Residents’ perspectives and responses to environmental degradation in the upper Dadu River, eastern Tibetan Plateau

Environmental degeneration in the Tibetan Plateau attracts worldwide attention, whereas case studies on how the residents understand and respond to environmental degeneration are scarce. Using a Participatory Rural Appraisal method, this paper investigates how the people in different regions in the upper Dadu River understand and respond to environmental degeneration, based on comparative field surveys in three villages, in which Danzamu village is chosen from villages in the valley region, Kerma village from mountainside region, Rico village from the mountain and plateau region. The results show that： （1） although awakened to environmental degeneration, the residents in different regions have different responses. As agricultural labors have been transferred to the secondary and tertiary industries, population pressure in Danzamu and Kerma villages is mitigated. Residents in Danzamu village actively respond to natural disasters and forest degradation, as their livelihoods never rely on forests and rangelands again. Whereas the residents in Kerma village negatively respond to natural disasters, forest and meadow degradation and the ruin of wildlife resources, as their livelihoods still rely on stockbreeding. Labors in Rico village are hard to transfer to the secondary and tertiary industries, so they have to raise more livestock to make a living. Active measures are just taken to avoid livestock loss, not to avoid forest and meadow degradation and the ruin of wildlife resources. So the most fragile region is the mountain and plateau region and mountainside region, not the valley region. （2） Livelihood strategy is the key factor affecting the residents to respond to population pressure and environmental degeneration. So the framework of sustainable livelihood strategy should be used to explain and intervene in issues of population pressure and environmental degradation in ecotones. （3） Transferring agricultural labors to the secondary and tertiary industries were favorable to improving people＇s livelihood. It is necessary to reduce the education fees to speed up the pace of labors transferring in the mountainside region. In the mountain and plateau region, preferable ways also include the development of towns, highways, education equipment and other establishments.

Livelihood Strategy Change and Land Use Change——Case of Danzam Village in Upper Dadu River Watershed,Tibetan Plateau of China

Land use change in rural China since the 1980s, induced by institution reforms, urbanization, industrialization and population increase, has received more attention. However, case studies on how institution reforms affect farmers＇ livelihood strategies and drive land use change are scarce. By means of cropland plots investigations and interviews with farmers, this study examines livelihood strategy change and land use change in Danzam Village of Jinchuan County in the upper Dadu River watershed, eastern Tibetan Plateau, China. The results show that, during the collective system period, as surplus labor forces could not be transferred to the secondary and tertiary industries, they had to choose agricultural involution as their livelihood strategy, then the farmers had to produce more grains by land reclamation, increasing multiple cropping index, improving input of labor, fertilizer, pesticide and adopting advanced agricultural techniques. During the household responsibility system period, as labors being transferred to the secondary and tertiary industries, farmers chose livelihood diversification strategy. Therefore, labor input to grain planting was greatly reduced, which drove the transformation of grain to horticulture, vegetable or wasteland and decrease of multiple cropping index. This study provides a new insight into understanding linkages among institution reforms, livelihood strategy of smallholders and land use change in rural China.

An integrated north–south paleo-Dadu-Anning River: New insights from bulk major and trace element analyses of the Xigeda Formation

The Xianshuihe-Anninghe fault extends SE–S and constitutes the southeastern margin of the Tibetan Plateau.However,the Dadu River which is associated with the fault does not flow following the path,but makes a 90ºturn within a distance of 1 km at Shimian,heading east,and joins the Yangtze River,finally flowing into the East China Sea.Adjacent to the abrupt turn,a low and wide pass near the Daqiao reservoir at Mianning separates the N–S course of the Dadu River from the headwater of the Anning River which then flows south into the Yunnan Province along the Anninghe fault.Therefore,many previous studies assumed southward flow of the paleo-Dadu River from the Shimian to the Anning River.However,evidences for the capture of the integrated N–S paleo-Dadu-Anning River,its timing,and causes are still insufficient.This study explored the paleo-drainage pattern of the Dadu and Anning Rivers based on bulk mineral and geochemical analyses of the large quantities of fluvial/lacustrine sediments along the trunk of the Dadu and Anning Rivers.Similar with sands in the modern Dadu River,the Xigeda sediments also exhibit a granitoid affinity with the bulk major mineral compositions of quartz(>50%),anorthite(about 10%),orthoclase(about 5%),muscovite(about 5%),and clinochlore(about 4%).Correspondingly,bulk major elements show high SiO_(2),with all samples>60%,and some of them>70%,low TiO_(2)(≤0.75%),P_(2)O_(5)(≤0.55%),FeO*(≤5%),and relatively high CaO(1.02%–8.51%),Na_(2)O(1.60%–2.52%),and K_(2)O(2.17%–2.71%),with a uniform REE patterns.Therefore,synthesizing all these results indicate that these lacustrine sediments have similar material sources,which are mainly derived from its course in the Songpan-Ganzi flysch block,implying that the paleo-Dadu originally flowed southward into the Anning River and provided materials to the Xigeda ancient lake.The rearrangement of the paleo-Dadu River appears to be closely related to the locally focused uplift driven by strong activities of the XianshuiheXiaojiang fault system.

Changes of wetland landscape patterns in Dadu River catchment from 1985 to 2000, China

Based on the interpretation and vector processing of remote sensing images in 1985 and 2000, the spatial changes of wetland landscape patterns in Dadu River catchment in the last two decades were studied using spatial analysis method. Supported by Apack soft-ware, the indices of wetland landscape pattern were calculated, and the information entropy （IE） was also introduced to show the changes of wetland landscape information. Results showed that wetland landscape in this region was characteristic of patch-corridor-matrix configuration and dominantly consisted of natural wetlands. Landscape patterns changed a little with low fragment and showed concentrated distribution with partial scattered distribution during the period from 1985 to 2000. The values of patch density and convergence index kept stable, and the values of diversity, evenness indices decrease, while dominance and and IE showed a slight fractal dimension indices were increased. All types of wetland landscapes had higher adjacency probabilities with grassland landscape in 1985 and 2000, and there was extremely weak hydrological link and large spatial gap among river, glacier, reservoir and pond wetlands due to low adjacency matrix values. Since their cumulative contribution exceeded 81% through the PCA analysis, the agriculture activities would be the main driving force to the landscape changes during the past 15 years.

Exploration and practice of intelligent engineering in Dadu River hydropower construction

In view of the difficulties in promoting intelligent management in the field of engineering construction,based on the concept of intelligent enterprise and the actual situation of hydropower project-construction management,this paper puts forward the basic concept,main features and general idea of intelligent engineering.Based on a review of the exploration,pilot construction and comprehensive practice of intelligent engineering in the hydropower construction of Dadu River,the practical results of the intelligent engineering of Dagangshan,Houziyan,Shaping-II and Shuangjiangkou hydropower stations are summarized.The technical system and management model of engineering an early-warning decision centre,intelligent dam project,intelligent underground project,intelligent electromechanical project,intelligent security control,intelligent service guarantee,intelligent environmental and water protection,and intelligent resource control in Shuangjiangkou hydropower station are introduced.It is proposed that intelligent engineering is a high integration of information technology,industrial technology and management technology.And it is pointed out that intelligent engineering will lead in the new development of water conservancy and the hydropower industry,and even the engineering-construction field,throughout the world.

Land cover changes based on plant successions: Deforestation, rehabilitation and degeneration of forest in the upper Dadu River watershed

To link regional land use/cover changes with environmental effects, land cover changes are required to reflect vegetation successions, whereas the land cover classification systems commonly used nowadays cannot serve this purpose. In this paper, a new land cover classification system is established in which land covers are classified by the vegetation succes-sions, taking Zamtang County, Barkam County and Jinchuan County in the upper Dadu River watershed as a study area. Using multi-temporal remote sensing images, the land cover data of 1967, 1986 and 2000 are obtained by means of integration of unsupervised classification and visual interpretation methods. The database facilitates the study of land use/cover changes, en-vironmental effects and ecological construction. Land cover changes reflect the main ecological processes in the upper Dadu River watershed. The landscape composed mainly of grasslands, wildwoods and alpine scrubs in 1967 was changed to that of grasslands, secondary forests, al-pine scrubs, fragmentary wildwoods, artificial forests, secondary scrubs in 2000, meanwhile, the landscape got more fragmentized. The total area of the forests decreased by 9.43%. Study results have shown the process of restoration of logged areas in forest centers. From 1967 to 2000, only 6.86 percents of logged areas were converted to shrubs, meadows or crop-lands, and the rest were converted into artificial forests or secondary forests. So the ecological shelter functions will be restored, stage by stage. Firewood collection, charcoal production and overgrazing are the three major triggers for the extensive degradation of alpine oak forests, Sa-bina tibetica forests and meadows. The arid valley grasslands expanded too. The degradation of vegetation in the southern slopes impairs ecological shelter functions and affects livelihood of local residents, so it is essential to find effective measures for ecological restoration and recon-struction. Field investigations have found that the current measures have not concerned with how to keep the livelihood of local farmers and herders. The most important measure for ecological protection and restoration is to help the farmers and herders to raise the living standard, which means that they will never need to rely only on the colonizing of croplands, the logging of forests and the grazing of livestock to make a living.

大渡河上游阿娘寨古堰塞湖的发现及其特征

古堰塞湖的沉积特征研究是开展堰塞湖古环境、古气候研究的基础。大渡河上游小金川两岸多地出露粉砂质黏土、砂和砾石构成的堰塞湖剖面,通过沉积学分析、光释光测年以及对堵江坝体的岩性构造分析,认为小金川在距今(15.7±1.9)~(9.1±1.0)ka期间发生了一次重大的堵江—堰塞—溃决事件,且该古堰塞湖的沉积环境随时间和空间的变化发生迁移:时间上,堰塞湖经历了形成、充填和溃决3个阶段;空间上,从下游至上游划分出深—半深湖、浅湖、滨湖和河湖交汇区4个沉积区,该古堰塞湖是由阿娘寨古滑坡堵江形成,据此命名为阿娘寨古堰塞湖。该古滑坡主要受控于岩性和构造作用。本次研究进一步丰富了青藏高原东南缘山区大型古堰塞湖的研究成果,其沉积特征、年代和成因特征为后续的深入研究提供了基础材料。

大渡河流域极端气温时空分布特征研究

【目的】全球气候变化下,极端气候事件发生的频率、强度等日益增强,其可对流域环境等产生重大影响。大渡河流域不仅是我国长江上游生态屏障和川滇生态屏障的重要组成部分,也是长江流域干旱半干旱河谷的重点分布区域,流域内保护鱼类分布较多,对气候变化敏感。为此,探究大渡河流域极端气温指数时空分布特征。【方法】以大渡河流域为研究对象,基于该流域1964—2018年共55年的逐日气象数据,采用线性拟合、Sen′s斜率估计以及Mann-Kendall非参数检验等方法对大渡河流域的极端气温指数进行了分析;利用协同克里金法进行空间插值,分析了极端气温指数的空间分布规律。【结果】大渡河流域极端气温事件存在明显的年际变化,16个极端气温指数中有11个指数呈上升趋势,5个指数呈下降趋势。除气温极值外,上升速率最快的是SU25,上升速率为2.0 d/10 a;下降速率最快的是FD0,下降速率为1.6 d/10 a。除CSDI和WSDI在流域内变化趋势为0外,其余各极端气温指数变化速率在空间分布上有明显的差异性,海拔高度为导致大渡河流域极端气温指数空间分布特征的主要影响因子。【结论】在时间尺度上,大渡河流域极端气温指数中表征暖的指数均呈上升趋势;表征冷的指数(除TNn和TNx外)均呈下降趋势;其他指数中GSL上升速率较快。这表明该流域在近55年内整体呈变暖趋势,冬季变短夏季变长,且适宜植被生长的温度持续时间增长。突变检验表明各极端气温指数突变除TN10外均为显著突变,且突变年份集中在2000年前后。在空间尺度上,冷指数中ID0、FD0上游上升速率高于中下游,暖指数中TR20、SU25中下游上升速率大于上游,GSL上游上升速率明显高于中下游。流域整体呈变暖趋势且中下游更容易发生极端高温事件。研究成果可为大渡河流域极端气候灾害预警和水生态保护提供科学依据。

泸定地震大渡河区域灾害调查及格林函数库应用可行性探讨

2022年9月5日,四川省甘孜州泸定县发生M_(S)6.8地震,造成了较为严重的人员伤亡.震后中国地震局地球物理研究所科考队对泸定M_(S)6.8地震中大渡河干流上的几座梯级水电站和极震区等附近区域进行了灾害调查.调查结果表明梯级电站在本次地震中受影响较小,不影响正常运转.地震发生后,我们也采用经验格林函数方法并考虑震源参数的不确定性特征,对震区的石棉擦罗地区(位置①)、大渡河流域兴康高速特大桥区域(位置②)、历史地震古滑坡—摩岗岭附近区域(位置③)等三个典型位置合理范围的地震动加速度时程进行了快速估计.初步结果表明:位置①和③建筑物存在被本次地震破坏的可能性;位置②桥梁受地震破坏的可能性较小.最后,结合本次灾害调查结果、工程自建地震监测台网、典型位置地震动快速估计的结果,本文对重点工程区域建设基于实际小震波形的格林函数数据库应用前景的可行性进行了探讨.

水电开发对大渡河上游鱼类资源的影响与保护对策

分析大渡河上游水电开发建设运行过程中鱼类种类组成的演变趋势及存在的问题,为制定适宜的保护措施、减缓工程建设运行给水生生态带来的影响提供参考数据。2019-2021年对大渡河上游干流及支流鱼类资源状况进行了调查,将数据按照双江口以上河源区、双江口至丹巴河段、丹巴至泸定河段分段,通过计算相对重要性指数和种类相似性指数进行了对比分析。结果表明,大渡河上游共调查到鱼类3目8科22属36种,其中,鲤形目鱼类27种,占总种数的75.00%,鲤科12种,占鲤形目鱼类的44.44%;土著鱼类24种,占总种数的66.67%。其中,珍稀保护及特有鱼类12种,占土著鱼类总种数的50.00%,包括2种国家级保护鱼类、3种省级保护鱼类和11种长江上游特有鱼类;外来种12种,占总种数的33.33%,主要为鲤科、鳅科和鮰科等鱼类,其中,鲤科种类居多,占50.00%。大渡河裸裂尻鱼(Schizopygopsis chengi)、齐口裂腹鱼(Schizothorax prenanti)、重口裂腹鱼(S.davidi)是大渡河上游优势种,不同河段优势种有所不同,丹巴以上河段比较近似。受水电开发等活动影响,大渡河上游土著鱼类资源呈衰减趋势,而外来种增加。为切实保护好大渡河上游鱼类资源,建议尽快开展鱼类栖息地保护区划分、重要支流的生境修复、外来种控制,并开展电站的联合生态调度研究。

大渡河干流已建水电站生态基流目标值复核分析

以大渡河干流已建水利水电工程为研究对象开展回顾性评价,为推动后续生态基流研究和水资源管理提供参考。研究采用多种水文学方法,包括Tennant法、Texas法、Q90法、多年最小月平均流量法和NGPRP法,计算大渡河干流已建梯级水电站的生态基流目标值。根据计算结果中各控制断面的最小值、最大值和平均值,建立生态基流目标值的参考区间,分别对应底线、优和良好的标准线,并对大渡河干流已建梯级水电站生态基流目标进行了回顾性评价。结果表明,大多数断面的现行生态基流目标值均在最大和最小参考值区间范围,设置基本合理。针对不同历史条件下或不同行业领域中存在的生态基流相关概念内涵和适用边界条件的不一致问题,以及拦河工程生态基流调度的实际问题,研究提出生态基流目标体系的双指标控制法,并提出了大渡河干流已建梯级水电站生态基流目标建议值,建议双江口、猴子岩、深溪沟、龚嘴、铜街子水电站的生态基流目标采用日均和瞬时双控值,分别设为121/52、160/78、327/188、366/149和366/236 m^(3)/s,而沙湾和安谷水电站均设为366 m^(3)/s。

耦合坝前水位优化的梯级水电站入库流量计算方法研究

水库出入库流量对于水电站调度运行非常重要。实际生产中的水库出入库流量一般由水位、出力、闸门开度等数据结合水库水电站特征曲线求得,但受坝前水位波动等众多因素影响,水库出入库流量的正确性及流域上下游电站间的径流逻辑一致性经常遭到破坏。为解决水位波动对径流一致性的影响,以大渡河流域下游梯级水电站为例,基于多点平均水位代替单点值的思路,以区间谬误率最小为目标,建立了梯级电站多点水位取值及水量平衡计算时间点的优选模型。并基于2019年1月至2021年12月的运行数据进行了验证分析,结果发现水位优化处理后,梯级电站的区间谬误率均有不同程度降低,其中深枕区间与龚铜区间效果最好,深枕区间下降幅度约为40%,龚铜区间下降幅度约为30%。研究成果可为其他流域的相关研究提供参考。

大型水库健康评价方法与应用——以大渡河瀑布沟水库为例

水电开发会影响河流水动力和水环境条件,干旱的地理环境、密集的水电工程等复杂的影响因素导致大渡河生态系统比较脆弱,水库生态系统的长期健康运行面临挑战。参考SL/T 793-2020《河湖健康评估技术导则》,基于大渡河瀑布沟水库特性增设针对性指标;融合现场监测和遥感反演技术,全面获取水库水生态数据;综合层次分析法和熵权法识别评价指标权重,构建了更具全面性和准确性的水库健康评价模型,对该水库的生态健康状况进行综合评估和退化风险诊断。结果表明:瀑布沟水库健康状况总体得分为84.16分,属于非常健康状态;水、盆、生物、功能得分分别为92.97,85.66,59.63分和98.14分,反映出瀑布沟水库整体生态健康但生物多样性有待提升的现状。研究结果可为大渡河瀑布沟水库的健康管理和生态综合整治提供科学支撑。

基于水文水力学水生态结合法的大渡河生态流量研究

大渡河是长江上游重要支流,水电资源丰富,流域内现存大量特有物种和珍惜物种,具有较高的生态及经济价值。生态流量是保障河道生态环境不退化、维持河道健康的重要指标,开展对大渡河生态流量的计算,对大渡河水生态环境保护和水资源合理利用具有重要意义。当前对生态流量的研究众多,本文基于大渡河中下游2008—2017年天然来水情况,分别选取水文学方法中的Tennant法、改进Tennant法,水力学法中的湿周法,以及鱼类生境适宜度法,提出了水文-水力学-水生态的结合法(下称结合法)。将结合法计算的生态流量与多年实测流量对比,确定需要进行生态补水的月份,并根据水利部印发的第四批重点河湖生态流量保障目标对大渡河生态流量进行满足程度分析。研究结果表明:结合法考虑了水文学、水力学以及不同月份鱼类繁殖的需求,满足年内不同时段河道生态需求。大渡河中下游泸定站2—4月、沙湾站2月的来流量无法满足生态需水,应进行生态补水,使河道流量满足鱼类繁殖要求。与水利部制定的大渡河生态流量保障目标相比,本文计算的生态流量在鱼类繁殖期高于保障目标,在非鱼类繁殖期低于保障目标。本文提出的结合法考虑了河道生态需水的年内差异,且计算方法简便,实用性较强,大渡河生态流量的计算能够为年内生态补水提供科学依据。

基于积雪数据的HBV模型改进及应用

大渡河流域内站点分布较少,历史观测数据不足,给该地区的融雪径流预报带来困难。基于欧洲中期天气预报中心提供的最新一代高分辨率陆面再分析数据集ERA5-Land,将积雪覆盖率和积雪平均深度引入度日因子雪量计算公式中,对HBV模型的积融雪模块进行改进,以提升融雪径流计算的可靠性。以大渡河上游为研究对象,选取1961—2018年的水文气象资料对模型进行率定和验证,并以2019年为例进行试预报研究。结果表明,通过引入ERA5-Land再分析数据,以及对积融雪模块进行改进,发挥了其在模拟积融雪上的优势,有效提升了融雪径流预报精度,对大渡河流域具有适用性。研究成果可为稀缺资料地区融雪径流模拟预报提供经验。

大渡河流域中高山区农村生活污水治理模式初步研究--以汉源县为例

根据大渡河流域中高山地区农村生活污水点多面广、污水来源分散、间隙性排放,且统一纳管进入城镇污水处理厂集中处理难度大的特点,本文以汉源县农村生活污水治理模式为例,考察了其污水处理设施处理效果,并对运维费用进行了分析。结果表明,本案例厌氧+芦苇湿地组合工艺能满足四川省地方标准《农村生活污水处理设施水污染物排放标准》(DB 51/2626-2019)一级标准要求,化学需氧量(COD_(Cr))、氨氮(NH_(3)-N)及总磷(TP)3种污染物去除率分别达到52.2%~79.6%、46.0%~79.2%、33.2%~84.9%,年运维费比有动力设施具有明显优势。本案例可为大渡河流域中高山区农村生活污水治理提供参考。

双江口水库对下游梯级水库群发电-航运联合调度影响研究

选取岷江流域为研究对象,按双江口水电站投产前后划分2种情景,构建SWAT水文模型和水库群联合调度模型,对比分析双江口水电站对下游梯级水库群发电与航运的影响。研究结果显示,在双江口水电站运行后,下游梯级电站入库流量显著提升,有效增加了水库兴利库容。目标水库群在每年枯水期平均发电量增加了50.59亿kW·h,其中双江口水库枯水期平均发电20.36亿kW·h,经济效益增幅超过16亿元;目标水库群年平均发电量提高了139.58亿kW·h,其中双江口水库年均发电108.69亿kW·h,经济效益增幅超40亿元。此外,岷江高场站的航运流量在不同保证率下也有所提升:90%保证率下提升了15.48%,95%保证率下提升了13.11%,98%保证率下提升了7.74%。研究结果为大型水库群枯水期联合调度及航运优化提供了重要的决策支持和理论指导。

大渡河上游玛柯河至脚木足河段浮游植物群落特征调查

为了解大渡河上游水域生态环境现状,该研究于2017-2018年春冬季2次对大渡河上游玛柯河至脚木足河段浮游植物进行收集分析,查明了浮游植物的动态变化和群落结构特征。结果显示,此次调查水域的浮游植物共鉴定出102种(属),隶属于6门46属。其中硅藻门占绝对优势,有76种(属),占浮游植物总物种数的74.5%。各河段春季的浮游植物平均密度和生物量比冬季都有显著的增加,分别增加了3.7和2.8倍,但总体呈现低密度和低生物量的特征。为获得该水域浮游植物本底资源现状及水生态监测提供了基础数据。

二郎山—折多山大渡河深切峡谷区地质灾害发育特征及对输变电工程的影响

以二郎山—折多山大渡河深切峡谷区输电走廊沿线为研究对象,基于遥感解译及地质灾害调查对区内地质灾害发育特征以及对输变电工程的影响进行了研究。结果表明:研究区内地质灾害主要形成控制因素有地形地貌、坡向、地质构造、工程地质岩组、年降雨量等;地质灾害主要分布于2200 m以下高程,坡度介于15°~50°,崩塌主要发育于坚硬或较坚硬岩,滑坡发育于软硬互层岩组;崩塌、滑坡主要分布于降雨量为834~965 mm的区域,泥石流主要分布于降雨量为892~1085 mm的区域;二郎山—折多山大渡河深切峡谷区输电走廊沿线现状地质灾害发育对输变电工程的杆塔及其基础的稳定性造成威胁。研究成果可为输电走廊沿线地质灾害评价与防治提供理论依据,为输变电工程规划选线、设计及施工提供技术指导。

大渡河上游某河段鱼类栖息地适宜性评价

以大渡河上游某水电站坝下13 km大渡河干流河段和坝下支流入大渡河汇合口以上4 km支流河段鱼类栖息地为研究河段,从鱼类有效栖息地面积计算、支流河底连通性模拟两方面开展栖息地适宜性评价,重点分析评价了产卵期齐口裂腹鱼和重口裂腹鱼两种目标鱼类对流速与水深的适宜性指标,得到了研究河段鱼类栖息地适宜性指数和等级:坝下干流鱼类栖息地适宜性指数为0.68,适宜性等级为适宜;支流河口以上4 km河段鱼类栖息地适宜性指数为0.58,适宜性等级为一般适宜评价。