高寒区抽水融冰渠道水温沿程衰减规律——以红山嘴水电站为例   总被引：1，自引：0，他引：1       下载免费PDF全文

郑铁刚  宗全利  孙双科  吴素杰 《水科学进展》2018,29(5):667-676

抽水融冰技术是解决高寒区引水式电站冬季运行冰害问题的有效措施之一。为研究抽水融冰对电站引水渠道冬季引水的水温控制规律,以红山嘴水电站为例,基于RNG κ-ε模型数值模拟研究结果,从热流量比角度探讨了渠道水温沿程衰减规律,并采用2013年2月和2014年1月原型观测结果进行了验证。结果表明:渠道水温沿程衰减过程可分为骤降段、过渡段和缓降段3部分,各段范围受外界条件控制;衰减曲线呈幂函数分布,相关系数达到98%;对比气温对渠温沿程衰减的影响表明,随着大气温度的降低,渠道水温沿程衰减速度明显加快;-10 ℃为水温衰减过程变化转折点,当气温高于-10 ℃时,可以近似认为渠温衰减规律一致,渠温沿程变化主要受到热流量比值影响;低于-10 ℃时,气温对渠道水温沿程变化影响显著。  相似文献   

Using climate to relate water discharge and area in modern and ancient catchments     

《Sedimentology》2018,65(4):1378-1389

Models relating sediment supply to catchment properties are important in order to use the geological record to deduce landscape evolution and interplay between tectonics and climate. Water discharge (Q _w) is an important factor in the widely used ‘BQART ’ model, which relates sediment load to a set of measurable catchment parameters. Although many of the factors in this equation may be independently estimated with some degree of certainty in ancient systems, water discharge (Q _w) certainly cannot. An analysis of a world database of modern catchments with 1255 entries shows that the commonly applied equation relating catchment area (A ) to water discharge (Q _w = 0·075A^0·8) does not predict water discharge from catchment area well in many cases (R ² = 0·5 and an error spanning about three orders of magnitude). This is because the method does not incorporate the effect of arid and wet climate on river water discharge. The inclusion of climate data into such estimations is an opportunity to refine these estimates, because generalized estimates of palaeoclimate can often be deduced on the basis of sedimentological data such as palaeosol types, mineralogy and palaeohydraulics. This paper investigates how the relationship between catchment area and river discharge varies with four runoff categories (arid, semi‐arid, humid and wet), which are recognizable in the geological record, and modifies the coefficient and exponent of the above‐mentioned equation according to these classes. This modified model yields improved results in relating discharge to catchment area (R ² = 0·95 and error spanning one order of magnitude) when core, outcrop or regional palaeoclimate reconstruction data are available in non‐arid systems. Arid systems have an inherently variable water discharge, and catchment area is less important as a control due to downstream losses. The model here is sufficient for many geological applications and makes it possible to include variations in catchment humidity in mass‐flux estimates in ancient settings.  相似文献   

Characteristics of Lake Breezes and Their Impacts on Energy and Carbon Fluxes in Mountainous Areas     

Lujun XU  Huizhi LIU  Qun DU  Yang LIU  Jihua SUN  Anlun XU  Xiaoni MENG 《大气科学进展》2021,38(4):603-614

In mountainous lake areas, lake–land and mountain–valley breezes interact with each other, leading to an "extended lake breeze". These extended lake breezes can regulate and control energy and carbon cycles at different scales. Based on meteorological and turbulent fluxes data from an eddy covariance observation site at Erhai Lake in the Dali Basin,southwest China, characteristics of daytime and nighttime extended lake breezes and their impacts on energy and carbon dioxide exchange in 2015 are investigated. Lake breezes dominate during the daytime while, due to different prevailing circulations at night, there are two types of nighttime breezes. The mountain breeze from the Cangshan Mountain range leads to N1 type nighttime breeze events. When a cyclonic circulation forms and maintains in the southern part of Erhai Lake at night, its northern branch contributes to the formation of N2 type nighttime breeze events. The prevailing wind directions for daytime, N1, and N2 breeze events are southeast, west, and southeast, respectively. Daytime breeze events are more intense than N1 events and weaker than N2 events. During daytime breeze events, the lake breeze decreases the sensible heat flux(Hs) and carbon dioxide flux(F_{CO_2}) and increases the latent heat flux(LE). During N1 breeze events, the mountain breeze decreases Hs and LE and increases F_{CO_2}. For N2 breeze events, the southeast wind from the lake surface increases Hs and LE and decreases suppress carbon dioxide exchange.  相似文献   

The First Global Carbon Dioxide Flux Map Derived from TanSat Measurements     

Dongxu YANG  Yi LIU  Liang FENG  Jing WANG  Lu YAO  Zhaonan CAI  Sihong ZHU  Naimeng LU  Daren LYU 《大气科学进展》2021,38(9):1433-1443

Space-borne measurements of atmospheric greenhouse gas concentrations provide global observation constraints for top-down estimates of surface carbon flux.Here,the first estimates of the global distribution of carbon surface fluxes inferred from dry-air CO_2 column (XCO_2) measurements by the Chinese Global Carbon Dioxide Monitoring Scientific Experimental Satellite (Tan Sat) are presented.An ensemble transform Kalman filter (ETKF) data assimilation system coupled with the GEOS-Chem global chemistry transport model is used to optimally fit model simulations with the Tan Sat XCO_2 observations,which were retrieved using the Institute of Atmospheric Physics Carbon dioxide retrieval Algorithm for Satellite remote sensing (IAPCAS).High posterior error reduction (30%–50%) compared with a priori fluxes indicates that assimilating satellite XCO_2 measurements provides highly effective constraints on global carbon flux estimation.Their impacts are also highlighted by significant spatiotemporal shifts in flux patterns over regions critical to the global carbon budget,such as tropical South America and China.An integrated global land carbon net flux of 6.71±0.76 Gt C yr~(-1) over12 months (May 2017–April 2018) is estimated from the Tan Sat XCO_2 data,which is generally consistent with other inversions based on satellite data,such as the JAXA GOSAT and NASA OCO-2 XCO_2 retrievals.However,discrepancies were found in some regional flux estimates,particularly over the Southern Hemisphere,where there may still be uncorrected bias between satellite measurements due to the lack of independent reference observations.The results of this study provide the groundwork for further studies using current or future Tan Sat XCO_2 data together with other surfacebased and space-borne measurements to quantify biosphere–atmosphere carbon exchange.  相似文献   

辽东湾红沿河附近海域2017—2018年冬季气温-水温-冰情关系研究     

马玉贤  王玉  於凡  许宁  袁帅  史文奇 《冰川冻土》2022,44(5):1482-1491

辽东湾是我国冰情最严重海域,每年冬季都会受到海冰的显著影响,冰情预测评估可为辽东湾涉海活动提供防冰抗冰的技术依据。建立气温-水温-冰情的相关性,结合便于获取的现场高精度连续气象数据和高精度冰情预测模型,可实现局地小尺度的冰情快速预测评估。基于2017—2018年冬季辽东湾东岸红沿河附近海域实测气象-水温-冰情同步观测数据,结合辽东湾大尺度整体冰情（浮冰面积）,推演局地气温、水温与不同尺度冰情评价参数（浮冰范围与冰厚）的相关关系,提出基于不同气温区间的气温变化规律的冰底热通量选取方法,进而建立适用于辽东湾的气温-水温-冰情评估方法。相关性分析结果显示：观测点气温与水温存在明显相关性;浮冰范围与气象数据存在明显相关性,临界温度为 -5 ℃的累计负气温能很好拟合本年度盛冰期浮冰范围。基于HIGHTSI进行数值模拟后发现：水温与块体积法计算冰底热通量时,冰水间的热传递系数取2.2×10^-5是可行的;水温对冰情的影响表现在海冰冰厚最大值与冰期长短。为弥补辽东湾其他海域因缺少实测海水温度观测数据欠缺、冰底热通量选取不准选取导致的冰情模拟预测评估困难的问题,本文依据水温与气温的相关性,将水温随气温变化划分为结冰区（气温小于-10 ℃时水温维持冰点附近）、过渡区（气温为-10~-5 ℃时水温处于-1.4~-0.4 ℃）、融冰区（气温高于-5 ℃时水温随气温的增大逐渐增大）,进而提出适用于辽东湾所有海域的冰底热通量计算方法和冰情评估方法。  相似文献   

基于Hkr值的北天山冰川侵蚀空间分布特征及其主控因素研究     

姚盼  王杰  林文旺  曾兰华  陈仁容 《冰川冻土》2022,44(4):1260-1269

确定冰川侵蚀的主控因素及其与各影响因素间的相互作用方式,不仅对深入认识冰川侵蚀的物理机制和理解冰川作用区地貌演化具有重要的意义,也是探讨构造、气候、地形间相互关系的根本。然而,以往的学者仅在构造活动略单一的区域研究冰川侵蚀的主控因素,致使对构造的影响认识不足,那么,构造是否是冰川侵蚀的主控因素呢？又是如何作用于冰川侵蚀？北天山第四纪冰川作用规模巨大,留下了丰富的冰川遗迹,其气候与构造条件也多样,因而成为探讨上述问题的理想区域。本文在北天山北坡自西向东选取了7个冰川流域,基于每个流域的Hkr值和冰川侵蚀影响因子的定性定量数据,分析了该区域冰川侵蚀的分布规律及其影响因素。结果表明,北天山各流域冰川侵蚀自西向东有减小趋势,该变化趋势是构造、气候、地形共同作用所致。其中,山顶高度和降水对冰川侵蚀的影响最显著,两者均通过对冰川规模施加作用来控制冰川侵蚀,而构造也可能通过影响顶点高程、积累区面积、冰川规模,进而作用于冰川侵蚀,但是其是否发挥主要作用有待进一步认识。因此,冰川规模可能才是导致北天山各冰川流域侵蚀差异的根本原因。  相似文献   

青藏高原南部及邻区深部碳释放规模与成因     

赵文斌  郭正府  李菊景  马琳  刘嘉麒 《岩石学报》2022,38(5):1541-1556

不同构造背景下的深部碳释放通量与机制研究对于深刻理解长时间尺度的气候变化具有重要意义,以往的相关研究多集中在洋中脊、大洋俯冲带和大陆裂谷等地质单元,缺少对大陆碰撞带深部碳释放规模与机理的关注,从而制约了对大陆碰撞带深部碳循环过程及其气候环境效应的进一步认识。青藏高原起源于印度和欧亚大陆的碰撞,是研究大陆碰撞带深部碳循环的理想地区。为此,在近年来青藏高原温室气体释放野外观测与研究的基础上,本文估算了高原南部及邻区火山-地热区的CO₂释放规模并探讨了其释放模式。气体He-C同位素地球化学与温泉水热活动特征等显示,青藏高原南部及邻区的深部碳释放主要受深部岩浆房、断裂和浅部水热系统等因素的控制。依据深部流体源区和上升运移控制因素的差异,可以将青藏高原南部及邻区的深部碳释放划分为三大类：(1)以壳内水热系统脱碳为主的藏南地区;(2)深大断裂控制的以水热系统脱碳为主的川西地区;(3)深部岩浆房和浅部水热系统共同控制的滇西南地区。青藏高原南部土壤微渗漏CO₂释放通量介于18.7～52.3Mt/yr之间,温泉溶解无机碳释放通量约为0.13Mt/yr;高原邻区...  相似文献   

安徽马鞍山市当涂地区地下水水化学特征及演化机制          下载免费PDF全文

李状  苏晶文  董长春  叶永红  杨洋 《中国地质》2022,49(5):1509-1526

【研究目的】 了解长江中下游平原地区地下水流系统并深入分析其地下水水化学特征及其演化机制。【研究方法】 综合马鞍山市当涂地区的水文地质条件、水动力场等,基于研究区水化学基本特征,运用多元统计分析、水化学图件、离子比值和反向水文地球化学模拟等方法对该地区浅层地下水水化学演化进行分析。【研究结果】 结果表明：（1）研究区地下水主要为低矿化度偏碱性水,地下水组分中阳离子以Ca²⁺和Mg²⁺为主,阴离子以HCO₃^-和SO₄^2-为主。（2）研究区地下水水化学类型主要可分为7类,其中松散岩类孔隙含水岩组和碎屑岩类孔隙裂隙含水岩组的水化学类型主要为HCO₃^-Ca型、HCO₃^-Ca·Na型、HCO₃·Cl-Ca·Na型以及HCO₃^-Ca·Mg型;基岩类裂隙含水岩组的化学类型主要为HCO₃·SO₄-Ca·Mg型和SO₄·HCO₃^-Ca·Mg型。（3）研究区浅层地下水水样超标率为46%,总体水质较差,超标率较高的组分依次为Mn、高锰酸盐指数（COD_Mn）、硝酸盐（以N计）、Fe、As、氨氮（以N计）等。（4）研究区地下水的化学组分主要受到岩石风化作用的控制;此外,还存在Na-Ca的正向阳离子交替吸附作用。反向水文地球化学模拟结果进一步定量论证了水岩相互作用对本区浅层地下水组分的形成和演化起着主导作用。【结论】 研究区地下水主要为低矿化度偏碱性,主要可分为松散岩类孔隙水、碎屑岩类孔隙裂隙水和基岩类裂隙水。主要离子比例和反向水文地球化学模拟揭示了本区浅层地下水化学组分主要是地下水溶滤方解石、白云石等碳酸盐矿物、石英、长石等硅酸盐矿物,高岭土等黏土矿物以及岩盐、石膏等达到过饱和之后形成的。  相似文献   

地下水与地表水水量交换识别及交换量计算——以新汴河宿州段为例          下载免费PDF全文

束龙仓  宫荣  栾佳文  龚建师  陶小虎  赵贵章  陶月赞 《水科学进展》2022,33(1):57-67

为提高地下水与地表水交换量计算结果的准确性,本文利用水力联系、水头差、水温、氡-222、氢氧稳定同位素构建综合识别方法（HHTRO）,对新汴河宿州段地下水与地表水水量交换进行识别,并计算交换量。计算结果表明:研究河段单位河长地表水补给地下水的水量变化范围为8.69~366.82 m3/（d·m）,地下水补给地表水的水量变化范围为0.72~120.90 m3/（d·m）;研究河段左岸为地下水补给地表水,单位河长净补给量为45.26 m3/（d·m）;河段右岸为地表水补给地下水,单位河长净补给量为214.33 m3/（d·m）;研究河段地下水与地表水水量交换以地表水补给地下水为主,地表水补给地下水的比例为55.14%。本研究可推动地下水与地表水交换量计算方法的发展,为流域或区域水资源评价提供必要的理论方法。  相似文献   

长江口沉积物-水界面砷的迁移转化机制与微生物调控分析     

张玉婷  段丽琴  宋金明  张乃星  尹美玲  李学刚  袁华茂 《地学前缘》2022,29(4):144-155

为探析长江口沉积物-水界面砷的迁移转化机制,本文分析了2019年夏季长江口4个站位上覆水和间隙水中总As浓度及形态的剖面变化特征,耦合氧化还原敏感元素(Fe、Mn和S)的剖面变化剖析了沉积物-水界面砷循环的Fe-Mn-S控制机制,同时结合砷相关功能基因探讨了沉积物-水界面砷迁移转化的微生物调控过程,估算了沉积物-水界面总As的扩散通量。结果表明,除A7-4站位外,长江口其他3个站位间隙水总As以As³⁺为主要存在形态,且总As浓度均在上覆水中为最低值(0.748~1.57 μg·L^-1),而在间隙水中随着深度增加而逐渐增加并在6~9 cm深度达到峰值(7.14~26.9 μg·L^-1)。间隙水总As及As³⁺浓度的剖面变化趋势与溶解态Fe²⁺、Mn²⁺相似,其均在中间层出现高值,说明沉积物Fe/Mn还原带砷的释放可能是随固相Fe(Ⅲ)或Mn(Ⅳ)的还原而转移到间隙水中的。氧化层和Fe/Mn还原带过渡区间隙水砷浓度与砷异化还原菌功能基因arrA和arsC丰度存在对应关系(除A1-3站外),说明砷异化还原菌将溶解As⁵⁺或固相As⁵⁺还原为溶解As³⁺可能是该过渡层砷迁移转化的另一重要过程。硫酸盐还原带的间隙水总As和As³⁺浓度降低,但由于间隙水的低S^2-浓度不利于砷硫化物生成,因此深层间隙水砷可能与铁硫矿物结合而被移除。底层环境氧化还原条件是影响沉积物-水界面砷迁移转化的重要因素,随底层水DO浓度的降低,砷迁移转化更倾向于微生物还原控制。长江口沉积物-水界面总As的扩散通量为1.18×10^-7~2.07×10^-7 μmol·cm^-2·s^-1,均表现为沉积物间隙水中总As向上覆水释放,即沉积物是研究区域水体总As的来源之一。  相似文献