HYDROLOGIC MODELING WITH REMOTELY SENSED DATABASES1

ABSTRACT: An integrated remotely sensed database was used as the basis for a hydrologic and sediment transport modeling effort for an agricultural area of western Puerto Rico. Classified spectral images of airborne radiance data provided ground cover information and were used in conjunction with topographic and soils data to guide model construction and provide input to the water balance and sediment yield simulations. Runoff and sediment discharge from hydrologically homogeneous regions were routed through the drainage network and combined at the basin outlet. The model was used to simulate four years of observed sediment discharge from the basin. Relative contributions to the total sediment yield of forested and agricultural areas were determined and compared.     

遥感在滑坡调查中的应用

本文介绍了遥感技术在滑坡的现状调查和防治中的应用.提出了航天、航空遥感图像上滑坡现状、规模、易滑地点、稳定性评价等的直接和间接判读标志;并展望了遥感技术在滑坡动态监测中的应用前景.     

Investigation of sustainable energy alternatives for powering remote communities in northern Ontario

ABSTRACT

Remote communities in the North of Ontario survive in isolation as their proximity to the southern industrial sector of the province limits their accessibility to the major grid. The lack of grid connection has led to antiquated methods of power generation which pollute the environment and deplete the planet of its natural resources. Aside from the primary means of electricity generation being by diesel generators, generation infrastructure is deteriorating due to age and the stagnation of the power supply has led to communities facing load restrictions. These challenges may be resolved by introducing clean energy alternatives and providing a fuel blend option. The primary energy sources investigated in this research are solar, wind, and hydrogen. To assess the viability of these energy production methods in Northern communities, an exergy analysis is employed as it utilizes both the first and second law of thermodynamics to determine systems’ efficiency and performance in the surroundings. Local weather patterns were used to determine the viability of using wind turbines, solar panels and/or hydrogen fuel cells in a remote community. Through analysis of the resources available at the community, it was determined that the hydrogen fuel cell was best suited to provide clean energy to the community. Wind resulted in low efficiency in the range of 2–3% while solar efficiencies resulted in ranges of 18 – 19%, as the seasonal variations between the three years is not very great. Due to the higher operating efficiencies observed of the PV panels it would also be an attractive alternative to diesel generators however, the lack of consistent operation above 30% efficiency throughout the year, resulted in hydrogen fuel cells being a better alternative.     

Developing sinks for CO<Subscript>2</Subscript> through forestation of temperate coastal barriers: an environmental business

Since the 1940s, some sectors of the sand dune barriers of Buenos Aires Province have been forested to fix the sand in the neighborhoods of resort villages. Man took advantage of the maritime climate and the shallow groundwater to introduce pine forests. Today, these forests reach more than 20 m in height and have developed soils of more than 0.05 m in thickness on former arid sands. Field data were referred to Landsat (TM) composite and Normalized Difference of Vegetation Index, NDVI, images to calculate forest density and covered area. Considering published tables of wood density for each species, the amount of total carbon storage was estimated on 318 t C ha^-1 (Mg=10⁶ g) in biomass and 86 t C ha^-1 in soils. The three areas analyzed at Miramar, Necochea and Claromecó have captured 658,868 t of carbon in the last 50 years. It is estimated that 150,000,000 t C could be sequestered within temperate dune barriers of Argentina, Uruguay and Brazil. Besides this ecological point of view, there is an important socio-economic factor that cannot be excluded.Presented at and revised subsequent to the 4th LOICZ Open Science Meeting, Bahía Blanca, Argentina. October 1999.     

Use of Remote Sensing Techniques to Determine the Effects of Grazing on Vegetation Cover and Dune Elevation at Assateague Island National Seashore: Impact of Horses

The effects of grazing by feral horses on vegetation and dune topography at Assateague Island National Seashore were investigated using color-infrared imagery, lidar surveys, and field measurements. Five pairs of fenced and unfenced plots (300 m²) established in 1993 on sand flats and small dunes with similar elevation, topography, and vegetation cover were used for this study. Color-infrared imagery from 1998 and field measurements from 2001 indicated that there was a significant difference in vegetation cover between the fenced and unfenced plot-pairs over the study period. Fenced plots contained a higher percentage of vegetation cover that was dominated by American beachgrass (Ammophila breviligulata). Lidar surveys from 1997, 1999, and 2000 showed that there were significant differences in elevation and topography between fenced and unfenced plot-pairs. Fenced plots were, on average, 0.63 m higher than unfenced plots, whereas unfenced plots had generally decreased in elevation after establishment in 1993. Results demonstrate that feral horse grazing has had a significant impact on dune formation and has contributed to the erosion of dunes at Assateague Island. The findings suggest that unless the size of the feral horse population is reduced, grazing will continue to foster unnaturally high rates of dune erosion into the future. In order to maintain the natural processes that historically occurred on barrier islands, much larger fenced exclosures would be required to prevent horse grazing.     

Monitoring Forest Carbon Sequestration with Remote Sensing and Carbon Cycle Modeling

Sources and sinks of carbon associated with forests depend strongly on the management regime and spatial patterns in potential productivity. Satellite remote sensing can provide spatially explicit information on land cover, stand-age class, and harvesting. Carbon-cycle process models coupled to regional climate databases can provide information on potential rates of production and related rates of decomposition. The integration of remote sensing and modeling thus produces spatially explicit information on carbon storage and flux. This integrated approach was employed to compare carbon flux for the period 1992–1997 over two 165-km² areas in western Oregon. The Coast Range study area was predominately private land managed for timber production, whereas the West Cascades study area was predominantly public land that was less productive but experienced little harvesting in the 1990s. In the Coast Range area, 17% of the land base was harvested between 1991 and 2000. Much of the area was in relatively young, productive-age classes that simulations indicate are a carbon sink. Mean annual harvest removals from the Coast Range were greater than mean annual net ecosystem production. On the West Cascades study area, a relatively small proportion (< 1%) of the land was harvested and the area as a whole was accumulating carbon. The spatially and temporally explicit nature of this approach permits identification of mechanisms underlying land base carbon flux. Published online     

武汉湖泊富营养化遥感调查与评价

利用武汉东湖各子湖多年可靠的地面监测资料和1999年9月Landsat-7的TM各波段的卫星遥感数据,建立了各子湖的营养状态指数与TMb5图像上的灰度值之间的线性关系模型,并运用该模型对武汉各湖泊进行富营养化评价。同时基于地面监测资料,用日本学者相崎守弘提出的修正富营养化指数法对武汉主要湖泊的富营养化程度进行评价。两种方法评价结果都显示,武汉大多数湖泊呈富营养化状态,一些湖泊已接近甚至达到极富营养化。在用两种方法同时评价的十个湖泊中,有四个湖泊的评价结果完全一致,其余的六个湖泊富营养化程度只相差一个级别。两种方法评价结果存在差异,可能有以下三个原因;（1）遥感方法反映了是图像所在时段的某一个区域上的平均值,营养化指数法反映的是若干个采样站的年平均值;（2）TM图像的获取时间比地面监测的时间晚;（3）遥感影像可能受到云、泥沙等悬浮物、高等水生植物以及湖泊水深等的影响。遥感评价结果与地面监测结果基本一致,利用遥感进行湖泊水体富营养化监测价是可行的,有效的,利用该方法可进行大范围的湖泊富营养化调查评价。     

Use of chemical cues in detection of conspecific predators and prey by newts, <Emphasis Type="Italic">Notophthalmus viridescens</Emphasis>

Summary. Detection of heterospecific predators and prey via chemical cues is well known, but only a few studies have examined the potential for such discrimination in cannibalistic systems. In newts, Notophthalmus viridescens, adults are opportunistic predators of conspecific larvae. I used a laboratory bioassay to determine whether larvae and adults distinguish between chemical stimuli from members of the different age classes. Larvae distinguished between chemical stimuli from larvae and adults by decreasing their activity only following exposure to stimuli from adults. Decreased activity is consistent with an antipredator response in many prey species, including larval newts. In contrast, adults increased their activity and increased time spent in open areas in response to stimuli from larvae, but not to stimuli from adults. Increased activity is consistent with a feeding response; adults also showed increased activity and increased time in open areas in response to chemical stimuli from familiar heterospecific prey (brine shrimp). The proximate cue that allowed the newts to distinguish between the different age classes is not associated with short-term dietary differences because all stimulus animals were fed the same prey. Stimulus strength was controlled by diluting the stimulus solutions according to the volume of the stimulus animal. Therefore, there appear to be intrinsic differences in the chemical signatures of larval and adult newts.     

印度大地震的可预警信息研究

20 0 1 0 1 2 6印度西北部的普杰地区发生了 7 8级强烈地震。对这次强震事件 ,利用卫星遥感监测地气系统射出长波辐射的数值产品资料 ,分析了以普杰为中心整个西亚范围内 ,事件发生前后共计 6个月的月平均辐射场的分布特征及其演变过程。发现自震前 2个月至震时当月 ,普杰地区始终是一个辐射 (热 )场的高值中心 ,震后明显消散。据此认为印度大地震有可识别的预警信息 ,提出利用卫星遥感技术及其产品 ,有可能为“突破”短临地震预报开拓出一种新的预测技术生长点     

基于3S技术的震害快速评估

地震是人类面临的重大自然灾害之一，破坏性地震发生后，对震害的快速评估有利于政府及有关部门对灾情迅速做出应急反应，实施救援。地理信息系统（GIS）、遥感（RS）和全球定位系统（GPS）合称为3S技术。随着计算机技术和地球空间科学的发展。3S技术已逐渐应用于防灾减灾领域。探讨了应用3S技术替代传统的经验性估计决速评估震害的技术路线、方法和前景。首先，归纳了目前防震减灾信息及辅助决策系统建设取得的成绩和存在的问题。通过两个破坏性地震的震害实例，说明了应用基于GIS的系统快速评估震害的可能性和有待重点解决的问题。然后。通过新疆一次地震的遥感图像的变化检测，展示了震害快速评估中借助遥感数字图像处理技术的前景。在上述综合分析的基础上，讨论了三者结合的重要性、潜在功能和优点。