Spatiotemporal features of soil and water loss in Three Gorges Reservoir Area of Chongqing

Soil and water loss has been the most serious eco-environmental problem in the Three Gorges Reservoir Area of Chongqing.In this paper the authors studied the spatiotemporal features of soil and water loss from 1999 to 2004 based on RS and GIS techniques.The results showed that:(1) The soil and water loss area decreased from 1999 to 2004.(2) Soil and water loss mainly exists in purple soil,yellow soil,limestone soil,paddy soil and yellow brown soil distributed areas.(3) The dry slope land and sparse woodland that are intensively influenced by human activities experienced most serious soil and water loss.(4) Soil and water loss in the study area indicated an obvious vertical differentiation characteristic.(5) There is a significant correlation between soil and water loss and slope.(6) There is no obvious correlation between soil and water loss and aspect.(7) Soil and water loss mainly exists in the values of R between 300 and 340 distribution area.The very-high soil and water loss has obvious correlation with R.

Mercury pollution in the Chongqing part of the Three Gorges Reservoir area and its remediation and prevention

Mercury pollution in the Three Gorges Reservoir area of P.R.China merits special attention.We investigated into the current situation in the Chongqing part of the Reservoir area,identified the pollution sources and proposed some suggestions for the remediation and prevention of mercury pollution in this area.Atmospheric mercury in Chongqing was mainly from coal burning and releases of mercury-containing products such as various types of lights and fever thermometers.Urban drainage in Chongqing and Changshou,and runoffs from the high mercury background area in the lower reaches of the Wujiang River contributed most of the mercury in the water of the Yangtze River.A majority of the blame should be laid on mercury and gold mining in the Wujiang valley.We suggested foresting sloping lands to relieve soil erosion and prevent mercury-bearing soil from running into rivers,educational activities to discourage use of mercury-containing products and improved infrastructure to collect mercury-containing wastes for reducing mercury releases,more facilities for treating wastewater and solid waste to accommodate increased requirements of discharge,and growing selected perennial plants in mercury-contaminated land to absorb the mercury in soil.We also suggested concerted operation of a dedicated water-quality monitoring system,reinforced legislation and an effective administrative mechanism to ensure lasting efforts are invested in curbing mercury releases and restoring mercury contaminated land and water in the Reservoir area.

Relationship between the temporal-spatial distribution of archaeological sites and natural environment from the Paleolithic Age to the Tang and Song Dynasties in the Three Gorges Reservoir of Chongqing area

The temporal-spatial distribution features including time distribution,horizontal and vertical spatial distribution of archaeological sites from the Paleolithic Age to the Tang and Song Dynasties in the Three Gorges Reservoir of Chongqing area are analyzed based on GIS spatial analysis.The successive pollen record of deposited peat stratum since the Paleolithic Age in the Dajiuhu Basin of Shennongjia is used in combination with the research of the historical environmental evolution to reconstruct the Paleoenvironment in the Three Gorges Reservoir of Chongqing area.Through the comparison of the temporal-spatial distribution of the archaeological sites and the natural environment,the relation between the distribution of the archaeological sites and the natural environment evolution and disaster changes from the Neolithic Age to the Tang and Song Dynasties has been discussed.Study shows that 677 archaeological sites from the Paleolithic Age to the Tang and Song Dynasties in the Three Gorges Reservoir of Chongqing area increase gradually from west to east and from high land to low land.Most of the sites are distributed along the river and aggregated at the confluence.Obviously,the altitudes of archaeological sites in the Paleolithic Age and the Neolithic Age are much higher than those of historical sites.The analysis suggests:(1)the human beings of every times would like to choose the first or the second river terrace as living sites which are nearer to the water source and are easier to with- stand flood.The pre-historical sites of earlier ages are often located at the higher altitude place because of the tectonic uplift and downcutting of rivers since Holocene.(2)Due to the rugged terrain in Chongqing area,most of the sites are located along the river sides,for example,the wide river valley and terrace,which could provide wider living space caused by the lateral erosion and deposition of the river course.(3)The early residents mainly relied on fishing,hunting and agriculture,and the rugged terrain of the mountainous area restricted the development of farming.However,in the confluence region,the fertilized plain provided an ideal location for farming and fishing.(4)The temporal-spatial distribution of archeological sites in this area is significantly affected by the climate condition.

Evaluation on the human settlements environment suitability in the Three Gorges Reservoir Area of Chongqing based on RS and GIS

To explore geographical differences in quantitative characteristics and spatial pattern of human settlements environmental suitability （HSES） in the Three Gorges Reservoir Area （TGRA）, terrain, climate, hydrology, vegetation and other natural factors were selected to build the livable environmental evaluation, and the quantitative analysis was conducted through Remote Sensing（RS） and Geographic Informational System （GIS） to reveal geo- graphical characteristics and spatial patterns of HSES. The results are obtained as follows： （1） inhabitants of the TGRA of Chongqing are concentrated in the area with moderate h.igh HSES, which is 78% of the total population distributed in 48% of the study area; （2） the HSES is closely related to the terrain, and it forms an arc-banded spatial succession pattern： relatively low in the northeast and the southeast while comparatively high in the west and the south; （3） large numbers of people are distributed in the area with low suitability （with higher population density than the average of the western China）, but economic development level in these areas is quite low. Moreover, these areas are ecological sensitive and fragile, many kinds of eco-environmental problems have been caused by human activities. Therefore, population migration and layout are reasonable options for the development of these areas.

An environmental flow assessment method based on the relationships between flow and ecological response: A case study of the Three Gorges Reservoir and its downstream reach

The current environmental flow assessment of Chinese rivers is thought to have three shortcomings: The first is that environmental flow requirements of reservoirs in dammed rivers are usually not explicitly considered; the second is that enough attentions have not been paid to the inherent links between flow regime and ecological processes; the third is that most studies focus on the variable range of merely one hydrological element such as discharge needed by riverine ecosystems. Here, first proposed is a holistic method for environmental flow assessment, the flow-ecological response relationship method that is suitable for large rivers with relatively abundant ecological data. Based on the conceptual models and quantitative relationships between flow and ecological response, this method comprehensively considers the ecological conservation requirements of both reservoir and its downstream reach. Then, it is applied to assessing the environmental flows of the Three Gorges Reservoir and its downstream reach by the following steps: 1) Construction of conceptual models of flow-ecological response; 2) identification of ecological targets of environmental flows and their key periods; 3) development of the quantitative relationships between hydrological indicators and ecological indictors; 4) preliminary assessment of environmental flow according to the tradeoff between ecological targets and water demands of human. The environmental flow hydrographs obtained have explicit ecological conservation targets, time schedule of achieving each target, and characteristics of multiple hydrological elements such as flow, water level, frequency, timing, duration and rate of change. The case study has tested the reasonability and feasibility of this method, and the results of this study are expected to provide technical support and decision reference for improving the operation of the Three Gorges-Gezhouba cascade reservoirs.

重庆三峡库区城乡融合发展与共同富裕面临的主要问题及对策

城乡融合是城乡协调发展的重要阶段,共同富裕是中国特色社会主义建设的本质要求。阐述了重庆三峡库区城乡融合发展与共同富裕面临的主要问题,从规划引领、产业突破、人口流动、激活要素、人—地—业融合、创新共同富裕手段、加大投入、科技支撑、示范先行及长效机制等九个方面提出了促进重庆三峡库区城乡融合高质量发展与衔接实现共同富裕的路径措施。

基于不同评价单元的三峡库区滑坡易发性对比——以重庆市云阳县为例

为探究不同评价单元对区域滑坡易发性评估的影响,基于网格单元与斜坡单元对三峡库区典型县域重庆市云阳县开展了滑坡易发性研究。首先选取高程、坡度、曲率等22个评价因子,根据研究区988个历史滑坡数据,通过30 m×30 m的栅格数据提取斜坡单元,并基于网格单元及斜坡单元分别建立22个滑坡影响因子地理空间数据库;然后利用随机森林与贝叶斯优化算法来构建滑坡易发性模型,对研究区滑坡进行易发性评估;最后结合ROC(受试者工作特征)曲线与混淆矩阵结果检验评价单元的易发性模型预测精度。结果表明:易发性评估的结果可划分为低、较低、中、较高、高5个等级;基于网格单元的滑坡易发性模型中,高程、与道路距离、坡度这3个因子对滑坡发生的贡献率大,基于斜坡单元的模型中,I_(NDV)(归一化植被指数)、剖面曲率、平面曲率这3个因子对滑坡发生的贡献率大,并且2个模型的滑坡密度均随着滑坡易发性等级的升高而变大;与网格单元相比,斜坡单元能更好地解释地形间的联系,以斜坡单元(AUC=0.744)为最小评价单元的滑坡易发性模型比网格单元(AUC=0.714)精度更高。

重庆三峡库区塔罗科血橙不同树形的冠层特性、产量和品质分析

以11年生枳橙砧塔罗科血橙为试验对象,设计圆头形、主干形、开心形等3种树形处理,研究不同树形对血橙冠层特性、快速叶绿素荧光、果实产量及品质等的影响,提出重庆三峡库区塔罗科血橙最适宜的树形,为血橙优质丰产树形培养和树体改造提供技术支撑与理论依据.结果表明,3种树形的冠层特性存在明显差异,其中冠层透光性从强到弱依次为开心形、主干形、圆头形;主干形和开心形的PSII原初最大光能转换效率(Fv/Fm)、春梢叶片单位面积吸收的光能(ABS/CSo)明显提升,反应中心的热消耗(DIo/RC)和秋梢叶片单位面积热耗散能量(DIo/CSo)显著降低.主干形和开心形均能有效提升春、秋梢叶片的光合结构性能(PI abs,PI total),以主干形处理相对最佳.2022-2023年度产量、单果质量、固酸比和维生素C含量从高到低均依次为主干形、开心形、圆头形,可溶性固形物和花色苷含量从高到低依次为开心形、主干形、圆头形.因此,重庆三峡库区塔罗科血橙宜选择主干形树形进行培养,以获得最佳产量和品质.

冲刷及整治工程叠加作用下武汉河段滩槽调整特征与成因

大型水库的修建引起了坝下游的滩槽调整,进而对河势、航运、防洪及生态等产生显著影响。为探究滩槽调整的驱动机制,采用1952—2022年水沙和1959—2021年地形观测资料,以长江武汉河段为例,分析了床沙组成、来水来沙及整治工程等因素的影响。研究表明:①武汉河段枯水河槽冲刷量占全河槽冲刷量的90.4%,断面趋向窄深化,河相系数减小。不同江心洲及汊道冲淤出现差异性调整,2001—2021年,铁板洲和白沙洲洲体面积分别减少了63.1%和61.5%,潜洲和天兴洲洲体面积分别增大了212.3%和14.5%;2013年后,铁板洲左右汊均冲,天兴洲汊道左淤右冲。②来沙量锐减,河床以0.125 mm≤d<0.25 mm的细沙居多,抗冲性较弱,是冲刷加剧的先决条件;三峡水库的削峰补枯作用加剧了枯水倾向汊河的冲刷幅度;整治工程改变了滩槽冲淤的横向分布,是江心洲差异性调整的主导因素,也是天兴洲保持左淤右冲的重要原因。③三峡水库蓄水前,洲滩之间演变联动性强;三峡水库蓄水后,来沙减少和中水期时间延长导致洲滩冲刷萎缩,洲滩之间演变联动性变弱;整治工程实施后,工程保持了心滩稳定且其缓流滞沙效应提高了抗冲性,心滩淤长的同时限制了边滩发育,叠加来沙进一步减少,边滩之间、心滩之间演变联动性进一步变弱,边滩与心滩之间演变联动性再次增强。

清江梯级水库防洪库容分配方案研究

针对清江梯级水库10亿m 3防洪库容分配问题,在探明清江梯级水库防洪调度控制条件和调度方式的基础上,设置了7种防洪库容分配可行方案,分析了不同分配方案下清江梯级水库配合三峡水库对荆江河段的防洪效果和基于长系列径流资料的清江梯级电站发电效益。研究结果表明:相比于原均匀分配方案,在确保上下游防洪安全的前提下,建议多预留一定防洪库容至下游隔河岩水库,推荐水布垭、隔河岩水库库容按照“水4隔6”“水3隔7”方案进行防洪库容分配,以提升防洪、发电两方面的效益。研究成果可为清江梯级水库防洪库容科学运用提供决策参考。

三峡水库对城陵矶防洪补偿控制水位研究Ⅱ——风险分析与运用方案

乌东德、白鹤滩水库投运后,长江上游水库群联合防洪调度为进一步提高三峡水库对城陵矶防洪补偿控制水位创造了有利条件。为提高三峡水库对城陵矶防洪补偿控制水位,针对金沙江下游梯级防洪库容投入运用条件,基于三峡坝址不同典型年的不同频率设计洪水,开展了荆江防洪和库区回水风险分析,提出了金沙江下游梯级配合三峡水库的等比例分级拦蓄方式,在确保荆江及库区防洪安全的前提下,提出了三峡水库对城陵矶防洪补偿控制水位优化运用方案,给出了金下梯级预留防洪库容与三峡水库对荆江防洪库容的等效关系。研究结果表明:提出的等比例分级拦蓄方式综合了拦量和削峰两种模式,有效利用了金下梯级防洪库容,调度效果最好;提出的水位优化运用方案具备较好的防洪减灾效果,丰富完善了长江上游水库群联合防洪调度方案,可进一步减少中下游超额洪量。研究成果可为长江水库群实际洪水调度提供技术支撑和决策参考。

三峡水库对城陵矶防洪补偿控制水位研究Ⅰ——需求分析与优化条件

城陵矶地区是长江中下游洪灾最频发的区域之一,是长江水库群防洪的重点保护对象。金沙江下游乌东德、白鹤滩、溪洛渡、向家坝4座梯级水库与三峡水库组成的巨型水库群防洪能力巨大,显著改变了流域防洪调度格局。在概括分析城陵矶地区防洪需求,回顾三峡水库对城陵矶地区防洪补偿控制水位不同阶段成果的基础上,剖析了优化防洪补偿控制水位的研究要点,研究了金沙江下游梯级防洪库容投入情况,进而明确了提高防洪补偿控制水位的有利条件。研究结果表明:在三峡水库水位达到城陵矶防洪补偿控制水位158.00 m后,金沙江下游梯级水库在预留40.93亿m^(3)防洪库容的基础上,尚有30亿~60亿m^(3)富余防洪库容可配合运用,为进一步提高三峡水库对城陵矶防洪补偿控制水位创造了良好条件。

金沙江下游梯级联合调度对川渝河段防洪效果评价

金沙江下游四级梯级水库联合调度为长江川渝河段提供了防洪安全保障,对其防洪调度效果进行评价,可以科学衡量与评估川渝河段防洪调度效果,促进流域洪水资源化利用。基于金下四级联合防洪调度方案,建立防洪、发电、生态和航运4个准则下的评价指标体系,采用改进的层次分析法和熵权法,构建川渝河段梯级水库防洪调度效果评价模型,综合考虑防洪和兴利效益,评估不同来水频率和不同起调水位的梯级水库防洪调度效果;对比溪-向两库联合调度与金下四级联合调度效果,分析乌东德、白鹤滩水库建成投产对于川渝河段防洪调度及洪水资源化利用的综合效果。结果表明:①随着乌-白两库起调水位升高,金下四级防洪调度效果系数呈现先升高后降低的趋势。②对于20,30,50 a一遇和100 a一遇洪水,乌东德和白鹤滩水库分别从(965 m和795 m)、(975 m和790 m)、(955 m和790 m)、(952 m和795 m)起调时,金下四级防洪调度效果系数最大,梯级水库联合防洪调度方案最优。③乌东德、白鹤滩水库建成投产后,川渝河段洪水资源化利用效果提升。研究成果可用于多功能、多保护对象的梯级水库防洪调度效果评价,为地区防洪调度决策提供依据。

金沙江下游-三峡梯级水库2023年联合调度实践

金沙江下游-三峡梯级水库是治理和保护长江的关键性工程。为了进一步提高梯级水库应对持续枯水的能力,保障水资源综合利用效益全面发挥,结合2023年长江上游水雨情特点,全面分析了梯级水库应对持续枯水所实施的联合补水、汛期水位动态控制、联合蓄水等优化调度措施,总结提炼了梯级水库联合调度的成效和经验。实践结果表明:枯水期梯级水库累计向下游补水约243亿m^(3),有效保障了长江中下游供水安全以及航运、生态等综合效益;通过汛期抬水位、蓄水期精细化预报调度,有效提升了水资源利用效率,保障了梯级水库实现蓄满目标。提出的调度措施和经验可为今后流域控制性水库群联合调度方式优化提供重要参考。

三峡水库秋汛期水沙特点及秋汛洪水对库区冲淤的影响

长江上游秋汛洪水是三峡水库重要水沙事件,对三峡库区冲淤特性有直接影响。基于1954-2022年实测资料分析表明,近70年来长江上游秋汛期来水量变化不大,来沙量均值在2013年前后减幅达到87%。2013年以后,三峡库区秋汛洪水的来沙高度集中于嘉陵江流域,占寸滩沙量的70%以上,秋汛洪水通过影响嘉陵江的水沙条件,进而间接影响三峡水库秋汛期的入库水沙条件。与汛期洪水相比,秋汛洪水的泥沙90%以上在库区淤积,且库尾淤积更加突出。实测资料分析结果表明,秋汛洪水期间适时加大水库下泄流量,可显著增大排沙量,减轻库区淤积。研究成果对加深三峡水库淤积特性认识、优化三峡水库秋汛洪水调度具有重要意义。

三峡库区(重庆段)乡村地名文化景观的空间分布特征及成因

地名体现鲜明的地方特色,承载丰富的文化内涵。开展乡村地名研究对多民族融合地区的乡土文化传承具有重要的现实意义。目前多民族融合的水系流域乡村地名空间分布特征及影响因素研究相对较为缺乏。本文以三峡库区(重庆段)乡村地名为研究对象,综合运用数理统计、平均最邻近距离、核密度估计法分析其空间分布特征及成因。研究表明:(1)乡村地名分布呈现空间集聚特征。自然景观类乡村地名密度呈现东北和西南高、中部低的空间格局;以地形、水文、生物等命名的乡村地名主要分布于库区东北部山区及西南部海拔较低的平坦地区;地理方位类和颜色类乡村地名主要呈点状分布。(2)人文景观类乡村地名集聚分布范围较广且空间差异明显。数字类和人工建筑类乡村地名主要分布于库区东北部山区及西南部城区;军事活动类和历史政治类乡村地名集聚于西南部海拔较低的主城区;姓氏类和园林景观类乡村地名集中分布于东北部山区;美愿与纪念类和多民族文化类乡村地名空间分布基本一致。(3)乡村地名是地形地貌、水文特征、生物资源、经济发展、历史传承、民族文化等因素共同作用的产物。该研究可为三峡库区的多民族融合发展、乡土文化传承等研究提供科学参考。

基于PLUS-InVEST模型的土地利用及生境质量预测研究--以三峡库区(重庆段)为例

本文以三峡库区(重庆段)为例,基于2000年、2010年及2020年3期的土地利用数据,运用PLUS模型从自然发展、城镇发展、耕地保护和生态保护4种情景展开模拟预测,再利用InVEST模型对三峡库区(重庆段)的生境质量进行评估。结果表明:(1)2000—2020年间,三峡库区(重庆段)主要土地利用类型为耕地、林地,各地类间转换激烈,建设用地显著扩张;(2)2030年4种预测情景下土地利用差异显著,水域不断增加,未利用地持续减少,耕地仅在耕地保护情景下增加,林地仅在耕地保护情景下减少,草地仅在生态保护情景下增加;(3)模拟出的2030年4种情景中,除生态保护情景下生境质量有所改善外,其余3种情景生境质量都在一定程度上有所恶化。

三峡水库蓄水后长江中游嘉鱼河段河床演变特性分析

嘉鱼河段是长江中游典型的碍航河段之一,需重点关注河床演变特性。根据1970~2021年实测水下地形资料,全面分析了该河段的冲淤、岸线、河床形态、洲滩深槽等变化,研究该河段自2003年三峡水库蓄水运用及2006年实施航道整治工程以来河床演变特性。结果表明:自三峡水库蓄水运用以来,该河段岸线基本稳定,河床冲刷部位主要在枯水河槽;近些年断面形态逐渐趋于稳定,岸线变化不大;河段内洲滩平面位置保持相对稳定的状态,仅在复兴洲尾部左缘、燕窝镇对面江中形成了一个新的江心洲;深槽平面位置较为稳定。研究成果可为该河段防洪调度、河道治理等提供参考。

荆江河段泥沙冲淤对三峡水库汛期排沙的响应

三峡水库汛期排沙研究大多关注库区的减淤效应,对坝下游河道的冲淤影响尚需进一步研究,对优化水库调度和河道保护利用具有重要意义。以三峡水库下游荆江河段为对象,建立了荆江长河段二维水沙数学模型,并结合实测资料分析,基于三峡水库2018年7月排沙调度,通过设置不同的排沙比(7%~100%),计算分析了荆江河段冲淤对三峡水库排沙比的响应。结果表明:虽然荆江河段全年总体冲刷,但排沙比较大时汛期仍可能淤积,上荆江河段受排沙调度影响相对较大;总体而言,2018年汛期水沙条件下,30%左右的排沙比是荆江河段洪季冲淤的临界点;排沙比提高后,汛期淤积部位大部分为边滩等缓流区,以及弯曲河段凹岸等,主槽仍冲刷,对维护滩槽高差具有积极意义。

三峡水库运行前后长江中下游干流及两湖的径流过程变化

为探索三峡水库运行前后长江中下游干流及两湖径流过程的变化及其驱动因素,利用宜昌、监利、大通、七里山、湖口共5个水文站的流量资料,分析了各站径流过程的变化特征及其成因。结论:(1)各站年径流量均减少,但除七里山站之外,其它各站减少比例均小于10%且变化不显著;(2)干流各站月径流量最大减幅发生在10月,而七里山站、湖口站分别发生在7月、4月;(3)干流各站月径流量最大增幅发生在3月,而七里山站、湖口站分别发生在1月、6月;(4)宜昌站,1-4月径流量增加是三峡水库入库径流增加和水库调度的共同作用结果,6-8月径流量减少的主因是三峡水库入库径流量减少,5、9、10月径流量变化的主因是三峡水库调度;(5)监利站,径流量的变化与宜昌站表现出高度的一致性,但冬季各月径流量的增幅均大于宜昌站;(6)大通站,4-6月径流量变化方向与湖口站一致,其它月份变化方向均与宜昌站一致。(7)七里山站,7月径流量减少的主因是洞庭湖流域来水减少,9、10月径流量减少的主要原因是荆江分流减少,但洞庭湖流域来水减少也是重要原因。(8)湖口站,4、5月径流量减少的主因是流域降水减少,9、10月径流量减少的主要原因是鄱阳湖汛期水位降低、低水位提前、蓄水量减少。