at low levels in resource-based cities. The development environment in most cities has remained stable, and the social welfare has increased and distributed more equitably in the Area. The technological introduction and the rationalization of the industrial structure were the primary obstacle factors for the Area in realizing HID, and the upgrading of the industrial location index was critical to the upper reaches of the curve. This paper was expected to provide new ideas for studying industrial transformation and practical policy proposals for regional development in the Curve Area. 相似文献
10.
1 Introduction Driven by interactions of climate change, policy introduction, population pressure and overstocking, many fragile ecotones on the Tibetan Plateau have undergone fast land cover changes, such as deforestation, meadow degeneration or even des… 相似文献
11.
Maintenance of steady streamflow is a critical attribute of the continental river systems for safeguarding downstream ecosystems and agricultural production.Global climate change imposes a potential risk to water supply from the headwater by changing the magnitude and frequency of precipitation and evapotranspiration in the region.To determine if and to what extent the recent climate changes affected streamflow in major river systems,we examined the pattern of temporal variations in precipitation,temperature,evapotranspiration and changes in runoff discharge during 1958–2017 in the headwater region of the Yellow River in northeastern Tibetan Plateau.We identified 1989 as the turning point for a statistically significant 14% reduction in streamflow discharge(P 0.05) for the period 1989–2017 compared with 1958–1988,approximately coinciding with changes in the monthly distribution but not the interannual variations of precipitation,and detected a mismatch between precipitation and runoff after 2000.Both annual precipitation and runoff discharge displayed fourand eight-year cyclic patterns of changes for the period 1958–1988,and a six-year cyclic pattern of changes for the period 1989–2017,with two intensified two-year cyclic patterns in the changes of precipitation and a three-year cyclic pattern in the change of runoff further detected for the later period.Our results indicate that the temporal changes in runoff are not strictly consistent with the temporal variations of precipitation in the headwater region of Yellow River during the period 1958–2017.In particular,a full recovery in annual precipitation was not reflected in a full recovery in runoff toward the end of the study period.While a review of literature yielded no apparent evidence of raised evapotranspiration in the region due to recent warming,we draw attention to increased local retention of rainwater as a possible explanation of differential changes in precipitation and runoff. 相似文献
12.
Under the integrated influences of global climate changes and overgrazing, China rangeland has degraded over recent years. Maduo County locates in the Source Region of Yellow River and its rangeland has experienced expansive degradation. The government of Qinghai Province launched an eco- immigration policy in 2004. In order to analyze the responses of herd families to the eco- immigration and the reasons for these responses, the authors used three periods MSS and TM images for recent 25 years and interview survey data of 144 herd families in recent two years, getting the following results: (1) the rangeland had degraded extensively for recent 28 years; and (2) the immigrant families were mainly composed of the old, with little or no livestock. What's more, the percentage of immigrant households that share one rangeland certificate with parents or brothers in the immigrant family was 54.5%. Therefore, it is hard to greatly decrease the overgrazing degree through eco- immigration with those previous characteristics of eco- immigrant family structure. 相似文献
13.
Based on the analysis of suspended sediment elements at estuaries, influence of human activities and estuarine regulation projects on the turbidity maximum zone was studied according to the measurement data between 1959 and 2011. It was found that human activities had little effect on the seaward water while the sharp decrease of sediment volume and concentration in runoff led to the sharp decrease of turbidity maximum zone in the estuary. The concentration at outside sea and Hangzhou Bay did not change, and that along the Subei coast also decreased a little, which had no influence on the turbidity maximum zone. Compared with the concentration between 1959 and 1999, the peak of concentration moved upstream in the estuary, and the concentration in 2000-2009 decreased by about 24.73% with a narrower variation range along the river to the sea. The suspended sediment concentration in North Passage was low in upstream and downstream because of the decrease of seaward sediment and coarsening of bed material, while it was relatively high in the middle due to the influence of sediment cross the north jetty. 相似文献
14.
Since the reform and open-up,the economy in the Yellow Sea coastal zone has rapidly developed and the regional structure of socio-economy has changed a lot,but meanwhile it has also caused increasingly serious environmental problems. The discussion on relationship between economic development and environment[1-12] has become the focus of research. The present research mainly focuses on the following aspects: first, the study on coordinately development of regional PRED system, including de… 相似文献
15.
LESLEY HEAD 《The Australian geographer》1999,30(2):141-158
Western Australia's Ord River Irrigation Scheme has been controversial since its establishment more than twenty-five years ago. A substantial expansion of the scheme, known as Ord Stage Two, is currently underway as a joint project of the Western Australian and Northern Territory governments. In this study I examine and compare Stages One and Two in the context of the significant social and economic changes that have occurred during this period, focusing on attitudes to, and conceptualisations of, nature and the human place in it. Despite a context in which consideration of both Aboriginal and environmental issues is now integrated into the development process, three colonial themes persist in the rhetoric of Stage Two. These are the empty landscape, the invisible Aborigine, and the idealisation of agricultural land use. When expressed together these three help to naturalise the development process as both inevitable and strategically implemented. The contradictions inherent in this process enhance existing doubts about the social and ecological sustainability of continuing attempts to 'develop' Australia's north. 相似文献
16.
《The Journal of geography》2012,111(2):76-78
Abstract As a result of advances in GIS, students from a range of disciplines (epidemiology, public health, medical sociology, and anthropology) are seeking to learn how to apply a mapped, spatial perspective to issues of disease and health. This paper describes a pilot program whose intent has been to develop an interdisciplinary, skills-based course in medical mapping using a case-based approach. The focus of its first module is the famous nineteenth-century case of a cholera epidemic in Soho, London. Here, however, that case–critical to a range of disciplines—is an opportunity to introduce modern GIS tools and their applicability to the issues surrounding the mapping of diseases in general. 相似文献
17.
The provincial pattern of the relationship between urbanization and economic develop-ment in China简 总被引:10,自引:1,他引:9
Understanding the relationship between China's urbanization and economic de- velopment on a provincial scale is of profound theoretical and practical significance. Based on data from 124 countries or regions throughout the world and 31 provinces or autonomous regions in China, applying improved methods using the quadrant map approach, this paper analyzed the spatial pattern of the relationship between China's urbanization and economic development level. The study identified the following results. (1) The 31 province-level re- gions fall into six categories: only one region is in the category of sharp over-urbanization, 3 regions are in medium over-urbanization, 11 slight over-urbanization, 8 basic coordination, one medium under-urbanization, and seven slight under-urbanization. (2) There are signifi- cant regional differences on a provincial scale in the relationships between urbanization and the level of economic development. (3) The provincial pattern of urbanization and economic development is significantly different between east and west. The eastern coastal areas are mainly over-urbanized, while the central and western regions are mainly under-urbanized. (4) The relationship between urbanization and the level of economic development is similar to the Matthew effect. Hence, two important insights are proposed. First, the phenomenon of over-urbanization in some developed regions should be viewed with some concern and vigi- lance. Second, urbanization needs to be speeded up moderately in the central and western regions. 相似文献
18.
Suspended sediment load in the turbidity maximum zone at the Yangtze River Estuary:The trends and causes简 总被引:6,自引:2,他引:4
Based on the analysis of suspended sediment elements at estuaries, influence of human activities and estuarine regulation projects on the turbidity maximum zone was studied according to the measurement data between 1959 and 2011. It was found that human activi- ties had little effect on the seaward water while the sharp decrease of sediment volume and concentration in runoff led to the sharp decrease of turbidity maximum zone in the estuary. The concentration at outside sea and Hangzhou Bay did not change, and that along the Subei coast also decreased a little, which had no influence on the turbidity maximum zone. Com- pared with the concentration between 1959 and 1999, the peak of concentration moved up- stream in the estuary, and the concentration in 2000-2009 decreased by about 24.73% with a narrower variation range along the river to the sea. The suspended sediment concentration in North Passage was low in upstream and downstream because of the decrease of seaward sediment and coarsening of bed material, while it was relatively high in the middle due to the influence of sediment cross the north jetty. 相似文献
19.
Mary Beth Pudup 《The Professional geographer》2013,65(4):561-562
This article tests the explanatory power and interactions among five alternative explanations of environmental knowledge: (1) local information availability, (2) neighborhood characteristics, (3) environmental attitudes, (4) personal empowerment, and (5) information seeking. Using random forest and conditional inference trees, the article analyzes survey responses and finds that attitudes about personal empowerment and frequent information seeking are the strongest predictors of knowledge. The study offers random forest and conditional inference trees as statistical tools for complex data sets and studies that test hypotheses generated from multiple theories. We discuss the influence of knowledge differences over inclusive sustainability discussions. 相似文献
20.
《Urban geography》2013,34(4):353-359
In a network society, the increasing fragmentation of individual activity and travel patterns has a major impact on visitors' use of places and spaces throughout the day. The aim of this study is to determine the main dimensions underlying diurnal weekday variations in visitor populations in Dutch municipalities, and to identify the salient spatial and transportation-related features of these municipalities that contribute to the dimensions of these temporary populations. Using the 1998 Netherlands National Travel Survey for six representative one-hour time periods, we performed an exploratory factor analysis to capture the underlying dimensions. The solution comprised one dimension referring to participation in activities, two dimensions related to the size of the territory in which visitor populations operate combined with the use of different transport modes, one dimension expressing the direction in which interlocal movement occurs, and three dimensions capturing different life-cycle stages within the visitor population. 相似文献