共查询到20条相似文献,搜索用时 15 毫秒
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研究目的是采用水文模型系统(HMS)模拟峨嵋河流域暴雨水文过程,并为长江上游地区气候和水文响应研究提供可靠的信息。HMS是一种分布式水文模型可用于研究各种气候因子和地表覆盖变化而引起的水文过程响应,该系统(HMS)利用气象、土壤类型、土地利用和地表覆盖、数字高程(DEM)和降雨径流等资料,研究气候、陆面、地表水和地下水的相互作用机理。在本次研究中,采用SCS Curve Number(CN)和Green-Ampt(GA)方法来计算径流过程,用GIS来数字化DEM、土壤、土地利用和陆地覆盖数据。通过用不同时间间隔的降雨和不同计算方法的水力参数模拟水文过程,来检验降雨的时间尺度效应和水力参数的空间变异性对水文过程的影响。结果表明,HMS对峨嵋河流域暴雨洪水的模拟及预测具有较好的适用性。 相似文献
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Peter J. Hernes Robert G.M. Spencer Brian A. Pellerin Brian A. Bergamaschi 《Geochimica et cosmochimica acta》2008,72(21):5266-5277
Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled weekly in 2006 in order to investigate seasonal concentrations and compositions of dissolved organic carbon (DOC). Average DOC concentrations nearly doubled from winter baseflow (2.75 mg L−1) to summer irrigation (5.14 mg L−1), while a concomitant increase in carbon-normalized vanillyl phenols (0.11 mg 100 mg OC−1 increasing to 0.31 mg 100 mg OC−1, on average) indicates that this additional carbon is likely vascular plant-derived. A strong linear relationship between lignin concentration and total suspended sediments (r2 = 0.79) demonstrates that agricultural management practices that mobilize sediments will likely have a direct and significant impact on DOC composition. The original source of vascular plant-derived DOC to Willow Slough appears to be the same throughout the year as evidenced by similar syringyl to vanillyl and cinnamyl to vanillyl ratios. However, differing diagenetic pathways during winter baseflow as compared to the rest of the year are evident in acid to aldehyde ratios of both vanillyl and syringyl phenols. The chromophoric dissolved organic matter (CDOM) absorption coefficient at 350 nm showed a strong correlation with lignin concentration (r2 = 0.83). Other CDOM measurements related to aromaticity and molecular weight also showed correlations with carbon-normalized yields (e.g. specific UV absorbance at 254 nm (r2 = 0.57) and spectral slope (r2 = 0.54)). Our overall findings suggest that irrigated agricultural watersheds like Willow Slough can potentially have a significant impact on mainstem DOC concentration and composition when scaled to the entire watershed of the main tributary. 相似文献
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针对西苕溪流域水质安全问题,基于WEAP建模平台,构建了西苕溪流域水资源评估与规划模型。在模型验证基础上,分析了西苕溪流域2001~2020年河道水功能目标满足度及水供需关系,识别了流域水资源利用存在的问题,并探讨了水源地和中下游区水质安全保障措施及其改善水质的效用,在此基础上提出了西苕溪流域水质安全保障方案。研究表明:TN是影响水源地供水安全的限制性因素,TN、TP是影响河道水功能的重要指标。通过综合实施废水处理厂、节水型设备、退耕还林等水资源管理措施能起到较好地削减TN产出的效果,水源地河道TN浓度降低,基本上能保证全年实现河道Ⅲ类水功能目标,中下游河道TP、TN浓度亦能达到Ⅲ类水功能要求。 相似文献
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Problems in hydrology frequently have moving fronts and dynamic driving mechanisms such as wells. Since the location of important
features changes during a simulation, accurate modeling requires uniformly fine resolution or the ability to change resolution
during the simulation. We will describe an algorithm for refinement and unrefinement of tetrahedral/triangular meshes that
has been implemented in the adaptive hydrology (ADH) code. The codes including the refinement/unrefinement algorithms are
implemented in parallel to accommodate problems with large run time and memory requirements. In this paper, we describe the
parallel, adaptive grid algorithm used in ADH and show the resulting grids from some example problems. 相似文献
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Determining the optimum cell size of digital elevation model for hydrologic application 总被引:1,自引:0,他引:1
Scale is one of the most important but unsolved issues in various scientific disciplines that deal with spatial data. The
arbitrary choice of grid cell size for contour interpolated digital elevation models (DEM) is one of the major sources of
uncertainty in the hydrologic modelling process. In this paper, an attempt was made to identify methods for determining an
optimum cell size for a contour interpolated DEM in prior to hydrologic modelling. Twenty-meter interval contour lines were
used to generate DEMs of five different resolutions, viz., 30, 45, 60, 75, and 90 m using TOPOGRID algorithm. The obtained DEMs were explored for their intrinsic quality using four
different methods, i.e., sink analysis, fractal dimension of derived stream network, entropy measurement and semivariogram
modelling. These methods were applied to determine the level artifacts (interpolation error) in DEM surface as well as derived
stream network, spatial information content and spatial variability respectively. The results indicated that a 90 m cell size
is sufficient to capture the terrain variability for subsequent hydrologic modelling in the study area. The significance of
this research work is that it provides methods which DEM users can apply to select an appropriate DEM cell size in prior to
detailed hydrologic modelling. 相似文献
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《Tectonophysics》1987,141(4):317-334
The Cameroon Line, a major geological feature in Central Africa, has been considered successively as a series of horsts and grabens, a continental rift and a mega-shear zone. It is marked out by about 60 anorogenic complexes and a dozen volcanic centres, all of which have alkaline affinity.Remote sensing allows us recognition of the main lineament trends: N70°, N-S, N135° and E-W, while autocorrelation analysis reveals a major fault zone striking N30° in western Cameroon and N15° in the northern region. A mega left-lateral shear zone is the model that best accounts for the fracture pattern and associated features such as linear and circular structures alignment of subvolcanic complexes, syntectonic leucogranites marking out older shear zones and vein dykes. The N70° Adamawa fault zone, a Pan-African fracture reworked during Albian-Aptian times, is the only shear zone of continental scale that could have initiated “en echelon” mega-tension gashes within the Cameroon Line during a Cainozoic left-lateral transcurrent movement. 相似文献
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Drought adaptation policy development and assessment in East Africa using hydrologic and system dynamics modeling 总被引:2,自引:0,他引:2
Drought is a natural disaster that affects millions of people across the globe. Lack of rainfall reduces crop yields and livestock productivity and, in turn, food availability and income. In developing countries, these effects are even more detrimental. As droughts become more frequent, adaptation is a fundamental concern for countries and their policymakers. To support a development of drought adaptation policies, a combined hydrologic and system dynamics model was developed for a region in East Africa, focused on the Horn of Africa (i.e., a region bordering Kenya, Somalia, and Ethiopia), an area that has endured multiple droughts in the last few decades. The model simulates the interdependencies between water availability, land degradation, food availability, and socioeconomic welfare. The impacts of new adaptation policies on the region were evaluated over a 10-year simulation period using historical weather data. It was found that a combination of increased hydraulic infrastructure and innovative agricultural practice policy can reduce domestic water deficits by 54–100 % while increasing the income per capita up to 285 % over the 10 years. Innovatively combining hydrologic and systems dynamic modeling produces a realistic simulation of water scarcity and the effects on natural systems. Implementation of policies within the model aids the selection process by evaluating multiple options, quantifying the effectiveness the policies have on individual stakeholder livelihood (i.e., pastoralist, agro-pastoralists, and farmers), and analyzing the overall outcome to ensure equitable costs and benefits among the stakeholders. 相似文献
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提出用基于加速遗传算法的模糊层次分析法筛选指标体系、确定各评价指标和各子系统的权重,用BP神经网络模型滚动预测评价指标,用集对分析方法构造评价指标样本值隶属于可变模糊集"水安全评价标准等级"的相对隶属度函数,建立了流域水安全预警评价的智能集成模型(IMI-FEM)。IMI-FEM对巢湖流域水安全系统未来5年的预警评价结果说明:水资源、水环境和水灾害防治安全子系统的安全状况将分别处于2.73~2.74级、3.30~3.32级和2.54~3.43级,社会经济安全子系统的安全状况将维持在3.33级,流域水安全系统的总体安全状况将处于2.98~3.20级,处于临界安全;主要限制指标为水资源开发利用率、人均水资源量、单位面积水资源量、万元农业产值用水量、单位面积化肥施用量、生态环境用水率、环保投资占GDP比例、单位面积蓄水工程总库容、水利工程投资占GDP比例、区域开发指数、人口密度和科技教育投入占GDP比例。 相似文献
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A first-order seismotectonic model was created for South Africa. This was done using four logical steps: geoscientific data
collection, characterisation, assimilation and zonation. Through the definition of subunits of concentrations of earthquake
foci and large neotectonic and structural domains, seismotectonic structures, systems and domains were created. Relatively
larger controls of seismicity exist between the Great Escarpment and the coast. In the south, this region is characterised
by large aeromagnetic anomalies and large EW trending faults. In the west, it is characterised by the NW–SE trending Wegener
stress anomaly, radial-trending dykes and earthquake clusters. In the east, it is characterised by a large neotectonic domain
where several large historical earthquakes occurred. In the centre of South Africa, several clusters of earthquake activity
are found, often related to mining activity. Further north, seismicity is related to both mining activity and neotectonic
deformation. This work contributes to the development of a seismotectonic model for South Africa by (1) bringing together,
digitally, several data sets in a common GIS platform (geology, geophysics, stress, seismicity, neotectonics, topography,
crustal and mantle structure and anisotropy), (2) understanding the significance of data sets for seismotectonic zonation
and limitations thereof and (3) obtaining a reasonable regional model for use in seismic hazard assessments. 相似文献
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Salaheddine El Adlouni 《Natural Hazards》2018,94(1):299-317
A spatial quantile regression model is proposed to estimate the quantile curve for a given probability of non-exceedance, as function of locations and covariates. Canonical vines copulas are considered to represent the spatial dependence structure. The marginal at each location is an asymmetric Laplace distribution where the parameters are functions of the covariates. The full conditional quantile distribution is given using the Joe–Clayton copula. Simulations show the flexibility of the proposed model to estimate the quantiles with special dependence structures. A case study illustrates its applicability to estimate quantiles for spatial temperature anomalies. 相似文献
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随着计算机技术的发展,以消息传递接口(MPI)标准为代表的高性价比集群计算技术使并行计算在大量传统的专业领域也得到了广泛应用.数字流域模型因需要对大范围流域进行分布式的水文、泥沙过程模拟而提出了较大规模的计算需求.同时,基于分水岭的单元划分方式和专门的河网编码方法使数字流域模型的并行化计算具有先天优势.提出了一种典型的并行调度流程,用于完成产汇流计算的动态任务分配.在自主搭建的MPI计算集群上进行的应用实验表明,集群计算提高了数字流域模型的计算效率,能够作为模型的计算平台.最后指出了此应用计算平台的发展方向. 相似文献
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黄河数字流域模型是“数字黄河”的重要组成部分,在数字流域模型框架下,以坡面为基本单元,建立了包括植被截留、融雪、地表蓄滞、表层土蓄滞、中层土蓄滞和深层土蓄滞共6层的产流模型.模型在垂向上考虑3层出流:地表超渗产流、表层土侧向渗流和中层土侧向渗流,既反映当前的降水过程,又体现前期降水过程和土壤前期含水量的影响,比较适合黄河流域的产流特点.在坡面产流的基础上,还给出了坡面单元侵蚀产沙公式,用于建立流域产沙数学模型.应用建立的模型,给出了3个计算实例:黄河全流域水量计算、小花区间汛期洪水模拟和多沙粗沙区产沙计算.实践表明:建立的模型基本具备了在黄河全流域进行降雨-径流模拟、侵蚀产沙计算的功能,辅以降雨预报模块则可进行洪水预报. 相似文献
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S. Verma S. K. Mishra A. Singh P. K. Singh R. K. Verma 《Environmental Earth Sciences》2017,76(21):736
Incorporation of initial soil moisture (V 0) in the Soil Conservation Service Curve Number (SCS-CN) methodology helps to avoid the sudden jumps in Curve Number (CN) and, in turn, in computed runoff. It invoked the development of an enhanced (yet simple) Soil Moisture Accounting (SMA) procedure-based-SCS-CN inspired model, by incorporating initial moisture (V 0). Its performance is tested using a dataset of 152 small to large watersheds of USDA (total 38,169 storm events), and compared with original SCS-CN method, Mishra and Singh (Acta Geophys Polon 50(3):457–477, 2002), Michel et al. (Water Resour Res 41(2):W02011, 2005) and Singh et al. (Water Resour Manag 29(11): 4111–4127, 2015) model using four statistical indices (RMSE, R 2, PBIAS and NSE) and rank grading system (RGS). The proposed model scores highest (= 691 marks out of maximum 2280 marks) (Rank I) followed by Singh et al. (Water Resour Manag 29(11):4111–4127, 2015) model with 642 marks (Rank II), Michel et al. (Water Resour Res 41(2):W02011, 2005) model with 376 marks (Rank III) and Mishra and Singh model with 362 marks (= Rank IV). The original SCS-CN model, however, performs the poorest of all with 209 marks (Rank V). 相似文献
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为高效高精度地模拟流域雨洪过程,应用动力波法求解二维圣维南方程,并耦合水文过程,建立了包含流域降雨产流、汇流、下渗以及洪水演进等过程的高性能流域雨洪数值模型。该模型的优势在于使用非结构网格,可较好地处理不规则边界,准确贴合复杂地形表面,使得模型能精确计算模拟流域雨洪过程,同时引入GPU技术加速计算,使得大尺度流域雨洪计算成为可能。最后,将模型应用于V型经典算例及2个实际流域雨洪算例,所得结果与实测吻合较好,计算所用时间较短,表明该模型可以快速且精确模拟流域雨洪过程。研究结果有助于实现对实际流域雨洪灾害进行合理高效的预测,为应急抢险工作提供有力支撑。 相似文献
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Kalisa Wilson Igbawua Tertsea Ujoh Fanan Aondoakaa Igbalumun S. Namugize Jean Nepomuscene Zhang Jiahua 《Natural Hazards》2021,106(3):2047-2076
Natural Hazards - Precipitation and temperature are critical climatic variables that drive catastrophic climatic events including droughts and floods. These variables continue to fluctuate, thereby... 相似文献
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William Bosworth 《International Journal of Earth Sciences》1994,83(4):671-688
Large areas of north-east Africa were dominated by regional extension in the Late Phanerozoic. Widespread rifting occurred in the Late Jurassic, with regional extension culminating in the Cretaceous and resulting in the greatest areal extent and degree of interconnection of the west, central and north African rift systems. Basin reactivation continued in the Paleocene and Eocene and new rifts probably formed in the Red Sea and western Kenya. In the Oligocene and Early Miocene, rifts in Kenya, Ethiopia and the Red Sea linked and expanded to form the new east African rift system.This complex history of rifting resulted in failed rift basins with low to high strain geometries, a range of associated volcanism and varying degrees of interaction with older structures. One system, the Red Sea rift, has partially attained active seafloor spreading. From a comparison of these basins, a general model of three-dimensional rift evolution is proposed. Asymmetrical crustal geometries dominated the early phases of these basins, accompanied by low angle normal faulting that has been observed at least locally in outcrop. As rifting progressed, the original fault and basin forms were modified to produce larger, more through-going structures. Some basins were abandoned, others experienced reversals in regional dip and, in general, extension and subsidence became focused along narrower zones near the rift axes. The final transition to oceanic spreading was accomplished in the Red Sea by a change to high angle, planar normal faulting and diffuse dike injection, followed by the organization of an axial magma chamber. 相似文献