Applications of AnnAGNPS model for soil loss estimation and nutrient loading for Malaysian conditions     

A. Shamshad  C.S. LeowA. Ramlah  W.M.A. Wan HussinS.A. Mohd. Sanusi 《International Journal of Applied Earth Observation and Geoinformation》2008

The study evaluated the performance and suitability of AnnAGNPS model in assessing runoff, sediment loading and nutrient loading under Malaysian conditions. The watershed of River Kuala Tasik in Malaysia, a combination of two sub-watersheds, was selected as the area of study. The data for the year 2004 was used to calibrate the model and the data for the year 2005 was used for validation purposes. Several input parameters were computed using methods suggested by other researchers and studies carried out in Malaysia. The study shows that runoff was predicted well with an overall R² value of 0.90 and E value of 0.70. Sediment loading was able to produce a moderate result of R² = 0.66 and E = 0.49, nitrogen loading predictions were slightly better with R² = 0.68 and E = 0.53, and phosphorus loading performance was slightly poor with an R² = 0.63 and E = 0.33. The erosion map developed was in agreement with the erosion risk map produced by the Department of Agriculture, Malaysia. Rubber estates and urban areas were found to be the main contributors to soil erosion. The simulation results showed that AnnAGNPS has the potential to be used as a valuable tool for planning and management of watersheds under Malaysian conditions.  相似文献   

Accuracy assessment of lidar-derived digital elevation models   总被引：2，自引：0，他引：2  

Fernando J.  Aguilar  Jon. P.  Mills 《The Photogrammetric Record》2008,23(122):148-169

Despite the relatively high cost of airborne lidar-derived digital elevation models (DEMs), such products are usually presented without a satisfactory associated estimate of accuracy. For the most part, DEM accuracy estimates are typically provided by comparing lidar heights against a finite sample of check point coordinates from an independent source of higher accuracy, supposing a normal distribution of the derived height differences or errors. This paper proposes a new methodology to assess the vertical accuracy of lidar DEMs using confidence intervals constructed from a finite sample of errors computed at check points. A non-parametric approach has been tested where no particular error distribution is assumed, making the proposed methodology especially applicable to non-normal error distributions of the type usually found in DEMs derived from lidar. The performance of the proposed model was experimentally validated using Monte Carlo simulation on 18 vertical error data-sets. Fifteen of these data-sets were computed from original lidar data provided by the International Society for Photogrammetry and Remote Sensing Working Group III/3, using their respective filtered reference data as ground truth. The three remaining data-sets were provided by the Natural Environment Research Council's Airborne Research and Survey Facility lidar system, together with check points acquired using high precision kinematic GPS. The results proved promising, the proposed models reproducing the statistical behaviour of vertical errors of lidar using a favourable number of check points, even in the cases of data-sets with non-normally distributed residuals. This research can therefore be considered as a potentially important step towards improving the quality control of lidar-derived DEMs.  相似文献   

半参数平差模型估计量的精度评定     

潘雄  刘立龙  陈刚  田玉刚 《测绘工程》2008,17(6):13-15

将半参数估计理论引入测量数据处理理论中,利用Blight和Ott提出的思想,用多项式函数来表示半参数平差模型中的非参数分量,从而得到了半参数平差模型中参数分量和非参数分量的Bayes估计量,通过理论证明,半参数模型参数分量的Bayes估计为通常意义下高斯马尔可夫模型参数估计值与参数期望的加权平均,是一致、渐近无偏和渐近有效估计量,并且其方差小于参数模型中参数估计量的方差。在一定情况下推广了平差理论,具有一定的理论价值。  相似文献   

大民屯凹陷烃源岩有机质丰度的恢复   总被引：2，自引：0，他引：2       下载免费PDF全文

逯向阳 《沉积与特提斯地质》2008,28(4):14-17

烃源岩有机质丰度的恢复具有重要的现实和理论意义。笔者在对比多种方法的基础上,对大民屯凹陷的烃源岩的有机质丰度进行了恢复。  相似文献   

山东郓城矿井建设项目环境经济损益分析     

张梁  史登峰 《地质灾害与环境保护》2008,19(3):28-31

建设项目环境影响评价中的环境经济损益分析部分,目前多是定性的简单分析,不能满足环境影响评价精度要求。本文对山东里能集团有限公司巨野矿区郓城矿井环境影响评价时,探讨了定量化的环境经济损益分析。  相似文献   

多源遥感影像数据的融合方法探讨   总被引：1，自引：0，他引：1  

孔庆楠 《测绘与空间地理信息》2008,31(4)

在分析和总结多源遥感影像数据融合的基础上,探讨了多源遥感影像数据融合的层次、模型、结构及其特点.归纳总结了多源遥感影像数据融合方法,目的是提高多光谱影像分辨率的同时保持色调不变,从另一个角度理解为在已知低分辨率多光谱影像和高分辨率全色影像的基础上,模拟生成高分辨率多光谱影像.本文介绍了遥感影像融合技术,系统阐述了几种常见的遥感影像融合方法及其应用.  相似文献   

1∶500,1∶1000,1∶2000系列数字化测绘产品的精度目标与实现     

李云星 《测绘与空间地理信息》2008,(1)

1∶500,1∶1000,1∶2000系列数字化测绘产品按其生产工艺和用途的不同其精度规格也不尽相同,但产品的精度状况始终是测绘生产部门与用户所关心的问题。本文列举了现行有关规范的相关精度指标、规格,并结合产品的用途、特点和测绘生产的实际,简要阐述精度目标的控制与实现过程,对测绘实际工作有一定的参考价值。  相似文献   

GPS RTK校准检测试验场建设的研究     

彭江华  孙忠胜  贺浩 《地理空间信息》2008,6(3):19-20

叙述了GPSRTK接收机校准检测试验场建设的方法,介绍了GPSRTK接收机校准检测的步骤,提出了GPSRTK校准检测的项目和结果判定方法,为未来的GPSRTK国家检定规程的出台做了有益地探索。  相似文献   

QuickBird影像制作1：10000DOM方法探讨   总被引：1，自引：0，他引：1  

曹立  刘伟  周靖  翟黎明 《地理空间信息》2008,6(3):7-9

随着卫星遥感影像数据更加广泛地应用于测绘,针对QuickBird影像制作1：10000 DOM的方法,从正射纠正的三种不同方式进行了实验和探讨,分析了利用外业控制点或者在原有DRG、DOM上选取控制点制作DOM的方法、精度、工作量,总结提出了方便、快捷、实用的工作模式。  相似文献   

应用GPS数据与重力数据确定大地水准面     

于小平  张廷玉  刘财  陈增宝  许惠平  庞贺民 《吉林大学学报(地球科学版)》2008,38(5)

作为GPS/重力边值问题理论及方法的应用,在对GPS/重力方法确定(似)大地水准面的原理进行简要介绍与分析的基础上,利用收集到的N区的600个GPS/重力数据和48个高精度GPS水准数据,计算出该区域的(似)大地水准面。通过拟合法和系统差直接改正法进行的精度分析表明,应用GPS/重力数据结合水准方法确定的该地区(似)大地水准面的精度达到厘米级精度。  相似文献