PERCEPTION OF COLOR SEQUENCES ON MAPS OF ATMOSPHERIC PRESSURE

Impervious surface cover is often associated with low socioeconomic status (SES) and vegetation with high SES in urban areas in both developed and developing countries. This study documents the relationships among land cover, number of years urbanized (YR), topographic slope, and socioeconomic indicators, including a socioeconomic marginality index (MI), in Tijuana, Mexico. Unlike in other urban areas, vegetation cover decreased slightly and impervious cover increased significantly with increasing SES in Tijuana. This pattern was due to (1) slightly higher vegetation cover in tracts with high MI (low SES), where informal settlements were sometimes on steep slopes with remnant patches of vegetation; (2) significantly higher soil cover and low impervious cover in tracts with high MI due to unpaved roads and vacant lots, and (3) low vegetation cover and high impervious cover in tracts with low MI, which included the city center and new suburban developments with high population densities. YR, slope, and population density were important secondary predictors of land cover and SES. Approximately half of the variance in the proportion of the population with drainage and with piped water supply was explained by a multiple regression with land cover, slope, and YR, whereas fertility and infant mortality correlated with but were not predicted well by land cover. The combination of rapid population growth, variable topography, semiarid climate, and history of service development in Tijuana resulted in unexpected associations between SES and land cover, with implications for the environment and public health.     

Typologies of sprawl: investigating United States metropolitan land use patterns

We investigate patterns of residential and nonresidential land use in 311 United States metropolitan (Extended Urban) areas in 2000 using four measures: intensity, compactness, mixing, and core-dominance. A cluster analysis revealed four distinctive groups of land use patterns: (1) Most-Intense, Least-Compact, Least-Mixed, More-Monocentric Development, (2) Less-Intense, Most-Compact, Less-Mixed, Less-Monocentric Development, (3) Least-Intense, Less-Compact, Most-Mixed, Most-Monocentric Development, (4) More-Intense, More-Compact, More-Mixed, Polycentric Development. Bivariate statistics demonstrated that geographic, historic, economic, demographic, and transport variables differentiate land use pattern types. Based on their multidimensional distinctions, we label the four types of metropolitan areas: Ascendants, Insulars, Redevelopers, and Cosmopolitans.     

Simulated impacts of 3D urban morphology on urban transportation in megacities: case study in Beijing

Urban morphology and morphology change and their impacts on urban transportation have been studied extensively in planar urban space. The essential feature of urban space, however, is its three-dimensionality (3D), and few studies have been conducted from a 3D perspective, overly limiting the accuracy of studies on the relationships between urban morphology and transportation. The aim of this paper is to simulate the impacts of 3D urban morphologies on urban transportation under the Digital Earth framework. On the basis of the principle that population distribution and movement are largely confined by 3D urban morphologies, which affect transportation, high spatial resolution remote sensing imagery and a thematic vector data-set were used to extract urban morphology and transportation-related variables. With a combination of three research methods – factor analysis, spatial regression analysis and Euclidean allocation – we provide an effective method to construct a simulation model. The paper indicates three general results. First, building capacity in the urban space has the most significant impact on traffic condition. Second, obvious urban space otherness, reflecting both use density characteristics and functional characteristics of urban space, mostly results in heavier traffic flow pressure. Third, no single morphology density indicator or single urban structure indicator can reflect its contribution to the pressure of traffic flow directly, but a combination of these different indicators has the ability to do so.     

Evaluation of chemical composition changes of surface water in Boguchan Reservoir (Siberia,Russia)

Abstract

Mathematical transformation models of TDS (total dissolved salts) and organic substance concentration as BOD₅ (biochemical oxygen demand) in water of the Angara River and the proposed Boguchan Reservoir have been developed. Having filled the reservoir to a water level of 208 m, in an average year it is shown that increase in surface water mineralization is expected in the cross-section of Boguchan Hydroelectric Power Station giving TDS of up to 20–40 mg/dm³, and values of BOD₅ will increase to 2.0–3.9 mgO₂/dm³. In a low-water year the value of BOD₅ may be as great as 5 mgO₂/dm³; mineralization, in contrast, decreases. Several years after reservoir filling, the values of BOD₅ would decrease, but water quality of the upper part of the reservoir would still depend on the degree of treatment of wastewater discharged to it.

Editor D. Koutsoyiannis

Citation Savichev, O.G. and Matveenko, I.A., 2013. Evaluation of chemical composition changes of surface water in Boguchan Reservoir (Siberia, Russia). Hydrological Sciences Journal, 58 (3), 706–715.     

Effects of helical flow in one‐dimensional modelling of sediment distribution at river bifurcations

Complex flow processes at river bifurcations and the influence of the layout of a bifurcation make it difficult to predict sediment distribution over the downstream branches in case bedload transport dominates. In one‐dimensional models we need a nodal point relationship that prescribes the distribution of sediment over the downstream branches. We have identified which factors need to be included in such a relationship for the division of bedload transport at bifurcations. Next, irrotational flow theory for idealized geometries has been used to derive a simple physics‐based nodal point relationship that accounts for the effects of helical flow in the situation that a channel takes off under an angle from a straight main channel. This first step towards a complete nodal point relationship is applicable to bedload transport situations if the flow is clearly curved and if there is no pronounced bed topography. The relationship has been tested against data from a unique set of laboratory measurements, numerical data and data from a scale model of the Rhine bifurcation at Pannerden in the Netherlands. We find that the derived model yields a reasonable prediction of the sediment division over the downstream branches, and yields better predictions than the Wang et al. model for the situation considered. Considering the relative complexity and limited accuracy of the nodal point relationship for the effect of helical flow alone, however, we conclude thatderiving a practical physics‐based 1‐D relationship including all relevant processes is not feasible. We therefore recommend 2‐D or 3‐D modelling for all cases in general where morphological evolution depends on the division of bedload transport at bifurcations. Copyright © 2012 John Wiley & Sons, Ltd.     

Wood dynamics in upland streams under different disturbance regimes

This paper presents reach scale large wood (LW) budgets of 12 upland streams in the Okanagan Basin of British Columbia. The study included 100 m long reaches at three wildfire sites and three undisturbed sites in the Interior Douglas‐fir (IDF) biogeoclimatic zone, and three recent Mountain Pine Beetle (MPB) infestation sites and three undisturbed sites in the Montane Spruce (MS) zone. Detailed information on wood recruitment, output and storage were obtained from repeated annual surveys. Recruitment from the riparian zone was found to dominate wood inputs, with fluvial import of secondary importance. In undisturbed streams, wood exhumation was found to be of tertiary importance, but was not observed in disturbed streams. Relative wood length was found to be a strong predictor of wood stability, with wood length to channel width and wood diameter to channel depth ratios of 1:1 forming an approximate maximum threshold of wood mobility. Volumetric decomposition was, on average, a third of the value of fluvial export, and the average residence time of wood in the channels was 20 years. In undisturbed reaches, wood storage indicated a slow depletion of wood from the channels. In the disturbed reaches, wildfire was found to significantly increase annual wood recruitment by more than an order of magnitude over undisturbed or control streams. MPB had not significantly increased LW recruitment, but is expected to increase over the coming decades. Storage rates at the disturbed streams indicated a net accumulation of wood over the study period. Copyright © 2012 John Wiley & Sons, Ltd.     

数学形态滤波法在GPS基线分析中的应用

通过GAMIT软件得到福建省连续观测GPS基准站基线时间序列,并引人数学形态滤波法,过滤基线中的白噪音和脉冲扰动.以福建省主要断裂带为研究背景,研究GPS基线时间序列、跨断层短水准观测资料与福建主要断层的相关性,分析了影响基线变化的因素,以及地壳水平运动与应力积累的关系.     

都江堰城市空间形态演变周期性特征及其驱动机制

以都江堰市1980-2011年期间的建成区各年份的土地利用数据和社会经济数据为基础,借助城市周期扩张理论和分形理论,以GIS技术为支撑,揭示了都江堰城市形态演化的周期性、过程和机制.研究表明:1.都江堰城市形态演变遵循“外部扩张,内部填充”的周期扩张规律,演变周期为12～ 13 a,下一阶段将进入以内部填充为主的发展阶段;2.都江堰城市形态具有明显的分形特征,形态演变与所处的发展周期阶段有关;3.居住用地扩张是城市演变的内生因素,公共绿地空间分布不均衡,破碎化现象严重.4.都江堰城市形态主要受自然地理环境、经济发展、城市规划以及不可抗拒自然灾害的明显影响.     

Nebkha （coppice dune） formation and significance to environmental change reconstructions in arid and semiarid areas

Environments in arid and semiarid regions are extremely sensitive to climate changes.High wind activity in these regions has resulted in an extensively developed arid geomorphology,but past environmental changes are poorly understood because of the absence of relatively high-resolution proxies.The accumulation characteristics of nebkhas,which have developed extensively in these regions,can be used as a method of reconstructing environmental changes.Here we summarized recent advances in research on the formation,development,and sediment characteristics of nebkhas and their significance to environmental changes in arid and semiarid regions.Based on the studies of our colleagues,we suggested that research on nebkha formation can provide distinct clues about environmental changes in arid and semiarid regions;however,continued studies are needed.     

Characterization of active fault scarps from LiDAR data: a case study from Central Apennines (Italy)

A high-resolution digital elevation model (DEM, 1 ms spacing) derived from an airborne light detection and ranging (LiDAR) campaign was used in an attempt to characterize the structural and erosive elements of the geometry of the Pettino fault, a seismogenic normal fault in Central Apennines (Italy). Four 90- to 280 m-long fault scarp segments were selected and the surface between the base and the top of the scarps was analyzed through the statistical analysis of the following DEM-derived parameters: altitude, height of the fault scarp, and distance along strike, slope, and aspect. The results identify slopes of up to 40° in faults lower reaches interpreted as fresh faces, 34° up the faces. The Pettino fault maximum long-term slip rate (0.6–1.1 mm/yr) was estimated from the scarp heights, which are up to 12–19 m in the selected four segments, and the age (ca. 18 ka) of the last glacial erosional phase in the area. The combined analysis of the DEM-derived parameters allows us to (a) define aspects of three-dimensional scarp geometry, (b) decipher its geomorphological significance, and (c) estimate the long-term slip rate.