Study of Dongting Lake area variation and its influence on water level using MODIS data / Etude de la variation de la surface du Lac Dongting et de son influence sur le niveau d’eau,grâce à des données MODIS

Abstract

Abstract MODerate-resolution Imaging Spectroradiometer (MODIS) is a new generation remote sensing (RS) sensor and its applications in hydrology and water resources have attracted much attention. To overcome the problems of slow response in flood disaster monitoring based on traditional RS techniques in China, the Flood Disaster Monitoring and Assessing System (FDMAS), based on MODIS and a Geographic Information System (GIS), was designed and applied to Dongting Lake, Hunan Province, China. The storage curve of Dongting Lake for 1995 was obtained using 1:10 000 topographic map data and then a relationship between water level at the Chenglingji hydrological station and lake area was derived. A new relationship between water level and lake area was obtained by processing MODIS images of Dongting Lake from April 2002 to April 2003 and the influence of lake area variation on water level was analysed with the 1996 flood data. It was found that the water level reduction reached 0.64 m for the 1996 flood if the original lake area curve was replaced with the area curve of 2002. This illustrates that the flood water level has been considerably reduced as a result of the increased area of Dongting Lake since the Chinese Central Government’s ?return land to lake? policy took effect in 1998.     

A dual-porosity model for nitrogen leaching from a watershed/Un modèle à double porosité pour le lessivage de l’azote d’un bassin versant

Abstract

Abstract The MASONW (MACRO + SOILN + Watershed) model describing nitrogen leaching in watersheds was developed and tested. The model is based on the MACRO and SOILN models. The dual-porosity model MACRO simulates water flow on the field scale. The SOILN model describes turnover and leaching of nitrogen. Two main features of a watershed have been added into these two models: (a) the existence of a river system, and (b) variable thickness of the aeration zone within a watershed. Good agreement between the output of the MASONW model and observed data for water discharge and nitrate concentrations were achieved in the Odense watershed (496 km²) in Denmark.     

Pulse generation models for daily intermittent streamflows / Modèles de génération d’impulsions pour des débits journaliers intermittents

Abstract

Abstract Generating pulses and then converting them into flow are two main steps of daily streamflow generation. Three pulse generation models have been proposed on the basis of Markov chains for the purpose of generating daily intermittent streamflow time series in this study. The first one is based on two two-state Markov chains, whereas the second uses a three-state Markov chain. The third model uses harmonic analysis and fits Fourier series to the three-state Markov chain. Results for a daily intermittent streamflow data series show a good performance of the proposed models.     

中国沿海地区灾害发生的环境和社会经济背景*

本文研究了中国沿海地区灾害发生的自然环境背景,特别讨论了地质构造因素、气候因素和地貌因素对灾害的影响.制定了孕灾环境区划,全区按地貌类型划分为北部平原和南部低山丘陵孕灾区以及10个易灾亚区.分析了灾害发生的社会经济背景,区域承灾能力和人类活动对灾害的影响.最后根据地球系统各圈层相互作用及外部强迫因子对灾害发生的影响,讨论了一般灾害的发生和发展规律.     

Spatio-temporal differentiation of landscape ecological niche in western ecological frangible region: A case study of Yan’an region in northwestern China

In this study, we attempt to put forward a conception of landscape ecological niche, enlightened by international scholars on extending the ecological niche theory from spatial niche to functional niche. That is helpful for comprehensively appraising landscape spatial patterns and ecological functions, also, presents a new method for analyzing landscape fea-tures from multidimensional aspects. The practice process is demonstrated by taking Yan’an region in northwestern China as a case. Firstly, the indices system including spatial attribute and functional attribute is established for assessing landscape ecological niche. Additionally, two-dimensional figures are drawn for comparing the spatio-temporal features of landscape ecological niche in 1987 and 2000 among the 13 administrative counties. The results show that from 1987 to 2000, towards Yan’an region, spatial attribute value of landscape ecological niche changes from 1.000 to 1.178 with an obvious increment, and functional attribute value changes from 0.989 to 1.069 with a little increment, both of which enhance the regional landscape ecological niche. Towards each county, spatial attribute value of landscape eco-logical niche increases to different extent while functional attribute value changes dissimilarly with an increment or a decrement.     

Spatio-temporal differentiation of landscape ecological niche in western ecological frangible region： A case study of Yan＇an region in northwestern China

In this study, we attempt to put forward a conception of landscape ecological niche, enlightened by international scholars on extending the ecological niche theory from spatial niche to functional niche. That is helpful for comprehensively appraising landscape spatial patterns and ecological functions, also, presents a new method for analyzing landscape features from multidimensional aspects. The practice process is demonstrated by taking Yan＇an region in northwestern China as a case. Firstly, the indices system including spatial attribute and functional attribute is established for assessing landscape ecological niche. Additionally, two-dimensional figures are drawn for comparing the spatio-temporal features of landscape ecological niche in 1987 and 2000 among the 13 administrative counties. The results show that from 1987 to 2000, towards Yan＇an region, spatial attribute value of landscape ecological niche changes from 1.000 to 1.178 with an obvious increment, and functional attribute value changes from 0.989 to 1.069 with a little increment, both of which enhance the regional landscape ecological niche. Towards each county, spatial attribute value of landscape ecological niche increases to different extent while functional attribute value changes dissimilarly with an increment or a decrement.     

长江口九段沙下段冲淤演变水动力机制分析

概述了长江口深水航道整治一期工程及工程对九段沙下段地形冲淤的影响.根据已建立的σ坐标系下三维非线性水流数学模型,用新测水文资料对模型进行验证.利用所建立的模型,结合由现场测量得到一期工程前后九段沙下段近期地形演变,数值模拟了北槽区域流通量、底层欧拉余流和北槽中下段平面水流特征,以综合分析北槽水域水动力变化对九段沙下段地形冲淤变化的影响.     

生态旅游胜地—九顶山

对九顶山的生物景观，水体景观，地质遗迹景观，天然气景观和人文景观等方面进行了详尽的描述，并划分出平水河景区，云湖景区，楠木沟景区，紫岩山景区，白云山景区，仙女洞景区和天池景区等七个景区，从科学性，美学性，文化性以及区位条件和功能方面对景观进行了评述。进而提出了开发的初步构想。     

一个世界最早光象分类体系的探讨——复原先秦“十煇”的研究

《周礼》十煇为世界最早的光象分类体系。其含义历来众说纷纭。有探讨、重建并评价的必要。本文比照历史上有影响的五家十煇定义,分析其含糊矛盾之处,提出复原十煇原义的三条原则,从而重建了十煇原义表,介绍了古代观测十煇的方法。最后对《周礼》十煇这个光象分类体系进行了评价。     

沿海渔业天气警报服务系统

本文简要地介绍了建立沿海渔业天气警报服务系统的必要性,系统的设计特点,现场试验情况以及今后建台布网的设想。特别是把短波单边带通信,地面波传播方式和双音报警技术引入天气警报服务系统,开辟了短波单边带气象通应用的新领域。