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141.
基于GIS和生态位适宜度模型的园地适宜性评价——以湖北宜昌市夷陵区为例 总被引:2,自引:0,他引:2
生态位适宜度是对经典生态位理论和方法的深化与发展,在合理优化和发挥作物、环境最大共生效应,及农业结构调整和布局中具有重要的理论和实际意义。以宜昌市夷陵区园地为研究对象,将生态位适宜度模型引入到适宜性评价研究中,构建了5个因素12个因子的指标体系并提出了语言型、阈值型和空间型指标的量化方法,采用加权求和与限制因子模型对各评价单元柑橘的生态位适宜度值及限制因子进行了定量分析。结果表明:研究区生态位适宜度值整体较高,最大值达0.893,生境条件基本能满足柑橘的生长发育需求;园地适宜性评价结果以2级为主,所占面积达41.34%,1级地也达到21.58%;限制该地区园地生产潜力的生态因子主要为:土壤质地、冷月平均气温和道路通达度。同时,丰富了土宜评价的理论和方法体系,能直接指导农业生产实践、促进园地的合理开发利用与管理 相似文献
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现行的泥石流总量计算方法普遍存在计算参数较难获取或难以精确获取的问题,加上汶川地震灾区沟谷内分布大量的由崩塌、滑坡体等形成的固体松散物质;所以多数泥石流总量计算公式在汶川震区存在局限性.参考适用于以崩塌、滑坡体为主要物源的泥石流总量计算公式;分析研究区范围内地形地貌发育状态与降雨因素及其地质条件之间的影响关系;将地貌指数(Strahler积分)应用于泥石流总量计算,尝试解决缺乏降雨数据情况下泥石流总量计算问题.根据“8.13”四川清平群发性泥石流数据初步回归分析得到适合于汶川震区的泥石流总量计算模型. 相似文献
144.
People growing crops in kitchen gardens eat locally self-produced food and are the subject of growing attention as the potential for a more sustainable development. A survey was carried out in two provinces in northern Italy to gather information on the consumption of local horticultural products, peoples’ expectations of authorities in the case of a nuclear accident and peoples’ behaviour in the absence of official information. Results show that up to 70% of the owners of kitchen gardens possess diets comprised of more than 60% of self-produced vegetables and can be regarded as particular groups of population. In the case of a dispersion of radioactive material, the local population would take advantage of official information on preventive measures to protect farms and local crops from contamination. Results of the survey show differences in the attitude of the population due to age, gender and past experience. 相似文献
145.
Testing and Improving Temperature Thresholds for Snow and Rain Prediction in the Western United States 下载免费PDF全文
Seshadri Rajagopal Adrian A. Harpold 《Journal of the American Water Resources Association》2016,52(5):1142-1154
The phase of precipitation at the land surface is critical to determine the timing and amount of water available for hydrological and ecological systems. However, there are few techniques to directly observe the precipitation phase and many prediction tools apply a single temperature threshold (e.g., 0°C) to determine phase. In this paper, we asked two questions: (1) what is the accuracy of default and station optimized daily temperature thresholds for predicting precipitation phase and (2) what are the regions and conditions in which typical temperature‐based precipitation phase predictions are most suited. We developed a ground truth dataset of rain vs. snow using an expert decision‐making system based on precipitation, snow depth, and snow water equivalent observations. This dataset was used to evaluate the accuracy of three temperature‐threshold‐based techniques of phase classification. Optimizing the temperature threshold improved the prediction of precipitation phase by 34% compared to using 0°C threshold. Developing a temperature threshold based on station elevation improved the error by 12% compared with using the 0°C temperature threshold. We also found the probability of snow as a function of temperature differed among ecoregions, which suggests a varied response to future climate change. These results highlight a current weakness in our ability to predict the effects of regional warming that could have uneven impacts on water and ecological resources. 相似文献
146.
近50年鄱阳湖五大流域降水变化特征研究 总被引:16,自引:1,他引:15
基于鄱阳湖流域在江西省内部分对应的79县市气象站1960~2006年逐日降水观测资料,采用线性回归的方法分别研究五大流域的年降水量、降水日数、暴雨日数等3要素的变化趋势,并用Mann法进行了变化趋势的显著性检验,用距平与均方差之比达到15和20作为气候异常检验指标,对各流域的各时间序列进行了异常检验,采用了Mann Kendall法对各时间序列进行突变检测。结果表明:(1)各流域的年降水量变化趋势基本一致,年降水量与年暴雨日数密切相关;饶河流域强降水事件较多,降水强度大,赣江中游流域降水时间分布相对较均匀,强降水事件较少;(2)各流域年降水量、暴雨日数总体呈波动上升趋势,20世纪90年代以来暴雨日数异常偏多的概率最大;(3)年降水日数以20世纪80年代中期为界,之前呈波动上升趋势,之后呈波动下降趋势,2002年至今各流域降雨日数明显偏少;(4)各流域的年降水量、降水日数、暴雨日数均未出现趋势性的突变;(5)近50年来鄱阳湖流域降水时间分布不均的情况加剧,旱涝灾害风险增加。 相似文献
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Demirak A 《Environmental monitoring and assessment》2007,129(1-3):189-196
In this study, the chemical composition of the rainwater in Yatağan, which is a region surrounding a coal power plant was
investigated from February to April 2002. Rainwater samples were obtained from Yatağan, located northwest of Muğla City in
Turkey. pH values and concentrations of major ions (Ca2+, Na+, K+, , , ) in the rainwater samples were analyzed. The pH varied from 5.1 to 7.9 with an average of 6.7 which was in alkaline range
considering 5.6 as the neutral pH of cloud water in equilibrium with atmospheric CO2. In the total of 30 rain events, only three events were observed with water in the acidic range (<5.6), which occurred after
continuous rains. The equivalent concentration of components followed the order: Ca2+ > > Na+ > > > K+ > H+. The anion and cation concentrations in the rainwater samples showed a high sulphate concentration (131 μEq/l), as well as
high sodium (40 μEq/l) and calcium (298 μEq/l) concentrations. These values indicate that one probable source of the high
sodium concentration is fly ash, after the coal burning process and the power plant can be effective on level concentrations in rainwater. In addition, the dust-rich local and surrounding limestone environment might have caused the
high concentration of Ca2+ in rainwater of the Yatağan Basin. Due to a large contribution of these cations to the sulphate neutralization action, the
rainwater of this region displays only a moderate acidity, which does not cause significant environmental impact. 相似文献
150.