基于GIS的路面积雪灾害风险分析与区划研究

以宁夏高速公路为对象,利用1981—2018年25个常规气象站观测资料及交通相关数据资料,基于GIS、AHP等方法,从致灾因子的危险性、孕灾环境的敏感性、承灾体的易损性三方面进行高速公路路面积雪灾害风险分析与区划研究。结果表明:全区年平均积雪日数在6.5~86.7d,年平均降雪日数在10.3~64.5d,最大积雪深度在8~35cm,自南向北减少(浅),南部山区明显多(深)于北部地区。路面积雪灾害主要出现在冬季、初春和晚秋,大到暴雪级的路面积雪主要出现在秋冬转换的10~11月和冬春交替的3~4月。风险分析与区划研究结果表明,高风险区位于福银高速(G70)、青兰高速(G22)六盘山区东南麓区段;较高风险区位于福银高速(G70)固原市原州区段、青兰高速(G22)固原市隆德西段段、固西高速、彭青高速路段;同心以北的银川市、石嘴山市、吴忠市各路段风险总体较低。     

Relationships between dissolved and particulate carbohydrate temporal patterns and mucilaginous aggregates formation: evidences from time series analysis and biochemical composition of aggregates

A 3-year monitoring of dissolved and particulate carbohydrate concentrations in four transects located in the Adriatic and Tyrrhenian Seas was performed in order to get information on the role played by carbohydrates in the mucilage formation in these areas. The application of time series analysis pointed out that the concentration of dissolved carbohydrates does not vary significantly in coincidence of the mucilage appearance showing an almost constant state with respect to time. In contrast, wider temporal variations of carbohydrate amounts, either increase or decrease, were observed when mucilages were lacking or reduced. This almost constant state of carbohydrate amounts observed in presence of mucilages that we define 'steady state' could be associated to an alteration of the complex chemical equilibrium between synthesis and degradation (either hydrolysis or oxidation) reactions of the organic polymers which are typical of the humification processes in the marine environment. The results of this study suggest that the monitoring of carbohydrates can represent an useful tool for the comprehension of the most relevant phenomena of mucilage appearance in the Northern Adriatic Sea.     

藏北高原土壤温度异常变化及其与雪灾关系初析

通过对ＧＡＭＥ－Ｔｉｂｅｔ野外工作期间所得藏北高原一个年周期的土壤温度资料的初步分析,发现藏北高原１９９７￣１９９８年冬半年土壤日温差的分布存在明显的异常现象;指出了这种异常现象的发生可能与藏北高原１９９７年冬天的特大雪灾有关。从浅层土壤日温差的异常变化,定性地说明了藏北高原１９９７￣１９９８年冬半年不同地点雪灾的严重程度,但由于受资料的限制,目前尚无法进行定量的评估。     

气候环境实验室降雪环境模拟技术研究

目的建立实验室降雪环境模拟技术,为飞机等武器装备降雪环境适应性试验验证提供技术支持。方法基于对自然降雪和实验室模拟降雪机理的对比与分析,提出影响实验室内模拟降雪的关键因素,并结合理论分析和试验研究,得出实验室内模拟降雪环境的冷负荷计算方法和最优成雪的水粒直径。结果建立了实验室降雪环境模拟技术,采用该降雪环境模拟技术,降雪强度及降雪品质均满足飞机等武器装备降雪环境适应性试验验证需求。结论建立的降雪环境模拟技术切实有效,可用于实验室飞机等武器装备降雪环境适应性试验研究。     

A COMPARISON OF GEOSTATISTICAL METHODOLOGIES USED TO ESTIMATE SNOW WATER EQUIVALENT1

ABSTRACT: The need to monitor and forecast water resources accurately, particularly in the western United States, is becoming increasingly critical as the demand for water continues to escalate. Consequently, the National Weather Service (NWS) has developed a geostatistical model that is used to obtain areal estimates of snow water equivalent (the thtal water content in all phases of the snowpack), a major source of water in the West. The areal snow water equivalent estimates are used to update the hydrologic simulation models maintained by the NWS and designed to produce extended streamflow forecasts for river systems throughout the United States. An alternative geostatistical technique has been proposed to estimate snow water equivalent. In this research, we describe the two methodologies and compare the accuracy of the estimates produced by each technique. We illustrate their application and compare their estimation accuracy using snow data collected in the North Fork Clearwater River basin in Idaho.     

SNOWPACK CHANGES RESULTING FROM TIMBER HARVEST INTERCEPTION,REDISTRIBUTION, AND EVAPORATION1

ABSTRACT: Three processes were examined as causing snowpack changes in forest clearings. Two of the three contribute to increases and one counteracts by reducing snowpack. The two that increase snowpack are redistribution and decreased loss to interception. Snow evaporation from a clearing counteracts snowpack increases. Research has indicated that as vegetation density increases, so too does the loss to interception. As snow in the canopy reaches the limit that the canopy can hold (the threshold amount) evaporation increases. Aerodynamics of the forest canopy were studied as well. As timber is cut, wind patterns are disturbed, creating disruptions in the wind velocity gradient depositing snow in openings. This redistribution leads to an increased snow water equivalent and augments runoff. Snow evaporation was shown to increase proportionally with opening size. Evaporation offsets the water yield gains derived from forest cut. It was found that this offset is inclusive to the measurements of water yield changes in experimental forests. An optimal size of harvest block may be five tree heights in width as suggested by numerous studies.     

WATER SUPPLY FORECASTING IN REAL-TIME1

ABSTRACT: A strategy is developed for making seasonal water supply forecasts in real time. It links the traditional regression based forecasting techniques to real-time data acquired by systems such as the Soil Conservation Service SNOTEL and the U.S. Bureau of Reclamation Hydromet networks. The concept is based on interpolating between the forecast values obtained by using real-time data in the forecast equations that bracket the real time. Different interpolation procedures were examined and the procedure for calculating confidence intervals about the forecast estimates is developed. The entire conceptual procedure is demonstrated using data from the Reynolds Creek, Idaho, experimental watershed maintained by the USDA-ARS Northwest Watershed Research Center in Boise, Idaho.     

PREDICTING WILDERNESS SNOW WATER EQUIVALENT WITH NONWILDERNESS SNOW SENSORS1

ABSTRACT: Ten pairs of snow sensors were analyzed to investigate the feasibility of predicting snow water equivalent at high-elevation, telemetered snow sensor sites from lower-elevation sensors. The need for this analysis stems from an agreement between the California Department of Water Resources and the USDA Forest Service to temporarily allow snow sensors in California's wilderness areas so that a predictive relationship can be developed. After 10 or 15 years, the agreement calls for the sensors to be removed. Initial efforts to a priori select sensor pairs were based on proximity, colocation within a basin, and annual precipitation amount, but regression yielded poor fits (R² < 0.65) and high standard errors in eight of the ten cases. Analysis of the results suggested that eleva-tional similarity was the most important selection criteria, and that all available sensors near the target site should be analyzed via a regression screening. Using elevation for selection and the regression screening, five sensors that initially had poor fits were reanalyzed. Each of the five sensors was paired with between two and five new sensors, and R² values improved between 27 and 46 percent. Various data smoothing and editing algorithms were evaluated, but they rarely resulted in improved fits.     

川西高原积雪稳定性分布格局及其驱动因子分析

在气候变暖的背景下,川西高原积雪出现剧烈变化,对地区水循环过程、生态系统以及社会经济带来严重影响。基于MODIS积雪遥感数据以及环境因子数据,通过构建稳定度指标及最大熵模型探讨川西高原不同稳定性积雪的空间分布格局及其驱动因子,并对不同稳定性积雪的适宜分布区进行分析,结果表明：（1）川西高原大多数地区的积雪属于高度不稳定性积雪,其他稳定性积雪在川西高原分布面积较小;（2）川西高原积雪在海拔越高的地方稳定性越好;（3）不同稳定性积雪分布格局的影响因素存在差异,海拔和降水是影响稳定性积雪分布格局的主要因素。     

西藏那曲牧区雪灾区域危险度的模糊综合评价研究

在野外调查和分析的基础上,选取10月至次年5月的平均气温和平均降水,以及稳定的积雪日数、平均积雪深度、草场现有载畜量、冷季草地超载比例、冬储草量等7个因子为那曲地区雪灾区域危险度的评价因子,将模糊综合评价的数学模型应用于雪灾区域危险度的评判。以西藏那曲地区的5个县为例,具体介绍了雪灾区域危险度模糊综合评价的方法和步骤。