输沙量 、侵蚀量与泥沙输移比的流域尺度关系——以赣江流域为例

输沙量、侵蚀量与泥沙输移比的流域尺度转换研究是当前流域侵蚀产沙研究领域的前沿课题,旨在通过尺度转换理论将坡面小区试验研究成果转换到流域的更大范围。以赣江流域实测输沙量和计算侵蚀量与泥沙输移比数据为基础,探讨了该流域3个变量的流域尺度关系,进而研究分析了3个变量尺度转换的可能性。3个变量与流域面积的关系散点图和相关方程都反映了这3者与流域面积不存在明显的相关关系,相悖于前人反比关系的结论。文章还阐述了流域面积的内涵及输沙量、侵蚀量和输移比的影响因素与流域面积的关系,发现3个变量的影响因素与流域面积不存在尺度效应。由此推断在赣江流域输沙量、侵蚀量和泥沙输移比实现尺度转换存在的可能性不大。这一研究结论是否成立或是否具有普遍性意义还有待于更多流域的研究成果来进一步证实。     

无定河流域的人工沉积汇及其 对泥沙输移比的影响

依据1956~1996年的资料,计算出了无定河流域历年的人工沉积汇、侵蚀量、泥沙输移比,进行了时间序列分析,并运用回归分析方法,建立了统计关系,揭示了无定河流域人工沉积汇对泥沙输移比的影响。研究表明,无定河流域侵蚀量和产沙量有明显的减小趋势;人工沉积汇先是增大,达到峰值后再减小;泥沙输移比先减小而后增大。这说明,无定河泥沙输移比的时间变化趋势,主要受人工沉积汇的控制。建立的多元回归方程表明,坝地面积增大对流域泥沙输移比减小的贡献最大;地表径流系数减小对流域泥沙输移比减小的贡献居第二位;在3个降水因子中,最大30日降水的贡献最大,汛期降水次之,最大1日降水再次之。在坡面措施和沟道措施中,沟道措施对流域泥沙输移比减小的影响要大于坡面措施。     

黄土丘陵沟壑区流域系统侵蚀与产沙关系

从长期来看流域系统的侵蚀与产沙基本可以达到平衡,泥沙输移比约等于１。但次降雨或分年度泥沙输移比有相当大的变幅,在短期内会经常存在泥沙的滞留和滞留的泥沙被重新锓蚀搬运,而出现泥沙输移比小于１和大于１的情况。这主要与降雨的空间分布和洪峰增减幅度及径流深度增减幅度密切相关。流域系统次降雨泥沙输移比及各级沟道含沙水流的挟沙能力变化可用单位面积上洪峰增减幅度变化时暴雨洪水的剪切力的转化机制来描述。     

基于GIS的小流域土壤侵蚀与产沙的简化模拟

将泥沙输移能力公式与USLE公式相结合,建立了一个简化的分布式小流域产沙模型,并将其应用于川中丘陵区小流域的土壤侵蚀与泥沙输移的空间分布模拟。得到的主要结论:1.该模型适用于川中丘陵区小流域产沙的模拟;2.魏城河流域1980—1987年8 a平均土壤侵蚀量为16.8×104t,侵蚀模数为675.8 t/(km2.a),模拟得到的输沙模数为238.6 t/(km2.a),泥沙输移比为0.35;3.魏城河流域主要以微度侵蚀为主,占到全流域总面积的68%,强度侵蚀占流域面积的1%,主要分布在坡度较陡的流域边缘地带;4.相对其他因子,降雨与坡度对该流域侵蚀产沙的影响更为突出。     

三峡水库修建前长江宜昌-武汉段泥沙输移比及其影响因子

运用泥沙收支平衡(Sediment budget)的概念确定长江中游宜昌-武汉河段的泥沙输移比,并运用数理统计方法,研究了1955～1997年间河道泥沙输移比对水沙变化的响应.从总体上看,河道泥沙输移比有较显著的增大趋势.输移比的变化可分为4个阶段:1955～1962年为快速增大;1963～1975年亦为增大,但增速减慢;1976～1979年为迅速减小;1980～1997年为较快增大.在分析了若干水沙指标对河道泥沙输移比的影响的基础上,建立了宜昌-汉口河段泥沙输移比与宜昌站的来水量和来沙量以及3口分水比和分沙比、宜昌站洪峰流量之间的多元回归方程.1980～1997年间的方程表明,宜昌站来水量越多、3口分流比越小,宜昌一汉口河段泥沙输移比越大;宜昌站来沙量越少,3口分沙比越大,泥沙输移比越大;宜昌站洪水流量越大,泥沙输移比越小.     

泥沙输移比影响因子及其关系模型 研究现状与评述

泥沙输移比是目前预测流域产沙量的一种较实用的方法,本文介绍了国内外泥沙输移比研究的主要成果。分析并总结了泥沙输移比与流域面积、降雨／径流、地质地貌及泥沙颗粒因子之间的影响关系及其关系模型。最后,结合我国泥沙输移比研究的实际情况,提出了我国今后一定时期内在泥沙输移比研究方面的发展设想。     

黄土塬区坡面及小集水区泥沙输移比变化特征

文章首先推荐了计算泥沙输移比SDR时，所需侵蚀量、输移量的量测方法：侵蚀量用坡长为20m（水平距）、宽5m直线坡，在不同降雨及土地利用下，通过小区出口断面的泥沙量；输移量为坡长大于20m的径流小区小集水区出口处的拦蓄量。然后通过黄土塬区坡面坡度为9%的30m、40m、60m径流小区9年野外实验所得45组有效数据的分析，发现单宽最小径流率qmin和最大含沙量ρmax可判别坡面泥沙侵蚀与输移的对比关系，即输移比SDR，并依据这些参数值，可将侵蚀输移状态划分为“侵蚀——输移区”，“侵蚀——堆积——输移区”和“侵蚀——输移挠动区”3个侵蚀输移状态类型区，同时通过研究给出了各区之间过度转换临界值的计算公式，即ρmax=11.96 0.117qmin和qmin=0.187ρmax-85.676。并能过对21条塬面不同面积（0.5hm^2-41.3hm^2）、坡长（30m-965m)小集水区淤积（输移量）的测量，将测量值与标准小区侵蚀量作对比，计算出各自的输移比SDR，并分别建立了SDR与坡长L、SDR与集水面积A的关系式，即SDR=2.85L^-0.306和SDR=0.735A^-0.151，为快速估算塬面小集水区泥沙输移比SDR值提供了方便。最后，分析了植被覆盖、土壤含水状况、人为活动等其它基因素对泥沙输移比SDR的影响。     

我国土壤侵蚀与地理环境的关系

本文论述我国土壤侵蚀类型与自然地带性和非地带性因素的关系,分析影响侵蚀强度时空分布和侵蚀泥沙输移的环境因素及流域条件。     

黄土丘陵沟壑区人类活动对流域系统侵蚀、输移和沉积的影响

从长期来看,在治理度达到70%条件下与治理前相比泥沙输移比减小50%左右,治理的效益是十分显著的。在治理的过程中,与治理前相比泥沙输移比变幅明显减小,但在短期内由于暴雨洪水侵蚀力大于工程设计标准而发生毁、垮坝或淤平后,仍可以将前期滞留的泥沙重新搬运而出现泥沙输移比大于1的情况。在黄土高原地区治理前后流域系统次暴雨泥沙输移比均可用径流深度比来定量计算获得,泥沙输移比变化的动力机制可用径流深度增与减时水流剪切力的变化来解释     

黄土丘陵沟壑区人类活动对流域系统[2]侵蚀、输移和沉积的影响

从长期来看 ,在治理度达到 70 %条件下与治理前相比泥沙输移比减小 50 %左右 ,治理的效益是十分显著的。在治理的过程中 ,与治理前相比泥沙输移比变幅明显减小 ,但在短期内由于暴雨洪水侵蚀力大于工程设计标准而发生毁、垮坝或淤平后 ,仍可以将前期滞留的泥沙重新搬运而出现泥沙输移比大于 1的情况。在黄土高原地区治理前后流域系统次暴雨泥沙输移比均可用径流深度比来定量计算获得 ,泥沙输移比变化的动力机制可用径流深度增与减时水流剪切力的变化来解释     

近年我国区域水文研究的若干进展

我国区域水文学的研究是在解放后其正发展起来的。尽管迄今人们对区域水文学仍有不同的认识,例如区域水文学是否可以与水文地理学等同,或是区域水文学是否应隶属于区域地理学等等,但是作为水文学的分支学科是无疑的。区域水文学从整体的观点来研究区域水文情势。区城可以是功能区,如城市、出口加工中心区等,或为自然景观区,如干旱区、喀斯特区等,也可以是行政区。目前,许多水文水利工作者已在致力于区域水文学的研究。     

Alluvial and colluvial sediment storage in the Geul River catchment (The Netherlands) — Combining field and modelling data to construct a Late Holocene sediment budget

We used a combined approach of a two-dimensional erosion and hillslope sediment delivery model (WATEM/SEDEM) and detailed geomorphological reconstructions to quantify the different components in a sediment budget for the Geul River catchment (southern Netherlands) since the High Middle Ages. Hillslope erosion and colluvium deposition were calculated using the model, while floodplain storage was estimated using field data. Our results show that more than 80% of the total sediment production in the catchment has been stored as colluvium (mostly generated by hillslope erosion), while almost 13% is stored in the floodplain since the High Middle Ages (this situation resembles a capacity-limited system). Model results for the period prior to the High Middle Ages (with a nearly completely forested catchment) show that far less sediment was generated and that most of the sediments were directly transported to the main river valleys or out of the catchment (a supply-limited system). Geomorphological analysis of a large alluvial fan shows the sensitivity of the study area to changes in the percentage of arable land.Our combined field data-modeling study presents an elegant method to calculate a catchment sediment budget for a longer period and is able to identify and quantify the most important sediment storage elements. Furthermore, it provides a valuable tool to calculate a sediment budget while only limited dated fluvial sediment sequences are available.     

A sediment budget for a grazed semi-arid catchment in the Burdekin basin, Australia

In catchments adjacent to the Great Barrier Reef World Heritage Area in Queensland, Australia, there is a growing concern that sediments and nutrients being exported from the land are having a detrimental effect on coral reef communities. There is a need to determine the processes and rates of erosion from the major land use types, so that management intervention can be initiated to reduce sediment yields where required. This paper presents a sediment budget for Weany Creek, a 13.5 km² grazed semi-arid sub-catchment of the Burdekin River catchment, Australia. A range of field methods was used to measure erosion from hillslopes, gullies and stream banks, as well as identify the amount of sediment being deposited and remobilised on the bed of gullies and the stream network. The data suggests that at least during drought conditions, the primary erosion source in this catchment is gully erosion. However, the largest source of sediment in the budget is actually associated with the remobilisation of in-channel sediment stores. Overall, the sediment budget is comprised of  81% coarse material and 19% fine sediment and an agreement between the fine sediment yield estimated in the sediment budget and the yield measured at the catchment outlet is within 10%. The total sediment yield estimated for this catchment is  4205 t yr^− 1 and is much lower than expected for a catchment of this size. This may reflect the drought conditions during the measurement period; however, there is also the possibility that the primary erosion sources have been exhausted, and the rates of sediment loss may be much lower now than they may have been in the past. Nonetheless, the results show that stored sediment, which may have been deposited in the channel many decades ago, is an important contributor to end of catchment sediment yields and warrants further investigation.     

Advances in Holocene mountain geomorphology inspired by sediment budget methodology

The sediment budget, which links sediment sources to sediment sinks with hydroclimatic and weathering processes mediating the response, is applied to the analysis of sediments in three alpine lakes in British Columbia. We provide two ways of using the sediment budget as an integrating device in the interpretation of mountain geomorphology. These approaches differ in their resolution and ability to budget the major components of the fine-sediment cascade in glaciated environments. Taken together, they provide an integrated index of landscape change over the Holocene. The first example compares the hydroclimatic controls of lake sedimentation for the last 600 years (A.D. 1370–1998) preserved in varved sediments from two of the lake basins. This hydroclimatological approach incorporates contemporary monitoring, air photo analysis, and detailed stratigraphy of sedimentation events within a single varve to infer the timing, sources, and preferred pathways of fine-grained sediments reaching the lake basins. The results indicate that glaciers, hillslope, and channel instability within the major subbasins are the principal sediment sources to the lake basins. Transitory sediment storage of glacially derived sediments within the channels is believed to modulate the episodic and more frequent delivery of sediments from adjacent hillslope and fluvial storage sites and direct routing of glacial rock flour during years of prolonged glacial melt. The second example, relying on the phosphorus geochemistry of sediments in an alpine lake basin, considers the evolution of phosphorus forms (from mineral to occluded and organic fractions) as a function of the soil development, inherent slope instability, and repeated cycles of glaciation and neoglaciation over the Holocene. This geochemical approach demonstrates that both neoglaciation and full glaciation have essentially zeroed the system in such a way that a high proportion of mineral phosphorus remains in the present lake sediments and the bioavailability of phosphorus (a key to ecosystem development) is low. Both examples illustrate the importance of variable sediment sources; the seasonality, frequency, and magnitude of sediment transfers; and the profound influence of ice cover over contemporary, neoglacial and Pleistocene time scales. They also signal the value of including both clastic and dissolved components in the sediment budget.     

国内外道路侵蚀研究回顾与展望

道路引起的径流汇集及道路侵蚀的不断演化常常是沟蚀加剧的诱因,未铺装路面上形成的侵蚀沟及坡面侵蚀来沙在路面上的堆积,也会严重影响正常交通运输。国内外许多学者已从不同角度关注道路侵蚀。文章回顾近20年来国内外有关道路侵蚀的研究工作及所取得的成果,分析目前研究存在的主要问题。针对中国侵蚀环境特征及侵蚀产沙特点,对未来道路侵蚀研究工作开展进行展望。     

利用封闭湖泊流域进行古降水量重建的历史、现状及未来

回顾了利用封闭湖泊流域进行古降水量重建的简单历史,重点论述了其理论与方法的特点及发展源流;在此基础上,结合作者近几年在青藏高原开展的这方面的研究工作,对季风区进行此项研究的可能方法、理论依据及其初步应用进行了分析,重点阐述了其存在的缺点与不足及未来的改进方式。     

产沙模数与流域面积关系研究进展

流域面积是综合地表一切要素的黑箱变量,而产沙模数是流域产沙强度的重要体现。自20 世纪50 年代以 来,有关产沙模数随流域面积变化的研究受到了国内外学者的广泛关注。本文对多年来有关该方面的研究成果进 行总结、提炼,在此基础上,把产沙模数与流域面积的变化关系划分为5 种类型,即负相关关系,正相关关系,先增 加后减小的非线性关系,先减小后增加的非线性关系以及无显著关系等,继而对每种类型出现的原因给出了合理 的解释;在此基础上,指出产沙模数随流域面积变化的本质原因,即产沙模数随流域面积的变化是对流域内各种因 素及因素间相互作用的响应,产沙模数与流域面积之间没有内在的联系,产沙模数随流域面积的增加可以出现任 何变化。     

SEDIMENT BUDGETS AND RATES OF SEDIMENT TRANSFER ACROSS COLD ENVIRONMENTS IN EUROPE: A COMMENTARY

The sediment mass balance equation is the fundamental concept which underpins most sediment budget studies in cold climate environments. In these environments the interchange between water and ice plays a predominant geomorphological role. Such environments show a large variety of geomorphic processes which are conditioned by both contemporary environmental conditions but also the legacy of past events. In the northern Europe/Arctic fringe these cold regions are distributed in a fragmented fashion and are likely to be very sensitive to climate change scenarios. The significance of such changes for sediment transfer can only be established if we have good contemporary process understanding, the necessary tools to carefully monitor and model such changes, and can apply such methods at appropriate scales which integrate both sediment sources and sinks.     

Thesis: Ideology and Power Relations in Cultural Landscape Evaluations

Factors of importance to the generation of complex sediment rating curves involving hysteresis effects are discussed. Temporary storage of sediments in channels, and interaction between fluvial processes and some other sediment producing process, may be recognized as two fundamentally different situations associated with the phenomenon. An examination of sediment transport in glacierized river basins shows that variable discharge in broad shallow channels may cause temporary storage of sediments within the channel system. Implications for the sediment budget in river systems are discussed.     

Straight from the source's mouth: Controls on field-constrained sediment export across the entire active Corinth Rift,central Greece

The volume and grain-size of sediment supplied from catchments fundamentally control basin stratigraphy. Despite their importance, few studies have constrained sediment budgets and grain-size exported into an active rift at the basin scale. Here, we used the Corinth Rift as a natural laboratory to quantify the controls on sediment export within an active rift. In the field, we measured the hydraulic geometries, surface grain-sizes of channel bars and full-weighted grain-size distributions of river sediment at the mouths of 47 catchments draining the rift (constituting 83% of the areal extent). Results show that the sediment grain-size increases westward along the southern coast of the Gulf of Corinth, with the coarse-fraction grain-sizes (84^th percentile of weighted grain-size distribution) ranging from approximately 19 to 91 mm. We find that the median and coarse-fraction of the sieved grain-size distribution are primarily controlled by bedrock lithology, with late Quaternary uplift rates exerting a secondary control. Our results indicate that grain-size export is primarily controlled by the input grain-size within the catchment and subsequent abrasion during fluvial transport, both quantities that are sensitive to catchment lithology. We also demonstrate that the median and coarse-fraction of the grain-size distribution are predominantly transported in bedload; however, typical sand-grade particles are transported as suspended load at bankfull conditions, suggesting disparate source-to-sink transit timescales for sand and gravel. Finally, we derive both a full Holocene sediment budget and a grain-size-specific bedload discharged into the Gulf of Corinth using the grain-size measurements and previously published estimates of sediment fluxes and volumes. Results show that the bedload sediment budget is primarily comprised (~79%) of pebble to cobble grade (0.475–16 cm). Our results suggest that the grain-size of sediment export at the rift scale is particularly sensitive to catchment lithology and fluvial mophodynamics, which complicates our ability to make direct inferences of tectonic and palaeoenvironmental forcing from local stratigraphic characteristics.