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991.
本文论述了2002年运城市地下水超采状况及其引起的环境地质等一系列问题.并遵循可持续发展的思想,提出了地下水资源保护的几点意见. 相似文献
992.
本文采用流量级频率分析和统计分析方法,对黄河下游流量及泥沙含量对水环境容量的影响进行了研究分析.分析结果:河流在平滩流量时不仅输沙能力最大[8],而且输运污染物能力也最大,黄河下游水环境容量萎缩是平滩流量降低的必然结果. 相似文献
993.
ABSTRACT Spatial heterogeneity represents a general characteristic of the inequitable distributions of spatial issues. The spatial stratified heterogeneity analysis investigates the heterogeneity among various strata of explanatory variables by comparing the spatial variance within strata and that between strata. The geographical detector model is a widely used technique for spatial stratified heterogeneity analysis. In the model, the spatial data discretization and spatial scale effects are fundamental issues, but they are generally determined by experience and lack accurate quantitative assessment in previous studies. To address this issue, an optimal parameters-based geographical detector (OPGD) model is developed for more accurate spatial analysis. The optimal parameters are explored as the best combination of spatial data discretization method, break number of spatial strata, and spatial scale parameter. In the study, the OPGD model is applied in three example cases with different types of spatial data, including spatial raster data, spatial point or areal statistical data, and spatial line segment data, and an R “GD” package is developed for computation. Results show that the parameter optimization process can further extract geographical characteristics and information contained in spatial explanatory variables in the geographical detector model. The improved model can be flexibly applied in both global and regional spatial analysis for various types of spatial data. Thus, the OPGD model can improve the overall capacity of spatial stratified heterogeneity analysis. The OPGD model and its diverse solutions can contribute to more accurate, flexible, and efficient spatial heterogeneity analysis, such as spatial patterns investigation and spatial factor explorations. 相似文献
994.
Gianpaolo Coro Pasquale Pagano Anton Ellenbroek 《International Journal of Digital Earth》2020,13(5):567-585
ABSTRACTForecasting environmental parameters in the distant future requires complex modelling and large computational resources. Due to the sensitivity and complexity of forecast models, long-term parameter forecasts (e.g. up to 2100) are uncommon and only produced by a few organisations, in heterogeneous formats and based on different assumptions of greenhouse gases emissions. However, data mining techniques can be used to coerce the data to a uniform time and spatial representation, which facilitates their use in many applications. In this paper, streams of big data coming from AquaMaps and NASA collections of 126 long-term forecasts of nine types of environmental parameters are processed through a cloud computing platform in order to (i) standardise and harmonise the data representations, (ii) produce intermediate scenarios and new informative parameters, and (iii) align all sets on a common time and spatial resolution. Time series cross-correlation applied to these aligned datasets reveals patterns of climate change and similarities between parameter trends in 10 marine areas. Our results highlight that (i) the Mediterranean Sea may have a standalone ‘response’ to climate change with respect to other areas, (ii) the Poles are most representative of global forecasted change, and (iii) the trends are generally alarming for most oceans. 相似文献
995.
ABSTRACTEnvironmental flow standards are a management tool that can help to protect the ecosystem services sustained by rivers. Although environmental flow requirements can be assessed using a variety of methods, most of these methods require establishing relationships between flow and habitat of species of concern. Here, we conducted a synthesis of past flow–ecology studies in the southeast USA. For each state or interstate river basin, we used the published data to determine the flow metrics that resulted in the greatest changes in ecological metrics, and the ecological metrics that were most sensitive to hydrologic alteration. The flow metrics that were most important in preserving ecological metrics were high-flow duration and frequency, 3-day maximum and minimum, and number of reversals. The ecological metrics most sensitive to hydrologic alteration were mostly related to presence or absence of key indicator species. 相似文献
996.
Environmental records of lacustrine sediments in different time scales: Sediment grain size as an example 总被引:2,自引:0,他引:2
CHEN Jing’an WAN Guojiang David Dian Zhang ZHANG Feng & HUANG Ronggui . State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang China . Department of Geography Geology University of Hong Kong Pokfulam Road Hong Kong China 《中国科学D辑(英文版)》2004,47(10):954-960
Understanding the past is the key to know thepresent and to predict the future. As a core project ofthe International Geosphere Biosphere Program, PastGlobal Changes (PAGES) aims to reconstruct theevolution history of global climate, global environ-ment and global ecosystem with resort to all kinds ofnatural records, so as to reveal the change rules(change processes, change amplitude and change rate)of the global environment and thus provide scientificbasis for predicting climate changes p… 相似文献
997.
998.
DONGSheng GANBuhong HAOXiaoli 《中国海洋大学学报(英文版)》2004,3(1):111-114
1 Introduction InChina ,coastalcitiesaremostlyregionaleconomicdevelopmentcenters.Becauseoftheirspecialgeogra phiclocations ,typhoonsandassociatedstormsurgescauseheavylossesoflivesandproperties.In 1 992 Qing daowasfloodedduetothecoincidenceoftheastrono m… 相似文献
999.
CHEN Hao ZHOU Jinxing CAI Qiangguo LU Zhongchen & LI Zhongyan Institute of Geographic Sciences Natural Resources Research Chinese Academy of Sciences Beijing China Institute of Forestry Science Chinese Academy of Forestry Science Beijing China Research Center for Eco-Environment Sciences Chinese Academy of Sciences Beijing China Computing Institute of Science Engineering North China Electric Power University Beijing China 《中国科学D辑(英文版)》2005,48(2):230-240
Threshold of environmental elements in drainage basin sediment yield refers to, under effect of climate, underlying surface and human activity, a turning point of abrupt changes in drainage sediment yield related to environmental element characteristics. Previous studies on threshold of sediment yield of relevant drainage basins were mainly concentrated on impact of natural zones with a few researches on impact of other environmental elements. Particularly studies on compound environmental element threshold in drainage basin sediment yield remain blank today. Studies indicate that sediment yield in drainage basins is affected by compound interactions and complex actions. Based on single element analysis, the present paper gives quantitatively compound threshold of environmental elements affecting sediment yield of the drainage basin between Hekouzhen and Tongguan in the middle Yellow River by the method of multi-variant, polynomial formula regression analysis. 相似文献
1000.
Previous interdisciplinary paleoenvironmental and archaeological research along the Río Verde Valley of Oaxaca, Mexico, showed that Holocene erosion in the highland valleys of the upper drainage basin triggered geomorphic changes in the river's coastal floodplain. This article uses stratigraphic data from sediment cores extracted from Laguna Pastoría, an estuary in the lower Río Verde Valley, to examine changes in coastal geomorphology potentially triggered by highland erosion. Coastal lagoon sediments contain a stratigraphically and chronologically distinct record of major hurricane strikes during late Holocene times. Three distinct storm facies are identified from sediment cores obtained from Laguna Pastoría, which indicate that profound coastal environmental changes occurred within the region and are correlated with increased sediment supplied from highland erosion. The Chione/Laevicardium facies was deposited in an open bay while the Mytella/barnacle facies and sand facies were deposited in an enclosed lagoon following bay barrier formation. We argue that highland erosion triggered major geomorphic changes in the lowlands including bay barrier formation by 2500 cal yr B.P. These environmental changes may have had significant effects on human populations in the region. The lagoon stratigraphy further indicates an increase in mid–late Holocene hurricane activity, possibly caused by increased El Niño frequencies. 相似文献