GIS‐Based Spatial Precipitation Estimation: A Comparison of Geostatistical Approaches1

Abstract: As one of the primary inputs that drive watershed dynamics, the estimation of spatial variability of precipitation has been shown to be crucial for accurate distributed hydrologic modeling. In this study, a Geographic Information System program, which incorporates Nearest Neighborhood (NN), Inverse Distance Weighted (IDW), Simple Kriging (SK), Ordinary Kriging (OK), Simple Kriging with Local Means (SKlm), and Kriging with External Drift (KED), was developed to facilitate automatic spatial precipitation estimation. Elevation and spatial coordinate information were used as auxiliary variables in SKlm and KED methods. The above spatial interpolation methods were applied in the Luohe watershed with an area of 5,239 km², which is located downstream of the Yellow River basin, for estimating 10 years’ (1991‐2000) daily spatial precipitation using 41 rain gauges. The results obtained in this study show that the spatial precipitation maps estimated by different interpolation methods have similar areal mean precipitation depth, but significantly different values of maximum precipitation, minimum precipitation, and coefficient of variation. The accuracy of the spatial precipitation estimated by different interpolation methods was evaluated using a correlation coefficient, Nash‐Sutcliffe efficiency, and relative mean absolute error. Compared with NN and IDW methods that are widely used in distributed hydrologic modeling systems, the geostatistical methods incorporated in this GIS program can provide more accurate spatial precipitation estimation. Overall, the SKlm_EL_X and KED_EL_X, which incorporate both elevation and spatial coordinate as auxiliary into SKlm and KED, respectively, obtained higher correlation coefficient and Nash‐Sutcliffe efficiency, and lower relative mean absolute error than other methods tested. The GIS program developed in this study can serve as an effective and efficient tool to implement advanced geostatistics methods that incorporate auxiliary information to improve spatial precipitation estimation for hydrologic models.     

点声源环境噪声声场区域二维图形化表征方法研究

针对环境噪声监测中单一点声源声场图形化表征机理,依据点声源衰减规律建立了点声源声场二维平面表征算法,据此以网格化区域范围内非均匀布置少量监测点方法确定声源点,再经克里金插值法反演点声源声场平面分布规律,最后通过ArcGIS软件平台实现噪声图形化展示.以5×5网格化区域为例,其非均匀布点数应不少于3个,最佳布点数为3组共计6个点,其实测值与理论值最大误差为4.3％.仿真试验验证表明,点声源图形表征符合实际声场分布规律.     

基于EOF的浙江省降水变化时空分析研究

根据浙江省17个气象站点1959年-2010年逐日降水观测数据,采用z指数方法,并运用Morlet小波分析和Kriong空间插值法对浙江省近52年降水时空分布特征进行经验正交函数(EOF)方法对比分析.研究结果表明:从时间变化方面来看,1958年-2008年间的降水变化呈波动式下降趋势,减小趋势为0.643mm/a,年代际变化不大,年际变化幅度较大,且呈周期性变化,主周期约为12年,次周期为32年和3-4年;从空间变化方面来看,根据EOF分析,浙江省降水分布呈总体一致性,东南、西北近似对称.主体变化是由东南,东北沿海两个方向和西北向内陆递减,降水中心分布浙东南、浙东北和浙西南地区.     

便携式X-荧光分析土壤的准确度和质量控制研究

测定标土能反映便携式X-荧光光谱仪的准确度,采用便携式X-荧光光谱仪测定了国内外七种标准土样,计算了测定结果的相对误差,直观地反映了便携式X-荧光光谱仪的准确度和灵敏度.借鉴EPA对便携式X-荧光光谱仪测定结果的质控要求,分析了部分测定结果得不到质量控制要求的原因,结合中国土壤环境质量标准一、二、三级标准,分析了便携式X-荧光光谱仪测定值在不同标准限值时的准确度和灵敏度.选取了铅冶炼周围的土壤,分析了现场测定由于土壤的不均匀性、粒度效应以及湿度给结果带来的误差.为便携式X-荧光光谱仪的质量控制和数据的准确恒量提供了依据.     

流动注射在线UV消解测定环境水体中的总氮研究

采用San++流动分析仪在线UV消解测定环境水体中的总氮,样品浓度在0.00~5.0 mg/L与峰高有良好的线性关系(r=0.999 6)。进行了标准样品考核和实际水样的流动注射法和国标方法的比对分析。实验结果表明:采用流动注射在线消解测定水中TN,其标样测定值均在保证值范围内,相对标准偏差小于3%;两种方法测定实际水样的结果无显著性差异且具有很好的一致性,加标回收实验的回收率在90.0%~97.7%之间,能满足地表水及排放废水中TN监测要求。     

生活垃圾焚烧厂周边土壤汞污染特征及评价

生活垃圾焚烧汞污染排放问题一直受到广泛的关注,特别是汞在其周边环境土壤中沉积,可能影响环境和人体健康.以华北某生活垃圾焚烧厂为研究对象,对其周边土壤中汞的含量及分布特征进行了分析,并对土壤中汞的污染状况及对周边人群的健康风险进行了评价.土壤中汞的浓度范围为0.015~0.25 mg·kg-1,平均值为(0.088±0.064)mg·kg-1.土壤中汞的浓度明显受到了风向影响,在焚烧厂西北方向(下风向)上汞的浓度高于东南方向(上风向)上汞的浓度.通过克里格插值绘制的汞等浓度值线图进一步给出了汞在周边土壤中的空间分布特征,图中显示在焚烧厂的周边存在3个浓度相对较高的区域,分别位于焚烧厂的西北偏北、东北偏北、西南偏西方向.单项污染指数及地累积指数评价结果表明焚烧厂部分周边土壤样品受到了一定影响,但健康风险评价表明土壤汞未对当地人群造成健康危害.     

济南市大气污染时空特征研究

为不断改善济南市大气环境质量,在广泛收集与整理相关资料和数据基础上,基于综合污染指数评价法及Arc-GIS平台空间插值法研究并表征了济南市“十一五”期间大气主要污染物的时、空变化特征及发展趋势;研究结果表明：济南市“十一五”期间大气环境质量变化较大,2007～2009年污染较为严重,之后有所改善;大气污染物浓度呈明显的季节变化特征,冬季污染最严重,夏季空气质量最好;首要污染物为PM10;污染较严重区域集中在济南市东北部地区;其变化原因受地理气候条件、产业结构和能源结构影响较大.该研究方法及结论对其他大中城市大气环境质量时空变化研究具有一定借鉴价值.     

4阶导数光谱法同时测定酚类及芳胺的统计性检验

介绍４阶导数光谱法同时测定污水中酚类及芳胺方法的统计性检验，通过样品加标回收实验以及Ｆ检验和ｔ检验证明该方法的精密度和准确度均优于国家环保局推荐的４－氨基安替比林先度法删酚和萘乙二胺偶氮光度法测芳胺的实验方法。     

FLOOD WARNINGS AND FLOOD RESPONSES FOR THE RED RIVER OF THE NORTH1

ABSTRACT The flooding conditions in the basin of the Red River of the North are reviewed in terms of the accuracy of the flood forecasts and the response of both the floodplain occupants and government agencies to these forecasts. The flood prediction methods in Canada and the United States are compared. The accuracy of these prediction measures for the major floods in recent history is reviewed. The differences between the way in which the American and Canadian authorities approach the flood emergencies are outlined. The accuracy of the forecasts are plotted against a number of parameters which reflect the efficiency of the flood fighting measures initiated by those flood forecasts. The significant features of these plots are discussed.     

快速凯氏定氮仪与纳氏试剂光度法测定NH3-N的精密度及总不确定度比较

通过对实际水样中NH3-N的测定结果的精密度及总不确定度检验,比较快速凯氏定氮法和纳氏试剂光度法测试结果,置信概率为95%.双侧DIXON检验、精密度和不确定度检验,结果表明,两方法测定结果之间不存在显著性差异,具有一致性.