重庆市主体功能区识别的主导因素与空间稳定性约束机理     

汪洋  王力力  祁鹏卫  刘志海 《地理学报》2019,74(1):44-62

主体功能区规划已上升为国家制度和战略,对中国长期空间发展格局优化与再组织将发挥积极的引导和约束作用。从地域性角度出发,探寻主体功能区发生性（形成与演化）和反馈性（识别与规划）时空机理与规律是地理学具有时代意义的重要科学问题。以重庆市为例,通过国土空间开发条件综合评价,识别了主体功能区划分的适宜性空间格局。基于对西南山区发展约束条件的基本认识,提出了地域主体功能空间分异的主导性约束假设,设定地形和区位为原生性主导因素,验证了其与区划指标系统的定量关联性,以此为基础解析了主导因素约束机理并提出了地域主体功能区的空间稳定性机制。研究发现：① 开发与保护适宜性识别结果的格局指向清晰。城市化适宜的区域主要集中于都市区和部分周边区县,区域副中心（万州和黔江）适宜性也相对较高。生态保护适宜的区域集中于渝东北秦巴山区及部分三峡库区区县,同时包括渝东南武陵山区所在区县。② 地形和区位因子在本区域对主体功能区的识别与形成具有主导约束作用。回归分析显示,主体功能区划指标与地形因子相关性水平达到显著的超过70%,区位因子超过40%;两者综合后与区划标志变量（A、B指数）的相线性相关拟合度R²均超过0.8;地理探测器发现,地形和区位因子对区划指标的约束性分别有9个和7个达到0.05显著性水平,对A、B指数的解释度分别约为70%和60%,两者叠加后,约束水平全部达到显著,对A、B指数的解释度在90%左右。③ 空间稳定性机制表现为两个方面,其一是基于主导因素约束的稳定性传递机制,称为客观稳定性;其二是基于指标体系的局域相对性和算法的内部抵消机制,称为主观稳定性。两种机制的协同性验证了区划技术系统的地域适应性和科学性。  相似文献   

Non-point source pollution estimation in the Pingqiao River Basin,China, using a spatial hydrograph-separation approach     

Han Xue  Kaoru Takara  Bin He  Guangwei Huang  Weili Duan 《水文科学杂志》2019,64(8):962-973

For efficient and targeted management, this study demonstrates a recently developed non-point source (NPS) pollution model for a year-long estimation in the Pingqiao River Basin (22.3 km²) in China. This simple but physically reasonable model estimates NPS export in terms of land use by reflecting spatial hydrological features and source runoff measurements under different land-use types. The NPS export was separately analysed by a distributed hydrological model, a spatial hydrograph-separation technique, and an empirical water quality sub-model. Simulation results suggest that 57 890 kg of total nitrogen (TN) and 1148 kg of total phosphorus (TP) were delivered. The results, validated with observed stream concentrations, show relative errors of 23.3% for TN and 47.4% for TP. Countermeasures for urban areas (5.3% of total area) were prioritized because of the high contribution rate to TN (14.1%) and TP (26.2%) which is caused by the high degree of runoff (8.5%) and pollution source.  相似文献   

Streamwater ages in nested,seasonally cold Canadian watersheds     

Samuel Bansah  Genevieve Ali 《水文研究》2019,33(4):495-511

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Quantitative estimation of submarine groundwater discharge using airborne thermal infrared data acquired at two different tidal heights     

Ki‐mook Kang  Duk‐jin Kim  Yunjee Kim  Eunhee Lee  Bong‐Gwan Kim  Seung Hee Kim  Kyoochul Ha  Dong‐Chan Koh  Yang‐Ki Cho  Guebuem Kim 《水文研究》2019,33(7):1089-1100

Submarine groundwater discharge (SGD) plays an important role in coastal biogeochemical processes and hydrological cycles, particularly off volcanic islands in oligotrophic oceans. However, the spatial and temporal variations of SGD are still poorly understood owing to difficulty in taking rapid SGD measurements over a large scale. In this study, we used four airborne thermal infrared surveys (twice each during high and low tides) to quantify the spatiotemporal variations of SGD over the entire coast of Jeju Island, Korea. On the basis of an analytical model, we found a linear positive correlation between the thermal anomaly and squares of the groundwater discharge velocity and a negative exponential correlation between the anomaly and water depth (including tide height and bathymetry). We then derived a new equation for quantitatively estimating the SGD flow rates from thermal anomalies acquired at two different tide heights. The proposed method was validated with the measured SGD flow rates using a current meter at Gongcheonpo Beach. We believe that the method can be effectively applied for rapid estimation of SGD over coastal areas, where fresh groundwater discharge is significant, using airborne thermal infrared surveys.  相似文献   

Root‐zone moisture replenishment in a native vegetated catchment under Mediterranean climate     

Xiang Xu  Huade Guan  Grzegorz Skrzypek  Craig T. Simmons 《水文研究》2019,33(18):2394-2407

The root‐zone moisture replenishment mechanisms are key unknowns required to understand soil hydrological processes and water sources used by plants. Temporal patterns of root‐zone moisture replenishment reflect wetting events that contribute to plant growth and survival and to catchment water yield. In this study, stable oxygen and hydrogen isotopes of twigs and throughfall were continuously monitored to characterize the seasonal variations of the root‐zone moisture replenishment in a native vegetated catchment under Mediterranean climate in South Australia. The two studied hillslopes (the north‐facing slope [NFS] and the south‐facing slope [SFS]) had different environmental conditions with opposite aspects. The twig and throughfall samples were collected every ~20 days over 1 year on both hillslopes. The root‐zone moisture replenishment, defined as percentage of newly replenished root‐zone moisture as a complement to antecedent moisture for plant use, calculated by an isotope balance model, was about zero (±25% for the NFS and ± 15% for the SFS) at the end of the wet season (October), increased to almost 100% (±26% for the NFS and ± 29% for the SFS) after the dry season (April and May), then decreased close to zero (±24% for the NFS and ± 28% for the SFS) in the middle of the following wet season (August). This seasonal pattern of root‐zone moisture replenishment suggests that the very first rainfall events of the wet season were significant for soil moisture replenishment and supported the plants over wet and subsequent dry seasons, and that NFS completed replenishment over a longer time than SFS in the wet season and depleted the root zone moisture quicker in the dry season. The stable oxygen isotope composition of the intraevent samples and twigs further confirms that rain water in the late wet season contributed little to root‐zone moisture. This study highlights the significant role of the very first rain events in the early wet season for ecosystem and provides insights to understanding ecohydrological separation, catchment water yield, and vegetation response to climate changes.  相似文献   

基于向量式有限元的黏滞阻尼减震结构抗竖向连续倒塌动力反应分析          下载免费PDF全文

曲激婷  宋全宝 《地震工程学报》2019,41(6):1432-1439

向量式有限元是以向量力学为基础的一种新的结构分析方法,在处理结构大变形等复杂行为时具有较大的优势。基于向量式有限元理论建立了黏滞阻尼单元,对附加黏滞阻尼器的平面钢框架结构进行了抗竖向连续倒塌动力分析,结合拆除构件法,采用MATLAB编制可以考虑初始变形的瞬时卸载法程序,实现结构在构件拆除前的静力分析和构件拆除后动力分析的全过程统一。研究了阻尼器布置位置和参数在结构抗竖向连续倒塌中的性能需求,以失效点竖向位移时程曲线、梁端转角、动力放大系数和结构塑性铰分布为参考指标,对比分析布置阻尼器前后钢框架结构的抗连续倒塌能力。结果表明向量式有限元是一种研究结构竖向连续倒塌动力响应的有效方法,合理布置阻尼器能够有效控制剩余结构的变形和振动,降低构件内力,减少塑性铰个数,较大地提高结构的抗竖向连续倒塌能力。  相似文献   

Numerical modeling of lock-exchange gravity/turbidity currents by a high-order upwinding combined compact difference scheme     

Liang Zhao  Ching-Hao Yu  Zhiguo He 《国际泥沙研究》2019,34(3):240-250

This study presents two-dimensional direct numerical simulations for sediment-laden current with higher density propagating forward through a lighter ambient water. The incompressible NavierStokes equations including the buoyancy force for the density difference between the light and heavy fluids are solved by a finite difference scheme based on a structured mesh. The concentration transport equations are used to explore such rich transport phenomena as gravity and turbidity currents. Within the framework of an Upwinding Combined Compact finite Difference (UCCD) scheme, rigorous determination of weighting coefficients underlies the modified equation analysis and the minimization of the numerical modified wavenumber. This sixth-order UCCD scheme is implemented in a four-point grid stencil to approximate advection and diffusion terms in the concentration transport equations and the first-order derivative terms in the Navier-Stokes equations, which can greatly enhance convective stability and increase dispersive accuracy at the same time. The initial discontinuous concentration field is smoothed by solving a newly proposed Heaviside function to prevent numerical instabilities and unreasonable concentration values. A two-step projection method is then applied to obtain the velocity field. The numerical algorithm shows a satisfying ability to capture the generation, development, and dissipation of the Kelvin-Helmholz instabilities and turbulent billows at the interface between the current and the ambient fluid. The simulation results also are compared with the data in published literatures and good agreements are found to prove that the present numerical model can well reproduce the propagation, particle deposition, and mixing processes of lock-exchange gravity and turbidity currents.  相似文献   

洱海沉积物有色可溶性有机物(CDOM)三维荧光空间分布特性及指示意义   总被引：1，自引：0，他引：1  

赵海超  李艳平  王圣瑞  焦立新 《湖泊科学》2019,31(2):507-516

采用荧光光谱区域体积积分法定量研究洱海沉积物有色可溶性有机物（CDOM）三维荧光空间分布特性，结果表明，洱海沉积物CDOM中类腐殖酸组分占比最高（44.5%~74.2%），其次为溶解性微生物代谢产物（10.7%~20.4%）和类富里酸物质（8.19%~19.7%），而类蛋白组分占比最低，类腐殖酸占比与H/C和N/C均呈显著负相关；南部湖心平台区域沉积物类富里酸和类蛋白组分占比较高，其CDOM自生源占比较高；北部水生植物分布区溶解性微生物代谢产物占比较高，CDOM陆源性较强；中部深水区及南北湖湾区域类腐殖酸占比较高，随水深增加沉积物CDOM自生源特征增强.随沉积物深度增加类腐殖酸和溶解性微生物代谢产物占比呈下降趋势，类富里酸占比呈上升趋势，CDOM自生源特征增强，脂肪化程度增高.随湖泊富营养化程度增加沉积物CDOM受微生物代谢产物影响增强，陆源性增加，而自生源性降低，湖泊沉积物CDOM具有富营养化指示意义.  相似文献   

基于CMIP5模式鄱阳湖流域未来参考作物蒸散量预估   总被引：3，自引：0，他引：3  

刘子豪  陆建忠  黄建武  陈晓玲  张玲  盛颖东 《湖泊科学》2019,31(6):1685-1697

预测未来气候情境下鄱阳湖流域参考作物蒸散量(Reference crop Evapotranspiration,ET0)的时空分布可为流域水资源的优化管理,为科学应对气候变化对农业生产的影响提供基础数据支撑.利用鄱阳湖流域14个气象站点1961-2014年逐日气象数据,采用Penman-Monteith公式计算出历史ET0;基于同期美国环境中心(NCEP)再分析数据及2006-2100年CMIP5中CNRM-CM5模式在RCP4. 5和RCP8. 5情景下的预测数据,经统计降尺度模型(statistical downscaling model,SDSM)模拟和偏差校正,预测流域未来ET0;通过Mann-Kendall检验、普通克里金插值和空间自相关法分析了流域1961-2100年ET0的时空演变特征.结果表明:NCEP再分析资料与流域ET0建立的逐步回归降尺度模型模拟效果较好,CNRMCM5模式降尺度模拟结果经偏差校正后,精度明显提高,适宜流域未来ET0的预估.鄱阳湖流域在基准期1961-2010年ET0整体上呈减小趋势,空间分布上呈南北高、中间低的特点,表现出明显的空间差异性.RCP4.5、RCP8.5情景下未来3个时期鄱阳湖流域ET0较基准期均呈不同程度的增加趋势,其空间分布整体表现为东高西低、局地略有突出;无论是在基准期或是未来情景下的3个时期,ET0均具有较强的空间自相关性.在RCP8.5情景下,鄱阳湖1961-2100年干旱指数呈现出较为明显的上升趋势,流域的干旱状况随时间加剧,2011-2100年间流域绝大部分地区由湿润区转为半湿润区,干旱指数自南向北递减,赣江流域将是鄱阳湖流域未来干旱风险的重点防范区.  相似文献   

Sensitive and rapid detection of two toxic microalgae Alexandrium by loop-mediated isothermal amplification     

ZHANG Fengying  SHI Yanhong  JIANG Keji  XU Zhaoli  MA Lingbo 《海洋学报(英文版)》2018,37(2):139-146

A loop-mediated isothermal amplification (LAMP) assay was designed and evaluated for rapid detection of the toxic microalgae Alexandrium catenella and A. minutum, which can produce paralytic shellfish poisoning (PSP). Two sets of four specific primers targeting these two species were derived from the sequence of internal transcribed spacer (ITS) of ribosomal DNA. The method worked well in less than an hour under isothermal conditions of 65℃. LAMP specificity was validated in closely related algae as a comparison, suggesting the strict specificity of the LAMP primers. Two visual inspection approaches were feasible to interpret the positive or negative results. The detection limits of A. catenella and A. minutum samples using the LAMP assay were found to be 5.6 and 4.5 pg DNA, respectively. The sensitivity of this LAMP assay was 10 or 100-fold higher than Polymerase Chain Reaction (PCR) method in detecting the two microalgae. These characteristics of species specificity, sensitivity, and rapidity suggest that this method has the potentiality in the monitoring of red tide caused by A. catenella and A. minutum.  相似文献