Attributes and uncertainty of dissolved zinc data from a mined catchment     

Brian S. Caruso 《水文研究》1999,13(2):169-190

This study evaluated the attributes and uncertainty of non‐point source pollution data derived from synoptic surveys in a catchment affected by inactive metal mines in order to help to identify and select appropriate methods for data analysis/reporting and information use. Dissolved zinc data from the Upper Animas River Basin, Colorado, USA, were the focus of the study. Zinc was evaluated because concentrations were highest relative to national water quality criteria for brown trout, and zinc had the greatest frequency of criteria exceedances compared with other metals. Data attributes evaluated included measurement and model error, sample size, non‐normality, seasonality and uncertainty. The average measurement errors for discharges, concentrations and loadings were 0·15, 0·1 and 0·18, respectively. The 90 and 95% coefficients of confidence intervals for mean concentrations based on a sample size of four were 0·48 and 0·65, respectively, and ranged between 0·15 and 0·23 for sample sizes greater than 40. Aggregation of data from multiple stations decreased the confidence intervals significantly, but additional aggregation of all data increased them as a result of increasing spatial variability. Unit area loading data were approximately log‐normal. Concentration data were right‐skewed but not log‐normal. Differences in median concentrations were appreciable between snowmelt and both storm flow and baseflow, but not between storm flow and baseflow. Differences in unit area loadings between all flow events were large. It was determined that the average concentration and unit area loading values should be estimated for each flow event because of significant seasonality. Time weighted values generally should be computed if annual information is required. The confidence in average concentrations and unit area loadings is dependent on the computation method used. Both concentrations and loadings can be significantly underestimated on an annual basis when using data from synoptic surveys if the first flush of contaminants during the initial snowmelt runoff period is not sampled. The ambient standard for dissolved zinc for all events was estimated as 1600 μg l⁻¹ using the 85th percentile of observed concentration data, with a 90% confidence interval width of 200 μg l⁻¹. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

面向城市平原地区暴雨积涝汇水区分级划分的方法研究     

薛丰昌  盛洁如  钱洪亮 《地球信息科学学报》2015,17(4):462-468

汇水区划分是分布式水文模型计算的基础。针对现有方法使用DEM在平原城市地区划分的汇水区不符合实际地形情况,本文提出了一种面向城市平原地区分级划分汇水区的技术方法。该方法从城市用地分类角度出发将城市分为中心城区和郊区,依据城市排水主干水系进行汇水区一级划分,将影响中心城区和郊区的不同径流因子分别融入DEM中,利用细化的DEM进行二级汇水区划分;在此基础上,根据实际汇流情况,结合Voronoi图,对中心城区进行三级划分,最后通过GIS技术进行修正。该方法既结合了传统DEM生成子流域的算法,又融入了城市区域地物地貌特点,能更好地满足城市地区的需要。选择上海市嘉定区西北部地区为实验样区,利用该方法进行汇水区划分比较表明,其对于城市平原地区具有很好的适用性。  相似文献   

土地利用空间格局的置换变化与代换变化分析     

冉建波  陈兴伟 《地球信息科学学报》2015,17(6):661-667

为揭示土地利用空间格局的动态变化,本文基于土地利用转移矩阵,从类型间的空间转移过程出发,构建了置换变化与代换变化的计算模型,并对其2种变化进行了分析。置换变化是2种类型之间以相同面积发生空间位置的置换过程,且各种类型的数量结构保持不变;代换变化则是所研究类型的数量结构保持不变,而与之转换的其他类型数量上的增加或减少;从而将单一类型的总变化进一步细分为置换变化、代换变化与净变化。以晋江流域1985年与2006年2期土地利用格局的变化为例进行分析,结果显示：在1985-2006年间,晋江流域的土地利用空间格局发生了显著变化;园地、建设用地、未利用地呈现扩张态势,草地与旱地呈现萎缩变化,水域变化不大;这6种地类的交换变化面积相对较少,以置换变化为主。水田与林地则主要表现为空间位置的交换变化,其中,水田呈现出与林地、旱地2种类型之间的置换变化,而林地则主要是园地-林地与林地-草地这2对类型间的代换变化。结果表明,通过置换变化与代换变化的分析,更细化了各种类型之间的动态变化过程。  相似文献   

基于Pfafstetter规则的流域编码算法并行化方法     

王春  江岭  陈泰生  杨灿灿 《地球信息科学学报》2015,17(5):556-561

流域编码是以子流域划分进行流域相关研究的重要内容。Pfafstetter 流域编码以编码唯一、顾及流域拓扑关系及编码效率高等优点而被广泛采用。本文在流域相关研究的分析范围不断增大、数据精度越来越高的需求背景下,以Pfafstetter 编码为基础,对流域编码并行化方法进行研究。首先,分析了Pfafstetter 编码不全面和码位不一致的问题,改进了Pfafstetter 编码规则;然后,从数据并行的角度,讨论了并行计算环境下的数据划分及并行化策略,进而设计了流域编码并行算法;最后,利用长江中上游流域SRTM数据,在集群系统上对流域编码并行算法的正确性和并行性能进行了测试。实验结果表明,本文设计实现的流域编码并行算法可获取与实际较为一致的计算结果,且提高了编码计算效率,可为基于子流域划分的流域分析并行化提供参考。  相似文献   

Using the Climate Forecast System Reanalysis as weather input data for watershed models   总被引：4，自引：0，他引：4       下载免费PDF全文

Daniel R. Fuka  M. Todd Walter  Charlotte MacAlister  Arthur T. Degaetano  Tammo S. Steenhuis  Zachary M. Easton 《水文研究》2014,28(22):5613-5623

Obtaining representative meteorological data for watershed‐scale hydrological modelling can be difficult and time consuming. Land‐based weather stations do not always adequately represent the weather occurring over a watershed, because they can be far from the watershed of interest and can have gaps in their data series, or recent data are not available. This study presents a method for using the Climate Forecast System Reanalysis (CFSR) global meteorological dataset to obtain historical weather data and demonstrates the application to modelling five watersheds representing different hydroclimate regimes. CFSR data are available globally for each hour since 1979 at a 38‐km resolution. Results show that utilizing the CFSR precipitation and temperature data to force a watershed model provides stream discharge simulations that are as good as or better than models forced using traditional weather gauging stations, especially when stations are more than 10 km from the watershed. These results further demonstrate that adding CFSR data to the suite of watershed modelling tools provides new opportunities for meeting the challenges of modelling un‐gauged watersheds and advancing real‐time hydrological modelling. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

International Journal of Sediment Research(IJSR)-Order Form(2015)(ISSN 1001-6279)     

《国际泥沙研究》2014,(4)

正Editing Board address:IRTCES,20 West Chegongzhuang Rd.,Beijing 100048,ChinaIJSR is the journal of THE WORLD ASSOCIATION FOR SEDIMENTATION AND EROSION RESEARCH(WASER)and is edited by the International Research and Training Center on Erosion and Sedimentation(IRTCES).  相似文献   

基于分布式大流域径流模型的中国西北黑河流域水文模拟   总被引：1，自引：0，他引：1  

贺缠生  Carlo DeMarchi  Thomas E.Croley  冯起  Tim Hunter 《冰川冻土》2009,31(3):410-421

水资源短缺是中国西北干旱地区长期的问题,区域人口增加、城市化扩张,加之气候变化的影响进一步加剧了西北地区水资源短缺,也使生活用水、灌溉用水、工业用水和维持生态系统稳定的用水危险加剧.采用分布式大流域径流模型(DLBRM)模拟黑河流域水文(中国第二大内陆河,流域面积128 000 km2)来理解区域的冰川和积雪融化水、地下水、地表水、蒸散发等方面的分布,评估气候变化对水文的影响和冰川退缩对中游和下游来水量的影响.模拟结果表明,黑河流域的大部分产流那源于黑河上游地区的祁连山.模拟1990-2000年黑河河流日流量变化结果认为,黑河中游正义峡给下游的供水为10×108m3,其中地表径流占51%,层间流占49%.中游地区沙土具有较高的蒸腾发能力,近一半的地表水被蒸发掉.模拟实践证明,分布式大流域径流模型可以结合气候变化、水资源管理方面的成果,改进流域水文模拟的精度.  相似文献   

不同降雨条件下黄土高原浅层滑坡危险性预测评价   总被引：4，自引：0，他引：4  

庄建琦  彭建兵  张利勇 《吉林大学学报(地球科学版)》2013,43(3):867-876

黄土地区浅层滑坡发育非常广泛,由于其具有分布规律性差、前期变形迹象小、分布范围大、面小点多等特征,目前还无法进行有效预测,因此给黄土地区工程安全带来严重威胁。根据无限边坡模型,结合降雨入渗-土体强度衰减规律和GIS（地理信息系统）技术,构建了不同降雨条件下黄土地区浅层滑坡发育危险性评价模型,并将该评价模型应用到延河一级支流幸福川流域,预测在有效降雨量30、50、100、200 mm条件下,该流域浅层滑坡发育程度,并与当前较为流行的SINMAP模型(地形稳定性模型)进行对比。结果表明：①不稳定和潜在不稳定浅层滑坡主要分布在末级河流的两侧和源头,稳定和较稳定区域主要分布在一级河流河道两侧和塬面上;通过对比分析,SINMAP模型计算的结果与本文建立的模型在降雨强度30 mm时的计算结果较为一致。②在本文建立的模型评价结果中,随着有效降雨量的增加,F_s（稳定性系数）<1.00的不稳定区域所占比例逐渐增加,从30 mm的1.12%到200 mm的4.79%;相反,稳定区域则出现逐渐减少的趋势。③根据已发生灾害点的分布,随着有效降雨量的增加,研究区域已发生的灾害点分布在F_s<1.25的比例明显增加,从30 mm的62%到200 mm的88%,在SINMAP评价模型中,研究区域已发生的灾害点的64%分布在不稳定和潜在不稳定区域内,说明本文所建立的评价模型具有一定的精度。通过与SINMAP评价模型对比,本文建立的模型主要采用基于降雨入渗规律,而SINMAP评价模型主要基于降雨汇流过程,因此在利用过程中应根据区域特征选择利用。  相似文献   

A new approach for linking event‐based upland sediment sources to downstream suspended sediment transport     

Peng Gao  James Puckett 《地球表面变化过程与地形》2012,37(2):169-179

In this study, we proposed a new approach for linking event sediment sources to downstream sediment transport in a watershed in central New York. This approach is based on a new concept of spatial scale, sub‐watershed area (SWA), defined as a sub‐watershed within which all eroded soils are transported out without deposition during a hydrological event. Using (rainfall) event data collected between July and November, 2007 from several SWAs of the studied watershed, we developed an empirical equation that has one independent variable, mean SWA slope. This equation was then used to determine event‐averaged unit soil erosion rate, Q_S/A, (in kg/km²/hr) for all SWAs in the studied watershed and calculate event‐averaged gross erosion E_ea (in kg/hr). The event gross erosion E_t (in kilograms) was subsequently computed as the product of E_ea and the mean event duration, T (in hours) determined using event hydrographs at the outlet of the studied watershed. Next, we developed two linear sediment rating curves (SRCs) for small and big events based on the event data obtained at the watershed outlet. These SRCs, together with T, allowed us to determine event sediment yield SY_e (in kilograms) for all events during the study period. By comparing E_t with SY_e, developing empirical equations (i) between E_t and SY_e and (ii) for event sediment delivery ratio, respectively, we revealed the event dynamic processes connecting sediment sources and downstream sediment transport. During small events, sediment transport in streams was at capacity and dominated by the deposition process, whereas during big events, it was below capacity and controlled by the erosion process. The key of applying this approach to other watersheds is establishing their empirical equations for Q_S/A and appropriately determining their numbers of SWAs. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Agricultural land use optimal allocation system in developing area: Application to Yili watershed, Xinjiang Region   总被引：1，自引：0，他引：1  

Ying Zhang  Hongqi Zhang  Dongying Ni  Wei Song 《中国地理科学(英文版)》2012,22(2):232-244

In developing countries, land productivity involves little market, where the agricultural land use is mainly determined by the food demands as well as the land suitability. The land use pattern will not ensure everywhere enough land for certain cropping if spatial allocation just according to land use suitability. To solve this problem, a subzone and a pre-allocation for each land use are added in spatial allocation module, and land use suitability and area optimization module are incorporated to constitute a whole agricultural land use optimal allocation (ALUOA) system. The system is developed on the platform .Net 2005 using ArcGIS Engine (version 9.2) and C# language, and is tested and validated in Yili watershed of Xinjiang Region on the newly reclaimed area. In the case study, with the help of soil data obtained from 69 points sampled in the fieldwork in 2008, main river data supplied by the Department of Water Resources of Xinjiang Uygur Autonomous Region in China, and temperature data provided by Data Center for Resources and Environmental Sciences, Chinese Academy of Sciences, land use suitability on eight common crops are evaluated one by one using linear weighted summation method in the land use suitability model. The linear programming (LP) model in area optimization model succeeds to give out land area target of each crop under three scenarios. At last, the land use targets are allotted in space both with a six subzone file and without a subzone file. The results show that the land use maps with a subzone not only ensure every part has enough land for every crop, but also gives a more fragmental land use pattern, with about 87.99% and 135.92% more patches than the one without, while at the expense of loss between 15.30% and 19.53% in the overall suitability at the same time.  相似文献