基于改进U-Net的CMIP5全球气候模式降尺度方法及其在鄱阳湖流域的应用

利用降尺度方法对CMIP5全球气候模式进行空间降尺度并以此研究鄱阳湖流域未来气候时空变化趋势,能够为流域生态环境保护提供数据、技术和理论上的支持.通过简化原始网络结构,在网络首部添加插值层,采用反卷积算法作为上采样算法对传统U-Net网络进行改进,建立基于深度学习的气候模式空间降尺度模型(DLDM).以1965-200...     

CMIP5多模式集合对东北三省未来气候变化的预估研究

应用CN05观测资料,以及参与国际耦合模式比较计划第5阶段(CMIP5)中的26个模式,评估了新一代全球气候模式对东北三省气候变化模拟能力并选出4个较优模式,发现经过筛选得出的较优模式集合平均模拟结果的可靠性得到进一步加强,尤其体现在对气温的模拟上.在此基础上着重分析了多模式集合在不同典型浓度路径(RCPs)下对未来气候变化特征的预估.结果表明:21世纪的未来阶段,东北三省将处于显著增温的状态,且RCP8.5情景下的增温速率(0.53℃/10a)明显高于RCP4.5情景下的速率(0.22℃/10a);空间上,北部地区将成为增温幅度最大、增温速率最高的区域.未来降水将会相对增加,但波动较大,21世纪末期RCP4.5和RCP8.5情景下的降水增加幅度分别为11.24%和15.95%;空间上,辽宁省西部地区将成为降水增加最为显著的区域.根据水分盈亏量,21世纪未来阶段,RCP4.5情景下的东北三省绝大多数地区未来将相对变湿,尤其到了中后期;RCP8.5情景下则是中西部地区将相对变干,其余地区则会相对变湿.     

基于马尔科夫链模型的鄱阳湖流域水文气象干旱研究

基于气象和水文干旱的二维变量干旱状态基础上,通过一阶马尔科夫链模型对二维变量干旱状态进行频率、重现期和历时分析,建立水文气象干旱指数,从干旱灾害形成、演变和持续3方面对干旱灾害进行研究,同时预测未来6个月非水文干旱到水文干旱的概率.结果表明:(1)修河流域在干旱形成中危害大,抚河流域和修河流域在干旱演变中危害大,赣江流域和饶河流域在干旱持续中危害大;(2)鄱阳湖流域状态4(气象、水文干旱)发生的频率最高,为0.30,连续湿润或者干旱的概率最大,湿润状态(状态2)与水文干旱(状态4、状态5(气象湿润、水文干旱))的相互转移概率最低;(3)在长期干旱预测中,鄱阳湖流域从状态2转到状态4和状态5的平均概率为0.11,属最低,而状态1(气象、水文无旱)和状态3(气象干旱、水文湿润)到达状态4的概率为0.23,发生概率最大.修河流域在非水文干旱状态下未来发生气象、水文干旱状态的平均概率为0.28,是"五河"中最高的,而赣江流域在正常或者湿润状态下未来发生气象、水文干旱的概率最低,为0.18,该研究对于鄱阳湖流域水文气象干旱的抗旱减灾具有重要理论与现实意义.     

东亚地区晴空湍流未来变化趋势预估：基于CORDEX-WRF模式降尺度

利用耦合模式比较计划(CMIP5)的全球环流模式CNRM-CM5、GFDL-ESM2M、EC-EARTH和MPI-ESM-LR分别驱动区域气候模式(RCM)WRF,在国际间区域气候降尺度试验(CORDEX)框架下对东亚地区当代和RCP 8.5情景下未来气候进行高分辨率模拟.通过计算21个晴空湍流指数研究了东亚地区2041—2060年三个高度层上(200 hPa、250 hPa和300 hPa)五种强度湍流(轻度、轻-中度、中度、中-重度和重度)的季节变化特征.首先检验RCM对1981—2000年气候的模拟能力,结果显示,模式能够较好再现东亚地区高空变量气候平均态空间分布特征,同时对晴空湍流指数分布特征亦具有较好模拟能力.晴空湍流未来变化趋势预估结果显示,东亚地区所有季节中均存在湍流强度越强、湍流频率增幅越大的特征.各强度湍流增幅冬季最大,其次为春季和秋季,夏季最小.从不同高度对比来看,200 hPa和250 hPa各强度湍流增幅普遍大于300 hPa,且在夏季和秋季增幅随高度降低而减小,春季和冬季则250 hPa上增幅最大,300 hPa上增幅最小.就中国不同子区域而言,纬度越高的区域...     

Statistical downscaling of reference evapotranspiration in Haihe River Basin: applicability assessment and application to future projection

Future changes in reference evapotranspiration (ET₀) are of increasing importance in assessing the potential impacts on hydrology and water resources systems of more pronounced climate change. This study assesses the applicability of the Statistical Downscaling Model (SDSM) in projecting ET₀, and investigates the seasonal and spatial patterns of future ET₀ based on general circulation models (GCMs) across the Haihe River Basin. The results indicate that SDSM can downscale ET₀ well in term of different basin-averaged measures for the HadCM3 and CGCM3 GCMs. HadCM3 has a much superior capability in capturing inter-annual variability compared to CGCM3 and thus is chosen as the sole model to assess the changes in future ET₀. There are three homogeneous sub-regions of the Haihe River Basin: Northwest, Northeast and Southeast. Change points are detected at around 2050 and 2080 under the A2 and B2 scenarios, respectively. The Northwest is revealed to have a slight to strong increase in ET₀, while the Northeast and the Southeast tend to experience a pattern change from decrease to increase in ET₀.

EDITOR M.C. Acreman

ASSOCIATE EDITOR J. Thompson     

Variation of reference evapotranspiration and its contributing climatic factors in the Poyang Lake catchment,China

By using linear regression (parametric), Mann–Kendall (nonparametric) and attribution analysis methods, this study systematically analysed the changing properties of reference evapotranspiration (ETr) calculated using the Penman–Monteith method over the Poyang Lake catchment during 1960–2008 and investigated the contribution of major climatic variables to ETr changes and their temporal evolution. Generally, a significant decreasing trend of annual ETr is found in the catchment. The decrease of annual ETr in the Poyang Lake basin is mostly affected by the decline of summer ETr. Over the study period, climatic variables, i.e. sunshine duration (SD), relative humidity (RH), wind speed (WS) and vapour pressure all showed decreasing trends, whereas mean daily temperature (DT) increased significantly. Multivariate regression analysis indicated that SD is the most sensitive climatic variable to the variability of ETr on annual basis, followed by RH, WS and DT, whereas the effect of vapour pressure is obscure. Although recent warming trend and decrease of relative humidity over the catchment could have increased ETr, the combined effect of shortened SD and reduced WS negated the effect and caused significant decrease of ETr. Our investigation reveals that the relative contributions of climatic variables to ETr are temporally unstable and vary considerably with large fluctuation. In consideration of the changes of climatic variables over time, further analysis indicated that changes of mean annual ETr in 1970–2008 were primarily affected by SD followed by WS, RH and DT with reference to 1960s. However, WS became the predominant factor during the period 2000–2008 compared with reference period 1960s, and followed by SD. Copyright © 2013 John Wiley & Sons, Ltd.     

基于Copula函数的鄱阳湖水系径流丰枯遭遇多维分析

鄱阳湖流域5大水系来水变化与湖区水文极值事件有密切关系,研究径流变化特征与丰枯遭遇规律对区域防洪抗旱有重要意义.本文运用Copula函数构建了鄱阳湖水系多维径流联合分布模型,采用特枯、偏枯、平水、偏丰和特丰的径流丰枯分类,定量研究了鄱阳湖5大水系丰枯遭遇的问题,探讨了多维丰枯遭遇同步联合概率的变化特征.结果表明：鄱阳湖水系河流之间的径流具有较高的相关性,Gaussian Copula函数能较好地模拟二维至五维的径流联合分布.多条河流的丰枯遭遇随着维数的增加,丰枯组合增加,丰枯同步的联合概率明显下降,且丰枯同步的最大联合概率趋向于丰枯两端.对于相同的概率区间,非汛期径流的丰枯同步联合概率明显大于年径流和汛期径流,而年径流和汛期径流之间的丰枯同步联合概率差别较小.同处于流域北部或南部或相邻的河流之间的组合,其同步联合概率相较其他组合大,而南、北河流组合的同步联合概率相对较小.该研究可为流域水资源管理及水旱灾害预防提供科学依据.     

Study on consumption efficiency of soil water resources in the Yellow River Basin based on regional <Emphasis Type="Italic">ET</Emphasis> structure

Based on the regional water resources character, the concept of soil water resources is first redefined, and then associated with their transfer relationship in the hydrological cycle, Evapotranspiration (ET)-based consumption structure and consumption efficiency of soil water resources are analyzed. According to ET’s function in productivity, the consumption efficiency of soil water resources is divided into three classes: high efficient consumption from vegetation transpiration, low efficient consumption from soil evaporation among plants with high vegetation coverage and inefficient consumption from soil evaporation among plants with low vegetation coverage and bare soil evaporation. The high efficient and low efficient consumption were further classified as productive consumption. The inefficient consumption is considered non-productive consumption because it is significant in the whole hydrological cycle process. Finally, according to these categories, and employing a WEP-L distributed hydrological model, this paper analyzes the consumption efficiency of soil water resources in the Yellow River Basin. The results show that there are 2078.89×10⁸ m³ soil water resources in the whole basin. From the viewpoint of consumption structure, the soil water resources are comprised of 381.89×10⁸ m³ transpiration consumption from vegetation and 1697.09×10⁸ m³ evaporation consumption from soil among plants and bare soil. From the viewpoint of consumption efficiency, soil water resources are composed of 920.11×10⁸ m³ efficient consumption and 1158.86×10⁸ m³ of inefficient consumption. High efficient consumption accounts for 41.5 percent of the total efficient consumption of the whole basin, low efficient for 58.5 percent. Furthermore, consumption efficiency varies by region. Compared with ET from different land use conditions, the whole basin appears to follow the trend of having the greatest proportion of consumption as inefficient consumption, followed by low efficient consumption, and then the least proportion as high efficient consumption. The amount of inefficient consumption in some regions with vegetation is less than in other regions without vegetation. The amount of inefficient consumption in grasslands is much greater than in forestlands. However, the proportion of low efficient consumption is the greatest in crop fields. The amount of high efficient consumption in grasslands and forelands is similar to the corresponding low efficient consumption. However, the low efficient consumption in grasslands is larger than in the forelands. Therefore, when adjusting the utilization efficiency of soil water resources, vegetation coverage and plant structure should be modulated in terms of the principle of decreasing inefficient consumption, improving low efficiency ET and increasing high efficiency ET according to area character. Supported by the Project of the National 973 Program of China (Grant Nos. 2006CB403404 and G1999043602), the Project of the National Science Research for the 11th Five-Year Plan (Grant No. 2006BAB06B06), and the Innovation Team Project of the National Natural Science Foundation of China (Grant No.50721006)     

基于长短记忆模型的鄱阳湖流域径流模拟及其演变的归因分析

气候变化和人类活动直接或间接的影响着全球和区域水文循环过程,是导致水文水资源时空分布的主要因素,同时也是流域-湖泊水文情势变化的根本原因.本文基于长短记忆模型构建了鄱阳湖气象—径流模型,同时引入了基准期的概念,定量区分了导致鄱阳湖流域径流变化的主要影响因素.研究结果表明:在同时考虑计算效率和模拟效果的前提下,采用10 ...     

鄱阳湖流域上游铀尾矿库周边水体中铬形态及健康风险评估

以鄱阳湖流域上游铀尾矿库周边水体为研究对象,在研究铬(Cr)污染程度的基础上,采用水文地球化学模拟软件PHREEQC计算Cr各不同赋存形态的浓度,讨论不同条件下Cr形态的变换规律以及健康风险评价,对研究水体中Cr生物有效性具有实际意义.结果表明:铀尾矿区排放水、渗滤水、浅层地下水中Cr浓度均未超出相关标准值.水体中Cr主要赋存形态大多为Cr(Ⅲ)的水解产物Cr(OH)²⁺和Cr(OH)₂⁺. pH和电子活度(pe)共同影响Cr在水体中的赋存形态,当pH=3～5时,以CrF²⁺为优势离子;当pH>5时,随pH递增,pe值对Cr赋存形态的影响增加,pe值增大,Cr(Ⅲ)水解产物浓度逐渐减少,而Cr(Ⅵ)氧化产物逐渐增加.浅层地下水中的Cr不会对人体产生致癌风险和非致癌风险,但当p H、pe变化时,Cr致癌风险系数均高于ICRP和USEPA推荐的最大可接受值.由于Cr(Ⅵ)的毒性远强于Cr(Ⅲ),故应密切关注水体中pe与pH值,避免污染加重.     

1960年以来气候变化与人类活动对鄱阳湖流域生态径流改变的影响

基于鄱阳湖流域五河水文站1960-2013年逐日径流量和14个国家级气象站的日气象数据,本文利用长短记忆模型框架构建神经网络模型来开展鄱阳湖流域的径流过程模拟,结合生态赤字与生态盈余等生态径流指标,定量分析了鄱阳湖流域的水文变异特征.同时,利用差异化的情景模拟方式,定量区分了人类活动和气候变化对鄱阳湖流域生态径流变化的...     

基于连通性指数(IC)的近30年鄱阳湖流域水系结构与水文连通演变评估

由于气候变化和人类活动等多重影响,流域河湖水系格局与连通程度发生了显著变化,进而引发洪涝灾害等一系列水资源问题。本文以鄱阳湖流域为研究区,基于Google Earth Engine(GEE)提取1989—2020年5期水系数据,采用图论方法构建水系评价体系,定量分析该地区近30年来水系格局和结构连通性的时空演变特征,并结合该时期地形、土地利用和归一化植被指数(NDVI)等数据,利用连通性指数(index of connectivity,IC)评估功能连通性的动态变化,进而探讨水文连通与径流量和输沙量的联系。结果表明,近30年来鄱阳湖流域水系结构趋于复杂化,主要体现在流域北部。除干流外,其他等级河流的数量和长度均有所增加,其中Ⅲ级河流最为明显。河网密度、水面率、河网复杂度和发育系数均呈增加趋势,2000年后的变化率约为2000年前的两倍。水系连通环度、节点连接率和水系连通度总体增加,结构连通性呈好转趋势且变化幅度较小。功能连通分析表明,近30年来大部分流域IC减少,流域下游靠近主河道的平坦地区IC较高,上游远离河道的植被密集区域IC较低。此外,IC与年径流量和输沙量表现为显著的正相关性(...     

施氮和增温对鄱阳湖灰化薹草(Carex cinerascens Kukenth.)湿地秋草生长期氧化亚氮排放的影响

湿地是地球上十分重要的氮库,而且对大气氮沉降增加、气候变暖等全球变化响应非常敏感。目前关于湿地氧化亚氮(N₂O)的研究还存在较大的区域不均衡性,湿地N₂O排放对全球变化的响应也具有很大的不确定性。因此,本研究通过在鄱阳湖灰化薹草(Carex cinerascens Kukenth.)湿地开展N₂O通量原位监测及全球变化模拟实验,以揭示鄱阳湖灰化薹草湿地N₂O排放变化特征及其对施氮和增温的响应关系。结果表明,鄱阳湖灰化薹草湿地总体上是N₂O弱源,平均N₂O通量为(5.77±1.45) μg/(m²·h)。施氮对鄱阳湖灰化薹草湿地N₂O通量有显著影响,相对于不施氮,施氮可显著提升2.7倍的N₂O排放通量。增温及其与施氮的交互作用对N₂O通量的影响不显著。鄱阳湖灰化薹草湿地N₂O排放过程主要由湿地植物调节,而与空气温度、土壤温度、土壤水分等非生物因素无显著相关关系。研究结果有利于深入认识全球变化与湖泊湿地N₂O排放的互馈作用,并为评估全球变化背景下湖泊湿地N₂O收支平衡提供重要支撑;未来还需要加强多因子交互作用研究并开展长期连续监测,从而为阐明湿地氮循环对全球变化的响应机制和构建气候预测模型提供验证数据和理论依据。