河流枯水区域参数遥感地学分析应用

河流枯水是河川水文情势的一种表现。本文以云南李仙江布固江流域为例,利用空间遥感信息,通过水文下垫面要素的地学分析与制图,在其水文下垫面单元分区的基础上,确定区域水文模型参数,参照实测水文资料,进行河流枯水资源量的估算。这对缺资料等地区的枯水综合研究具有重要的现实意义。     

对加强广西红树林生态系统保护工作的思考

正红树林是湿地生态系统的重要组成部分,是生长在热带、亚热带河川、海岸滩涂潮间带的乔灌木群落,是由陆地向海洋过渡的特殊生态系统,红树林素有"海上森林"、"海底森林"、"海岸卫士"、"海水淡化器"等美称。作为海岸湿地生态系统惟一的木本植物,它具有防风搏浪、护岸护堤、调节气候等功能,对抵御海潮、风浪等自然灾害,维护和改善海湾、河口地区的生态环境具有不可替代的作用。     

广西典型海湾物质输运滞留时间研究

为研究广西典型海湾物质输运的时间尺度,建立了钦州湾和铁山港湾水动力与物质输运数学模型,计算了钦州湾和铁山港湾物质输运的滞留时间和半交换周期,探讨了滞留时间随入海径流量的变化以及与半交换周期的关系.结果显示,钦州湾的滞留时间为413 - 595 h,半交换周期为148 - 178 h,铁山港湾的滞留时间为215 - 598h,半交换周期约为50 h,钦州湾和铁山港湾的滞留时间均随径流量增大而减小.铁山港的滞留时间在小流量情况下随径流量的变化显著,在大流量下随径流量变化较小,而钦州湾的滞留时间随径流量大致呈线性变化.钦州湾和铁山港的滞留时间和半交换周期之间尚无明确的函数关系,这反映了不同海域的水深、地形及径流与潮汐相互作用的差异性和复杂性.     

蓟县基准站长期重力变化特征研究

基于蓟县GNSS基准站1998~2018年近20 a的绝对重力长期变化资料，联合地面大地测量（绝对重力、GNSS）、地表及地下水文数据和GRACE卫星重力数据，计算并分析由地表垂直位移、地下水及地表水负荷等不同物理信号产生的重力效应，获取各影响因素的长期重力变化特征，并对结果进行深入分析研究，得出以下结论：1）蓟县基准站绝对重力近20 a的长期变化总体呈下降趋势，变化率为－1.64±0.53 μGal/a；2）2004~2017年井水位数据显示，蓟县GNSS基准站所在地区地下水水位呈现明显的下降趋势，变化率为－0.66±0.07 m/a，产生的重力效应为－1.94±0.22 μGal/a，是影响该点重力变化的最主要因素；3）综合分析蓟县基准站地面绝对重力和其他各因素重力效应的长期变化特征认为，该点存在每年0.43±0.58 μGal的重力上升变化，可能与首都圈地区上地幔顶部高密度物质的上涌有一定关系。     

大亚湾网箱养殖区生物—化学特性与营养状况的周日变化

根据1998年11月对大亚湾大棚澳网箱养殖区进行的定点24h连续水质监测资料，分析并探讨了该养殖区海水生物－化学各要素的垂直分布和周日变化规律，并用单项指标评价法和改进的营养状态质量指数（NQI）法，参照营养指数（E）对该网箱养殖区涨水的营养状况进行了评价和研究，结果表明，各项要求的平均值大最都表层＞中层＞底层；周日变化主要受潮汐运动和海水中生物的节律性生理活动的综合影响；表层海水的富营养化率明显高于中层海水，其各单项指标处于中度－富营养状态，而中层和底层海水则分别处于贫－中度和贫－富营养状态；PO4－P相对贫乏，为养殖区富营养化的最关键限制因素。     

DEM在湖泊水文变化研究中的应用进展

在全球变化背景下,湖泊水文的动态变化不仅是评估和预测气候与环境变化的重要指示剂,同时对社会可持续发展、水资源的开发与利用、生态文明建设等产生重要影响。湖泊水文的动态变化受到湖滨及湖底地形的控制,数字高程模型（DEM）成为湖泊水文研究的重要数据源。随着遥测技术的发展,高分辨率、区域/全球大尺度DEM数据的获取手段快速发展、数据源不断丰富,DEM对推动湖泊水文动态研究进展起到了关键作用。本文首先基于Web of Science平台对DEM在湖泊水文动态研究中的相关文献进行了分析,阐述了该主题现有研究在发文时间、发文数量增减态势、研究区域与热点地区、文献所涉及的DEM数据等方面的特点。接着,围绕着DEM在湖泊水文动态的研究中4个主要方向：湖泊水域变化、湖泊水位变化、湖泊水量变化、湖泊水文灾害情势,重点总结：DEM与其他遥感观测平台、实地观测及模型模拟等多源数据的融合策略,数字地形分析与水文学分析、遥感影像分析等方法的集成策略,以及DEM数据不确定性等对湖泊水文变化研究的影响。最后,本文论述了目前DEM在湖泊水文研究中存在的关键问题,并结合技术发展趋势和研究热点问题,提出了可能的解决路径和未来的研究前景。     

低盐度海水对企鹅珍珠贝存活的影响

对企鹅珍珠贝稚贝、中贝和成贝在降低盐度的海水中存活状态进行了观察和研究。在水温20～23℃，以不同盐度梯度（8、12、16、20、24、28、30和33）的海水暂养稚贝并定时检查，在广东的四个海区，对盐度变化时中贝及成贝的养殖成活率进行了观察。结果表明：盐度低于16的3个组，稚贝在60h内全部死亡，盐度20～24海水中，稚贝虽只有部分死亡，但活力较差；稚贝在14的海水中4h后转入正常海水，可全部存活，而超过8h后再移入正常海水的稚贝会陆续死亡；在盐度18海水中，稚贝一直未分泌足丝附着，而移入正常海水，6h就有小苗附着；大万山岛附近海域在雨季盐度可降至20以下，6～9月不适合养殖，而其它实验点可以通过深吊避免海水盐度变化造成企鹅珍珠贝死亡。     

蓝色风情的澫尾金滩

翻开中国地图，你会看到一条使海陆分隔的长长曲线：它自辽宁的鸭绿江口朝西南方向逶迤而下，曲曲折折地走向广西东兴的北仑河口，全长为18000多公里。一位专家介绍说，广西海岸带外的北部湾位于大陆架上，深50米左右，其间有800多个小岛，最大的是涠洲岛；钦州、防城、东兴的海湾内岛屿，原来属于陆地上的侵蚀残丘，后因海水入侵而与陆地隔开形成岛屿。东兴的、万尾金滩就是中国海岸线最南端的一枚玉坠，她晶莹剔透，让你留恋往返。     

用交叉点数据计算中国近海海平面变化

讨论了由测高卫星升、降弧段海面高在交叉点上的约束监测海平面变化的方法；用TOPEX／POSIDON测高数据计算了中国黄海、东海、南海海域的海平面变化，其中黄海、东海海域受两个月周期分量的振荡信号影响，而南海海域以年周期变化为主要表现特征；分析了3个海区海平面变化的相关性，扣除两个月的周期分量振荡信号后，其海平面变化的相关性达到90％以上；分析了海水面积随纬度带的变化对不同纬度分布的海区海平面变化量的影响。     

广西4大海湾红树林区硅含量的变化特征及其影响因素

利用2007年12月至2008年11月对广西沿海4个海湾红树林区进行系统调查的数据资料,分析不同海湾红树林区Si含量的变化特征及其与环境因素的关系。结果表明,广西海湾红树林区Si含量较高,年平均值高达52.26μmol·dm-3,明显高于20世纪80年代河口区的30.83μmol·dm-3;在季节上主要依赖于径流的变化而呈夏高、冬低,春、秋季适中的特征,区域分布亦具有随S下降而增加,随硅藻占浮游植物比例上升而下降的良好规律,依次排列为廉州湾>钦州湾>珍珠湾>铁山港红树林区。相关分析显示,影响研究海区Si含量变化的主要因素是陆源径流与海水的物理混合过程,其次是生物作用,有机体分解的化学过程影响相对较小。Si与N、P营养盐的关系极为密切,其中Si与N的同源性极好,4个季节均达到了非常显著(p值<0.01)的正相关水平;而Si与P含量之间却出现明显分区现象,海湾特征尤为突出。     

A Modified Groundwater Module in SWAT for Improved Streamflow Simulation in a Large,Arid Endorheic River Watershed in Northwest China

Interactions between surface water and groundwater are dynamic and complex in large endorheic river watersheds in Northwest China due to the influence of both irrigation practices and the local terrain. These interactions interchange numerous times throughout the middle reaches, making streamflow simulation a challenge in endorheic river watersheds. In this study, we modified the linear-reservoir groundwater module in SWAT (Soil and Water Assessment Tools, a widely used hydrological model) with a new nonlinear relationship to better represent groundwater processes; we then applied the original SWAT and modified SWAT to the Heihe River Watershed, the second largest endorheic river watershed in Northwest China, to simulate streamflow. After calibrating both the original SWAT model and the modified SWAT model, we analyzed model performance during two periods: an irrigation period and a non-irrigation period. Our results show that the modified SWAT model with the nonlinear groundwater module performed significantly better during both the irrigation and non-irrigation periods. Moreover, after comparing different runoff components simulated by the two models, the results show that, after the implementation of the new nonlinear groundwater module in SWAT, proportions of runoff components changed-and the groundwater flow had significantly increased, dominating the discharge season. Therefore, SWAT coupled with the non-linear groundwater module represents the complex hydrological process in the study area more realistically. Moreover, the results for various runoff components simulated by the modified SWAT models can be used to describe the hydrological characteristics of lowland areas. This indicates that the modified SWAT model is applicable to simulate complex hydrological process of arid endorheic rivers.     

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IMPACT OF FUTURE SEA LEVEL RISE ON FLOOD AND WATER LOGGING DISASTERS IN LIXIAHE REGION

ＩＭＰＡＣＴＯＦＦＵＴＵＲＥＳＥＡＬＥＶＥＬＲＩＳＥＯＮＦＬＯＯＤＡＮＤＷＡＴＥＲＬＯＧＧＩＮＧＤＩＳＡＳＴＥＲＳＩＮＬＩＸＩＡＨＥＲＥＧＩＯＮ许朋柱ＩＭＰＡＣＴＯＦＦＵＴＵＲＥＳＥＡＬＥＶＥＬＲＩＳＥＯＮＦＬＯＯＤＡＮＤＷＡＴＥＲＬＯＧＧＩＮＧＤＩ...     

Impact of future sea level rise on flood and water logging disasters in lixiahe region

Lixiahe region is one of the susceptible area to flood and waterlogging disasters in China due to its low topographic relief and having difficulty in draining floodwater away. The condition will be more serious if sea level rises in the future. The estimated results by some scientists indicate that the sea level could rise probably 20–100 cm by 2050. However, what the effect will future sea level rise exerts on flood drainage and on flood or waterlogging disasters? A hydrological system model has been developed to study the problem in the lower reaches of the Sheyang River basin. Predicted results from the model show that, if sea level rises, drainage capacity of each drainage river will decrease obviously, and the water level will also rise. From the change of drainage capacity of drainage rivers the trends of flood and waterlogging disasters are analyzed in the paper if the severe flood that happened in the past meets with future sea level rise. Some countermeasures for disaster reduction and prevention against sea-level rise are put forward.     

TRMM及GPM降水数据在高寒内陆河流域的准确性评估

降水数据的准确性和时空分辨率成为水文过程模拟的关键.卫星遥感降水资料的日益丰富为资料缺乏区的水文模拟带来了新的突破.本研究拟在资料缺乏、下垫面复杂,观测难、建模难的柴达木盆地高寒内陆河流域—巴音河中上游,基于近5年的TMPA 3B42、GPM IMERG V5及GPM IMERG V6逐日降水数据和气象站点观测数据建立...     

Tree-ring reconstruction of streamflow for Palgong Mountain forested watershed in southeastern South Korea

Tree-ring chronologies from pine, oak and black locust tree species were used to reconstruct annual streamflow and examine hydrological drought years for Palgong Mountain forested watershed in southeastern South Korea for the period from 1954-2015. The backward elimination multiple regression analysis provided the statistically significant predictor chronologies of streamflow. The final calibration and verification test models accounted for 84.8% and 81.6%, respectively, of the variability in streamflow observed in the gage data. Further verification of the validity of the reconstructed model was undertaken with the Pearson Correlation Coefficient, the Reduction of Error Test, and the Durbin-Watson Statistics and indicated fidelity of the model for reconstructing the annual streamflow. Analyses of the reconstructed annual streamflow indicate that the most persistent years of high flows above the median annual discharge occurred from 1986-2008. This period included 7 single or multiple years of highest flow above the 90th percentile discharge and multiple years of high flows with a time interval of 2-6 years, although with intervening multiple years of low flows below the 10th and 50th percentile. In comparison, the most persistent years of low flows below the median annual discharge occurred from 1954-1985 and 2009-2015. This period included 8 single or multiple years of lowest flow below the 10th percentile discharge and multiple years of low flows with a time interval of 2-9 years, although also with intervening multiple years of high flows above the 50th percentile. No single years of extreme hydrological droughts below the 10th percentile were identified from 1986-2015 whereas a greater proportion of high flows above the 90th percentile occurred during this period. The persistent single or multiple years of lowest flows between 1954 and 1985 were the recent most critical hydrological drought years identified in the Palgong Mountain forested watershed providing supportive evidence of the severity of past hydrological droughts during that period, applicable to the southeastern South Korea where the study watershed is located. This interpretation agrees with the hydrological drought event years identified from 1951 to the early 1980s in a related national study that used precipitation proxy data to reconstruct past occurrences of droughts in Korea.     

Snow cover variation and streamflow simulation in a snow-fed river basin of the Northwest Himalaya

Snowmelt is an important component of any snow-fed river system.The Jhelum River is one such transnational mountain river flowing through India and Pakistan.The basin is minimally glacierized and its discharge is largely governed by seasonal snow cover and snowmelt.Therefore,accurate estimation of seasonal snow cover dynamics and snowmeltinduced runoff is important for sustainable water resource management in the region.The present study looks into spatio-temporal variations of snow cover for past decade and stream flow simulation in the Jhelum River basin.Snow cover extent(SCE) was estimated using MODIS(Moderate Resolution Imaging Spectrometer) sensor imageries.Normalized Difference Snow Index(NDSI) algorithm was used to generate multi-temporal time series snow cover maps.The results indicate large variation in snow cover distribution pattern and decreasing trend in different sub-basins of the Jhelum River.The relationship between SCE-temperature,SCE-discharge and discharge-precipitation was analyzed for different seasons and shows strong correlation.For streamflow simulation of the entire Jhelum basin Snow melt Runoff Model(SRM) used.A good correlation was observed between simulated stream flow and in-situ discharge.The monthly discharge contribution from different sub-basins to the total discharge of the Jhelum River was estimated using a modified version of runoff model based on temperature-index approach developed for small watersheds.Stream power - an indicator of the erosive capability of streams was also calculated for different sub-basins.     

北极熊栖息地稳定性的遥感评估方法

北极熊是北极最重要的哺乳动物之一,近年来数量却在减少。海冰作为北极熊狩猎、活动和繁殖的平台,是其栖息地的重要组成部分。因此其种群栖息地变化主要依赖于海冰变化。本文基于美国雪冰中心的海冰密集度和NOAA提供的ETOPO1基岩数据,分析了北极海冰密集度、开阔水域面积、海冰消退时间、海冰出现时间、开阔水域季节长度的年际变化,进而评价北极熊栖息地的稳定性。结果表明,海冰密集度呈现降低的趋势,开阔水域面积增大,多年冰数量减少,大多变为一年冰。海冰消退时间提前,海冰出现时间延后,开阔水域季节长度大幅增加,与1992年相比增加了72 d。19个栖息地中,巴伦支海是开阔水域面积和季节长度变化贡献最大的海域,增加速度分别为9.71×10³ km²/a和71.69 d/10a。以开阔水域季节长度变化率为依据,将北极熊栖息地划分为稳定、次稳定和不稳定3个等级。总共有3个稳定栖息地,包括分布在相对其他栖息地而言纬度较低的楚科奇海、西哈得孙湾和南哈得孙湾。13个次稳定栖息地,包括拉普捷夫海、喀拉海、东格陵兰、巴芬湾、戴维斯海峡、福克斯湾、布西亚湾、麦克林托克海峡、梅尔维尔子爵海峡、挪威湾、北波弗特、南波弗特和兰开斯特海峡。3个不稳定栖息地,均位于70°N以北,包括北极盆地、巴伦支海和凯恩盆地。稳定区主要位于低纬度,不稳定区全部位于高纬度。该分级结果表明高纬度地区虽然海冰覆盖多,但是年际变化十分显著,不稳定的3个区域内北极熊对海冰变化适应时间更少,年际迁移变化大,对北极熊的生存发展更为不利。     

Cumulative impact of dam constructions on streamflow and sediment regime in lower reaches of the Jinsha River,China

The cumulative effect of cascade hydropower stations on river ecological environment has been widely concerned because of the significant streamflow hydrology change induced by dam constructions. The characteristics of the change in the lower reaches of the Jinsha River, China are analyzed based on long-term(1952–2015) hydrological and sedimentological data. The averaging coefficient, reservoir regulation coefficient(RRC), incoming sediment coefficient(ISC), and sediment transport modulus(STM), which reflect the variation of streamflow and sediment regimes, are defined and calculated. The results show that the construction and regulation of reservoirs reduces flow in flood season, increases flow in dry season, significantly altering the monthly discharge regimes. These alterations also led directly to changes in the timing of extreme flows at Pingshan Station. The monthly flow records at the basin outlet are reconstructed using stepwise regression, to reduce reservoir impacts. Comparisons of observed and reconstructed monthly flows demonstrate that the previous studies overestimated the cumulative effects of cascade reservoirs on flow processes. Furthermore, this study clearly illustrates that the reduction in sediment trapping and sediment transportation capacity together lead to the sharp reduction in annual sediment yield at the Pingshan Station. The earlier constructed reservoirs have more obvious effects on the ISC and STM than the more recent reservoirs and the effect of sediment trapping is related to reservoir location, on the main stream versus tributaries.     

Identification of Suitable Hydrologic Response Unit Thresholds for Soil and Water Assessment Tool Streamflow Modelling

Use of a non-zero hydrologic response unit(HRU) threshold is an effective way of reducing unmanageable HRU numbers and simplifying computational cost in the Soil and Water Assessment Tool(SWAT) hydrologic modelling. However, being less representative of watershed heterogeneity and increasing the level of model output uncertainty are inevitable when minor HRU combinations are disproportionately eliminated. This study examined 20 scenarios by running the model with various HRU threshold settings to understand the mechanism of HRU threshold effects on watershed representation as well as streamflow predictions and identify the appropriate HRU thresholds. Findings show that HRU numbers decrease sharply with increasing HRU thresholds. Among different HRU threshold scenarios, the composition of land-use, soil, and slope all contribute to notable variations which are directly related to the model input parameters and consequently affect the streamflow predictions. Results indicate that saturated hydraulic conductivity, average slope of the HRU, and curve number are the three key factors affecting stream discharge when changing the HRU thresholds. It is also found that HRU thresholds have little effect on monthly model performance, while evaluation statistics for daily discharges are more sensitive than monthly results. For daily streamflow predictions, thresholds of 5%/5%/5%(land-use/soil/slope) are the optimum HRU threshold level for the watershed to allow full consideration of model accuracy and efficiency in the present work. Besides, the results provide strategies for selecting appropriate HRU thresholds based on the modelling goal.