太平洋西海岸森林砍伐对洪水特征的影响

据加拿大Carnation Creek生态试验站20a的森林水文观测资料,应用回归分析和协方差检验,研究了森林砍伐以前、道路修筑、砍伐中和砍伐后各时期洪水参数的变化,统计结果表明,森林砍伐后,洪峰和洪量有显著的增大,一般增幅在20％～30％之间,年径流量增长15％～20％,但洪峰滞时和洪水形态变化不大。     

Geomorphic effects of rural-to-urban land use conversion on three streams in the Central Redbed Plains of Oklahoma

This research evaluates the impact of rural-to-urban land use conversion on channel morphology and riparian vegetation for three streams in the Central Redbed Plains geomorphic province (central Great Plains ecoregion) of Oklahoma. The Deep Fork Creek watershed is largely urbanized; the Skeleton Creek watershed is largely rural; and the Stillwater Creek watershed is experiencing a rapid transition from rural to urban land cover. Each channel was divided into reaches based on tributary junctions, sinuosity, and slope. Field surveys were conducted at transects in a total of 90 reaches, including measurements of channel units, channel cross-section at bankfull stage, and riparian vegetation. Historical aerial photographs were available for only Stillwater Creek watershed, which were used to document land cover in this watershed, especially changes in the extent of urban areas (impervious cover).The three streams have very low gradients (< 0.001), width-to-depth ratios < 10, and cohesive channel banks, but have incised into red Permian shales and sandstone. The riparian vegetation is dominated by cottonwoods, ash, and elm trees that provide a dense root mat on stream banks where the riparian vegetation is intact. Channels increased in width and depth in the downstream direction as is normally expected, but the substrate materials and channel units remained unchanged. Statistical analyses demonstrated that urbanization did not explain spatial patterns of changes in any variables. These three channels in the central Redbed Plains are responding as flumes during peak flows, funneling runoff and the wash-load sediment downstream in major runoff events without any effect on channel dimensions. Therefore, local geological conditions (similar bedrock, cohesive substrates and similar riparian vegetation) are mitigating the effects of urbanization.     

Recent large-magnitude floods and their impact on valley-floor environments of northeastern Yellowstone

The Lamar River watershed of northeastern Yellowstone contains some of the most diverse and important habitat in the national park. Broad glacial valley floors feature grassland winter range for ungulates, riparian vegetation that provides food and cover for a variety of species, and alluvial channels that are requisite habitat for native fish. Rapid Neogene uplift and Quaternary climatic change have created a dynamic modern environment in which catastrophic processes exert a major influence on riverine–riparian ecosystems. Uplift and glacial erosion have generated high local relief and extensive cliffs of friable volcaniclastic bedrock. As a result, steep tributary basins produce voluminous runoff and sediment during intense precipitation and rapid snowmelt. Recent major floods on trunk streams deposited extensive overbank gravels that replaced loamy soils on flood plains and allowed conifers to colonize valley-floor meadows. Tree-ring dating identifies major floods in 1918, ca. 1873, and possibly ca. 1790. In 1996 and 1997, discharge during snowmelt runoff on Soda Butte Creek approached the 100-year flood estimated by regional techniques, with substantial local bank erosion and channel widening. Indirect estimates show that peak discharges in 1918 were approximately three times greater than in 1996, with similar duration and much greater flood plain impact. Nonetheless, 1918 peak discharge reconstructions fall well within the range of maximum recorded discharges in relation to basin area in the upper Yellowstone region. The 1873 and 1918 floods produced lasting impacts on the channel form and flood plain of Soda Butte Creek. Channels may still be locally enlarged from flood erosion, and net downcutting has occurred in some reaches, leaving the pre-1790 flood plain abandoned as a terrace. Gravelly overbank deposits raise flood-plain surfaces above levels of frequent inundation and are well drained, therefore flood-plain soils are drier. Noncohesive gravels also reduce bank stability and may have persistent effects on channel form. Overall, floods are part of a suite of catastrophic geomorphic processes that exert a very strong influence on landscape patterns and valley-floor ecosystems in northeastern Yellowstone.     

Erosion of Access Tracks in Kalamunda National Park,Western Australia: Causes and management implications

Construction of access tracks in national parks and other reserves in the south-west of Western Australia is an essential feature of park management. However, their construction was often carried out with little or no appreciation of soil and slope characteristics and potential erodibility, or the effect of slope and stream sedimentation on terrestrial and aquatic flora and fauna. This paper reports on the findings of a study carried out in Kalamunda National Park, a small reserve in the Darling Ranges east of Perth. Tracks were surveyed and the extent of erosion and sedimentation measured. Erosion-indicating and erosion-influencing variables were measured. Track alignment angle (to the contour) and track gradient were the two site variables most significantly correlated with measures of erosion severity. The most important upslope (on-track) factor was track length, and the most important upslope (off-track) factor was the abundance of granite outcrops. Seasonal conditions were important, particularly in relation to soils with relatively high clay contents. When wet, these soils were more likely to suffer from surface drainage problems and increased runoff, associated with decreased cohesion. On the other hand, the more common sand-textured soils are generally more erodible when wet. Several management measures are recommended. These fall into three categories: those relating to track closure or realignment (to avoid the most erosion-susceptible sites); those relating to actual track design and maintenance, or site management; and those relating to modification of visitor behaviour .     

基于SWAT的典型沼泽性河流径流演变的气候变化响应研究——以三江平原挠力河为例

SWAT（Soil and Water Assessment Tool）是流域尺度的分布式水文模型,具有评价气候变化对径流影响的优势。利用SWAT模拟了三江平原典型沼泽性河流——挠力河流域3个水文站（上游的宝清站、保安站和中游的菜嘴子站）1974～1992年年径流量演变特征及变化趋势。在对模型参数敏感性分析的基础上,对模型的参数进行了率定和验证,率定期为1975～1982年,验证期为1983～1992年。率定期的模型效率指数ENS都大于0．85,皮尔逊相关系数都大于0．9,相对误差都小于10％;验证期,模型效率指数ENS有所减小,但也都大于0．61,模型对年径流的模拟结果令人满意。将率定的SWAT应用于气候变化的水文响应研究,结果发现,1995～2004年相对1975—1985年的年径流量变化只有部分是由气候因素引起的,气候因素对3个水文站（宝清站、保安站和菜嘴子站）的年径流量变化的影响率分别为25．7％、11．4％、39．9％,说明还有其他因素影响研究区的年径流量。     

祖厉河流域降雨径流泥沙变化特征研究

祖厉河流域位于年降水量200～400 mm之间过渡带,是气候变化最敏感和最为复杂的区域之一。运用祖厉河流域1955-2013年径流量、输沙量与年降雨量的变化趋势、时段特征进行了分析。结果表明：祖厉河流域降雨量、径流量和输沙量存在年际变化大、逐年减小的变化趋势;年降雨量在1995年出现突变点,降雨量存在明显的丰水和枯水变化,丰水时段（1955-1989年）年降水量为376.2 mm,枯水时段（1990-2013年）年降水量为224.9 mm;径流量和泥沙量的突变点分别出现在1995年和2000年;依据UF_k值信度变化趋势,将径流量、输沙量变化分为非显著减少（1955-1971年）、显著减少（1972-1985年）、较显著减少（1986-2000年）和极显著减少（2001-2013年）四个时期。     

STORMWATER MANAGEMENT IN A SMALL MICHIGAN WATERSHED

This study examines stormwater flooding problems on Arcadia Creek, a typical small watershed in Michigan, which is undergoing urbanization. Land-use change has increased the impervious area and, hence, surface runoff while decreasing the natural storage capacity along the channel by elimination of marshes and swamps. However, creation of flow constrictions at culverts, construction of retention ponds, and other results of human interference have led to hydrologic segmentation of the basin and less downstream discharge but a more peaked hydrograph than expected. Continued haphazard urbanization of the basin could increase runoff and decrease storage to a point where downstream flooding would become a far more serious problem. A cooperative approach is needed among the three governments who have jurisdiction over the basin to preserve upstream storage capacity through both structural and policy measures. This would not only greatly facilitate flood control but obviate the need for expensive channel reconstruction to increase conveyance capacity.     

Holocene vegetation history of Bundjalung National Park and Bungawalbin Creek,north‐eastern New South Wales

Few studies have been conducted into the environmental history of the North Coast region of New South Wales (NSW). To address this, two sedimentary sequences located in the coastal Bundjalung National Park and at Bungawalbin Creek, just north of the Park (both near Evans Head, NSW) have been investigated. Palynological and geochemical analyses were used to reconstruct the history of the sites. Fossil pollen evidence representing much of the Holocene period — basal radiocarbon dates of 8700 ± 60 years BP and 6600 ± 60 years BP are available from the Bundjalung National Park and Bungawalbin Creek sites, respectively — indicates a dynamic past environment, with an overall tendency towards drier conditions. This evidence is supported, in part, by charcoal analyses indicating an increase in the occurrence of fire over time. Chemical analyses of the sediments indicate that the Bungawalbin site was strongly influenced by estuarine conditions, whereas the Bundjalung National Park site was only influenced indirectly by estuarine conditions.     

基于小波分析的江河源区汛期和枯水期径流特征(英文)

By decomposing and reconstructing the runoff information from 1965 to 2007 of the hydrologic stations of Tuotuo River and Zhimenda in the source region of the Yangtze River, and Jimai and Tangnaihai in the source region of the Yellow River with db3 wavelet, runoff of different hydrologic stations tends to be declining in the seasons of spring flood, summer flood and dry ones except for that in Tuotuo River. The declining flood/dry seasons series was summer > spring > dry; while runoff of Tuotuo River was always increasing in different stages from 1965 to 2007 with a higher increase rate in summer flood seasons than that in spring ones. Complex Morlet wavelet was selected to detect runoff periodicity of the four hydrologic stations mentioned above. Over all seasons the periodicity was 11-12 years in the source region of the Yellow River. For the source region of the Yangtze River the periodicity was 4-6 years in the spring flood seasons and 13-14 years in the summer flood seasons. The differences of variations of flow periodicity between the upper catchment areas of the Yellow River and the Yangtze River and between seasons were considered in relation to glacial melt and annual snowfall and rainfall as providers of water for runoff.     

The effect of the Changjiang River on water regimes of its tributary Lake East Dongting

The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary lakes, we made a case study in Changjiang River and one of its tributary lakes, Lake East Dongting (Lake ED) during a 35-year study period (1980–2014). Specifically, we investigated Lake ED’s discharge ability into Changjiang River using stage-discharge relationship curves, and hence the changes of the lake discharge ability under different hydrologic conditions of the Changjiang River. The results show that (1) the Changjiang River does exert a huge impact on the water regimes of Lake ED. And this impact varies seasonally. A variation of 3000 m³/s in Changjiang River’s runoff would change the lake water level by about 1.1 m in dry seasons, by 0.4 m in wet seasons, and by 0.6 m during severe summer floods. (2) Changes in the Changjiang River runoff triggered by the Three Gorges Dam since 2003 have led to dramatic water regime variations in Lake ED. Other factors, including reduction of lake inflow and the lake bed erosion, also exacerbated the water regime variations in Lake ED.     

IMPACTS OF URBANIZATION ON SURFACE HYDROLOGY,LITTLE EAGLE CREEK,INDIANA, AND ANALYSIS OF LTHIA MODEL SENSITIVITY TO DATA RESOLUTION

Land-use change in urbanizing areas can significantly alter the hydrology of a watershed and can have serious impacts on wetland water balances, downstream flooding, and groundwater recharge. Most currently available models used in determining the hydrologic impacts of urbanization are not well suited to long-term hydrologic analysis or are too complex and data intensive for widespread practical application. The Long-Term Hydrologic Impact Assessment (LTHIA) model run on a Geographic Information System (GIS) is a relatively simple, user-friendly model that uses the Curve Number method to estimate changes in surface runoff between different stages of development. Application of the model to a large, rapidly urbanizing watershed near Indianapolis, Indiana, suggests that average annual runoff depths increased by more than 60% from 1973 to 1991, with even greater increases for some individual sub-basins. These results are consistent with runoff changes estimated from historical stream flow data in the watershed. A sensitivity analysis to determine minimum data requirements shows that a precipitation record length of 15 years or more is required to produce consistent results with LTHIA and that the highest possible resolution land-use and soils data should be used. The LTHIA model is now available on the Internet at http://www.ecn.purdue.edu/runoff. [Key words: hydrology, urbanization, modeling, GIS.]     

A Simplified Basin Model For Simulating Runoff: The Struma River GIS

A GIS-based distributed-parameter runoff simulation model for the Struma River Basin in southwestern Bulgaria calculates the monthly snow/rain proportion, direct or surface runoff, snow cover and snowmelt, soil moisture, evapotranspiration, and total runoff. Simulation during the Bulgarian hydrologic year from November to October was compared with observed runoff data. The model closely replicates mean monthly runoff from climate conditions during the years 1961 –1990 as well as specific years. The simplified GIS model simulates hydrologic processes under limited data availability.     

基于小波分析的长江和黄河源区汛期、枯水期径流特征

利用db3小波分解和重构1965~2007年长江源沱沱河站、直门达站和黄河源吉迈站、唐乃亥站春汛期、夏汛期和枯水期流量数据,除沱沱河外,各站春汛期、夏汛期和枯水期流量皆呈下降趋势,各站流量下降速率依次为夏汛期>春汛期>枯水期。沱沱河站多年流量呈增加趋势,夏汛期变化速率依然高于春汛期。应用复Morlet小波分别分析上述4个水文站实测流量的周期特征。黄河源总体存在11~12a波动周期;长江源春汛期有4~6a波动周期,夏汛期有13~14a波动周期。不同流域春汛期、夏汛期和枯水期主周期分布规律不同。     

30-year response to damming of a Mediterranean river in California,USA

Dry Creek is a major tributary of the Russian River in Northern California (USA) that has experienced hydrologic and morphologic alterations after the closure of Warm Springs Dam in 1983. Our objective is to present a detailed diagnosis of the modification of the creek’s flow and sediment regimes, and interpret the alterations regarding the ecomorphologic evolution previously observed in the creek. Statistical analysis of the river’s flow and sediment series indicates that dam operation has had significant impacts on the magnitude and frequency of occurrence of the highest floods, and the magnitude, variability, and duration of low and very low flows. Similarly, sediment concentration and discharge have also experienced major alterations. Loss of habitat complexity for native flora and fauna (especially endangered salmonids), channel incision, and vegetation encroachment are some of the negative trends found for the creek over the last 30 years, since river regulation began. We discuss the present dynamics of the river and propose, on that basis, the improvement of its hydromorphic functioning as part of future large-scale restoration initiatives.     

A HYDROLOGIC MODEL FOR LOWER COASTAL PLAIN WATERSHEDS,SOUTHEAST UNITED STATES

A disributed, physically-based, watershed hydrologic simulation model, called COASTAL, has been specifically designed for use on watersheds of low relief where streamflow is supplied predominantly by ground water discharge. To use the model, the watershed is divided into square grid elements that are modeled by the lumped parameter approach. I nput data include daily temperature, daily precipitation, topographic elevation, soil field capacity, soil wilting point, aquifer hydraulic conductivity, aquifer thickness and land use for each grid element and a watershed stream rating curve. One or more years of daily streamflow data are needed to calibrate the model. Yearly correlation coefficients between measured and simulated daily streamflow averaged 0.85 and ranged from 0.70–0.91 in tests of the model using 1957-1964 data for the Hurricane Creek watershed, Georgia. Correlation coefficients between measured and predicted annual, monthly, and annual maximum streamflow for the eight years tested were 0.97, 0.93, and 0.82, respectively.     

A Simplified Basin Model For Simulating Runoff: The Struma River GIS

A GIS‐based distributed‐parameter runoff simulation model for the Struma River Basin in southwestern Bulgaria calculates the monthly snow/rain proportion, direct or surface runoff, snow cover and snowmelt, soil moisture, evapotranspiration, and total runoff. Simulation during the Bulgarian hydrologic year from November to October was compared with observed runoff data. The model closely replicates mean monthly runoff from climate conditions during the years 1961 –1990 as well as specific years. The simplified GIS model simulates hydrologic processes under limited data availability.     

Characteristic of tradeoffs between timber production and carbon storage for plantation under harvesting impact: A case study of Huitong National Research Station of Forest Ecosystem

The tradeoffs and optimizations of ecosystem services are the key research fields of ecology and geography. It is necessary to maximize the overall benefit of timber production and carbon storage for forest ecological development in China. We selected the Huitong National Research Station of Forest Ecosystem as our study area, and used InVEST model to evaluate timber production and carbon storage quantitatively. The results showed that: (1) While timber production increased with harvesting intensity over the planning horizon, carbon storage decreased. There were tradeoffs between timber production and carbon storage according to the significant negative relationship. (2) While the overall benefit of timber production and carbon storage increased with harvesting intensity, the value of tradeoffs decreased. T1 and T2 scenarios, with harvesting intensity of 10%–20% every 10 years, are the optimum management regimes for the two ecosystem services to gain more benefit and less tradeoffs. (3) The current harvesting intensity in Huitong County was slightly higher than the optimum harvesting intensity. On practical dimension, these findings suggested that obvious objectives are needed to formulate the corresponding countermeasures of tradeoffs, in order to realize the improvement of ecosystem services and the optimization of ecosystem structures.     

Tourism and deforestation in the Mt Everest region of Nepal

Over the past 50 years the Sherpa-inhabited Mt Everest region of Nepal has become a premier international mountaineering and trekking destination. Tourism development has brought prosperity to many Sherpas. It has also, however, had adverse impacts on regional forests and alpine vegetation because of the use of firewood by camping groups and inns and the felling of trees to construct inns and other tourist facilities. Concern that tourism was causing widespread deforestation helped catalyse the 1976 establishment of an inhabited protected area, Sagarmatha (Mt Everest) National Park, in the Khumbu region and spurred the implementation of a series of forest conservation and alternative energy development measures both within the national park and in a recently declared buffer zone in the adjacent Pharak region. This paper examines the changing pressures that tourism has placed on regional forests and alpine vegetation over the past half century and their role in regional vegetation change. This analysis is based primarily on detailed accounts of past and present forest use and change obtained during fieldwork conducted in all Khumbu and Pharak villages, along with corroborating evidence from early foreign visitors' accounts and photographs. Contrary to some early reports it now appears there has actually been little deforestation since 1950. The continuing use of firewood by inns, however, has contributed to the thinning of forests in some parts of the national park and to the depletion of shrub juniper in the most heavily visited alpine regions. There has been a greater impact on forests just outside the national park, which have been heavily thinned over an extensive area in order to provide timber to build inns within the national park.     

我国水土保持措施对水资源影响研究综述

随着我国政府各有关部门和专业人员对水土流失问题及水资源问题的日益关注, 流域水 土保持综合治理对下游水资源的影响已成为当前解决流域水资源供需矛盾问题的重中之重。本 文在径流小区域尺度和流域尺度上, 分别对我国近几十年来在水土保持单项措施对水资源的影 响以及流域综合治理的减水效益方面的主要研究成果进行了综合分析, 对各重点治理大流域的 减水效益进行了对比分析。最后, 阐述了目前该研究中存在的问题, 并提出今后的主要研究方向。     

嫩江流域近45年来径流演变规律研究

采用随机水文学方法对嫩江流域1956~2000年的年径流量序列演变特征进行分析。结果表明,嫩江流域径流的水文周期是32a,整体而言,45a径流序列不存在明显的趋势性。此外,对嫩江流域用水性消耗程度进行分析。结果表明,人类用水性消耗量对流域水循环整体影响程度为5%,但是在流域内部影响程度存在较大差异。洮儿河子流域影响因子达到16%,反映该地区人类取用水消耗量较大。从年际分析,整个流域在70年代的影响因子要高于其它年段,呈现出越是枯水年段人类用水影响程度越大的现象。