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161.
城市河流水利风景资源开发研究 总被引:1,自引:1,他引:1
城市河流水利风景资源开发具有积极的现实意义,是当地城市旅游的重要组成部分之一。在对水利风景资源进行分类的基础上,构建了城市河流水利风景资源开发评价体系。以广东省肇庆市西江三峡为案例,进行了城市河流水利风景资源开发实证研究。 相似文献
162.
Remote sensing is a fundamental tool for the analysis of spatial and temporal trends in lake ecosystems. A major challenge in using these approaches is determining the possible influence of reflectance from submerged vegetation or the lake bottom. In the present study, we examine the water leaving radiance measured in a large number of sites in Taihu Lake, a large shallow lake in southeast China. Due to the high concentrations of suspended sediment and phytoplankton biomass, a majority of the lake can be considered optically deep (i.e. bottom reflectance could be ignored). However, optically shallow waters were present in the shallow bays on the eastern side of the lake. In these areas, submerged vegetation was present. To explore the contribution of the lake bottom and submerged vegetation on remotely sensed reflectance, we compared two modeling approaches (Hydrolight and the LEE). The results show that differences in optical and physical characteristics of the lake bottom strongly influence the spectral characteristics of the measured reflectance. The resulting impact on the estimate of chlorophyll-a concentrations was tested using datasets with and without sites where bottom effects may occur. A significant improvement in the predictive capacity of the reflectance based estimated of phytoplankton biomass was made when areas with bottom influences were removed from the calibration procedure. 相似文献
163.
Chinook salmon (Oncorhynchus tshawytscha) in Lake Huron consist of wild and hatchery-reared fish distributed among several populations. This study tested whether otolith chemistry can be used to identify the natal origin of Chinook salmon in this system. Concentrations of nine elements (Mg, K, Mn, Fe, Zn, Rb, Sr, Ba, and Pb) in the otoliths of Chinook salmon juveniles from 24 collection sites (17 streams and 7 hatcheries) around Lake Huron were analyzed using laser-ablation inductively-coupled mass spectrometry. Differences in otolith chemistry were found between rearing environments (wild and hatchery), among geological regions (Precambrian, Ordovician, Silurian, Devonian, and Carboniferous), and among collection sites. Discriminant function analysis showed high classification accuracies of juveniles to their rearing environment (wild versus hatchery, 82%), geological region (84%), and collection site (87%) of origin. With these values, there is excellent potential for otolith chemistry to be used to predict the natal origin of adults, and thus inform research and management of Chinook salmon in Lake Huron. 相似文献
164.
To determine whether large wood (LW, ≥1‐m length, ≥10‐cm diameter) plays a role in Chinook salmon (Oncorhynchus tshawytscha) redd (i.e. egg nest) placements in a regulated, Mediterranean‐climate, medium‐sized river (where channel width is less than the upper quartile of length of potential instream wood pieces), characteristics of 527 large wood pieces, locations of 650 redds, and mesohabitat delineations (riffle, run, glide, pool) were collected during a spawning season along a 7.7 km reach directly below Camanche Dam on the Mokelumne River, CA. LW was regularly distributed across the study reach an average 70 LW pieces km‐1. Some LW clustering was evident at islands and meander bends. Spawners built 85% of redds within one average channel width (31 m) of LW. Spawners utilized LW within a 10 m radius 36% of the time in the upper 3 km rehabilitated reach, and 44% of the time in the lower 4.7 km marginal habitat reach. A greater percentage of LW was utilized in riffles in the upper 3 km reach where 90% of redds were built, while a larger percentage of spawners used LW in riffles in the lower 4.7 km reach. LW‐redd interactions occurred at greater rates than by random chance alone in the lower 4.7 km reach, which implies that LW aids spawning in marginal habitats. River managers and salmonid spawning habitat rehabilitation (SHR) projects should take LW additions into consideration as an important component of river rehabilitation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
165.
Analysis of black water aggregation in Taihu Lake 总被引:1,自引:0,他引:1
Black water aggregation (BWA) in Taihu Lake is a disaster for the lake environment. It is a phenomenon resulting from water environmental deterioration and eutrophication caused by accumulation of pollutants in the lake, according to research on the water quality, pollutants of BWA, and occurrence mechanisms of BWA. Dead algae are the material base of BWA, the polluted sediment is an important factor for the formation of BWA, and hydrological and meteorological conditions such as sun light, air temperature,... 相似文献
166.
167.
基于日本2005年针对中小河流制定的洪水淹没风险区域图制作指南,对日本中小河流洪水
淹没区域风险图的制作进行了较详细的介绍,其中归纳了其所需资料、洪水淹没分析方法和淹没区域
风险区域图的具体制作,对我国山区河流洪水风险区域图编制具有重要的借鉴意义。 相似文献
168.
河湖功能区划是加强流域管理的一项新举措.对于自然属性和社会经济属性较为均一的区域,河流功能难以按其沿河道的空间分异性进行划分.基于这一特点,提出了区域层面河湖功能区划的概念,建立了由因素层、区划层和功能层构成的区域层面河湖功能区划体系,并提出了区划的方法和程序.进行了太湖流域区域层面河湖功能区划实践,将该区域共划分为3类13个河湖功能区,给出了每一区的功能定位和管理措施.结果表明,区域层面河湖功能区划的概念与方法合理可行,为平原河网区的河湖管理提供了一个新途径. 相似文献
169.
170.
Water holes characteristic of the middle sections of fragmented, lowland, semi‐arid rivers act as refuge areas for biota during low flow and drought. However, river regulation and catchment development has altered the hydrological and nutrient status of these refuges. A series of artificial ponds were used to imitate these habitats and experiments were designed to determine whether stochastically fluctuating water levels with maximum amplitude of 65 cm would counteract the influence of nutrient enrichment on the growth of three key aquatic plant species. The species (Cyperus gymnocaulos, Triglochin procerum and Typha domingensis) represented different functional groups that inhabit contrasting zones across the elevation gradient. Each species was grown at a different elevation within the experiment reflecting each species' elevation preference and supplied with the equivalent to 0, 10 or 30 g N m?2 year?1. Under a static water regime nutrient enrichment doubled the total biomass of all three species. In contrast under a fluctuating water regime, nutrient addition did not influence total biomass of either T. domingensis or T. procerum and the performance of C. gymnocaulos was reduced by ca. 30%. These data suggest that if environmental flows were managed to provide a natural stochastically fluctuating water regime, this would nullify the influence of nutrient enrichment and limit the distribution and spread of invasive species such as Typha, that exists under the current altered conditions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献