降雨侵蚀力对露天矿排土场边坡水土流失的影响研究

降雨侵蚀力反应降雨引起的土壤侵蚀潜在能力,是水土保持研究中的主要指标之一。以露天煤矿排土场不同覆盖类型边坡为研究对象,分析了日降雨侵蚀力与边坡侵蚀的关系。结果表明,从控制坡面径流深来看,降雨侵蚀力的作用受到了乔灌草和灌草配置的显著影响,其产生的坡面径流仅为对照区的42.9%和52.6%。从控制坡面侵蚀量来看,三种植物配置措施都具有显著减少功能,土壤侵蚀量仅为对照区的2.3%~6.7%。降雨侵蚀力与边坡水土流失量存在线性正相关,其中坡面径流深对降雨侵蚀力的响应快于土壤侵蚀量。     

梯级水库作用下的长江流域水文设计成果修订研究

长江流域水文成果复核选取了48个水文站点作为研究对象,考虑站点上游已建具有较强调节能力的大型水库调蓄影响,对径流、洪水进行还原分析计算以保证系列的一致性,并对径流、洪水设计成果的变化进行对比分析。径流成果分析表明,延长系列后干支流主要控制站点的径流成果较为稳定,多年平均年径流量和各站点20%、50%和75%频率年径流设计值的相对变化均在5%以内;洪水成果分析表明,延长洪水系列后的百年一遇设计洪水成果与前期不同阶段采用成果相比变化不大,基本均在4%以内。     

关于南洞地下河系统南边界问题的讨论

岩溶水系统的划分研究是水均衡分析、水资源评价的基础。南洞地下河是中国南方4个超大型地下河系统之一,其水文地质条件复杂,开发潜力巨大。由于南洞地下河系统蒙自盆地内有第三系阻水深槽存在,使得该区地下水位高于南北两侧,部分研究认为该阻水带是南洞地下河系统的南边界。本次通过进一步收集盆地内部和外围水文地质钻孔及地热钻孔资料、野外调查、洞穴探测及示踪试验,认为盆地内阻水深槽并不阻挡深部地下水,南洞地下河系统南边界应南移至南部地表分水岭一带。蒙自盆地及南部地下水流向应整体由南向北。     

1956-2018年中国江河径流演变及其变化特征

地表水资源是维系区域生态平衡和促进经济社会发展的制约性要素,河川径流是地表水资源的主要形式,二者的丰枯变化均直接影响流域水资源管理。基于江河实测径流量资料和水资源公报资料,初步分析了1956—2018年中国主要江河实测径流量和中国十大水资源区地表水资源的变化和演变特征。结果表明:①除长江大通站外,中国主要江河代表性水文站实测年径流量均呈现下降趋势。②黄河上游唐乃亥站实测年径流量为非显著性减少趋势,黄河花园口站实测径流量呈现显著性减少趋势;1980—2000年和2001—2018年唐乃亥站实测径流量较基准期1956—1979年分别变化1.8%和-5.9%,而同时期花园口站实测径流量分别减少26.7%和41.0%。③地理分布上,黄河是中国南北地区径流变化的分水岭,黄河以南地区江河径流量为非显著性变化,黄河以北江河径流量为显著性减少趋势,特别是海河流域,实测径流量减少最为显著;21世纪以来,黄河以北河流实测径流量较1980年之前减少幅度超过25%,海河减幅高达80%以上。④1956—2018年全国地表水资源量约为27266亿m 3,较第二次全国水资源评价结果偏少122亿m 3。21世纪以来,海河、黄河、辽河地表水资源明显减少,进一步加重了区域水资源供需矛盾。     

Snowmelt-generated runoff and soil erosion in Fife,Scotland

The hydrology and contrasting erosional responses of two snowmelt events on arable farmland in Fife, Scotland, are compared. Snowmelt-generated runoff in January 1993 caused widespread soil erosion across eastern Scotland. Gullying was exemplified by three sites in Fife, where thaw of a drifted snowpack was augmented by rainfall to produce a larger erosive response than meteorological data alone would have predicted. Up to 127 m³ of soil was lost from individual gullies in fields sown to winter cereals. In February 1996 snowfall of comparable depth again covered the field area, but a more uniform snowpack, slower thaw, greater crop cover and lower rainfall during the thaw phase combined to lessen the impact of erosion. These case studies demonstrate the complexity of the erosion/runoff relationship for rain on snow events, in which erosional severity depends not just on snow depth but on snow distribution, thaw rate and the amount and timing of rainfall during the thaw phase. © 1998 John Wiley & Sons, Ltd.     

The hydrology of three high-altitude forests in Central Himalaya,India: a reconnaissance study

In this preliminary study the partitioning of rain-water into various components of the hydrological cycle in three high-altitude forests of contrasting tree physiognomies (namely, Aesculus indica, Quercus semecarpifolia and Abies pindrow) were studied in the Nandadevi Biosphere Reserve, Central Himalaya, India. The results are compared with the hydrological characteristics of low-altitude forests of this region. The study has indicated a significant role of tree physiognomy with regard to rainfall partitioning into the various components of the hydrological cycle. It is suggested that A. pindrow (an evergreen tree) should be considered superior to A. indica (a deciduous tree) with regard to soil and water conservation in this region. This work is of relevance to land management programmes pertaining to afforestation, logging and regeneration. © 1998 John Wiley & Sons, Ltd.     

Late Devensian ice sheet characteristics: a palaeohydraulic approach

Glacial meltwater channels are incised into bedrock and diamicton along much of the length of the Mid-Cheshire Ridge. Detailed mapping of one such system near the town of Helsby reveals a dendritic channel network developed in the opposite direction to the regional ice flow during the last (Late Devensian) glaciation. The channels formed subglacially, under atmospheric and not hydrostatic pressure, presumably as the ice sheet downwasted during deglaciation. Morphological and palaeohydraulic evidence suggests that not all of the network was necessarily active contemporaneously. Former water levels in the channels can be estimated due to the presence of bar surfaces, giving a calculated palaeodischarge of at least 111 m³ s⁻¹. The ablation rates required to account for this large discharge are an order of magnitude greater than those obtained from theoretical calculations and those observed in modern glacial environments. This implies that some form of high-magnitude discharge, such as a seasonal flood event, must have taken place in this area during deglaciation. This picture of the Late Devensian ice sheet suggests that during recession the ice sheet was static, crevassed and relatively thin (<50 m). This study also shows that there is no simple relationship between meltwater channel direction and ice dynamics, and that care is required when using the former to make inferences about the latter. Copyright © 1998 John Wiley & Sons, Ltd.     

Hydrogeochemistry of shallow groundwater in an upland Scottish catchment

The hydrogeochemistry of shallow groundwater has been characterized in the Allt a'Mharcaidh catchment in the Scottish Cairngorms in order to: (i) assess the spatial and temporal variation in groundwater chemistry; (ii) identify the hydrogeochemical processes regulating its evolution; and (iii) examine the influence of groundwater on the quality and quantity of stream flow. Shallow groundwater in superficial drift deposits is circumneutral (pH∽7·1) and base cation concentrations are enriched compared with precipitation and drainage water from overlying podzolic soils. Modelling with NETPATH suggests that the dominant geochemical processes that account for this are the dissolution of plagioclase, K-feldspar and biotite. Groundwater emerging as springs from weathered granite underlying high altitude (>900 m) alpine soils shows similar characteristics, though weathering rates are lower, probably as a result of reduced residence times and lower temperatures. Chemical hydrograph separation techniques using acid neutralizing capacity (ANC) and Si as tracers show that groundwater is the dominant source of baseflow in the catchment and also buffers the chemistry of stream water at high flows: groundwater may account for as much as 50–60% of annual runoff in the catchment. Climate and land use in the Cairngorms are vulnerable to future changes, which may have major implications for hydrogeological processes in the area. © 1998 John Wiley & Sons, Ltd.     

Factors influencing surface runoff generation in a Mediterranean semi-arid environment: Chicamo watershed,SE Spain

A deeper knowledge of the hydrological response of semi-arid Mediterranean watersheds would be useful in the prediction of runoff production for assessing flood risks and planning flood mitigation works. This study was conducted to identify the runoff generation mechanisms and their controlling factors at the hillslope scale in a Mediterranean semi-arid watershed. Four zero-order microcatchments were selected to measure rainfall and runoff for a three-year period. Two groups of soil were differentiated with respect to the hydrological response. The fine textured, poorly permeable soils of low organic carbon content had a greater runoff coefficient (9%) and lower runoff threshold (3·6 mm) than more permeable, coarser textured soils of medium organic carbon content (<3%, and 8 mm, respectively). The influence of rainfall characteristics on the hydrological response was different. Rain intensity was the major rainfall parameter controlling the runoff response in the microcatchments on fine textured, low infiltrability soils with a poor plant cover, while total rainfall was more closely correlated with runoff in coarser textured, highly permeable soils with a denser plant cover. It can be concluded that there are two runoff generation mechanisms: (i) an infiltration-excess overland flow in the more degraded areas with low organic carbon content (<0·5%) and low infiltrability (>5 mm h⁻¹); and (ii) a saturation-excess overland flow in the less degraded areas with a high organic carbon content (>2%), high infiltrability (>8 mm h⁻¹) and covered by a dense plant cover (>50%). © 1998 John Wiley & Sons, Ltd.     

考虑径流成分的雅鲁藏布江月径流模拟

通过构建雅鲁藏布江流域分布式水文模型SWAT,并以1989~1998年为率定期,1999~2005年为验证期对3个水文站(奴各沙、羊村、奴下)的月径流进行了模拟。从模型参数组里选取径流成分模拟不同的2组参数,以Nash-Sutcliffe效率系数(NS)、相关系数(R~2)及相对误差(PBIAS)为评价指标,来分析模型的模拟结果好坏。结果表明:率定期内,在径流成分1下奴各沙、羊村站和奴下站的R~2值高达0.9以上,NS系数分别为0.9、0.92和0.72,PBIAS的值为7.1%、18.5%及34.2%,但径流成分与实际情况出入较大。而径流成分2下,模拟得到的评价指标虽然不是很高,但径流成分比较合理。验证期总体结论一致。因此,建议在模型率定验证中要充分考虑径流成分的作用,从而提高模型模拟的精度。