Sea Level Prediction in the Yellow Sea From Satellite Altimetry With a Combined Least Squares-Neural Network Approach     

Jian Zhao  Yanguo Fan  Yuxiang Mu 《Marine Geodesy》2019,42(4):344-366

Accessible high-quality observation datasets and proper modeling process are critically required to accurately predict sea level rise in coastal areas. This study focuses on developing and validating a combined least squares-neural network approach applicable to the short-term prediction of sea level variations in the Yellow Sea, where the periodic terms and linear trend of sea level change are fitted and extrapolated using the least squares model, while the prediction of the residual terms is performed by several different types of artificial neural networks. The input and output data used are the sea level anomalies (SLA) time series in the Yellow Sea from 1993 to 2016 derived from ERS-1/2, Topex/Poseidon, Jason-1/2, and Envisat satellite altimetry missions. Tests of different neural network architectures and learning algorithms are performed to assess their applicability for predicting the residuals of SLA time series. Different neural networks satisfactorily provide reliable results and the root mean square errors of the predictions from the proposed combined approach are less than 2?cm and correlation coefficients between the observed and predicted SLA are up to 0.87. Results prove the reliability of the combined least squares-neural network approach on the short-term prediction of sea level variability close to the coast.  相似文献   

Response of Microbial Communities in Soil to Multi-level Warming in a Highland Barley System of the Lhasa River     

FU Gang  SUN Wei  LI Shaowei  ZHONG Zhiming 《资源与生态学报(英文版)》2019,10(4):373-378

No studies have examined the effect of experimental warming on the microbial biomass and community composition of soil in agricultural ecosystem on the Qinghai-Tibet Plateau. Thus it is unclear whether the influences of experimental warming on microbial communities in soil are related to warming magnitude in croplands on this Plateau. This study performed warming experiment (control, low- and high-level) in a highland barley system of the Lhasa River in May 2014 to examine the correlation between the response of microbial communities in soil to warming and warming magnitude. Topsoil samples (0-10 and 10-20 cm) were collected on September 14, 2014. Experimental warming at both low and high levels significantly increased soil temperature by 1.02 ℃ and 1.59 ℃, respectively at the depth of 15 cm. Phospho lipid fatty acid (PLFA) method was used to determine the microbial community in soil. The low-level experimental warming did not significantly affect the soil’s total PLFA, fungi, bacteria, arbuscular mycorrhizal fungi (AMF), actinomycetes, gram-positive bacteria (G⁺), gram-negative bacteria (G^-), protozoa, the ratio of fungi to bacteria (F/B ratio), and ratio of G⁺ to G^- (G⁺/G^- ratio) at the 0-10 and 10-20 cm depth. The low-level experimental warming also did not significantly alter the composition of microbial community in soil at the 0-10 and 10-20 cm depth. The high-level experimental warming significantly increased total PLFA by 74.4%, fungi by 78.0%, bacteria by 74.0%, AMF by 66.9%, actinomycetes by 81.4%, G⁺ by 67.0% and G^- by 74.4% at the 0-10 cm depth rather than at 10-20 cm depth. The high-level experimental warming significantly altered microbial community composition in soil at the 0-10 cm depth rather than at 10-20 cm depth. Our findings suggest that the response of microbial communities in soil to warming varied with warming magnitudes in the highland barley system of the Lhasa River.  相似文献   

The Symbolic Wolf: A Construal Level Theory Analysis of the Perceptions of Wolves in the United States     

Kristina M. Slagle  Robyn S. Wilson  Jeremy T. Bruskotter  Eric Toman 《社会与自然资源》2019,32(3):322-337

Charismatic wildlife can be difficult to manage due to the controversies they generate among stakeholders, which may be rooted in their symbolic meaning. Using construal-level theory, we coded the images of gray wolves mentioned by respondents to a national survey (n?=?621) and an issue public survey (n?=?447) as symbolic (abstract) or corporeal (concrete). We analyzed the relationship between these representations of wolves and several perceptions that may perpetuate social conflict. Most people thought of wolves abstractly, and abstract thoughts were associated with positive feelings toward wolves and agreement with existence beliefs regarding wolves. Concrete representations were associated with identifying as a gun or property rights advocate, hunter, or farmer/rancher. Given these disparate views of wolves, engaging stakeholders through collaborative processes designed to foster a shared understanding of this species, while addressing the concerns of those groups, could be useful in reducing conflict concerning wolf management.  相似文献   

长山群岛海洋渔业资源的平均营养级变化特征     

孙才志  曹威威  肖春柳 《海洋通报》2019,38(1):87-95

根据长山群岛 1965-2016 年渔业统计资料，分析长山群岛海域主要捕捞渔获物产量、平均营养级 （Mean trophic level， MTL）、渔业均衡指数 （Fishing in balance index，FiB） 年际变化，探讨其海洋渔业资源利用状况，并利用小波分析方法研究52年来渔获物 MTL 周期变化特征。研究表明： （1） 长山群岛捕捞产量、MTL 和 FiB 指数呈阶段性变化； （2） 长山群岛渔业资源开发经历初期开发、扩张捕捞、过度捕捞、资源破坏等四个阶段，渔业资源环境正在逐渐恶化；（3） 受人类捕捞活动影响，MTL 在 15~19 年和 24~34 年两种时间尺度下呈周期波动，30 年为第一主周期，17 年为第二主周期。长山群岛渔业资源破坏日益严重，未来几年平均营养级将呈下降趋势。为防止渔业资源进一步衰退，应加强捕捞活动管理力度，落实海洋渔业资源保护制度；完善预警机制，构建海洋渔业资源监测系统；同时应积极调整长山群岛渔业产业结构，提高资源产出效率.  相似文献   

Water level observations from unmanned aerial vehicles for improving estimates of surface water–groundwater interaction          下载免费PDF全文

Filippo Bandini  Michael Butts  Torsten Vammen Jacobsen  Peter Bauer‐Gottwein 《水文研究》2017,31(24):4371-4383

Integrated hydrological models are usually calibrated against observations of river discharge and piezometric head in groundwater aquifers. Calibration of such models against spatially distributed observations of river water level can potentially improve their reliability and predictive skill. However, traditional river gauging stations are normally spaced too far apart to capture spatial patterns in the water surface, whereas spaceborne observations have limited spatial and temporal resolution. Unmanned aerial vehicles can retrieve river water level measurements, providing (a) high spatial resolution; (b) spatially continuous profiles along or across the water body, and (c) flexible timing of sampling. A semisynthetic study was conducted to analyse the value of the new unmanned aerial vehicle‐borne datatype for improving hydrological models, in particular estimates of groundwater–surface water (GW–SW) interaction. Mølleåen River (Denmark) and its catchment were simulated using an integrated hydrological model (MIKE 11–MIKE SHE). Calibration against distributed surface water levels using the Differential Evolution Adaptive Metropolis algorithm demonstrated a significant improvement in estimating spatial patterns and time series of GW–SW interaction. After water level calibration, the sharpness of the estimates of GW–SW time series improves by ~50% and root mean square error decreases by ~75% compared with those of a model calibrated against discharge only.  相似文献   

Long‐term hydrologic simulation using SCS‐CN‐based improved soil moisture accounting procedure     

Dilip G. Durbude  Manoj K. Jain  Surendra K. Mishra 《水文研究》2011,25(4):561-579

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A physically constrained wavelet-aided statistical model for multi-decadal groundwater dynamics predictions     

Fatih Gordu  Mahmood H. Nachabe 《水文研究》2021,35(8):e14308

A physically constrained wavelet-aided statistical model (PCWASM) is presented to analyse and predict monthly groundwater dynamics on multi-decadal or longer time scales. The approach retains the simplicity of regression modelling but is constrained by temporal scales of processes responsible for groundwater level variation, including aquifer recharge and pumping. The methodology integrates statistical correlations enhanced with wavelet analysis into established principles of groundwater hydraulics including convolution, superposition and the Cooper–Jacob solution. The systematic approach includes (1) identification of hydrologic trends and correlations using cross-correlation and multi-time scale wavelet analyses; (2) integrating temperature-based evapotranspiration and groundwater pumping stresses and (3) assessing model prediction performances using fixed-block k-fold cross-validation and split calibration-validation methods. The approach is applied at three hydrogeologicaly distinct sites in North Florida in the United States using over 40 years of monthly groundwater levels. The systematic approach identifies two patterns of cross-correlations between groundwater levels and historical rainfall, indicating low-frequency variabilities are critical for long-term predictions. The models performed well for predicting monthly groundwater levels from 7 to 22 years with less than 2.1 ft (0.7 m) errors. Further evaluation by the moving-block bootstrap regression indicates the PCWASM can be a reliable tool for long-term groundwater level predictions. This study provides a parsimonious approach to predict multi-decadal groundwater dynamics with the ability to discern impacts of pumping and climate change on aquifer levels. The PCWASM is computationally efficient and can be implemented using publicly available datasets. Thus, it should provide a versatile tool for managers and researchers for predicting multi-decadal monthly groundwater levels under changing climatic and pumping impacts over a long time period.  相似文献   

卫星测高数据监测青藏高原湖泊2010年—2018年水位变化     

廖静娟  薛辉  陈嘉明 《遥感学报》2020,24(12):1534-1547

青藏高原湖泊水位变化是气候变化和生态环境变化研究的重要指标。随着Cryosat-2观测数据的日益丰富和处理技术的提升，可以有效监测更多湖泊的水位变化信息。本研究构建了基于噪声去除技术、改进的波形重跟踪处理算法（ImpMWaPP）和误差混合动态模型为一体的高精度湖泊水位序列提取方法，利用Cryosat-2 SARIn数据获取到133个青藏高原湖泊2010年—2018年的高精度水位序列，并分析了这些湖泊水位变化的时空变化特征。总体上，青藏高原湖泊的水位继续呈上升趋势，但上升速度较2003年—2009年趋缓，年均变化率0.159 m/a。从地域分布上，北部湖泊的水位上升最为显著，而南部湖泊的水位则趋于稳定。从时间上，2010年—2012年和2016年—2018年，大多数湖泊的水位呈现快速上涨，而其他时间水位相对稳定或略有下降。  相似文献   

A biodiversity evaluation framework for restoration of aquatic macrophyte communities in shallow lakes driven by hydrological process management     

Shuhan Li  Tao Sun  Wei Yang  Baoshan Cui  Xinan Yin 《水文研究》2021,35(1):e13983

Macrophyte community diversity and composition respond to ecosystem conservation and local environmental factors. In this study, we developed a multidimensional diversity framework for macrophyte communities, including the taxonomic and functional alpha and beta diversity. We used the framework to explore the relationships among water level regimes and these diversity parameters in a case study of China's Baiyangdian Lake. Analysis of indicators of hydrologic alteration divided the water level from 1959 to 2019 into four regimes (dry, <6.42 m; low, 6.42–7.23 m; medium, 7.23–8.19 m; high, >8.19 m). Alpha and beta diversity were significantly higher in the medium regime than in the low and high regimes. Redundancy analysis indicated that the maximum water depth significantly affected taxonomic alpha diversity, and total nitrogen (TN) and chemical oxygen demand (COD) concentration significantly affected functional alpha diversity, respectively. Mantel tests showed that TN, Secchi depth (SD), and water depth in the high water level regime significantly increased the total beta diversity and turnover components. TN was the main factor that increased total taxonomic beta diversity. Water level regime mainly influenced interspecific relationships by changing the TN and COD concentration. The water level should be maintained between the medium and high water level regimes to promote restoration of the macrophyte community and improve ecosystem stability. The biodiversity evaluation framework would provide a deeper insight into the hydrological process management for restoration of aquatic macrophyte communities in shallow lakes.  相似文献   

Quality and timing of crowd-based water level class observations     

Simon Etter  Barbara Strobl  Ilja van Meerveld  Jan Seibert 《水文研究》2020,34(22):4365-4378

Crowd-based hydrological observations can supplement existing monitoring networks and allow data collection in regions where otherwise no data would be available. In the citizen science project CrowdWater, repeated water level observations using a virtual staff gauge approach result in time series of water level classes (WL-classes). To investigate the quality of these observations, we compared the WL-class data with “real” (i.e., measured) water levels from the same stream at a nearby gauging station. We did this for nine locations where citizen scientists reported multiple observations using a smartphone app and at 12 locations where signposts were set up to ask citizens to record observations on a paper form that could be left in a letterbox. The results indicate that the quality of the data collected with the app was better than for the forms. A possible explanation is that for each app location, a single person submitted the vast majority of the observations, whereas at the locations of the forms almost every observation was made by a different person. On average, there were more contributions between May and September than during the other months. Observations were submitted for a range of flow conditions, with a higher fraction of high flow observations for the locations were data were collected with the app. Overall, the results are encouraging for citizen science approaches in hydrology and demonstrate that the smartphone application and the virtual staff gauge are a promising approach for crowd-based water level class observations.  相似文献