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   

黑河中游夏季昼夜水汽同位素特征及水汽来源分析          下载免费PDF全文

孟鸿飞  张明军  王圣杰  邱雪  杜铭霞  张亚宁  余秀秀  周苏娥 《干旱区地理》2020,43(2):360-370

基于2012年6~8月的实测水汽同位素数据及相关气象数据，对黑河中游夏季昼夜的同位素基本特征、水汽来源方向及潜在蒸发源地进行了研究。结果表明：空气水汽线斜率白天大于夜晚和水汽过量氘值白天大于夜晚，综合说明白天局地蒸发较夜晚强烈；夏季受西风水汽影响显著。其中，6月主要受西风水汽和北冰洋水汽影响，7、8月主要受西风水汽和东南方向水汽影响，且8月受东南方向水汽影响最为明显；水汽运移路径上下垫面地形和气压带移动会影响水汽后向轨迹高度，西北方向上水汽输送通道较顺畅，风速较大，有利于水汽的输送；水汽蒸发源地主要集中在研究区周围及以东、以北部，其次是西北部。绿洲是主要的水汽蒸发源地，其次是城市和河流，白天较夜晚局地蒸发强烈且面积大。  相似文献   

A modified numerical model for moisture-salt transport in unsaturated sandy soil under evaporation     

Wei Wen  YuanMing Lai  ZheMin You 《寒旱区科学》2020,12(3):125-133

Soil salinization, caused by salt migration and accumulation underneath the soil surface, will corrode structures. To analyze the moisture-salt migration and salt precipitation in soil under evaporation conditions, a mathematical model consisting of a series of theoretical equations is briefly presented. The filling effect of precipitated salts on tortuosity factor and evaporation rate are taken into account in relevant equations. Besides, a transition equation to link the solute transport equation before and after salt precipitation is proposed. Meanwhile, a new relative humidity equation deduced from Pitzer ions model is used to modify the vapor transport flux equation. The results show that the calculated values are in good agreement with the published experimental data, especially for the simulation of volume water content and evaporation rate of Toyoura sand, which confirm the reliability and applicability of the proposed model.  相似文献   

Upper ocean high resolution regional modeling of the Arabian Sea and Bay of Bengal     

Suneet Dwivedi  Alok Kumar Mishr  Atul Srivastava 《海洋学报(英文版)》2019,38(5):32-50

In this paper, effort is made to demonstrate the quality of high-resolution regional ocean circulation model in realistically simulating the circulation and variability properties of the northern Indian Ocean(10°S–25°N,45°–100°E) covering the Arabian Sea(AS) and Bay of Bengal(BoB). The model run using the open boundary conditions is carried out at 10 km horizontal resolution and highest vertical resolution of 2 m in the upper ocean.The surface and sub-surface structure of hydrographic variables(temperature and salinity) and currents is compared against the observations during 1998–2014(17 years). In particular, the seasonal variability of the sea surface temperature, sea surface salinity, and surface currents over the model domain is studied. The highresolution model's ability in correct estimation of the spatio-temporal mixed layer depth(MLD) variability of the AS and BoB is also shown. The lowest MLD values are observed during spring(March-April-May) and highest during winter(December-January-February) seasons. The maximum MLD in the AS(BoB) during December to February reaches 150 m (67 m). On the other hand, the minimum MLD in these regions during March-April-May becomes as low as 11–12 m. The influence of wind stress, net heat flux and freshwater flux on the seasonal variability of the MLD is discussed. The physical processes controlling the seasonal cycle of sea surface temperature are investigated by carrying out mixed layer heat budget analysis. It is found that air-sea fluxes play a dominant role in the seasonal evolution of sea surface temperature of the northern Indian Ocean and the contribution of horizontal advection, vertical entrainment and diffusion processes is small. The upper ocean zonal and meridional volume transport across different sections in the AS and BoB is also computed. The seasonal variability of the transports is studied in the context of monsoonal currents.  相似文献   

甘肃陇中黄土高原农业灌溉耗水系数监测试验研究     

凡炳文  仲复捷 《地下水》2020,(1):83-87,254

选择甘肃省临洮县洮惠渠灌区为试验研究区,通过直接观读、自动监测等技术手段,获取试验灌区的引水量、退水量、土壤墒情、降水量及蒸发量等水文基础数据。以水文监测基础数据为依据,采用引排差法、水分平衡法等相结合的方法,开展了农业灌溉耗水系数试验研究。初步试验结果表明:试验灌区灌溉期平均耗水系数为0. 730,典型地块灌溉期平均耗水系数为0. 671,2016年试验灌区降水量较常年偏少13. 0%~26. 3%,总体上属轻度干旱年份。该研究成果可为甘肃陇中黄土高原区水资源管理提供技术支撑。  相似文献   

Cryospheric Changes and Their Impacts on Water Resources in the Belt and Road Regions     

Shichang Kang  Wanqin Guo  Tonghua Wu  Xinyue Zhong  Rensheng Chen  Min Xu  Jinlei Chen  Ruimin Yang 《地球科学进展》2020,35(1):1-17

“Belt and Road” regions include Asia, Europe and eastern and northern Africa, with a wide spatial distribution. The cryosphere is undergoing rapid changes in the Belt and Road regions with global warming, and has an important impact on water resources, ecosystems and Arctic waterways in these regions. This article reviewed recent cryospheric changes and associated impacts on water resources in the Belt and Road regions during the last decades. The main cognitions are as follows: \mathrm{①} Most glaciers are shrinking and glacier mass balances are most negative, but there are regional differences in the changes of glaciers. \mathrm{②} Global temperature rise has resulted in permafrost degradation, including a rise in permafrost temperature and decreasing permafrost thickness as well as an increase in active layer thickness. \mathrm{③} There is a significant decrease in snow cover extent and an increase in snow depth. Snow cover duration has shortened, the onset of snow cover has delayed, and the end of snow cover has advanced. However, there are still obvious regional differences in the changes of snow cover. \mathrm{④} Arctic sea ice has declined precipitously in both extent and thickness in summer, and multi-year sea ice has decreased，indicating the precipitous retreat of sea ice. The freeze-up date of some lakes has been delayed, the break-up date has advanced, and the ice cover duration of river/lake ice has significantly shortened. \mathrm{⑤} Glacial runoff has increased significantly in China. Snowmelt and permafrost degradation have also increased the basin runoff, which indicates the important impact of cryospheric changes on runoff. This study will provide a baseline and important scientific support for addressing climate change and regional sustainable development.  相似文献   

“一带一路”背景下中国国际航空网络的空间格局及演变     

杜方叶  王姣娥  谢家昊  杜德林 《地理科学进展》2019,38(7):963-972

2013年“一带一路”倡议提出将设施联通作为合作战略重点之一,航空网络作为设施联通的重要组成部分,其地位提升到新的高度。为评估“一带一路”倡议的提出对中国国际航空网络的影响,论文选取了2013年和2018年数据,从国际航线、国际航班以及通航城市3个方面分析“一带一路”倡议提出以来中国国际航空网络的空间格局及其演变特征。研究结果表明：① 整体上来看,“一带一路”倡议并未从根本上改变中国国际航空网络的空间格局,仍以东亚、东南亚、美国以及俄罗斯等地区和国家为主,5 a来其变化主要集中在进一步加深与已有城市的联系;② 从沿线国家来看,一带一路”倡议增加了与中国直接通航的沿线国家数量,并提升了沿线国家在中国国际航空网络中的地位;③ 越来越多的境内城市参与到中国对外开放格局中,且航线和航班在北京、上海、广州的聚集程度下降,而其他城市的航线和航班占比逐渐增加。  相似文献   

A Holistic Approach to Upwelling and Downwelling along the South-West Coast of India     

Phiros Shah  R. Sajeev  K. J. Thara  Grinson George  Muhammad Shafeeque  S. Akash 《Marine Geodesy》2019,42(1):64-84

An attempt has been made to develop a holistic understanding of upwelling and downwelling along the south-west coast of India. The main objective was to elucidate the roles of different forcings involved in the vertical motion along this coast. The south-west coast of India was characterized by upwelling during the south-west monsoon (May to September) and by downwelling during the north-east monsoon and winter (November to February). The average vertical velocity calculated along the south-west coast from the vertical shift of the 26?°C isotherm is 0.57?m/day during upwelling and 0.698?m/day during downwelling. It was concluded that upwelling along the south-west coast of India is driven by offshore Ekman transport due to the alongshore wind, Ekman pumping, horizontal divergence of currents and by the propagation of coastally trapped waves. Whereas downwelling along the coast is driven only by convergence of currents and the propagation of coastally trapped Kelvin waves. Along the west coast of India, the downwelling-favorable Kelvin waves come from the equator and upwelling-favorable waves come from the Gulf of Mannar region.  相似文献   

A critical zone observatory dedicated to suspended sediment transport: The meso-scale Galabre catchment (southern French Alps)     

Cédric Legout  Guilhem Freche  Romain Biron  Michel Esteves  Oldrich Navratil  Guillaume Nord  Magdalena Uber  Thomas Grangeon  Nico Hachgenei  Brice Boudevillain  Céline Voiron  Lorenzo Spadini 《水文研究》2021,35(3):e14084

The 20 km² Galabre catchment belongs to the French network of critical zone observatories (OZCAR; Gaillardet et al., Vadose Zone Journal, 2018, 17(1), 1–24). It is representative of the sedimentary lithology and meteorological forcing found in Mediterranean and mountainous areas. Due to the presence of highly erodible and sloping badlands on various lithologies, the site was instrumented in 2007 to understand the dynamics of suspended sediments (SS) in such areas. Two meteorological stations including measurements of air temperature, wind speed and direction, air moisture, rainfall intensity, raindrop size and velocity distribution were installed both in the upper and lower part of the catchment. At the catchment outlet, a gauging station records the water level, temperature and turbidity (10 min time-step). Stream water samples are collected automatically to estimate SS concentration-turbidity relationships, allowing quantification of SS fluxes with known uncertainty. The sediment samples are further characterized by measuring their particle size distributions and by applying a low-cost sediment fingerprinting approach using spectrocolorimetric tracers. Thus, the contributions of badlands located on different lithologies to total SS flux are quantified at a high temporal resolution, providing the opportunity to better analyse the links between meteorological forcing variability and watershed hydrosedimentary response. The set of measurements was extended to the dissolved phase in 2017. Both stream water electrical conductivity and major ion concentrations are measured each week and every 3 h during storm events. This extension of measurements to the dissolved phase will allow progress in understanding both the origin of the water during the events and the partitioning between particulate and dissolved fluxes of solutes in the critical zone. All data sets are available at https://doi.osug.fr/public/DRAIXBLEONE_GAL/index.html .  相似文献   

Integration of hyperspectral and LiDAR data for mapping small water bodies     

《International Journal of Applied Earth Observation and Geoinformation》2020

Inland water bodies are globally threatened by environmental degradation and climate change. On the other hand, new water bodies can be designed during landscape restoration (e.g. after coal mining). Effective management of new water resources requires continuous monitoring; in situ surveys are, however, extremely time-demanding. Remote sensing has been widely used for identifying water bodies. However, the use of optical imagery is constrained by accuracy problems related to the difficulty in distinguishing water features from other surfaces with low albedo, such as tree shadows. This is especially true when mapping water bodies of different sizes. To address these problems, we evaluated the potential of integrating hyperspectral data with LiDAR (hereinafter “integrative approach”). The study area consisted of several spoil heaps containing heterogeneous water bodies with a high variability of shape and size. We utilized object-based classification (Support Vector Machine) based on: (i) hyperspectral data; (ii) LiDAR variables; (iii) integration of both datasets. Besides, we classified hyperspectral data using pixel-based approaches (K-mean, spectral angle mapper). Individual approaches (hyperspectral data, LiDAR data and integrative approach) resulted in 2–22.4 % underestimation of the water surface area (i.e, omission error) and 0.4–1.5 % overestimation (i.e., commission error).The integrative approach yielded an improved discrimination of open water surface compared to other approaches (omission error of 2 % and commission error of 0.4 %). We also evaluated the success of detecting individual ponds; the integrative approach was the only one capable of detecting the water bodies with both omission and commission errors below 10 %. Finally, the assessment of misclassification reasons showed a successful elimination of shadows in the integrative approach. Our findings demonstrate that the integration of hyperspectral and LiDAR data can greatly improve the identification of small water bodies and can be applied in practice to support mapping of restoration process.  相似文献