排序方式： 共有10条查询结果，搜索用时 78 毫秒
1
1.
2.
Warming will affect snowline elevation, potentially altering the timing and magnitude of streamflow from mountain landscapes. Presently, the assessment of potential elevation‐dependent responses is difficult because many gauged watersheds integrate drainage areas that are both snow and rain dominated. To predict the impact of snowline rise on streamflow, we mapped the current snowline (1980 m) for the Salmon River watershed (Idaho, USA) and projected its elevation after 3 °C warming (2440 m). This increase results in a 40% reduction in snow‐covered area during winter months. We expand this analysis by collecting streamflow records from a new, elevation‐stratified gauging network of watersheds contained within high (2250–3800 m), mid (1500–2250 m) and low (300–1500 m) elevations that isolate snow, mixed and rain‐dominated precipitation regimes. Results indicate that lags between percentiles of precipitation and streamflow are much shorter in low elevations than in mid‐ and high‐elevation watersheds. Low elevation annual percentiles (Q25 and Q75) of streamflow occur 30–50 days earlier than in higher elevation watersheds. Extreme events in low elevations are dominated by low‐ and no‐flow events whereas mid‐ and high‐elevation extreme events are primarily large magnitude floods. Only mid‐ and high‐elevation watersheds are strongly cross correlated with catchment‐wide flow of the Salmon River, suggesting that changes in contributions from low‐elevation catchments may be poorly represented using mainstem gauges. As snowline rises, mid‐elevation watersheds will likely exhibit behaviours currently observed only at lower elevations. Streamflow monitoring networks designed for operational decision making or change detection may require modification to capture elevation‐dependent responses of streamflow to warming. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
3.
The anomalous channel pattern in the midland stretch of the river Karamana, having highly sinuous and incised course with varying floodplain, is analysed to determine the different stages of evolution of the river channel in response to the structural disturbances in the area. Geometric analysis of foliation, geospatial analyses of sinuosity index, hypsometry, channel and streamline changes, river channel cross-profile, longitudinal profile and derivation of fold structure from satellite images were attempted in evaluating the characteristic features of the selected river segment. Datasets used in the analysis were collected through the detailed fieldwork, structural mapping and interpretation of satellite images and satellite-derived digital elevation data. Systematic analysis of the channel pattern of the selected reaches of the river, in 1915, 1968 and 2008 classifies the river as tortuously meandering. Implications of tectonic disturbance can be inferred from the presence of channel incision, unpaired terraces, younger terrain with intense erosion, knick points, convex river long profile, and high hypsometric integral, oscillating and unpaired character of the river channel. Structural analysis along with GIS and remote sensing studies proved the presence of a major fold with a NW–SE-trending axial surface. An evolutionary model is proposed to elucidate the channel planform changes in response to the deformation and tectonic uplift of the region. 相似文献
4.
Hypsometric Analysis of Headwater Rock Basins in the Dolomites (Eastern Alps) Using High‐Resolution Topography 
下载免费PDF全文
下载免费PDF全文 Lorenzo Marchi Marco Cavalli Sebastiano Trevisani 《Geografiska Annaler: Series A, Physical Geography》2015,97(2):317-335
Hypsometric curves and integrals are effective tools for rapid quantitative assessments of topography. High‐resolution digital terrain models derived from airborne LiDAR data have been analysed to study the hypsometry of small headwater rock basins (drainage areas up to 0.13 km2) in three study areas in the Dolomites (Eastern Alps) that have similar lithologies and climatic conditions. Hypsometric curves in the studied rocky headwaters display a variety of shapes and present remarkable differences between neighbouring basins. Hypsometric integrals show generally high values in the three study areas (>0.42, mean values between 0.51 and 0.65). The extent of the scree slopes located at the foot of rock basins in the three study areas is larger in the area with lower hypsometric integrals and indicates consistency between the development of basin erosion, which is shown by the hypsometric integral, and debris yield, represented by the extent of scree slope. No clear relations were observed between the hypsometric integrals and basin area and shape. When extending the analysis to larger basins, which encompass rocky headwaters and downslope soil‐mantled slopes, a negative correlation is found between the hypsometric integral and catchment area, suggesting that the scale independency of the hypsometric integral occurs essentially in headwater rock basins. Geomorphometric indices (residual relief and surface roughness) have contributed to interpreting the variability of surface morphology, which is related to the geo‐structural complexity of the catchments. 相似文献
5.
6.
The links between entrance geometry,hypsometry and hydrodynamics in shallow tidally dominated basins
Peter J. de Ruiter Julia C. Mullarney Karin R. Bryan Christian Winter 《地球表面变化过程与地形》2019,44(10):1957-1972
Geomorphological characteristics of tidal basins control hydrodynamics and sediment transport potential within such basins, for example, by adjusting the balance in tidal asymmetry. In this study we examine the effects of entrance geometry on tidal velocity asymmetry, slack water asymmetry, bed shear stress patterns and hypsometric profile shapes by comparison of six shallow meso-tidal basins of Tauranga Harbour, New Zealand. Numerical model results show how tidal distortion increases with distance from a basin entrance. A simple ratio between basin width and entrance width defines levels of basin dilation. Sub-basins with a constricted geometry and deep entrance channels are associated with small bed shear stress values and high rates of flood-directed tidal velocity asymmetry in the sheltered basin centres, indicating a large potential for sediment deposition of larger particles. Moreover, slack water asymmetry within these basins is weakly ebb-directed, indicating a small potential for transport of fine sediments out of the basins. The constricted depositional basins are characterized by convex hypsometric profiles with elevated intertidal regions. Unconstricted geometries are associated with larger bed shear stress values and more ebb-directed tidal velocity asymmetry within basin centres, suggesting limited potential for overall sediment deposition. The slack tide duration asymmetry is weakly flood-dominant indicating that limited input of fine sediment into the basins is possible. The comparatively high-energy conditions within these exposed basins are associated with a less convex hypsometric intertidal profile. The ability to estimate tidal asymmetries is advantageous when developing management strategies related to ecosystem functioning, navigability or coastal protection in specific geomorphic settings. © 2019 John Wiley & Sons, Ltd. 相似文献
7.
青海达日地区发育了多条晚第四纪活动断裂带,以NW—NNW向和近SN向为主。通过航卫片解译和野外实地调查发现,达日断裂中段晚第四纪新活动性尤为显著,其性质以左旋走滑为主,至今部分地段仍保存了清晰的1947年达日7级地震地表破裂带,其破裂样式具有分段性和多样性,反映了局部构造应力的差异。达日地区作为典型的活动构造区,是研究新构造运动与地貌响应的理想场所。因此,文中采用ASTER GDEM V2数据提取了该地区的水系网络和亚流域盆地参数,计算了亚流域盆地面积-高程积分曲线和积分值(HI值),讨论了其构造活动性及地貌响应的关系。区内黄河的6个亚流域盆地的面积-高程积分曲线形态分析结果表明,这6个亚流域盆地均处于地貌演化阶段的"壮年期",其演化过程表现出很好的同步性,反映了区域性构造隆升或沉降作用的总体结果。而且,区内亚流域盆地的面积-高程积分值(HI值)分布特征表明,HI低值分布与第四纪断陷盆地和河谷盆地范围相一致,反映了局部不同构造沉降和侵蚀作用的结果;HI高值则主要出现在达日地震地表破裂带由NWW向NW转向的部位,以及早侏罗世与晚三叠世花岗闪长岩体分布的地方,也很好地反映了局部构造作用的变化和地层岩性的差异。 相似文献
8.
Tejpal Singh 《国际地球制图》2013,28(6):417-427
Hypsometric analysis describes the elevation distribution across an area of land surface. It is an important tool to assess and compare the geomorphic evolution of various landforms irrespective of the factor that may be responsible for it. The major factors governing the evolution of landscape are tectonics and/or climate and the variation in lithology. The present study takes into consideration the watersheds developed over actively deforming Mohand anticlinal ridge in the frontal part of NW Himalaya. The hypsometric analysis has been used as a morphometric parameter, i.e. hypsometric integral, to deduce its relationship with the area of watersheds. Statistical analysis of these parameters has been carried out by classifying them into different classes based on the natural breaks method. This brings out strong relationships for hypsometric integral classes and area classes with the number of watersheds in respective classes and the total area occupied by respective hypsometric and area classes. It has also been found that stronger relationships exist for watersheds on the southern flank as compared to watersheds of the northern flank. It also highlights the presence of an anomalous watershed on the northern flank that is possibly responsible for the weak statistical relationships on the northern flank. Removal of this anomalous watershed always brings out much stronger relationships for the northern flank. The anomalous watershed has been directly attributed to the difference in geologic structure as it is spatially related to the presence of the Bhimgoda Back Thrust (BBT) present in the area. The results are awe inspiring and very promising as they indicate some statistically strong relationships among the hypsometric integral and area of watersheds that are not apparent in the spatial distribution of these parameters, especially in actively deforming areas. 相似文献
9.
Hypsometry of glaciated landscapes 总被引：1，自引：0，他引：1
Hypsometry (frequency distribution of elevations) is often used to characterize landscape morphology, traditionally in the context of the degree of ?uvial dissection. Recently, the hypsometry of glaciated regions has been used to infer how rates of glacial erosion compare with tectonic uplift rates. However, many factors other than tectonics can also exert a major in?uence on the hypsometry of a glaciated landscape, resulting in a wide variety of hypsometries. Using examples from the eastern Sierra Nevada, California, the western Sangre de Cristo Range, Colorado, and the Ben Ohau Range, New Zealand, we demonstrate that, all else being equal, the hypsometries of neighbouring basins can indicate the relative degree of glacial modi?cation in each. A selection of drainage basins from the Rocky Mountains shows that the position of the equilibrium line altitude (ELA) within the drainage basin relief is a dominant variable in determining the hypsometry of a glaciated basin. This is a non‐linear effect: once the ELA falls to some critical level, the glaciers scour deeply below the ELA, causing a noticeably different hypsometry. The hypsometry of an arbitrary region encompassing many drainage basins can disguise the variation present in the hypsometries, and thus landforms, of the individual basins. Unique local circumstances, such as the presence of a mountain ice?eld (Waiho Basin, Southern Alps), substantial hanging valleys (Avalanche Creek, Glacier National Park), a narrow outlet canyon (Sawmill Creek, Sierra Nevada), and isolated geologic structures (Baker Creek, Sierra Nevada), can have a major impact on the hypsometry of an individual basin. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
10.
The eastern Himalayan syntaxis is located on the leading edge of Indian-Eurasian plate collision, and the uplift rate of Namche Barwa area is higher than that of the peripheral zones, which is considered as the core position of the eastern Himalayan syntaxis(Uplift Center).It is indicated according to the recent regional earthquake observation results that, the seismic activity is poor in the area of Namche Barwa, but with strong seismic activity in its southeast region. In order to study the current geodynamical characteristics of the eastern Himalayan syntaxis, the elevation frequency distribution and hypsometry curve of Namche Barwa area, its northwest and southeast as well as the northeast Assam area is analyzed using DEM data. It is shown according to the result that, the Namche Barwa area is in the mature stage of erosion and the regional tectonic uplift and denudation are in the highly balanced status. Influenced by plateau-climate weather effect, the denudation of this area is relatively poor, which indicates that the uplift of the Namche Barwa area is relatively slow at present. The geomorphology in the northwest and southeast as well as in northeast Assam is in young evolutionary phase, belonging to erosive infancy, and the geomorphology of northeast Assam is closer to the early stage of infancy. The geomorphic evolution stage on northwest side reflects that the regional erosion is poor and it still belongs to plateau-climate area; Influenced by south subtropical monsoons, there is rich rainfall in the area from southeast Namche Barwa to Assam area, and this area still belongs to erosive infancy, even the geomorphic development degree of northeast Assam is lower as it suffers from strong erosion effect, which means that the tectonic uplift in east Namche Barwa is very intensive, and the northeast Assam has the highest uplift rate. It is considered according to the research that, under the mode that India Plate moves towards the north at present, the core position of the eastern Himalayan syntaxis(Uplift Center)moves towards the southeast, and the new core position may be located in northeast Assam, where there is intensive regional tectonic uplift with high potential of great earthquake. 相似文献
1