基于鲸鱼优化算法的长短期记忆模型水库洪水预报     

丁艺鼎  蒋名亮  徐力刚  范宏翔  吕海深 《湖泊科学》2024,36(1):320-332

洪涝灾害是世界主要自然灾害之一,优化洪水预报方案对防洪决策至关重要,然而传统水文模型存在参数多、调参受人为因素影响,泛化能力弱等问题。针对上述问题,本文提出基于改进的鲸鱼优化算法和长短期记忆网络构建自动优化参数的WOA-LSTM模型,通过优化神经网络结构进一步增强该模型的稳定性和精确度,并且建立不同预见期下的洪水预报模型来分析讨论神经网络结构与预报期之间的关系。以横锦水库流域1986—1997年洪水资料为例,其中以流域7个雨量站点的降雨以及横锦站水文资料为输入,不同预见期下洪水过程作为输出,以1986—1993年作为模型的率定期,1994—1997年作为模型的检验期,研究结果表明:(1)以峰现时差、确定性系数、径流深误差和洪峰流量误差作为评价指标,相比较于LSTM模型和新安江模型对检验期的模拟结果表明WOA-LSTM模型拥有更高的精度、预报结果更稳定;(2)结合置换特征值和SHAP法分析模型特征值重要性,增强了神经网络模型的可解释性;(3)通过改变神经网络结构在一定程度避免由于预见期增加和数据关联性下降而导致的模型预报精度下降的问题,最终实验表明该模型在预见期1~6 h下都可以满足横锦水库的洪水预报要求,可以为当地的防洪决策提供依据。  相似文献   

数值预报产品与天气学结合的体会     

吕今 《内蒙古气象》2009,(2):29-30

文章主要阐述了如何将数值预报产品与天气学预报经验有机的结合起来。天气学着重研究天气系统进入本地区前各方面的动态变化,从中找出它的变化规律,再利用这些规律预测未来如何演变。数值预报从初始场开始,计算它的运动轨迹,着重研究大气环流和天气形势未来变化。虽然它们的研究起点、研究重点不同,但方向一致。把二者有机结合起来,可以形成从过去、现在到未来的一个完整的链条,从而有力的促进了预报质量的提高。  相似文献   

固沙植被区土壤质地与土壤微生物数量的关系   总被引：1，自引：1，他引：0  

吕星宇  张志山 《中国沙漠》2019,39(5):71-79

土壤微生物是荒漠生态系统的重要组分,参与成土过程与生物地球化学循环,其数量反映土壤质量,是判别退化生态系统恢复程度的重要指标。选取沙坡头固沙植被区土壤中的真菌、细菌、放线菌数量进行研究,分析了其时空分布、恢复特征及影响因子。结果表明：土壤微生物数量随固沙年限增加而增加,随土层深度增加而减少,夏秋季显著大于冬春季。三大类群微生物数量恢复曲线均呈现S型,在固沙植被建立18~24 a后恢复速率达到峰值,24~36 a后数量能够达到天然植被区的31.6%~83.7%。土壤微生物数量恢复过程主要受土壤细物质含量的影响,土壤pH是限制因子。土壤微生物对土壤状况与覆被变化敏感,能较早且敏感地指示生态系统功能的变化。  相似文献   

Variation and relationship between soil moisture and environmental factors in the source region of the Yangtze River from 2005 to 2016     

LingLing Song  ZongJie Li  Qing Tian  LieFu Wang  Jing He  RuiFeng Yuan  Juan Gui  BaiJuan Zhang  YueMin Lv 《寒旱区科学》2019,11(3)

This study analyzed soil moisture, soil erosion, and vegetation in the source region of the Yangtze River from 2005 to 2016. We found that soil moisture showed an increasing trend from 2005 to 2009 but decreased from 2009 to 2016. The surface soil moisture was severely affected by seasonal changes in the source region of the Yangtze River, especially in the soil from 0 to 40 cm. However, seasonal variation of soil moisture deeper than 40 cm was different from that in the upper layer. Soil moisture below 40 cm wasn't affected by the seasonal variation. Soil moisture from 0 to 50 cm and the average thickness of wind deposition showed a positive correlation in the study area from 2005 to 2016. For environmental protection in the source region of the Yangtze River, wind deposition played a role in water retention. Similarly, a positive correlation also existed between the average thickness of wind erosion and soil moisture. Deep-soil moisture was the key factor for vegetation structure on the Qinghai-Tibet Plateau. The results are also helpful for further understanding the variation of soil moisture on the Tibetan Plateau and providing a scientific basis for effectively protecting and controlling the ecological environment in the future.  相似文献   

The Gas to Dust Ratio in Three Star Forming Regionstwo     

Zhang-pan Lv  Bi-wei Jiang  Jun Li 《Chinese Astronomy and Astrophysics》2018,42(2):213-238

Gas to Dust Ratio (GDR) indicates the mass ratio of interstellar gas to dust. It is widely adopted that the GDR in our Galaxy is 100～150. We choose three typical star forming regions to study the GDR: the Orion molecular cloud — a massive star forming region, the Taurus molecular cloud — a low-mass star forming region, and the Polaris molecular cloud — a region with no or very few star formation activities. The mass of gas only takes account of the neutral gas, i.e. only the atomic and molecular hydrogen, because the amount of ionized gas is very small in a molecular cloud. The column density of atomic hydrogen is taken from the high-resolution and high-sensitivity all-sky survey EBHIS (Effelsberg-Bonn HI Survey). The CO J = 1 →0 line is used to trace the molecular hydrogen, since the spectral lines of molecular hydrogen which can be detected are rare. The intensity of CO J = 1 →0 line is taken from the Planck all-sky survey. The mass of dust is traced by the interstellar extinction based on the 2MASS (Two Micron All Sky Survey) photometric database in the direction of anti-Galactic center. Adopting a constant conversion coefficient from the integrated intensity of the CO line to the column density of molecular hydrogen, X_CO = 2.0 × 10²⁰ cm^?2 · (K · km/s)^?1, the gas to dust ratio N(H)/A_V is calculated, which is 25, 38, and 55 (in units of 10²⁰ cm^?2 · mag^?1) for the Orion, Taurus, and Polaris molecular clouds, respectively. These values are significantly higher than the previously obtained average value of the Galaxy. Adopting the WD01 interstellar dust model (when the V-band selective extinction ratio is R_V = 3.1), the derived GDRs are 160, 243, and 354 for the Orion, Taurus, and Polaris molecular clouds, respectively, which are apparently higher than 100～150, the commonly accepted GDR of the diffuse interstellar medium. The high N(H)/A_V values in the star forming regions may be explained by the growth of dust in the molecular clouds because of either the particle collision or accretion, which can lead to the reduction of extinction efficiency per unit mass in the V band, rather than the increase of the GDR itself.  相似文献   

Metamorphic,deformation, fluids and geological significance of low-temperature retrograde mylonites of Diancangshan metamorphic massif along Ailaoshan-Red River strike-slip fault zone,Yunnan, China     

Xuemei Cheng  Shuyun Cao  Junyu Li  Zunpu Yu  Yanlong Dong  Meixia Lv  Junlai Liu 《中国科学:地球科学(英文版)》2018,61(8):1023-1041

Diancangshan metamorphic massif is one of the four metamorphic massifs developed along the Ailaoshan-Red River strike-slip fault zone, Yunnan, China. It has experienced multi-stage metamorphism and deformation, especially since the late Oligocene it widely suffered high-temperature ductile shear deformation and exhumation of the metamorphic rocks from the deep crust to the shallow surface. Based on the previous research and geological field work, this paper presents a detailed study on deformation and metamorphism, and exhumation of deep metamorphic rocks within the Diancangshan metamorphic massif, especially focusing on the low-temperature overprinted retrogression metamorphism and deformation of mylonitic rocks. With the combinated experimental techniques of optical microscope, electron backscatter diffraction attachmented on field-emission scanning electron microscopy and cathodoluminescence, our contribution reports the microstructure, lattice preferred orientations of the deformed minerals, and the changes of mineral composition phases of the superposition low-temperature retrograde mylonites. All these results indicate that: (1) Diancangshan deep metamorphic rock has experienced early high-temperature left-lateral shear deformation and late extension with rapid exhumation, the low-temperature retrogression metamorphism and deformation overprinted the high-temperature metamorphism, and the high-temperature microstructure and texture are in part or entirely altered by subsequent low-temperature shearing; (2) the superposition of low-temperature deformation-metamorphism occurs at the ductile-brittle transition; and (3) the fluid is quite active during the syn-tectonic shearing overprinted low-temperature deformation and metamorphism. The dynamic recrystallization and/or fractures to micro-fractures result in the strongly fine-grained of the main minerals, and present strain localization in micro-domians, such as micro-shear zones in the mylonites. It is often accompanied by the decrease of rock strength and finally influences the rheology of the whole rock during further deformation and exhumation of the Diancangshan massif.  相似文献   

Dealkalization of Red Mud by Carbide Slag and Flue Gas          下载免费PDF全文

Xinke Wang  Yihe Zhang  Jingang Liu  Pan Hu  Ke Meng  Fengzhu Lv  Wangshu Tong  Paul K. Chu 《洁净——土壤、空气、水》2018,46(3)

  相似文献   

Flood coincidence analysis of Poyang Lake and Yangtze River: risk and influencing factors     

Bing?Jianping  Deng?Pengxin  Zhang?XiangEmail author  Lv?Sunyun  Marco?Marani  Xiao?Yi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(4):879-891

We build copula function-based joint distribution models for the annual maximum flood peaks of the Yangtze River and Poyang Lake, to analyze the coincidence probabilities, using scenarios that combine with the impoundment of three Gorges, define influencing indexes and relative contribution rates on flood coincidence at varying frequencies. The study shows the probabilities for coincidence of floods with 1000, 100, and 10-year return periods in both Yangtze main stem and Poyang Lake are respectively 0.02, 0.19 and 2.87%, with higher coincidence probabilities for shorter return periods; when 1000-year flood occurs in the Yangtze, the probabilities for Poyang Lake to encounter flood of the 1000, 100, or 10-year magnitude are higher than 16.08, 42.48 or 74.77% respectively; Poyang–Yangtze flood coincidence is affected by operation of the hydraulic engineering. The lowering of flood peaks caused by the Three Gorges impoundment and regulation of the lake have respectively reduced the probabilities of Poyang–Yangtze flood coincidence by about 7.0 and 1.97%, with average relative contribution rates ? 33.82 and ? 17.1%; influenced by hydrological projects in Poyang basin, variations in Poyang’s inflow flood have displayed an average contribution rate of 20.4% for the negative effect on extreme (P < 5% or P > 90%) flood coincidence, while having a positive contribution rate of 38.2% on floods of other return periods. The results can help increase our understanding of flood coincidence, and support flood control efforts in Poyang Lake; its analytical approach may also be useful to other applications of copula functions.  相似文献   

洪泽湖出入河流及湖体氮、磷浓度时空变化(2010—2019年)     

崔嘉宇  郭蓉  宋兴伟  张悦  陈晨  吕学研  董圆媛 《湖泊科学》2021,33(6):1727-1741

基于2010-2019年洪泽湖湖体水质逐月监测数据,筛选出影响湖体水质的主要污染物指标为总氮（TN）和总磷（TP）;选取洪泽湖周边25条主要入湖河流和2条出湖河流在2019年10月2020年9月的监测数据,探讨河流外源性输入对不同湖体区域氮磷的影响及其水期变化规律.结果发现：①湖体TN、TP浓度长期居高不下,年均浓度范围分别在1.39~1.86、0.080~0.171 mg/L波动.主要入湖河流TN、TP时空平均浓度（1.92~5.70和0.114~0.181 mg/L）,均高于同区域湖体（1.15~1.46和0.088~0.101 mg/L）,其中北部入湖河流肖河、马化河和五河与临近湖区TN、TP浓度呈现显著正相关,是影响北部湖体TN、TP浓度的主要河流;南部入湖河流维桥河和高桥河是临近湖区非极端降雨期TN、TP的主要来源.②调水工程对湖体及入湖河流TN、TP浓度分布影响显著,调水期湖体沿调水方向TP浓度逐渐上升,TN浓度则呈现先降后升的趋势,南部入湖河流维桥河和高桥河TN浓度达到水期峰值,分别为10.69和9.90 mg/L.③极端降雨期入湖河流的TN、TP浓度显著高于其它水期,由于湖体对TN、TP的富集作用不同,TP浓度呈现中间高,四周低,而TN浓度呈现沿洪水流向逐渐降低的规律.  相似文献   

乌梁素海悬浮颗粒物和沉积物有机碳同位素特征及来源     

耿悦  吕喜玺  于瑞宏  孙贺阳  刘心宇  曹正旭  李向伟  朱鹏航  葛铮 《湖泊科学》2021,33(6):1753-1765

悬浮颗粒物和沉积物是湖泊有机污染物的主要承载物质,其稳定同位素研究对有效识别有机质污染导致的湖泊富营养化具有重要意义.本研究选取乌梁素海为研究区,于2019年4月（融冰期）、7月（夏灌期）和10月（秋灌期）对湖区及入湖渠道的表层沉积物和悬浮颗粒物中有机碳的δ¹³C、C/N比及总有机碳（TOC、POC）和总氮（TON、PON）含量进行测定分析,联合采用δ¹³C、C/N及同位素多元混合模型研究湖泊有机碳来源及其贡献率.结果表明,乌梁素海悬浮颗粒物有机碳δ¹³C_POC的变化范围为-23.29‰~-29.75‰,呈现10月>4月>7月、入湖渠道>湖区的趋势,悬浮颗粒物POC/PON比变化范围为4.10~21.35,呈现出4月<7月<10月的时间变化,悬浮颗粒有机质主要来源于浮游植物（51.59%）、入湖渠道泥沙（34.60%）和大型水生植物（13.76%）.沉积物有机碳δ¹³C_TOC变化范围为-27.58‰~-22.68‰,呈现4月<10月<7月的变化,沉积物TOC/TON比变化范围为3.06~23.77,时空变化明显,沉积物有机质则主要源于入湖渠道挟带的泥沙,贡献达72.79%以上,而浮游植物与大型水生植物的贡献率相差较小,分别为11.85%和15.36%.本研究可以初步判定受入湖渠道影响的富营养化湖泊中悬浮颗粒物和沉积物有机碳来源,为改善湖泊有机污染和研究有机碳来源提供更多理解.  相似文献