Geometry and 3D seismic characterisation of post-rift normal faults in the Pearl River Mouth Basin,northern South China Sea

Based on high-resolution 3D seismic data acquired in the Pearl(Zhujiang)River Mouth Basin of the northern South China Sea,this study investigated the geometry,spatial extension,and throw distribution of the post-rift normal fault through detailed seismic interpretation and fault modeling.A total of 289 post-rift normal faults were identified in the study area and can be classified into four types:(1)isolated normal faults above the carbonate platform;(2)isolated normal faults cutting through the carbonate platform;(3)conjugate normal faults,and(4)connecting normal faults.Throw distribution analysis on the fault planes show that the vertical throw profiles of most normal fault exhibit flat-topped profiles.Isolated normal faults above the carbonate platform exhibit roughly concentric ellipses with maximum throw zones in the central section whereas the normal faults cutting through the carbonate platform miss the lowermost section due to the chaotic seismic reflections in the interior of the carbonate platform.The vertical throws of conjugate normal faults anomalously decrease toward their intersection region on the fault plane whereas the connecting normal faults present two maximum throw zones in the central section of the fault plane.According to the symmetric elliptical distribution model of fault throw,an estimation was made indicating that normal faults cutting through the carbonate platform extended downward between-1308 s and-1780 s(two-way travel time)in depth and may not penetrate the entire Liuhua carbonate platform.Moreover,it is observed that the distribution of karst caves on the top of the carbonate platform disaccord with those of hydrocarbon reservoirs and the post-rift normal faults cutting through the carbonate platform in the study area.We propose that these karst caves formed most probably by corrosive fluids derived from magmatic activities during the Dongsha event,rather than pore waters or hydrocarbons.

Surface Flood and Underground Flood in Xiangxi River Karst Basin： Characteristics, Models, and Comparisons

Xiangxi River Basin, located in western Hubei Province in central China, is a karst ridge-trough area with an inhomogeneous and complicated distribution of water resources. This paper compares the characteristics of surface and subsurface floods in this karst basin, utilizing a one-parameter Darcian model and the traditional exponential model. The observed hydrographs and inferred water components are strikingly similar for surface and subsurface floods. The Darcian model and the exponential model are based on different views of the flood generation process, with the former fitting the entire hydrograph with a single time constant, and the latter fitting only the recession limb with multiple time constants. Due to the anisotropy and heterogeneity of karst media, a combination of physical and chemical techniques including the use of 3S（remote sensing, geographical information system, global positioning system） method is proposed for an enhanced hydrological investigation to assess and characterize karst water resources in mountainous areas.

Distribution and Source of Organochlorine Pesticides in the Laolongdong Underground River Basin,China

The concentrations of organochlorine pesticides(OCPs) in the Laolongdong underground river basin in northern China were quantitatively analyzed using the gas chromatography-mass spectrometer(GC-MS).This study was to investigate the composition,distribution and source of OCPs in the waters.The concentrations of ∑OCPs ranged from 14.45 ng· L-1 to 307.92 ng· L-1 and the mean value is 79.42 ng· L-1.β-HCH and p,p '-DDT were the most abundant components in ∑HCHs and ∑DDTs,respectively.There are some differences among the temporal and spatial distributions of ∑OCPs in underground river basin,and the distributions of ∑HCHs and ∑DDTs were same with ∑OCPs.The sources of OCPs analysis indicated that HCHs mainly came from the input of lindane and DDTs was from the mixture input of newly technical DDTs and dicofol.

塔里木盆地塔河北部“过溶蚀残留型”断溶体发育特征及其成因

为了研究塔里木盆地塔河北部强剥蚀区海西早期古岩溶洞穴发育特征,用古地貌恢复、岩溶水系统分析、测井-岩心洞穴识别和地震属性刻画等方法进行了YQ5井区的洞穴类型样式识别、缝洞结构刻画和洞穴成因演化研究。研究结果表明:YQ5井区在塔河油田Ⅱ号和Ⅲ号古岩溶台地北部的地势平缓区,总体为多期次岩溶叠加改造后的残留地貌,主要发育幅差较小的溶峰洼地、溶丘洼地和溶丘平原,南部发育NE向展布的峰丛垄脊沟谷。与塔河油田主体区及斜坡区不同,YQ5井区地下和地表水系的流向与地貌趋势不一致,岩溶水系统遭受构造作用破坏,导致补给、径流和排泄的岩溶水循环过程不完整。YQ5井区主要发育暗河型洞穴和“过溶蚀残留型”断溶体。暗河型洞穴充填较为严重,洞穴的有效储集空间受到破坏,影响油气开发效果。岩溶台地的构造抬升造成区域侵蚀基准面的下降,顺走滑断裂的垂向侵蚀作用有利于“过溶蚀残留型”断溶体的持续发育和保存,油气开发效果好。“过溶蚀残留型”断溶体的发育主控因素为走滑断裂、地层剥蚀强度和负向地貌。与塔河古岩溶台地演化过程一致,YQ5井区的岩溶演化经历深切曲流期、岩溶改造期和下渗断溶期3个阶段。暗河型洞穴被持续改造破坏,断溶体则持续建造。

Comparing the performances of WRF QPF and PERSIANN-CCS QPEs in karst flood simulation and forecasting by coupling the Karst-Liuxihe model

Long-term rainfall data are crucial for flood simulations and forecasting in karst regions.However,in karst areas,there is often a lack of suitable precipitation data available to build distributed hydrological models to forecast karst floods.Quantitative precipitation forecasts(QPFs)and estimates(QPEs)could provide rational methods to acquire the available precipitation data for karst areas.Furthermore,coupling a physically based hydrological model with QPFs and QPEs could greatly enhance the performance and extend the lead time of flood forecasting in karst areas.This study served two main purposes.One purpose was to compare the performance of the Weather Research and Forecasting(WRF)QPFs with that of the Precipitation Estimations through Remotely Sensed Information based on the Artificial Neural Network-Cloud Classification System(PERSIANN-CCS)QPEs in rainfall forecasting in karst river basins.The other purpose was to test the feasibility and effective application of karst flood simulation and forecasting by coupling the WRF and PERSIANN models with the Karst-Liuxihe model.The rainfall forecasting results showed that the precipitation distributions of the 2 weather models were very similar to the observed rainfall results.However,the precipitation amounts forecasted by WRF QPF were larger than those measured by the rain gauges,while the quantities forecasted by the PERSIANN-CCS QPEs were smaller.A postprocessing algorithm was proposed in this paper to correct the rainfall estimates produced by the two weather models.The flood simulations achieved based on the postprocessed WRF QPF and PERSIANN-CCS QPEs coupled with the Karst-Liuxihe model were much improved over previous results.In particular,coupling the postprocessed WRF QPF with the Karst-Liuxihe model could greatly extend the lead time of flood forecasting,and a maximum lead time of 96 h is adequate for flood warnings and emergency responses,which is extremely important in flood simulations and forecasting.

广西漓江流域喀斯特地区植被不同恢复阶段植物优势种叶片和土壤的生态化学计量特征

为了解广西漓江流域喀斯特地区植被不同恢复阶段植物的养分利用及养分限制状况,选取5种植被群落代表5个植被恢复阶段(分别为灌草丛阶段、灌丛阶段、灌木林阶段、次生乔木林阶段、原生乔木林阶段),对各恢复阶段植物优势种叶片和土壤的生态化学计量指标进行比较和相关性分析。结果表明:该区域植物优势种叶片和土壤的有机碳(C)、全氮(N)、全磷(P)、全钾(K)、全钙(Ca)和全镁(Mg)含量及其比值随恢复进程波动变化。灌草丛阶段叶片C和P含量最高(469.84和1.21 g·kg^(-1)),且C∶K和N∶K最大(134.64和5.67);原生乔木林阶段叶片N、K和Mg含量最高(20.52、6.76和5.69 g·kg﹣1),且K∶P最大(5.83);次生乔木林阶段叶片Ca含量最高(34.05 g·kg^(-1)),且C∶P和N∶P最大(510.98和18.25);灌木林阶段叶片C∶N最大(34.61)。灌草丛阶段土壤C和N含量最高(114.25和4.26 g·kg^(-1)),且C∶N、C∶P、C∶K、N∶P和N∶K最大(27.00、170.98、13.75、6.37和0.52);原生乔木林阶段土壤P和Ca含量最高(1.03和6.42 g·kg^(-1));灌木林阶段土壤K含量最高(8.98 g·kg^(-1)),且K∶P最大(12.96);次生乔木林阶段土壤Mg含量最高(11.53 g·kg^(-1))。相关性分析结果显示:叶片C含量与土壤C、N、P、Ca含量呈显著(P<0.05)正相关,叶片N、Mg含量与土壤K含量分别呈显著正相关和极显著(P<0.01)负相关,叶片Ca含量与土壤Ca含量呈极显著负相关。综合分析结果表明:广西漓江流域喀斯特地区植被各恢复阶段植物生长均受磷限制,灌丛阶段植物生长还受氮限制,灌草丛阶段植物生长还受钾限制,因此,建议在该区域植被恢复和管理中适当增施有机肥。

Quantitative attribution analysis of soil erosion in different geomorphological types in karst areas: Based on the geodetector method

The formation mechanism and influencing factors identification of soil erosion are the core and frontier issues of current research. However, studies on the multi-factor synthesis are still relatively lacked. In this study, the simulation of soil erosion and its quantitative attribution analysis have been conducted in different geomorphological types in a typical karst basin based on the RUSLE model and the geodetector method. The influencing factors, such as land use type, slope, rainfall, elevation, lithology and vegetation cover, have been taken into consideration. Results show that the strength of association between the six influencing factors and soil erosion was notably different in diverse geomorphological types. Land use type and slope were the dominant factors of soil erosion in the Sancha River Basin, especially for land use type whose power of determinant(q value) for soil erosion was much higher than other factors. The q value of slope declined with the increase of relief in mountainous areas, namely it was ranked as follows: middle elevation hill> small relief mountain> middle relief mountain. Multi-factors interactions were proven to significantly strengthen soil erosion, particularly for the combination of land use type with slope, which can explain 70% of soil erosion distribution. It can be found that soil erosion in the same land use type with different slopes(such as dry land with slopes of 5° and above 25°) or in the diverse land use types with the same slope(such as dry land and forest with a slope of 5°), varied much. These indicate that prohibiting steep slope cultivation and Grain for Green Project are reasonable measures to control soil erosion in karst areas. Based on statistics of soil erosion difference between diverse stratifications of each influencing factor, results of risk detector suggest that the amount of stratification combinations with significant difference accounted for 55% at least in small relief mountain and middle relief mountainous areas. Therefore, the spatial heterogeneity of soil erosion and its influencing factors in different geomorphological types should be investigated to control karst soil loss more effectively.

清江流域岩溶地下水金属元素来源解析及健康风险评价

岩溶地下水是清江流域居民生产生活的重要水资源,甚至是部分地区唯一水源,因此揭示岩溶地下水金属元素来源及人群暴露的健康风险尤为必要。文章以清江流域岩溶地下水为研究对象,分析了46组岩溶地下水样品中10种金属元素(Al、Cu、Pb、Zn、Cr、Ni、Co、Cd、Mn和As)。利用多元统计分析和正定矩阵因子分解模型(PMF)对清江流域岩溶地下水金属元素分布特征、潜在来源及贡献份额进行分析,并利用健康风险评价模型评价金属元素通过不同摄入途径对成人和儿童暴露的潜在健康风险。结果表明,定性分析与PMF定量解析结果较为一致,定性结果表明,Co、Cu、Pb、Mn和Al主要受原生地质作用影响,Ni和Cd主要受工业活动影响,As主要受农业活动影响;PMF模型的定量结果显示,研究区主要有5大影响因子,因子1为矿业活动,平均贡献率为14.4%,因子2为轻工业生产活动,平均贡献率为26.3%,因子3为农业活动,平均贡献率为19.3%,因子4为道路交通作用,平均贡献率为17.8%,因子5为原生地质作用,平均贡献率为22.2%。居民通过饮用途径暴露的总健康风险高于皮肤渗入途径,成人通过饮用途径暴露的健康风险低于儿童,但成人通过皮肤渗入途径暴露的健康风险高于儿童。Cr是引起健康风险的主要致癌金属元素,在清江流域岩溶地下水资源开发利用时应重点关注。

漓江流域喀斯特综合干扰评价及其空间特征

喀斯特地区具有特殊的地质结构,生态环境脆弱性较高,辨识和量化人为、自然多重干扰是减少人类干扰影响及制定喀斯特景观管理政策的重要依据。基于漓江流域喀斯特发育地貌特征,旨在建立包括地貌、水文、气候、生物、社会5类因素以及15个具体干扰指标的喀斯特综合干扰指数,并通过空间相关分析探究地理因子对综合干扰解释力以及因子与指标间交互作用力的特征。结果显示:(1)漓江流域中游综合干扰指数高于上下游,自然地形地貌本底以及不同类型喀斯特景观分布的地带性是分异的主要原因;(2)干扰等级为显著干扰,综合干扰指数为0.336,空间上呈现出东部与北部低、西部与南部高的分布特征,具有明显的空间异质性;(3)地理环境和社会经济因素对综合干扰具有较强解释力,采石采矿、各类灾害、生产活动等多项干扰指标以及海拔高度具有较强空间关联关系。评估了漓江流域喀斯特综合干扰并分析其空间特征,研究结果对喀斯特生态环境保护及景观资源可持续发展政策制定具有重要参考价值。

漓江峰丛片区高位岩溶洼地洪涝水文过程及有效治理

漓江峰丛片区高位岩溶洼地洪涝频发,严重影响该地区农村经济发展和自然景观资源开发与保护。本研究选择在漓江峰丛片区暗嵅高位洼地开展洪涝水循环过程研究,对洼地内主要消水口(A01、A03落水洞)进行扩宽和疏通,加大过水能力,使洪涝水害得到有效治理。结果表明:洼地积水成涝对降雨响应迅速,降雨结束后,12~24 h内洼地积水深度就能达到最大,日降雨量超过50 mm或72 h累计降雨量超过90 mm,洼地就容易积水成涝。2023年4-7月共造成了8次洪涝灾害,洪涝总时长达417.5 h(18.6 d)。鱼嵅地下河出口排泄量达到大气降雨补给量的77.77%和87.32%,为暗嵅洼地地下水总排泄口,主要通过中部A01、A02、A03、A044个消水洞排水,4个消水洞不同的消水速度造成了出口流量的4个峰值。A01消水洞水力坡度小,下部管道受方解石矿渣堵塞,消水速度较慢,现仅对A01洞口进行整治,未能有效解决洼地洪涝问题。A03、A04消水洞位于方解石脉矿的南侧,未受到方解石尾矿渣的影响,岩溶管道过水通畅。通过疏通A04消水洞,并将南侧古蚕洼地的洪流引至A03消水洞,缩短洪涝时间66.71 h(2.8 d)。因此,修建好南部排水沟系统,使南部古蚕洼地的水全部通过A03、A04消水洞快速向鱼嵅地下河出口排泄,是进一步减轻暗嵅洼地洪涝受灾程度的重要措施。

SWAT模型在岩溶地区赤水河上游流域的污染特征模拟研究

赤水河流域上游地处云贵川三省交界处,为典型的山区型岩溶性地貌。文章利用SWAT模型,系统全面地验证其对径流量、污染物(TN、NH3-N、TP)负荷的模拟性能,分析流域的污染物迁移转化过程,验证其在岩溶地区的适用性。研究结果表明:(1)SWAT模型能较好地模拟赤水河流域上游的日径流量及氮磷日负荷量,验证期径流量、TN、NH3-N、TP的模拟性能指标R2分别为0.97、0.95、0.68、0.59。(2)赤水河流域上游水文循环途径主要为降雨-下渗-地下水-河流补给,氮污染物主要通过地下水完成迁移转化,磷污染物主要受地表径流迁移驱动。该研究能为地区决策管理部门深入打好污染防治攻坚战和创建美丽河流提供基础支撑,也能为SWAT模型在其他岩溶地区的应用提供案例借鉴。

基于MODFLOW的贺江岩溶流域地下水资源评价

运用地下水模拟软件MODFLOW构建了贺江上游岩溶流域的数值模型,在地下河发育部位,采用Drain模块刻画查明的地下河岩溶管道,利用区域地下水监测数据和枯水期地下河实测流量进行模型校正。该模型能较好地反映区域地下水位动态变化及不同类型含水层间水资源的补排关系,以及地下河枯季流量。模拟结果显示,降水量偏少时段,区内地下水处于亏损状态,丰水期获得大气降水补给后逐渐盈余。模拟期内,降水对地下水的补给量为3.54×108 m3,地下水排泄量为3.41×108 m3。区内岩溶含水层的主要补给来源为大气降水,年均贡献率66.0%;其次为花岗岩裂隙水,年均贡献量14.3%;碎屑岩裂隙水对岩溶水的补给贡献量仅为7.9%。花岗岩风化裂隙含水层具有良好的调蓄能力,其在枯水期对岩溶含水层的补给贡献大于大气降水。

连江流域中小河流洪峰模数分布规律初探

以连江流域中小河流(200~3000 km^(2))实测洪水资料为基础,无资料地区由设计暴雨推求设计洪水,统筹考虑上下游、干支流和下垫面条件等因素,并结合历史洪水调查资料、已有工程规划和设计洪水成果、基础地理信息数据等,绘制连江流域中小河流不同重现期下洪峰模数等值线图,探索洪峰模数分布规律。结果表明:连江中下游的乳源南部、英德西北部、阳山南部、连南中部和南部等区域洪峰模数较大,防御洪水过程中应当加以重视。本次研究成果可为防御连江流域中小河流洪水提供参考和决策依据,对连江流域水文分析计算、水利水电工程规划与设计具有一定的参考意义。

岩溶区洪水预报模拟研究——以阳朔金宝河流域为例

岩溶地区产汇流机制复杂,洪水预报的精度难以保证。为检验分布式水文模型(HEC-HMS)对岩溶地区山洪径流过程的模拟效果,以阳朔金宝河流域为例,利用水文气象及下垫面资料构建水文模型。基于修正的Morris筛选法分析模型的参数敏感性,并选取9场洪水进行模型参数率定和验证。研究结果表明:岩溶地区水文模型的主要敏感参数为径流曲线数(Curve Number,CN)、流域滞时、退水常数、峰值比和蓄量常数;参数对目标函数的敏感性随着雨强的增大而降低,且参数对峰现时间的敏感性受雨强影响较小;金宝河模拟场次洪水的径流深误差均小于20%、峰现时间误差均小于1 h,综合合格率为88.89%,平均Nash效率系数为0.85,达到乙级预报精度,遇龙河洪水预报同样也达到了乙级精度,表明所构建的模型对金宝河及其他岩溶山区小流域径流模拟具有良好的适用性;模型计算得出不同降雨重现期下易受灾点的预警时间和预警流量,可为该地区防洪预警提供依据。

岩溶分布式水文模型构建与应用

为了使分布式水文模型能够更好地应用于岩溶地区,针对岩溶地区的水文特性,对分布式模型加以改进,建立了一套可用于岩溶地区的分布式水文模型,并讨论了改进后的模型汇流时计算时间步长与最优计算次序对汇流的影响。模型构建时考虑到了岩溶地区的地下水中裂隙水与管道水对流域汇流的影响,从而对模型加以改进,使模型在物理意义上与汇流实际情况更加接近。以广西凤山县乔音河流域为例,对改进后的模型进行了应用研究,结果表明改进后的模型可以较好地模拟岩溶地区的降雨径流过程。

乡村振兴战略下练江流域乡村生活污水处理研究——以汕头市潮南区陈店镇为例

提升饮用水水质和污水治理是改善农村生态环境的关键措施。本文结合汕头市潮南区陈店镇污水管网的建设情况,分析研究区乡村生活污水处理现状,指出生活污水处理存在的问题,并提出科学对策,为练江流域其他地区乡村生活污水治理提供参考。

练江流域汕头分段乡村生活污水处理现状调查

通过对练江流域汕头分段6个乡镇和13家污水处理厂处理工艺和运行效果进行调查,针对流域生活污水处理现状,分析了制约练江流域乡村生活污水处理关键问题的原因,并结合实际情况科学地提出治理乡村生活污水的对策及建议,为潮汕地区乡村生活污水处理提供参考借鉴。

基于MCR模型的漓江流域生态安全格局构建

以典型喀斯特地貌的漓江流域为研究单元,基于景观生态风险度和景观连通性指数提取生态源地,在最小累计阻力模型和重力模型的帮助下识别潜在生态廊道和潜在生态节点并进行赋级,最终结合流域山水林田湖草沙一体化治理工程构建区域生态安全格局.结果表明:①流域景观生态风险呈“中部南部高、东部北部低”的空间特征,较高、高风险区占流域面积43.34%.②流域内存在5个生态源地,主要为林地和自然保护区,总面积达1689.05km^(2),占流域总面积28.99%.③识别潜在生态廊道6条和潜在生态节点38个,集中分布在灵田镇附近.④参考生态阻力面和未来规划,构建漓江流域为“生态保育、修复、管控一体,廊道带建设并行”的生态网络格局;此外为保证廊道带的顺利建设,在区县尺度上对灵川、兴安两地给予更多的生态补偿资金及技术支持.研究可为漓江流域生态系统功能提升及国土空间保护修复提供科学指导.

练江流域汕头分段乡村绿植配置合理性调查研究

随着城乡一体化建设速度的加快,国家对乡村建设的扶持力度加大,乡镇绿化工程数量日益增多。通过对练江流域汕头分段沿江地区进行走访调研与村民问卷调查,了解流域沿岸部分村庄植物配置与污水处理厂绿植规划建设情况。调研发现在美丽乡村建设的推动下,不少村庄的乡村风貌发生了明显变化,但由于缺乏相应的技术指导,目前该地区乡村绿植配置还存在重建设、轻绿化、盲目选择树种、栽培与管护脱节、保护意识不到位等问题。结合现场调研结果和文献资料调研,科学地提出了练江流域汕头分段乡村绿化建设配置建议,为各地乡村绿植规划提供参考,为建设美丽练江、美丽汕头、美丽中国贡献自己的一份力量。

塔北地区奥陶系地下河溶洞充填规律与储集性能

基于野外露头、油田钻井、测井及地震资料,从溶洞充填物类型及旋回组合分析入手,开展古岩溶地下河溶洞充填序列及规律研究,同时探讨其油气地质意义。研究结果表明,塔河油田奥陶系岩溶地下河溶洞充填率达89.9%,且以沉积砂泥岩和垮塌角砾岩充填为主,发育下粗上细多个组合旋回,构成多旋回沉积充填组合和多旋回垮塌-沉积充填组合2种类型。前者分布于岩溶斜坡下游地貌平坦区,放空漏失井比例小、低产井比例高;后者分布于地貌落差较大的岩溶斜坡上游区,放空漏失井比例大,出现大量高产井。分析认为,地下河迂回曲折的空间结构及其径流强搬运能力,使大量岩溶碎屑物质充填其中,导致其超高充填率;潜水面季节性升降使其充填物具旋回性及可对比性,加之水流冲蚀和构造活动,导致溶洞多期垮塌,构成了上游区多旋回垮塌-沉积充填组合,未充填空间发育;地下相对封闭的碳酸钙过饱和环境,使其充填物钙质胶结严重,孔隙度降低;未充填空间将是油气挖潜的重点靶区。