Derivation of a curve number and kinematic-wave based flood frequency distribution     

R. S. KUROTHE  N. K. GOEL  B. S. MATHUR 《水文科学杂志》2013,58(4):571-584

Abstract

The physically-based flood frequency models use readily available rainfall data and catchment characteristics to derive the flood frequency distribution. In the present study, a new physically-based flood frequency distribution has been developed. This model uses bivariate exponential distribution for rainfall intensity and duration, and the Soil Conservation Service-Curve Number (SCS-CN) method for deriving the probability density function (pdf) of effective rainfall. The effective rainfall-runoff model is based on kinematic-wave theory. The results of application of this derived model to three Indian basins indicate that the model is a useful alternative for estimating flood flow quantiles at ungauged sites.  相似文献   

Impact of soil and water conservation measures on catchment hydrological response—a case in north Ethiopia     

Jan Nyssen  Wim Clymans  Katrien Descheemaeker  Jean Poesen  Ine Vandecasteele  Matthias Vanmaercke  Amanuel Zenebe  Marc Van Camp  Mitiku Haile  Nigussie Haregeweyn  Jan Moeyersons  Kristine Martens  Tesfamichael Gebreyohannes  Jozef Deckers  Kristine Walraevens 《水文研究》2010,24(13):1880-1895

Impact studies of catchment management in the developing world rarely include detailed hydrological components. Here, changes in the hydrological response of a 200‐ha catchment in north Ethiopia are investigated. The management included various soil and water conservation measures such as the construction of dry masonry stone bunds and check dams, the abandonment of post‐harvest grazing, and the establishment of woody vegetation. Measurements at the catchment outlet indicated a runoff depth of 5 mm or a runoff coefficient (RC) of 1·6% in the rainy season of 2006. Combined with runoff measurements at plot scale, this allowed calculating the runoff curve number (CN) for various land uses and land management techniques. The pre‐implementation runoff depth was then predicted using the CN values and a ponding adjustment factor, representing the abstraction of runoff induced by the 242 check dams in gullies. Using the 2006 rainfall depths, the runoff depth for the 2000 land management situation was predicted to be 26·5 mm (RC = 8%), in line with current RCs of nearby catchments. Monitoring of the ground water level indicated a rise after catchment management. The yearly rise in water table after the onset of the rains (ΔT) relative to the water surplus (WS) over the same period increased between 2002–2003 (ΔT/WS = 3·4) and 2006 (ΔT/WS >11·1). Emerging wells and irrigation are other indicators for improved water supply in the managed catchment. Cropped fields in the gullies indicate that farmers are less frightened for the destructive effects of flash floods. Due to increased soil water content, the crop growing period is prolonged. It can be concluded that this catchment management has resulted in a higher infiltration rate and a reduction of direct runoff volume by 81% which has had a positive influence on the catchment water balance. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Convection in a rotating annulus having sidewalls of height-dependent thermal conductance     

Jae Min Hyun  Chang Yeong Kim 《地球物理与天体物理流体动力学》2013,107(3):149-162

Abstract

Thermal convection in a vertically-mounted, rotating annulus of a particular design proposed by Davies and Walin (1977) is investigated. The annulus used in the present study differs from the conventional type in some important aspects: the sidewalls are finitely conducting, and the thermal conductance of the sidewalls is height-dependent. The theoretical model due to Davies and Walin is briefly recounted. The present study aims to verify the theoretical model; we have acquired numerical solutions to the governing Navier-Stokes equations. The numerical results are supportive of the theoretical contentions. The near-linear dependence of the isothermal slope on the parameter D, which is a function of Ω and ΔT, is corroborated within reasonable limits. New data on the vertical and radial structures of the meridional and azimuthal flows are presented. The numerical results also confirm that the shape of the sidewall thickness has a substantial influence on the meridional flow patterns. In the bulk of the interior flow field, the dominant azimuthal flow field and the temperature field are linked by the thermal wind relation.  相似文献   

聚合物驱组合段塞分注实验研究     

李宜强  林丽华  梁双庆 《海洋地质译丛》2010,(1):85-89

萨尔图油田南二区东部140号断层以东地区葡11—4油层，以多段多韵律和正韵律沉积为主，平均孔隙度30．0％，平均空气渗透率1980×10^-3μm2。水驱结束时该油层平均含水92％，采出程度39．5％。计划对该区块实施聚合物驱开采。以往经验认为，组合段塞调整注聚技术能够有效改善流度控制作用。然而对组合注入情况下如何进一步提高驱油效果、注入井分注时机、层段注入强度对开发效果有何影响却很少探讨。通过室内驱油实验，在聚驱的组合段塞注入不同时机（水驱空白阶段、含水下降阶段、含水稳定阶段、含水回升阶段）下调整注入强度实施分注以及在含水回升分注基础上进一步调整注入强度，同时对比不分注实验，评价各方案驱油效果。实验表明：不实施分注时聚驱采收率在水驱基础上提高了19．07个百分点，而组合段塞注入时实施分注均能够在不分注基础上进一步提高驱油效果；空白水驱时实施分注采收率提高幅度最大，为26．55个百分点；随着分注时机的滞后采收率提高幅度增加值依次递减，分注时机越早越好。  相似文献   

Key Groundwater Control Factors of Deep Buried Coalfield by Landform and Sedimentation in the Northern Ordos Basin     

Jian Yang  Ji Liu  Hao Huang  Xiangyang Liang 《地球科学进展》2019,34(5):523-530

There were three landforms (i.e. desert, bedrock platform and loess gully) in deep-buried coalfield of northern Ordos Basin. Water inflow of working face in desert area was 1~2 orders of magnitude larger than that in other landform areas. In order to find out the key controlling factors of the directly water filled aquifers on the roof of the coal seam, we carried out research from the aspects of topography, landform and geological sedimentation. The results showed that desert landform provides abundant recharge water for underlying aquifers because of gentle topography, large precipitation infiltration coefficient, thick and water-rich quaternary system. While bedrock platform and loess gully landform were the water sources with weak recharge capacity of underlying aquifers. The sandstone-mudstone interbedding structure formed by continental deposits resulted in the absence of regional stable aquifers in Jurassic and Cretaceous strata on the roof of coal seams. Pumping tests of boreholes showed that all strata belong to weak to medium water-rich aquifers. The groundwater level of Cretaceous aquifer decreased by 20~130 m in three mines. There was a close hydraulic relationship between shallow and deep aquifers. The Mesozoic strata belonged to fluvial deposits. Qilizhen sandstone and Zhenwudong sandstone aquifers were mainly developed on the roof of the coal seam, which were characterized by thick medium-coarse sandstone sections. The geological and sedimentary conditions of direct water-filled aquifer were similar, but the amount of borehole water, cumulative pre-drainage water and water inflow from goaf in desert geomorphic area were much larger than those in bedrock platform and loess gully geomorphic area. The water-rich of the aquifer was mainly controlled by geomorphology, and the water sources of the deep aquifers were meteoric precipitation and Quaternary aquifer. In different mines with similar Quaternary conditions in Mu Us Desert, there were also great differences in the amount of borehole water, cumulative pre-drainage water and water inflow from goafs. The difference was related to the thickness and lithology of the aquifers. It reflected that the geological sedimentary conditions of the coal seam roof were also important factors to control the water-rich of the aquifers. Topography, landform and geological sedimentation were the key factors to control the water-rich of the aquifer directly and the water inflow from the working face.  相似文献   

老平台新增井槽技术的应用与发展     

谭越  杨光  王建文  王春升 《海洋地质译丛》2012,(2):106-110

老油田的二次开发难度较大,为充分利用老平台设备资源,解决现有海上平台存在的预留井槽不足的问题,曾提出并成功应用了内挂、外挂、新增桩腿外挂等增加井槽的方式,但井槽增加的方位和数量受到限制。结合两平台短距离连接和修井机双向滑移避让钻井船技术,提出了新的修井机共用方式。通过采用双向滑轨实现了修井机在新建平台和老平台间的往复滑移。此技术节约了开发投资,为今后类似项目提供参考和借鉴。  相似文献   

Seismic performance and comparison of three different I beam to box column joints     

Z.Saneei Nia  A.Mazroi  M.Ghassemieh  H.Pezeshki 《地震工程与工程振动(英文版)》2014,(4)

Despite the inherently advantages of the box column, finding the best option for the I beam to the box column connection is the main challenge in using the box column as a structural member for special moment frames. In this paper, the seismic performance of unreinforced connection, weakened connection and strengthened connection was evaluated through a comprehensive experimental program. The seismic comparisons were fabricated by assessing the strength, ductility and energy dissipation in each configuration. Three full scale tests with several connections were carried out. All the specimens were subjected to cyclic loading and prior to failure by forming a plastic hinge in the beam, all the connections managed to reach an inelastic rotation of more than 6.0% rad. The experimental and analytical results showed that the seismic performance of the strengthened connection with flange and shear plates turned out to be the most effective in the beam to the box column connection. Moreover, the normalized stress distribution of the continuity plates revealed that the possibility of the weld fracture in unreinforced connection is more than other specimens.  相似文献   

跨海高程传递方法的评价          下载免费PDF全文

赵庆海  欧阳桂崇  杨华忠 《海洋测绘》2012,(1):49-51

针对跨海高程传递的最新进展,介绍了几种高程传递的实用方法,对优缺点和适用范围进行了分析与评价。初步试验结果分析表明,对于10km内的高程传递,几种方法均满足三等水准的精度要求,对于更远距离的跨海高程传递还需进一步研究。  相似文献   

山西省阳泉市城市热岛效应特征分析     

李润春  崔建国  牛俊玫  李兴  岳凯杰  王晓敏 《气象与环境学报》2014,30(2):74-80

利用1972－2011年阳泉市3个国家级气象站资料、2011年36个乡镇区域自动站气温资料,分析了阳泉市城市热岛效应的年际变化、季节变化、月变化和日变化特征。结果表明：阳泉市存在弱的城市热岛效应,1972－2011年平均热岛强度0.554 ℃。阳泉市城市热岛强度整体呈显著上升趋势,热岛强度的增加主要是由于夏季热岛强度的增强;热岛强度冬、秋季强,春、夏季弱;12月最强,5月最弱;热岛强度日变化表现为12时最小,从傍晚开始随降温逐渐增大,到早晨气温降到最低时最大,日出之后迅速减小;2008－2011年最强热岛强度出现在2010年1月14日08时,达7.9 ℃。阳泉在升温天气热岛强度变幅增大,易在早晨形成较强城市热岛,下午形成城市冷岛;降温天气热岛强度变幅减小;温度变化较小时则易维持弱的城市热岛。阳泉市主要城市发展因子与霾日数、气温呈显著正相关,在目前的经济发展水平条件下,阳泉市城市化发展可能使城市温度增高,城市绿地面积的增加可能对热岛效应有缓解作用。  相似文献   

Statistical study on great geomagnetic storms during solar cycle 23          下载免费PDF全文

Qi Li  Yufen Gao  Peiyu Zhu  Huaran Chen  Xiuling Zhang 《地震科学（英文版）》2011,24(4):365-372

Characteristics of great geomagnetic storms during solar cycle 23 were statistically investigated. Firstly, we focused on the uniqueness of solar cycle 23 by analyzing both the great storm number and sunspot number from 1957 to 2008. It was found that the relationship between the sunspot number and great storm number weakened as the activity of the storms strengthened. There was no obvious relationship between the annual sunspot number and great storm number with Dstxi≤-300 nT. Secondly, we studied the relationship between the peak Dst and peak Bz in detail. It was found that the condition Bz≤-10 nT is not necessary for storms with Dst≤-100 nT, but seems necessary for storms with Dst≤-150 nT. The duration for Bz≤-10 nT has no direct relationship with the giant storm. The correlation coefficient between the Dst peak and Bz peak for the 89 storms studied is 0.81. After removing the effect of solar wind dynamic pressure on the Dst peak, we obtained a better correlation coefficient of 0.86. We also found the difference between the Dst peak and the corrected Dst peak was proportional to the Dst peak.  相似文献