面雨量不均对GIUH非线性改正探讨     

王煌赵会强  林隆钊孙春鹏 《水文》2004,24(6):14-16

地貌单位线(GIUH)基于流域地貌特征和概率方法，在我国许多地区得到广泛应用。针对面雨量分布不均问题，通过分析初始概率的变化，考虑GIUH的非线性改正，并用实际资料进行了验证。  相似文献   

Coastline configuration and geomorphologic development mode of arc-shaped coast in South China   总被引：1，自引：0，他引：1  

Dai Zhijun  Li Chunchu 《地理学报(英文版)》2004,14(4):473-480

1IntroductionArc-shaped bays are quite common on exposed sediment coast in South China, where the crenulate-bay beaches occur with the presence of two consecutive headlands and a predominant wave approach oblique to the alignment of the upcoast and downcoast headlands (Yasso, 1965). Oblique persistent swell striking a shoreline transports sediment alongshore and sculptures a coast into arc-shaped beaches. The shoreline of beach appearance mainly consists of straight segment and shadow segment…  相似文献   

Automatic Road Change Detection and GIS Updating from High Spatial Remotely-Sensed Imagery     

ZHANGQiaoping IsabelleCouloigner 《地球空间信息科学学报》2004,7(2):89-95

This paper presents a tramework for road network change detectlon In order to upctate the Canadian National Topographic DataBase (NTDB). The methodology has been developed on the basis of road extraction from IRS-pan images (with a 5.8 m spatial resolution) by using a wavelet approach. The feature matching and conflation techniques are used to road change detection and updating. Elementary experiments have showed that the proposed framework could be used for developing an operational road database updating system.  相似文献   

Controlling factors of gullying in the Maracujá Catchment,southeastern Brazil     

L. de A. P. Bacellar  A. L. Coelho Netto  W. A. Lacerda 《地球表面变化过程与地形》2005,30(11):1369-1385

Hundreds of gullies (‘voçorocas’) of huge dimensions (up to 400–500 m long, 150 m wide and 50 m deep) are very common in the small Maracujá Catchment in southeastern Brazil. These erosional features, which occur with an uneven intensity throughout the area, started due to bad soil management practices at the beginning of European settlement, at the end of the 17th century, and nowadays are still evolving, but at a slower rate. As surface soils are usually very resistant to erosion, the outcrop of the more erodible basement saprolites seems to be an essential condition for their beginning. An analysis of well known erosion controlling factors was performed, aiming to explain the beginning and evolution of these gullies and to understand the reasons for their spatial distribution. Data shows that geology and, mainly, geomorphology are the main controlling factors, since gullies tend to be concentrated in basement rock areas with lower relief (domain 2) of Maracujá Catchment, mainly at the fringes of broad and flat interfluves. At the detailed scale (1:10 000), gullies are more common in amphitheatre‐like headwater hollows that frequently represent upper Quaternary gullies (paleogullies), which demonstrate the recurrence of channel erosion. So, gullies occur in areas of thicker saprolites (domain 2), in places with a natural concentration of surface and underground water (hollows). Saprolites of the preserved, non‐eroded hollows are usually pressurized (confined aquifer) due to a thick seal of Quaternary clay layer, in a similar configuration to the ones found in hollows of mass movement (mudflow) sites in southeastern Brazil. Therefore, the erosion of the resistant soils by human activities, such as road cuts and trenches (‘valos’), or their mobilization by mudflow movements, seem to be likely mechanisms of gullying initiation. Afterwards, gullies evolve by a combination of surface and underground processes, such as wash and tunnel erosion and falls and slumps of gully walls. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

The data‐driven approach as an operational real‐time flood forecasting model     

Phuoc Khac‐Tien Nguyen  Lloyd Hock‐Chye Chua 《水文研究》2012,26(19):2878-2893

Accurate water level forecasts are essential for flood warning. This study adopts a data‐driven approach based on the adaptive network–based fuzzy inference system (ANFIS) to forecast the daily water levels of the Lower Mekong River at Pakse, Lao People's Democratic Republic. ANFIS is a hybrid system combining fuzzy inference system and artificial neural networks. Five ANFIS models were developed to provide water level forecasts from 1 to 5 days ahead, respectively. The results show that although ANFIS forecasts of water levels up to three lead days satisfied the benchmark, four‐ and five‐lead‐day forecasts were only slightly better in performance compared with the currently adopted operational model. This limitation is imposed by the auto‐ and cross‐correlations of the water level time series. Output updating procedures based on the autoregressive (AR) and recursive AR (RAR) models were used to enhance ANFIS model outputs. The RAR model performed better than the AR model. In addition, a partial recursive procedure that reduced the number of recursive steps when applying the AR or the RAR model for multi‐step‐ahead error prediction was superior to the fully recursive procedure. The RAR‐based partial recursive updating procedure significantly improved three‐, four‐ and five‐lead‐day forecasts. Our study further shows that for long lead times, ANFIS model errors are dominated by lag time errors. Although the ANFIS model with the RAR‐based partial recursive updating procedure provided the best results, this method was able to reduce the lag time errors significantly for the falling limbs only. Improvements for the rising limbs were modest. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

地表覆盖遥感产品更新完善的研究动向     

陈军  张俊  张委伟  彭舒 《遥感学报》2016,20(5):991-1001

近年来,多尺度地表覆盖遥感产品的不断涌现,为环境变化研究、地球系统模拟、地理国(世)情监测和可持续发展规划等提供了重要科学数据。为更好地满足广大用户日益增长的应用需求,应对地表覆盖遥感产品进行持续更新完善,保持其时效性、增强时序性、丰富多样性。针对大面积地表覆盖遥感产品更新完善所面临的主要问题,介绍和评述了国内外有关研究动向,包括影像与众源信息相结合的更新、数据类型细化与完善、地表覆盖真实性验证,并作了简要展望。  相似文献   

一幅新的第四纪地质及地貌图的编制——以宁夏与山东为例          下载免费PDF全文

闵隆瑞  王永  王成  许克民  庞健峰  迟振卿  董进 《中国地质》2016,(3):1026-1032

为了更好地与生态环境及灾害地质紧密结合,第二代全国区域地质志编制项目规定第四纪地质及地貌图为必编图件之一。图件内容包括第四纪地质体的时代、成因类型、岩性和地貌成因形态组合类型、活动断裂及海侵范围等重要地质内容,同时,附第四纪地质-地貌典型剖面和重要的地貌景点。图件特点:(1)图件的地理底图是首次用数字高程模型(DEM)数据灰度图作背景;(2)第四纪地质内容与地貌成因形态类型同编为一幅图;(3)第四纪地质体的面色用成因类型色表示;(4)地貌部分划分了不同级别成因形态类型和有特色的微地貌景点。总之,图面有立体感,地形高差明显,层次分明,色彩鲜艳,是一幅崭新的图件,可供防灾治理和地质旅游参考应用。  相似文献   

Effect of loading duration on uncertainty in creep analysis of clay          下载免费PDF全文

Fang Tan  Wan‐Huan Zhou  Ka‐Veng Yuen 《国际地质力学数值与分析法杂志》2018,42(11):1235-1254

Some studies suggest that creep parameters should be determined using a greater quantity of creep test data to provide more reliable prediction regarding the deformation of soft soils. This study aims to investigate the effect of loading duration on model updating. One‐dimensional consolidation data of intact Vanttila clay under different loading durations collected from the literature is used for demonstration. The Bayesian probabilistic method is used to identify all unknown parameters based on the consolidation data during the entire consolidation process, and their uncertainty can be quantified through the obtained posterior probability density functions. Additionally, the optimal models are also determined from among 9 model candidates. The analyses indicate that the optimal models can describe the creep behavior of intact soft soils under different loading durations, and the adopted method can evaluate the effect of loading duration on uncertainty in the creep analysis. The uncertainty of a specific model and its model parameters decreases as more creep data are involved in the updating process, and the updated models that use more creep data can better capture the deformation behavior of an intact sample. The proposed method can provide quantified uncertainty in the process of model updating and assist engineers to decide whether the creep test data are sufficient for the creep analysis.  相似文献   

市级自然资源调查监测体系构建探索——以徐州市为例     

楚亮  董士玲  付丽莉  徐雷 《中国地质调查》2021,8(3):106-112

自然资源调查是实现自然资源统一管理的重要前提和基础性工作。本文通过对自然资源分类体系、调查方案和数据库组织的研究,构建了以第三次国土调查和各类专项调查数据为基础的自然资源调查监测体系,提出了新的数据库组织和更新方法,并在江苏省徐州市进行了实践验证,形成了地市级调查成果,旨在为全国范围内地级市自然资源调查工作提供参考,构建可复制、可推广的调查体系。  相似文献   

IDENTIFICATION AND ANALYSIS OF NATURAL CHANNEL NETWORKS FROM DIGITAL ELEVATION MODELS     

MARCO PILOTTI  CLAUDIO GANDOLFI  GIAN BATTISTA BISCHETTI 《地球表面变化过程与地形》1996,21(11):1007-1020

The identification and analysis of natural channel networks from digital elevation models are discussed from the point of view of their environmental applications. An interactive, graphical software package that implements some of the most widely used techniques for the automatic recognition of channel networks and for the computation of some useful geomorphologic indices and functions is presented.  相似文献