RESEARCH: Managing Mountainous Degraded Landscapes After Farmland Abandonment in the Central Spanish Pyrenees

Genista scorpius. Under a dense shrub cover both runoff and sediment yield are strongly controlled. As the shrub cover becomes open, sediment yield and runoff increase greatly. A dense herbaceous cover yields high runoff coefficients but moderate soil losses. From the results obtained, the possibility of abandoned field reclamation by means of selective clearing of scrub is discussed.     

The Management of a Large Mediterranean Reservoir: Storage Regimens of the Yesa Reservoir,Upper Aragon River Basin,Central Spanish Pyrenees

Agriculture in Mediterranean countries is mainly based upon the irrigation of productive areas in the lowlands. For this reason, it is necessary to store large volumes of water in reservoirs located in mountain headwaters. These reservoirs have a relatively simple regimen of storage, increasing the water stored during the wet season (from October until May) and reaching the maximum volume shortly before the beginning of the hot, very dry season, when the water is released. This paper considers the storage regimen (inflow and outflow) of the Yesa Reservoir in the Spanish Pyrenees as an example of management of a large reservoir in a mountain Mediterranean environment, subject to a strong interannual variability. On average, the highest water storage level is achieved by retaining the high flows of the Aragón River in autumn and spring. Nevertheless, the irregularity of rainfalls and the existence of changes in the hydrological regimen lead to changes in the patterns of reservoir filling. Two patterns were identified in the Yesa Reservoir: (1) a quick increase of the stored volume in autumn, a stabilization in winter, and a new increase in spring; and (2) a continuous increase from October until May. These patterns are distributed in time over different periods since the construction of the reservoir in 1959, demonstrating the adjustment of the reservoir management to changes in the hydrological regimen.     

丝绸之路经济带资源环境成本及生态负荷强度的时空演变分析

为了科学地评价丝绸之路经济带生态系统对经济与社会发展的服务支撑能力,本研究引入生态系统服务理论,构建资源环境成本及绿色GDP核算、生态负荷强度模型,计算出丝绸之路经济带辐射国家2005—2012年的资源环境成本、生态负荷强度,并在此基础上利用探索性空间数据分析方法,对2005年以来丝绸之路经济带的生态负荷强度随时间演变的趋势及其空间分布特征进行分析和探讨(数据获取难易程度,仅分析了部分带内国家)。结果表明:在研究时段内,带内国家或地区的资源环境成本由2005年的675.02×108元攀升至1 178.51×108元(2005年可比价),生态负荷强度由0.3369下降到0.2307;丝绸之路经济带生态负荷强度呈现出由欧洲经济圈向中国西北地区集聚的空间分布特征,其中中亚及中国西北地区为高-高集聚区、欧洲经济圈为低-低集聚区;这种西、东集聚现象的显著性在研究时段内逐渐减弱,且区域生态效益或经济效益持续向周边溢出。     

Spatial and Temporal Patterns of Low Streamflow and Precipitation Changes in the Chesapeake Bay Watershed

Spatial and temporal patterns in low streamflows were investigated for 183 streamgages located in the Chesapeake Bay Watershed for the period 1939–2013. Metrics that represent different aspects of the frequency and magnitude of low streamflows were examined for trends: (1) the annual time series of seven‐day average minimum streamflow, (2) the scaled average deficit at or below the 2% mean daily streamflow value relative to a base period between 1939 and 1970, and (3) the annual number of days below the 2% threshold. Trends in these statistics showed spatial cohesion, with increasing low streamflow volume at streamgages located in the northern uplands of the Chesapeake Bay Watershed and decreasing low streamflow volume at streamgages in the southern part of the watershed. For a small subset of streamgages (12%), conflicting trend patterns were observed between the seven‐day average minimum streamflow and the below‐threshold time series and these appear to be related to upstream diversions or the influence of reservoir‐influenced streamflows in their contributing watersheds. Using multivariate classification techniques, mean annual precipitation and fraction of precipitation falling as snow appear to be broad controls of increasing and decreasing low‐flow trends. Further investigation of seasonal precipitation patterns shows summer rainfall patterns, driven by the Atlantic Multidecadal Oscillation, as the main driver of low streamflows in the Chesapeake Bay Watershed.     

基于GIS的关中地区人口分布时空演变特征研究

随着经济社会的快速发展,陕西省关中地区的人口分布发生了明显的变化。采用空间自相关、不均衡指数、人口重心以及偏移—分享分析等方法,结合GIS技术对20世纪90年代以来关中地区人口分布的时空演变特征进行了分析。结果表明:①关中地区各区县人口密度差异显著,整体分布呈中间高、南北低的态势,即位于渭河平原区的区县人口密度较高,其他地区人口相对稀疏;②各地区人口分布存在显著的正的空间自相关,表现为西安市市辖区周围地区呈现高高集聚,而北部、西部和东部的周边区县则存在低低集聚;③关中地区人口分布不均衡状态明显,且人口不均衡指数有不断增大的趋势;④各地区人口偏移增长量差异显著,地区之间的偏移增长量不断增大,人口重心逐步向关中东南方向移动。     

我国空间规划体系的整体演进历程解析——基于时空演进系统过程的分析框架

本文从国家视域角度对不同阶段我国空间规划的整体演进加以解析。空间规划体系演进本质上是在主导价值取向、社会经济模式、国家治理体系等整体背景环境的影响下,人（群）的需求/目标诉诸一系列有组织的空间治理工具,对地域空间系统进行综合干预的一个时空演进过程。我国空间规划体系的历程解析需要重点关注“社会经济阶段及国家战略导向—国家治理体系的整体安排与调整—地域空间特征与变化引致的治理尺度更易”所联立的三大子过程。研究发现,纵观1949年后我国空间规划体系的演变历程,规划的功能定位从单一工具向多类型的复杂工具体系发展;规划干预和空间治理的目标与任务也从开发建设导向变为开发保护兼顾,进而强调多元平衡和优化。而这一过程深受国家治理体系和战略取向的塑造,即由国家基本建设转变为以经济建设为中心,由社会经济调控向社会经济生态综合调整转变。     

秦皇岛雷暴天气的时空尺度分布与雷电灾害分析

利用2003-2012年3～10月秦皇岛地区5个气象站雷暴监测和雷电灾害资料,采用数理统计、天气综合分析方法,得出秦皇岛地区雷暴天气的时空尺度分布特征为：全区年雷暴发生频次总体上呈递减趋势,其中,2005年35次,2008年33次,2012年20次;6月份为全年雷暴发生的峰值时段,7月、8月次之,且与秦皇岛本地主汛期相吻合;在海岸带地区由于受海洋条件影响,个别年份雷暴最早出现在2月份,最晚出现在11月中旬;雷暴天气的日时段主要出现在下午至傍晚,占70%,夜间占20%,其他时段为10%;北部山区的雷电频次大于沿海地区,对应电力、化工等行业雷电灾害呈下降趋势,但是通讯、计算机、家电等弱电系统雷击事件呈递增趋势。     

Isolated Spring Wetlands in the Great Basin and Mojave Deserts,USA: Potential Response of Vegetation to Groundwater Withdrawal

Desert springs, often the sole sources of water for wildlife and cattle, support wetland and wetland/upland transition ecosystems including rare and endemic species. In the basin and range province in Nevada, USA, springs in the Great Basin and Mojave deserts are sustained by interconnected deep carbonate and shallow basin-fill aquifers which are threatened by proposed groundwater withdrawal to sustain rapidly expanding urban areas, a common problem in arid regions worldwide. This paper draws on historic groundwater data, groundwater modeling, and studies of environmental controls of spring ecosystems to speculate on the potential effects of groundwater withdrawal and water table decline on spring-supported vegetation. The focus is on springs in the Great Basin and Mojave deserts representative of those that may be affected by future, planned groundwater withdrawal. Groundwater withdrawal is expected to reduce spring discharge directly through reduced flows from the shallow basin-fill aquifer or through reduction of the hydraulic head of the deep carbonate aquifer. This flow reduction will truncate the outflow stream, reducing the areal cover of wetland and wetland/upland transition vegetation. Lowering the local water table may also reduce the amount of upland phreatophytic vegetation by causing water levels to drop below plant rooting depths. Percolation of salts to surface soils may be reduced, eventually altering desert shrub cover from halophytes to nonhalophytes. The extent of these effects will vary among springs, based on their distance from extraction sites and location relative to regional groundwater flow paths. On-site monitoring of biotic variables (including cover of selected hygrophytes and phreatophytes) should be a necessary complement to the planned monitoring of local hydrologic conditions.     

四川省2010~2019年突发环境事件时空分布特征分析

近年来,四川省高度重视环境应急管理工作,环境应急处置能力不断提升,但环境风险形势依然严峻,突发环境事件时有发生。通过对2010~2019年四川省10年突发环境事件进行统计分析,浅析四川省突发环境事件的规律特点,以期为四川省生态环境风险防控提供科学依据。研究表明,四川省突发环境事件呈现多发高发态势,6~8月为突发环境事件高发期;安全生产事故和交通事故次生的突发环境事件是主要事件类型;成都市和广元市是突发环境事件的高发区域;油类污染物和酸碱类污染物是主要污染物类型;跨界流域突发环境事件发生频率较高。应从流域突发环境事件风险评估、企业环境安全主体责任、环境应急物质储备体系和突发环境事件联防联控等方面加强四川省环境应急管理。     

基于EBM模型的长江经济带工业用水效率时空差异及影响因素分析

工业化进程的加快使得工业水资源需求不断增加,工业废水排放量也越来越大,如何提高工业用水效率从而缓解水资源压力成为日益严峻的问题。本文选取工业用水量、工业就业人数、工业固定资本和工业废水治理费用作为投入指标,以工业增加值与工业废水排放量作为期望与非期望产出指标。首先利用EBM模型计算长江经济带2008—2017年工业用水效率,其次利用泰尔指数来分析工业用水效率的区域差距,最后利用面板Tobit模型来分析影响不同地区工业用水效率的驱动因素。结果显示,近年来长江经济带的工业用水效率呈波动下降趋势,不同地区效率差异明显;经济发展水平、工业化程度、技术水平、水资源禀赋和政府环境管制力度对长江经济带的工业用水效率都有一定影响,但存在地区差异。     

Policy Windows, Policy Change, and Organizational Learning: Watersheds in the Evolution of Watershed Management

Employing in-depth, elite interviews, this empirical research contributes to understanding the dynamics among policy windows, policy change, and organizational learning. First, although much of the research on agenda setting—how issues attract enough attention that action is taken to address them—has been conducted at the national scale, this work explores the subnational, regional scale. With decentralization, regional-scale environmental decision-making has become increasingly important. Second, this research highlights the role of policy windows and instances of related organizational learning identified by natural resources managers. Having practitioners identify focusing events contrasts with the more typical approach of the researcher identifying a particular focusing event or events to investigate. A focusing event is a sudden, exceptional experience that, because of how it leads to harm or exposes the prospect for great devastation, is perceived as the impetus for policy change.