青藏高原东部牧区大—暴雪过程雪灾灾情实时预评估方法的研究

利用青藏高原东部牧区26个县气象站30a的大－暴雪过程资料,以雪灾形成的主导因子－持续积雪日数作为灾情评估的等级标准,应用逐步回归方法,建立了冬半年持续积雪日数对大－暴雪过程的累积降水量、平均气温、最大积雪深度和最低气温降温4个因子的回归方程。经F检验,所有方程的回归效果达到十分显著成显著的水平,从而建立了大－暴雪过程雪灾灾情的灾时预评估方法。通过对1996－1999年资料的对比试用,表明这种预评估方法具有较高的精度和业务化的潜力,可作为雪灾情报服务的一种手段。     

近50年来云贵高原太阳辐射变化特征及影响

到达地面的太阳辐射变化会对气候和生态环境产生较大影响。用云贵高原1961～2009年日射站辐射和气象观测资料,对多年来到达地面太阳总辐的年和季节变化趋势,及辐射变化对气候要素的影响进行了分析。结果表明：1961~1988年,总辐射呈明显下降趋势,之后发生逆转,1988~1994年总辐射呈显著上升趋势,1994年后其变化趋于缓和。总体呈现变暗－变亮－变缓的趋势。各季节总辐射变化的趋势为,秋季变化趋势极显著,春季变化的趋势显著,夏季变化的趋势较显著,冬季变化不明显。高原日照时数变化趋势与总辐射经历的变暗－变亮－变缓在时间上基本一致。总辐射变化对该地区的最高气温影响显著,但对蒸发量的影响不太明显。影响年辐射变化的各因子中,云量是影响高原总辐射变化的主要因素,相对湿度和能见度则影响较小     

青藏铁路沿线热喀斯特湖易发程度的区划评价

随着全球气候的持续转暖,青藏铁路沿线热喀斯特湖数量正在逐年增多、面积逐年增大。湖塘的形成虽然具有一定的随机性特点,但其发生的区域性和重复性特点是热喀斯特湖分布与出现的总体规律。在野外系统勘测调查的基础上,依据工程地质类比原则,结合专家打分、层次分析、信息量、统计量等模型方法,对区域内湖塘产生与发展起一定主导作用的历史因素(灾点密度、灾面密度)和基本地质环境因素(冻土类型、年均地温、植被覆盖度、土质类型、地形坡度)基于ArcGIS平台进行综合分析评价,得出楚玛尔河至风火山段青藏铁路沿线热喀斯特湖易发程度的空间分布。结果表明,占研究区总面积47.97%的高易发区占据了湖塘总数量的87.94%、总面积的91.15%,主要分布在楚玛尔河高平原、北麓河盆地和可可西里山间盆地;中易发、低易发、非易发三个区占据了研究区总面积的52.03%,却仅分布了占总数量12.06%、面积8.85%的热喀斯特湖,主要分布于可可西里山区、风火山山区及河谷地区,与2011年9月份野外考察的热喀斯特湖实际的空间分布状况保持了较好的一致性。     

进口高效菌用于青藏铁路污水处理应急保障的可行性研究

青藏铁路沿线污水处理安全运营保障体系中,应急状态下需要大量的接种备用活性污泥。在实验室研究基础上,考察了进口高效菌低温低压条件下对污染物的处理能力,最后将其应用到拉萨污水处理厂实际工程。实验室研究及实际对比实验结果表明,高效菌在低温低压下的处理性能和青藏高原实际的活性污泥性能基本相当,如与微生物固定化技术结合使用,可大大增加强化生化处理的效果。进口高效菌具有微生物活性高、培养时间短、保存携带方便,能快速提升生化系统处理能力的优点,可满足青藏线污水处理设施应急状态下处理能力快速提升和安全稳定运行的需要。     

Biophysical and anthropogenic controls of forest fires in the Deccan Plateau, India

Forest fires constitute one of the most serious environmental problems in several forested regions of India. In the Indian sub-continent, relatively few studies have focused on the assessment of biophysical and anthropogenic controls of forest fires at a landscape scale and the spatial aspects of these relationships. In this study, we used fire count data sets from satellite remote sensing data covering 78 districts over four different states of the Deccan Plateau, India, for assessing the underlying causes of fires. Spatial data for explanatory variables of fires pertaining to topography, vegetation, climate, anthropogenic and accessibility factors have been gathered corresponding with fire presence/absence. A logistic regression model was used to estimate the probability of the presence of fires as a function of the explanatory variables. Results for fire area estimates suggested that, of the total fires covering 47,043km(2) that occurred during the year 2000 for the entire Indian region, 29.0% occurred in the Deccan Plateau, with Andhra Pradesh having 13.5%, Karnataka 14.7%, Kerala 0.1%, and Tamilnadu 1.15%. Results from the logistic regression suggest that the strongest influences on the fire occurrences were the amount of forest area, biomass densities, rural population density (PD), average precipitation of the warmest quarter, elevation (ELE) and mean annual temperature (MAT). Among these variables, biomass density (BD) and average precipitation of the warmest quarter had the highest significance, followed by others. These results on the best predictors of forest fires can be used both as a strategic planning tool to address broad scale fire risk concerns, and also as a tactical guide to help forest managers to design fire mitigation measures at the district level.     

Evaluation of the MIKE SHE Model for Application in the Loess Plateau,China1

Abstract: Quantifying the hydrologic responses to land use/land cover change and climate variability is essential for integrated sustainable watershed management in water limited regions such as the Loess Plateau in Northwestern China where an adaptive watershed management approach is being implemented. Traditional empirical modeling approach to quantifying the accumulated hydrologic effects of watershed management is limited due to its complex nature of soil and water conservation practices (e.g., biological, structural, and agricultural measures) in the region. Therefore, the objective of this study was to evaluate the ability of the distributed hydrologic model, MIKE SHE to simulate basin runoff. Streamflow data measured from an overland flow‐dominant watershed (12 km²) in northwestern China were used for model evaluation. Model calibration and validation suggested that the model could capture the dominant runoff process of the small watershed. We found that the physically based model required calibration at appropriate scales and estimated model parameters were influenced by both temporal and spatial scales of input data. We concluded that the model was useful for understanding the rainfall‐runoff mechanisms. However, more measured data with higher temporal resolution are needed to further test the model for regional applications.     

Spatial Dynamics of Soil Moisture in a Complex Terrain in the Semi‐Arid Loess Plateau Region,China1

Abstract: Soil moisture is an important hydrological variable in reforestation practices in a water‐limited region of the Loess Plateau of northwestern China. The objective of this study was to quantify the spatial dynamics of soil moisture on a complex terrain. During 2004‐2006, a total of 313 sample points in two kinds of grid (2 × 2 m and 20 × 20 m) were arranged for soil moisture measurements (two soil layers: 0‐30 and 30‐60 cm) with Time Domain Reflectometry. The geostatistical properties of soil moisture patterns, the variance and correlation structure of the soil moisture, and the effects of terrain factors on soil moisture were analyzed. The results suggested that our sampling grid captured the spatial variability of soil moisture distributions for this complex terrain. Principal Component Analysis and Cluster Analysis statistics showed that soil moisture decreased as slope gradient increased; that sunny aspects (112.5°‐292.5°) had relatively lower soil moisture than did shady aspects (292.5°‐112.5°); that soil moisture was lowest in the SWW direction and highest in the NWN direction; and that hillslope aspect was the main factor affecting soil moisture in the 0‐ to 30‐cm soil layer, whereas the main factor for the 30‐ to 60‐cm layer was slope gradient. It was found that the relative values of soil moisture for steep slopes (>36%) with shady aspect (292.5°‐112.5°), gentle slopes (<36%) with sunny aspect (112.5°‐292.5°), and steep slopes with sunny aspect were 99, 82, and 80, respectively – assuming a soil moisture value of 100 for gentle slopes with shady aspect. The results of this study are expected to be relevant to and useful for reforestation planning and design, parameterization of distributed hydrology models, and land productivity assessment in the study region.     

退耕还林(草)的生态补偿机制完善研究——以西部黄土高原地区为例

生态补偿措施是退耕还林（草）工程顺利进行的重要保障。以退耕还林（草）在黄土高原地区的实施情况为例，通过问卷调查，应用生态经济学的相关理论进行分析，认为应从以下几个方面完善退耕还林（草）工程的生态补偿机制：首先，建立退耕还林（草）的补偿组织体系；其次。以退耕还林（草）所造成的农民机会成本的损失来确定补偿标准。根据工程的进程和资金的投入情况．可将生态补偿划分为基本补偿、产业结构调整补偿和生态效益外溢补偿三个阶段；第三，根据产业结构调整取得显著成效所需的时间来确定补偿年限；最后提出退耕还林（草）的补偿方式及可能的资金渠道来源。生态补偿计量方法的研究将是今后研究的重点和难点。     

公路建设项目景观视觉影响评价的方法研究

公路建设的景观视觉影响及其保护措施,是我国公路建设中环境保护的热点问题之一。本文在国内外相关研究的基础上,以青藏公路改建工程为例,采用矩阵分析的方法,从景观美学质量评价、视觉敏感度分析、工程活动影响等景观视觉影响要素出发,划分了青藏公路沿线的景观保护级别,建立起青藏公路景观视觉影响评价方法,并以公路施工建设中具有代表性的取土场为例,结合视觉冲击强度分级,进行了相关的景观视觉影响评价。     

Soil temperature and moisture sensitivities of soil CO2 efflux before and after tillage in a wheat field of Loess Plateau, China

As a conventional farming practice,tillage has lasted for thousands of years in Loess Plateau,China.Although recent studies show that tillage is a prominent culprit to soil carbon loss in croplands,few studies have investigated the influences of tillage on the responses of soil CO2 efflux(SCE) to soil temperature and moisture.Using a multi-channel automated CO2 efflux chamber system,we measured SCE in situ continuously before and after the conventional tillage in a rain fed wheat field of Loess Plateau,Chin...