干旱半干旱区城市生态效率时空演变及区域差异分析

研究西北干旱半干旱区城市生态效率,对其经济、资源、环境的协调统一以及生态文明建设的推进具有重要的现实意义。以西北干旱半干旱区38个城市为研究对象,运用三阶段DEA方法客观地测度了各城市2005—2016年生态效率,同时运用ESDA方法全面分析了生态效率的区域差异。结果显示：干旱半干旱区城市生态效率普遍较低,并呈现正向全局空间自相关关系;热点区域主要以乌鲁木齐、克拉玛依等为中心,冷点区域主要以平凉、固原等为中心,热点区域数量呈现先增后减再增的N形变动趋势,冷点区域数量则呈现先减后增再减的倒N形变动趋势     

干旱,半干旱地区水文地质研究现状

世界上近一半的国家都不同程度地受到干旱问题的影响,因而干旱、半干旱区的水文地质研究多年来一直是世界水文地质学界的研究热点。本文根据几年来所阅读的关于该方面的近百篇国内外文献资料,对干旱和半干旱地区地下水开发利用概况、地下水形成机理研究进展、干旱区大型盆地地下水运移所采用的两种模型、环境同位素技术在干旱区地下水研究中的应用、地下水流系统研究进展、地下水数值模拟及管理模型现状、干旱区包水带水文地质研究     

Simulation of the Bare Soil Surface Energy Balance at the Tongyu Reference Site in Semiarid Area of North China

The performance of a 1-D soil model in a semiarid area of North China was investigated using observational data from a cropland station at the Tongyu reference site of the Coordinated Enhanced Observing Period (CEOP) during the non-growing period, when the ground surface was covered with bare soil. Comparisons between simulated and observed soil surface energy balance components as well as soil temperatures and water contents were conducted to validate the soil model. Results show that the soil model could produce good simulations of soil surface temperature, net radiation flux and sensible heat flux against observed values with the RMSE of 1.54oC, 7.71 W m-2 and 27.79 W m-2, respectively. The simulated volumetric soil water content is close to the observed values at various depths with the maximal difference between them being 0.03. Simulated latent heat and ground heat fluxes have relatively lower errors in relative to net radiation and sensible heat flux. In conclusion, the soil model has good capacity to simulate the bare soil surface energy balance at the Tongyu cropland station and needs to be further tested in longer period and at more sites in semiarid areas.     

Modelling the hydrological response of debris‐free and debris‐covered glaciers to present climatic conditions in the semiarid Andes of central Chile

We apply the process‐based, distributed TOPKAPI‐ETH glacio‐hydrological model to a glacierized catchment (19% glacierized) in the semiarid Andes of central Chile. The semiarid Andes provides vital freshwater resources to valleys in Chile and Argentina, but only few glacio‐hydrological modelling studies have been conducted, and its dominant hydrological processes remain poorly understood. The catchment contains two debris‐free glaciers reaching down to 3900 m asl (Bello and Yeso glaciers) and one debris‐covered avalanche‐fed glacier reaching to 3200 m asl (Piramide Glacier). Our main objective is to compare the mass balance and runoff contributions of both glacier types under current climatic conditions. We use a unique dataset of field measurements collected over two ablation seasons combined with the distributed TOPKAPI‐ETH model that includes physically oriented parameterizations of snow and ice ablation, gravitational distribution of snow, snow albedo evolution and the ablation of debris‐covered ice. Model outputs indicate that while the mass balance of Bello and Yeso glaciers is mostly explained by temperature gradients, the Piramide Glacier mass balance is governed by debris thickness and avalanches and has a clear non‐linear profile with elevation as a result. Despite the thermal insulation effect of the debris cover, the mass balance and contribution to runoff from debris‐free and debris‐covered glaciers are similar in magnitude, mainly because of elevation differences. However, runoff contributions are distinct in time and seasonality with ice melt starting approximately four weeks earlier from the debris‐covered glacier, what is of relevance for water resources management. At the catchment scale, snowmelt is the dominant contributor to runoff during both years. However, during the driest year of our simulations, ice melt contributes 42 ± 8% and 67 ± 6% of the annual and summer runoff, respectively. Sensitivity analyses show that runoff is most sensitive to temperature and precipitation gradients, melt factors and debris cover thickness. Copyright © 2016 John Wiley & Sons, Ltd.     

半干旱区PM10质量浓度时空分布特征研究

 利用内蒙古额济纳旗、乌拉特中旗、东胜、朱日和、锡林浩特和通辽6个观测站2005年的PM10质量浓度（MPM）和相关气象要素资料,分析了半干旱地区MPM的时空分布特征。结果表明,在春季,尤其是4月,各个观测站的MPM都会出现极大值;非沙尘日里,MPM在四季中的日变化主要呈现单峰分布,峰值出现时间从春季到冬季逐渐推迟。MPM最大值是反映各观测站沙尘天气强度的主要因子;气象影响指数（IPM）与MPM的相关系数大于0.5。     

基于逻辑回归模型的泥石流易发性评价与检验：以金沙江上游奔子栏—昌波河段为例

基于地理信息系统(ArcGIS100)平台和小流域单元,采用逻辑回归(LR)模型对金沙江上游(奔子栏—昌波河段)干热河谷区进行泥石流易发性评价,并对预测结果进行总体检验与随机个案检验。评价与检验结果表明,得到的最优指标组合下LR评价模型的AUC值为827%;预测的极高易发区、高易发区面积合占全区面积的3598%,实发泥石流面积占泥石流总面积的6503%;在个案检验中,位于各等级分区的检验组样本实发泥石流比例随着分区易发性等级降低,依次为917%(极高)、750%(高)、364%(中等)、167%(低)、0(极低),表明评价效果良好。研究区泥石流集中发育于金沙江沿岸的东北部、中部和西南部,主导性的评价指标依次为距主干道路距离、岩性、距断裂带距离、雨季月平均降雨量。人类活动与季节性降雨为研究区干热河谷泥石流的主要诱发条件。基于逻辑回归模型的泥石流易发性评价方法提高了泥石流发生可能性的预测精度,可为干热河谷区泥石流预测预警和防治提供参考依据。     

Investigation of the rainfall variability in central Tunisia / Investigations sur la variabilité pluviométrique en Tunisie centrale

Abstract

The decrease in runoff of the Merguellil basin, Tunisia recorded during the decade 1989–1998 led to the study of several time series derived from daily rainfall. It was found that variability characteristics related to daily rainfall greater than 30 mm are significantly different among successive time periods. In addition, the probability distributions of these rains, recorded at different raingauge sites, are significantly different between the period 1976–1989 and the prior and posterior observation periods. Furthermore, the surface covered by daily rains greater than 30 mm decreased between 1976 and 1989. It was also noted that the probability distributions of the surfaces covered changed significantly after 1976. The combination of human action and pluviometric variability (rainfall increase in the period 1989–1998, notably the increase in the number of days of rainfall greater than 30 mm) may explain the decrease in runoff of Merguellil Wadi.     

Comparison of two stream gauging systems for measuring runoff and sediment yield for a semi‐arid watershed

Our ability to understand erosion processes in semi‐arid ecosystems depends on establishing relationships between rainfall and runoff. This requires collection of extensive and accurate hydrologic and sediment data sets. A supercritical flume with a total load traversing slot sediment sampler used on several sites at the Walnut Gulch Experimental Watershed (WGEW) near Tombstone, AZ has proven to be a reliable way to measure flow and sediment discharge from small watersheds. However, it requires installation of a costly structure that is only suitable for relatively small flows. A more commonly used method based on ease of installation and expense is the pump sampler. One example of this is a set of instrumentation developed by the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO), in which the pump sediment sampler is part of an in‐channel, fully automated system for measuring water velocity, depth, turbidity and collecting runoff samples. A 3.7 ha arid watershed at WGEW was instrumented with both systems and hydrologic and sediment data were collected and compared during a 2 year period. Total sediment yield for the entire period measured by the CSIRO pump sampler (11.6 t ha^‐1) was similar to that by traversing slot sampler (11.5 t ha^‐1). The pump sampler accurately estimated the amount of fine (< 0.5 mm) sediment fractions exported, but consistently underestimated the coarse (>0.5 mm) sediment fractions. Median sediment diameter of samples collected by traversing slot and pump sampler were 0.32 and 0.22 mm, respectively. This study outlines the benefits and limitations of the pump sampler based system for monitoring sediment concentration and yield in high‐energy headwater catchments, and makes recommendations for improvement of its performance. Copyright © 2012 John Wiley & Sons, Ltd.     

半干旱矿区沉陷地土地复垦模式研究

根据矿区土地复垦方案设计与规划的方法与技术,在研究半干旱矿区独特的自然地理条件的前提下,根据相关生态修复原理和方针,提出适宜该类矿区发展的土地复垦模式,并且以陕西大柳塔-活鸡兔矿区为例,列举了几种适宜本矿区的土地复垦模式.同时结合最新的科学研究成果给出了一些建议.     

半干旱的吉林西部地区水文地质环境与土地盐碱化

水是维系半干旱地区农业生态环境的主导活跃的因子.由于半干旱地区相对丰富的水资源,导致了土地盐碱化等一系列环境问题,不仅妨碍了农业生产的发展,也破坏了半干旱地区土地生态系统。对水资源的合理开发与利用,将有利于半干旱区农业生态环境的改善,促进农业生产的发展.本文综合分析了半干旱的吉林西部地区水文地质环境与土地盐碱化的关系。