A two-layer model for studying 2D dissolved pollutant runoff over impermeable surfaces     

Taotao Zhang  Yang Xiao  Dongfang Liang  Hongwu Tang  Junzeng Xu  Saiyu Yuan  Nairu Wang  Bin Luan 《水文研究》2021,35(5):e14152

Dissolved pollutants in stormwater are a main contributor to water pollution in urban environments. However, many existing transport models are semi-empirical and only consider one-dimensional flows, which limit their predictive capacity. Combining the shallow water and the advection–diffusion equations, a two-dimensional physically based model is developed for dissolved pollutant transport by adopting the concept of a ‘control layer’. A series of laboratory experiments has been conducted to validate the proposed model, taking into account the effects of buildings and intermittent rainfalls. The predictions are found to be in good agreement with experimental observations, which supports the assumption that the depth of the control layer is constant. Based on the validated model, a parametric study is conducted, focusing on the characteristics of the pollutant distribution and transport rate over the depth. The hyetograph, including the intensity, duration and intermittency, of rainfall event has a significant influence on the pollutant transport rates. The depth of the control layer, rainfall intensity, surface roughness and area length are dominant factors that affect the dissolved pollutant transport. Finally, several perspectives of the new pollutant transport model are discussed. This study contributes to an in-depth understanding of the dissolved pollutant transport processes on impermeable surfaces and urban stormwater management.  相似文献   

How soil texture,channel shape and cross-sectional area affect moisture dynamics and water loss in irrigation channels     

Zhifan Mu  Tianxiao Li  Dong Liu  Qiang Fu  Renjie Hou  Qinglin Li  Yi Ji  Song Cui  Mo Li 《水文研究》2021,35(4):e14155

To enhance the utilization efficiency of farmland irrigation water and reduce the leakage of water conveyance channels, the leakage process of channels was simulated dynamically. The simulated results were compared with data measured in laboratory experiments, and the performance of the model was evaluated. The results indicated that the simulated values of the model were consistent with the observation values, and the R² values varied between 0.91 and 0.99. In addition, based on the laboratory experiments, a water supply system (Mariotte bottles) and soil box were built using plexiglass. Three influencing factors, namely, the channel form, soil texture and channel cross-sectional area, were varied to observe and calculate the resulting cumulative infiltration amount, infiltration rate and wetting front migration distance. HYDRUS-3D software was used to solve the three-dimensional soil water movement equation under different initial conditions. The results demonstrated that the U-shaped channel was more effective than the trapezoidal channel in increasing the utilization efficiency of the water resources. A U-shaped channel with a small channel cross-sectional area should be adopted and the soil particle size should be prioritized in the construction of water conveyance channels for farmlands. The simulation results were in agreement with the observed results, which indicates that HYDRUS-3D is a reliable tool that can accurately simulate the soil moisture movement in water conveyance channels. The research results can provide a reference for the design and operation of farmland irrigation systems.  相似文献   

天然裂缝影响下的花岗岩水力裂缝扩展数值模拟     

王璜  王贵玲  岳高凡  甘浩男 《地质学报》2020,94(7):2124-2130

水力压裂技术是成功实现干热岩资源开发利用的重要手段之一，数值模拟技术能够精准预测水力裂缝扩展。针对典型花岗岩，借助黏性单元法，分别模拟了致密花岗岩和天然裂缝存在情况下的水力裂缝扩展特征，得出以下结论：致密花岗岩的水力裂缝形态单一，天然裂缝的存在增加了压裂后裂缝的复杂性；致密花岗岩水力裂缝拓展主要分为憋压和拓展两个交替往复的阶段，当存在天然裂隙时，水力压裂过程会变得复杂；天然裂缝存在时，水力裂缝的缝长和缝宽分别为致密花岗岩的5. 7倍和1. 7倍；缝网的形成需要借助复杂的压裂工艺实现。研究结果可以为增强型地热系统(EGS)储层水力刺激工作提供理论支持。  相似文献   

阿勒泰地区植被覆盖度及ET对气温变化的响应   总被引：1，自引：0，他引：1       下载免费PDF全文

韩飞飞  闫俊杰  郭斌 《干旱区地理》2019,42(6):1436-1444

研究气温对植被覆盖度和ET (Evapotranspiration，ET)的影响，对干旱区应对气候变化、维系生态系统稳定具有重要意义。基于阿勒泰地区及周边7个气象站，CRU数据集中的气温数据及MODIS ET数据，采用Mann-Kendall非参数检验、植被盖度反演等方法，对阿勒泰地区气温变化对植被覆盖度及ET的影响进行了研究。结果表明：（1）在1901—2016年过去的116 a间，阿勒泰地区年平均气温以0.18 ℃·(10 a)^-1速率增加，在1982年由突变前的2.2 ℃增加到突变后的3.5 ℃。（2）2000—2017年阿勒泰地区植被覆盖度变化的空间差异明显，植被覆盖度增加的面积与降低的面积总体相当；全区66.71%的区域植被覆盖度变化与气温呈负相关，而呈正相关的比例仅占18.55%，且全区气温变暖而盖度降低区域的占比达31.71%。（3）2000—2016年阿勒泰地区ET总体呈降低趋势，整个区域61.65%的面积温度降低、ET降低，而19.92%的区域表现为温度增加而植被ET降低。  相似文献   

Farmland Abandonment Research Progress: Influencing Factors and Simulation Model     

SONG Wei  ZHANG Ying 《资源与生态学报(英文版)》2019,10(4):345-352

Farmland abandonment is a global problem and considered one of the most important areas in land use change research. Farmland abandonment research currently focuses on understanding the factors that affect farmland abandonment and developing scientific models to simulate farmland abandonment. The study reviewed the natural and political factors driving farmland abandonment and summarized the main models for farmland abandonment simulation together with their advantages and disadvantages. We discuss the main ecological effects of farmland abandonment and propose farmland abandonment research directions. The study found that: (1) the influence of labor cost change and ageing labor force on farmland abandonment needs further investigation, (2) simulation models for farmland abandonment must include the decision-making mechanism of individual farmers and focus on macro large-scale abandonment prediction models, and (3) the influence of farmland abandonment on landscape culture must be investigated in detail.  相似文献   

非典型周期和气候突变的识别与判定          下载免费PDF全文

秦建国 《水文》2020,40(1):23-28

通过两种新方法分析了无锡站降水年际变化的突变性、周期性等特征,揭示了旱涝演化的自然规律。研究表明,1934、1978、2013年是我国近现代气候突变的临界点,这是旱涝演化的自然选择;无锡站年际降水的观测历史可分成四个特征不同的时段,每个时段节点对应的都是一次气候突变;气候突变会改变年际降水序列的一致性,分段法研究可以大幅度降低模拟难度、提高预测效率。发现并确认了3个气候突变点,实现了超长缺测中断期(13a)旱涝趋势的精确插补,完成了无锡站近百年降雨序列的周期性分析与旱涝趋势预测模拟,研究成果改变了近现代气候历史无法细分的现状。  相似文献   

基于重力测点和段差变化的前郭5.8级震群研究与三维反演     

王同庆  张品  刘金钊  陈兆辉  张双喜  朱传东 《大地测量与地球动力学》2019,39(5):469-475

利用东北地区近几年流动重力观测数据，分析前郭5.8级震群周边重力点值的时序变化特征，并基于重力段差变化对东北地区整体和局部重力变化引入能够反映异常显著性程度的指标量G和C值，最后对前郭5.8级震群前的重力场动态变化作三维密度反演。结果表明：1）前郭5.8级震群发震构造两侧的局部重力变化具有较明显的差异性，其变化趋势可作为识别构造活化或解耦运动的标志；2）显著性指标量G和C值能够为地震重力前兆的定量描述提供新思路；3）震前重力变化的反演结果显示地震发生在质量运移的过渡区域，垂向反演结果对本次地震的震源深度有一定的揭示意义。  相似文献   

埋深对恐龙化石的影响效果研究          下载免费PDF全文

陈诚  贾超  张尚坤  杜圣贤  罗文强  田京祥 《山东国土资源》2019,35(5)

已发现的恐龙化石大多数埋藏在不同深度的地层中,不同埋深化石所受风化破坏程度不尽相同。为深入研究恐龙化石的风化机理,探究恐龙化石的保护措施和方法,重点分析埋深产生的侧向压力对恐龙化石强度和破坏特性的影响。通过有限差分软件FLAC3D进行数值模拟,揭示埋深因素对恐龙化石保存的影响程度。试验结果表明:围岩对恐龙化石施加的侧向压力是影响恐龙化石变形和强度特性的一个重要因素。在弹性变形阶段,恐龙化石的初始强度、峰值强度随侧向压力的增大而不断增大。当应力超过了恐龙化石极限强度后进入塑性变形,其初始强度、峰值强度逐渐减小,最终达到残余强度。  相似文献   

湍流度随高度的变化及其对城市宏观地形的依赖     

李大全  孙武  欧阳睿康  黄盛  高梦媛  李庆祥  黄启明 《热带地理》2019,39(3):365-376

分别构建广州主建成区垂直比例尺为1﹕2 000、1﹕1 000和1﹕500的3个建筑物模型，利用大型边界层风洞，在西北和东南两风向下，基于中性流模拟分析了复杂城市地形下湍流度随高度的变化及其对宏观地形的依赖。结果表明：风廓线指数α与不同高度的湍流度之间的关系密切，利用现有模型，根据4类粗糙度边界层和不同垂直比例尺，可确定相应的湍流度随高度变化模型的主要系数，预测精度高。城市地形下最大湍流度面发育在0~0.2 h之间狭窄的范围内。用湍流度形态指数β来表征湍流度随高度的变化，无论城市屋脊还是平坦地形，随着风程区的延伸，廓线的指数α升高，湍流度形态指数β降低。表明同一高度湍流度值具有由迎风区、丘顶区向背风区增高，沿风程逐渐增大的规律，对地形部位和风程的依赖性强，与来流翻越简单地形时的特征一致。  相似文献   

中国耕地土壤相对湿度时空分异   总被引：4，自引：1，他引：3  

潘汉雄  朱国锋  张昱  郭慧文  雍磊磊  万巧卓  马惠莹  李森 《地理学报》2019,74(1):117-130

以全国653个农业气象站1993-2013年耕地的土壤相对湿度数据为基础,运用地统计方法,分析中国耕地土壤相对湿度时空分异特征与规律。结果表明：自1993年以来全国耕地的土壤相对湿度呈现波动上升趋势。全国耕地的土壤相对湿度普遍大于60%,分布区域自4月中旬开始随夏季风推移不断向北向西扩大,自10月下旬开始向东、南方向缩小。耕地土壤相对湿度值随土壤深度的增加而增加。年际尺度上,耕地的土壤相对湿度在夏秋季上升速度最快,变化幅度随土层深度增加而变小。土壤相对湿度与降水量存在较强的正相关关系,与潜在蒸发量、气温普遍存在较强的负相关关系。土壤相对湿度与各气象要素的相关性随深度加深而减弱。春、夏、秋季气象因素对旱地土壤相对湿度影响较大,冬季气象因素对水田影响更大。  相似文献