Estimating Generalised Flood Sew Coeficients for Peninsular Malaysia
Estimating Generalised Flood Sew Coeficients for Peninsular Malaysia
复制标题
估算马来西亚半岛的广义洪水缝系数
DOI：
--
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
H. An
中科院分区：
文献类型：
--
作者：
David Hong Jer Lang;Mohd Puad Amirah Hanim;Abdul Azia Intan Shafiliah;H. An
基于Log-Pearson 3型分布的年洪峰流量出现频率是常用的洪水估计方法，但它们对测站的偏态系数很敏感。通过使用由样本站偏差和广义无偏偏差计算的加权平均总体偏差系数，可以提高估计精度。美国水资源委员会(WRC)记录了估算广义偏斜系数的指南，并发布了美国的广义偏斜值地图。这张地图显示了美国每个1度经纬度四边形的倾斜系数值等值线和平均倾斜系数。根据WRC的指导方针，美国的许多州当局已经在州/地区的基础上单独制定了广义的倾斜系数。在马来西亚，Log Pearson Type 3分布已被广泛用于对数峰值估计，但没有可用的准则来估计与该分布相结合使用的广义偏斜系数，而且如果这些数据可用，可以获得更准确的结果，因此显然需要进行区域性的对数偏度研究。有了区域SEW资料，就可以借助HEC-SSP等软件简单、容易地计算出峰值低点。本文的目的是使用世界资源中心的指导方针，利用马来西亚半岛的年洪峰流量数据推导出通用的偏斜系数。世界资源中心推荐了几种估计和评估对数-皮尔逊3型分布的年洪峰流量的广义S-Ew的方法。站偏角(根据测站记录计算的偏斜系数)和从这些站偏角得出的无偏和加权偏角将被用于开发这些技术。在这项研究中，选择了马来西亚半岛66个年峰值流量在16个或更多的测站的峰值流量记录，用于计算站点偏斜。站点偏斜值从-0.831(对数10个单位)到1.475(对数10个单位)。本研究采用了世界资源中心推荐的三种估测年高峰流量综合偏差值的方法。这些方法是：(1)等值线图，(2)预测方程，(3)区域平均偏差。试图建立预测方程式的尝试没有成功。误差分析表明，区域平均偏差法的均方误差(MSE)低于全州广义偏斜系数等值线。因此，所选测量站的平均站偏角可用于估计半岛上任何测量点的总体偏角。平均偏角为-0.022(对数10单位)，相关的均方误差为0.05(对数10单位)。
Flood estimations based on itting the frequency of occurrence of annual peak discharges using the Log-Pearson Type 3 distribution are commonly used but they are sensitive to the skew coeficients of the gauging stations. The estimation accuracy can be improved by using a weighted average population skew coeficient calculated from the sample station skew and the generalised unbiased skew. The U.S. Water Resources Council (WRC) has documented guidelines for estimating the generalised skew coeficients and published a map of generalised skew values for the United States. The map shows isolines of skew coeficient values and the average skew coeficient for each 1-degree quadrangle of latitude and longitude for the United States. Following the WRC guidelines, many of the state authorities in the US have developed the generalised skew coeficients separately on a state/regional basis. In Malaysia, the Log Pearson Type 3 distribution has been widely used for lood peakestimation but there are no guidelines available for estimating the generalised skew coeficients for use in con–unction with the distribution and as more accurate results can be obtained if these data are available, it is clear that a regional lood skew study is needed. With the regional sew data available, the peak low can be simply and easily calculated with the aid of a software such as HEC-SSP. The aim of this paper is to use the WRC guidelines to derive the generalised skew coeficients using the peakannual discharge data of Peninsular Malaysia for general use.The WRC recommended several techniques for estimating and evaluating generalised s—ew of the Log-Pearson Type 3 distribution for the annual peakdischarges. Station skews (skew coeficients computed from gauging station records) and unbiased and weighted skews derived from these station skews are to be used to develop these techniques. In this study, peak discharge records at 66 gauging stations having 16 or more annual peak discharges in Peninsular Malaysia were selected for computing station skews. Station skew values ranged from -0.831(log10 unit) to 1.475 (log10 unit).The three techniques recommended by WRC used for estimating the generalised skew of annual peak discharges were adopted for this study. These methods are: (1) An isoline map, (2) a prediction equation (3) a regional mean skew. Attempts to develop a prediction equation were unsuccessful. An error analysis showed that the regional mean skew method has a lower MSE (mean square error) than that obtained from the state wide generalised skew coeficient contour map. As a result, the mean station skew for the selected gauging stations can be used to estimate the generalised skew for any gauging site in the peninsula.The mean skew is -0.022 (log10 unit) and the associated mean square error is 0.05 (log10 unit).