深度优先搜索的地图着色算法

在分析地图着色本质以及深度优先搜索算法优缺点基础上,本文提出一种基于深度优先搜索的地图着色方法,并以全国地图和全国县级行政区划图对本文算法进行了实验验证,取得了较好的着色结果.     

What should these rivers look like? Historical range of variability and human impacts in the Colorado Front Range,USA

Historical range of variability (HRV) describes the range of temporal and spatial variations in river variables such as flow regime or channel planform prior to intensive human alteration of the ecosystem. In mountainous river networks, HRV is most usefully applied to spatially differentiated geomorphic process domains with distinctive form and process. Using the Colorado Front Range as an example, three examples of how knowledge of HRV can assist river management and restoration are discussed. The examples involve instream wood load and channel morphology, beaver colonies and valley‐bottom form and process, and flow thresholds in regulated rivers. The question of what a river should look like – that is, what range of process and form the river included prior to intensive human alteration – can be addressed by (i) placing the river within a process domain, (ii) establishing correlations between form parameters that can be remotely sensed and reach‐scale process and form, so that the spatial extent, connectivity, and rarity of process domains within a river network or a region can be quickly assessed, (iii) inferring characteristics of the river prior to intensive alteration by documenting characteristics of the least altered reference rivers and by using proxy indicators of pre‐alteration conditions, and (iv) establishing process thresholds that must be exceeded to maintain form (e.g. flow thresholds to mobilize bed sediment). Once this context has been established, resource managers can better evaluate the options for restoring altered riverine form and function. Copyright © 2011 John Wiley & Sons, Ltd.     

大气环流模式（GCMs）在东南诸河流域的适用性评价

采用秩评分方法,选取NCEP再分析资料作为“实测”依据,以10个统计特征值为基础,评估了21个GCMs对东南诸河流域17个气候要素的模拟效果．结果显示：气候变量表现出不同的统计特征,GCMs对不同气候变量的模拟效果并不一致．与地面气象站点实测值对比,CSIRO：MK30、GFDL：CM21、GFDL：CM20、INM：CM30对降水和地面气温的模拟效果相对较好;流域高空气候要素的模拟效果更佳的模式有CGCM2．3．2、GISS：EH、BCCR：BCM20、GFDL：CM20对;综合所有气候变量,BCCR：BCM20、GFDL：CM20、CGCM2．3．2、GISS：EH的表现更优．优选出的GCMs可以为东南诸河流域气候变化的进一步研究提供科学依据．     

An empirical model of event scale cohesive bank profile evolution

The highly stochastic nature of riverbank erosion has driven the need for spatially explicit empirical models. Detailed bank profile surveys along a meander bend of the Brandywine Creek in Pennsylvania, USA, before and after 28 high flow events over a 2·5 year period are used to develop an empirical model of cohesive bank profile erosion. Two hundred and thirty‐six bank erosion observations are classified as hydraulic erosion or subaerial erosion. Threshold conditions required to initiate bank erosion cannot be defined based on field measurements. Using the near‐bank velocity and the number of freeze–thaw cycles as predictors, regression equations are derived for hydraulic erosion that specify the length, thickness, and location on the bank face of eroded blocks. An empirical discriminant function defines the critical geometry of overhang failures, and the volumes removed by overhang failures are computed using another regression equation. All the regression equations are significant, but have low correlation coefficients, suggesting that cohesive bank erosion has a strong stochastic component. Individual events typically remove small masses of soil (average volume 0·084 m³/m) a few centimeters thick (median = 0·057 m) and a few decimeters in length (median = 0·50 m) from the lower third of the bank. Hydraulic erosion is responsible for 87% of all erosion. When applied to three survey sites not used in its development, the profile model predicts the total volume of erosion with errors of 23%, 5% and 1%. Twenty‐four percent of computed erosion volumes for single events are within 50% of observed volumes at these three sites. Extending the approach to decadal timescales and to entire bends will require three‐dimensional observations of bank failure, and spatially and temporally explicit methods to account for the influence of individual large trees on bank failures and near‐bank hydraulic processes. Copyright © 2009 John Wiley & Sons, Ltd.     

网状河流和分汊河流的河型归属讨论

河流的河道平面形态分类有多种方案 ,其中Rust的分类因为分出了网状河流而得到沉积学家的更多关注。中国地貌学界和水利学界则更关注钱宁的分类 ,其中包括分汊河流。目前 ,许多研究人员把网状河流和分汊河流当作同一类型的河流。文中从河型的定义、河道平面形态、地下沉积物特征、水动力、新河道形成机理和发育的地貌部位等方面对分汊河流和网状河流进行对比 ,根据对比结果认为它们是不同的河型。为了便于沉积学家、水利学家以及地貌学家之间相互交流各自有关河流的研究成果 ,需要提出一个更符合实际的冲积河流分类方案。     

The effect of El Niño Southern Oscillation cycles on the decadal scale suspended sediment behavior of a coastal dry‐summer subtropical catchment

Rivers display temporal dependence in suspended sediment–water discharge relationships. Although most work has focused on multi‐decadal trends, river sediment behavior often displays sub‐decadal scale fluctuations that have received little attention. The objectives of this study were to identify inter‐annual to decadal scale fluctuations in the suspended sediment–discharge relationship of a dry‐summer subtropical river, infer the mechanisms behind these fluctuations, and examine the role of El Niño Southern Oscillation climate cycles. The Salinas River (California) is a moderate sized (11 000 km²), coastal dry‐summer subtropical catchment with a mean discharge (Q_mean) of 11.6 m³ s^?1. This watershed is located at the northern most extent of the Pacific coastal North America region that experiences increased storm frequency during El Niño years. Event to inter‐annual scale suspended sediment behavior in this system was known to be influenced by antecedent hydrologic conditions, whereby previous hydrologic activity regulates the suspended sediment concentration–water discharge relationship. Fine and sand suspended sediment in the lower Salinas River exhibited persistent, decadal scale periods of positive and negative discharge corrected concentrations. The decadal scale variability in suspended sediment behavior was influenced by inter‐annual to decadal scale fluctuations in hydrologic characteristics, including: elapsed time since small (~0.1 × Q_mean), and moderate (~10 × Q_mean) threshold discharge values, the number of preceding days that low/no flow occurred, and annual water yield. El Niño climatic activity was found to have little effect on decadal‐scale fluctuations in the fine suspended sediment–discharge relationship due to low or no effect on the frequency of moderate to low discharge magnitudes, annual precipitation, and water yield. However, sand concentrations generally increased in El Niño years due to the increased frequency of moderate to high magnitude discharge events, which generally increase sand supply. Copyright © 2014 John Wiley & Sons, Ltd.     

中国地级及以上城市“四化”协调发展效率的时空分异测度

以中国343个地级及以上行政单元为研究对象,运用数据包络分析和探索性空间数据分析,研究了2001年和2011年 “四化”协调发展及其效率的空间差异变化,借助地理加权回归模型揭示“四化”协调发展效率的影响因素及其空间差异。结果显示,中国地级单元2001年和2011年的“四化”协调发展及其效率均存在显著的空间分异,综合指数、耦合度和协调度空间差异呈现以西北-东南走向的“反胡焕庸线”为分界的态势。“四化”协调发展效率整体较低,效率值较高的地区集中在中部地区,达到“有效”状态的城市极少。10 a间平均效率值总体降低 ,高值区逐渐向东部沿海地区转移。城乡人均固定资产投资差异、人均GDP和人均社会消费品零售总额是影响“四化”协调发展效率的重要因素。     

Normal fault growth and linkage in the Gediz (Alaşehir) Graben,Western Turkey,revealed by transient river long‐profiles and slope‐break knickpoints

The Gediz (Ala?ehir) Graben is located in the highly tectonically active and seismogenic region of Western Turkey. The rivers upstream of the normal fault‐bounded graben each contain a non‐lithologic knickpoint, including those that drain through inferred fault segment boundaries. Knickpoint heights measured vertically from the fault scale with footwall relief and documented fault throw (vertical displacement). Consequently, we deduce these knickpoints were initiated by an increase in slip rate on the basin‐bounding fault, driven by linkage of the three main fault segments of the high‐angle graben bounding fault array. Fault interaction theory and ratios of channel steepness suggest that the slip rate enhancement factor on linkage was a factor of 3. We combine this information with geomorphic and structural constraints to estimate that linkage took place between 0.6 Ma and 1 Ma. Calculated pre‐ and post‐linkage throw rates are 0.6 and 2 mm/yr respectively. Maximum knickpoint retreat rates upstream of the faults range from 4.5 to 28 mm/yr, faster than for similar catchments upstream of normal faults in the Central Apennines and the Hatay Graben of Turkey, and implying a fluvial landscape response time of 1.6 to 2.7 Myr. We explore the relative controls of drainage area and precipitation on these retreat rates, and conclude that while climate variation and fault throw rate partially explain the variations seen, lithology remains a potentially important but poorly characterised variable. Copyright © 2016 John Wiley & Sons, Ltd.     

Wood and sediment storage and dynamics in river corridors

Large wood along rivers influences entrainment, transport, and storage of mineral sediment and particulate organic matter. We review how wood alters sediment dynamics and explore patterns among volumes of in‐stream wood, sediment storage, and residual pools for dispersed pieces of wood, logjams, and beaver dams. We hypothesized that: volume of sediment per unit area of channel stored in association with wood is inversely proportional to drainage area; the form of sediment storage changes downstream; sediment storage correlates with wood load; the residual volume of pools created in association with wood correlates inversely with drainage area; and volume of sediment stored behind beaver dams correlates with pond area. Lack of data from larger drainage areas limits tests of these hypotheses, but the analyses suggest that sediment volume correlates positively with drainage area and wood volume. The form of sediment storage in relation to wood appears to change downstream, with wedges of sediment upstream from jammed steps most prevalent in small, steep channels and more dispersed sediment storage in lower gradient channels. Pool volume correlates positively with wood volume and negatively with channel gradient. Sediment volume correlates well with beaver pond area. More abundant in‐stream wood and beaver populations present historically equated to greater sediment storage within river corridors and greater residual pool volume. One implication of these changes is that protecting and re‐introducing wood and beavers can be used to restore rivers. This review of the existing literature on wood and sediment dynamics highlights the lack of studies on larger rivers. Copyright © 2016 John Wiley & Sons, Ltd.     

公转轴应力场星球说——地球、火星南南西应力场四组三维构造系

介绍了对地球构造格局,运动方式及其动力源问题研究取得的新成果。它不同于流行已久的以地球自转轴旋转和以软流圈带动岩石圈漂移以及随机的地幔柱（流）为构造动力源的观点,而是与黄赤交角相关的沿公转轴方向的统一应力场,认为中国西部ＮＷＷ向压性,ＮＥＥ与ＮＮＷ是与黄赤交角相关的沿公转轴方向的统一应力场。认为中国西部ＮＷＷ向压性,ＮＥＥ与ＮＮＷ向两组共轭扭性及ＮＮＥ向张性带交接,为来自全球ＳＳＷ主压应力场形成的