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1.
Pim de Klerk Andreas Haberl Andreas Kaffke Matthias Krebs Izolda Matchutadze Merten Minke Jenny Schulz Hans Joosten 《Quaternary Science Reviews》2009,28(9-10):890-910
The Kolkheti lowlands of western Georgia have a unique vegetation and a rich cultural history. Palynological and macrofossil analysis accompanied by AMS 14C-dates of the deposits of the Ispani 2 mire near Kobuleti allow the reconstruction of regional vegetation, environmental history and local peatland development within the context of Black Sea level and cultural changes. Comparison of two adjacent peatland cores confirms spatial differences in wetland development. Prior to 5400 cal yr BP, the Ispani basin was a floodplain of an active river system where overbank deposits with fluvially transported Castanea pollen were deposited. Subsequently, a lake or lagoon developed in which reeds expanded. These were succeeded by herb-rich open alder carrs. After 1900 cal yr BP, Carpinus and Fagus expanded on the dry grounds, where formerly Quercus was more abundant. Also Castanea declined. Local reedbeds, that burned regularly, succeeded the alder carr. After 1000 cal yr BP, a percolation bog developed resulting in the formation of 4 m of loose, porous, and largely undecomposed Sphagnum austinii peat with Molinia roots. The upper 50 cm of the analysed section show extensive human impact on the landscape during the 20th century. 相似文献
2.
Long‐term sediment yield from a small catchment in southern Brazil affected by land use and soil management changes 
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下载免费PDF全文 Jean P.G. Minella Gustavo H. Merten Claúdia A.P. Barros Rafael Ramon Alexandre Schlesner Robin T. Clarke Michele Moro Leandro Dalbianco 《水文研究》2018,32(2):200-211
Sediments produced from eroding cultivated land can cause on‐site and off‐site effects that cause considerable economic and social impacts. Despite the importance of soil conservation practices (SCP) for the control of soil erosion and improvements in soil hydrological functions, limited information is available regarding the effects of SCP on sediment yield (SY) at the catchment scale. This study aimed to investigate the long‐term relationships between SY and land use, soil management, and rainfall in a small catchment. To determine the effects of anthropogenic and climatic factors on SY, rainfall, streamflow, and suspended sediment concentration were monitored at 10‐min intervals for 14 years (2002–2016), and the land use and soil management changes were surveyed annually. Using a statistical procedure to separate the SY effects of climate, land use, and soil management, we observed pronounced temporal effects of land use and soil management changes on SY. During the first 2 years (2002–2004), the land was predominantly cultivated with tobacco under a traditional tillage system (no cover crops and ploughed soil) using animal traction. In that period, the SY reached approximately 400 t·km?2·year?1. From 2005 to 2009, a soil conservation programme introduced conservation tillage and winter cover crops in the catchment area, which lowered the SY to 50 t·km?2·year?1. In the final period (2010–2016), the SCP were partially abandoned by farmers, and reforested areas increased, resulting in an SY of 150 t·km?2·year?1. This study also discusses the factors associated with the failure to continue using SCP, including structural support and farmer attitudes. 相似文献
3.
Vander Kaufmann Nilza Maria dos Reis Castro Cristóvão Vicente Scapulatempo Fernandes Gustavo Merten 《水文科学杂志》2013,58(12):2173-2185
AbstractSurface runoff and drainage were evaluated for southern Brazilian soils subjected to different rainfall intensities and management practices. Soils received up to four applications of simulated rainfall in sequences with one application per day. Seven lysimeters, each of 1 m3 volume, were used to measure drainage volume, with measurement of initial and final water content, times at which surface runoff and lysimeter drainage began, and the volume rates of flow. At the end of the second test, soils were subjected to two levels of disturbance (denoted by low and high soil movement) by opening furrows. These cultivation treatments altered the times at which lysimeter surface runoff and drainage were initiated, the rates of surface runoff, the final infiltration and internal drainage, and the components of the water balance throughout the series of trials. Mean times at which surface runoff was initiated in lysimeters subjected to greater soil disturbance were longer than those with little soil disturbance. Final infiltration rates were greater in lysimeters with little soil disturbance. It was also found that lysimeter surface runoff generation was influenced by the state of development of maize grown in the lysimeter.
Editor D. Koutsoyiannis; Associate editor G. Mahé 相似文献
4.
Estimating suspended sediment concentrations from turbidity measurements and the calibration problem 总被引：1，自引：0，他引：1
In situ turbidity meters are being increasingly used to generate continuous records of suspended sediment concentration in rivers. However, the usefulness of the information obtained depends heavily on the existence of a close relationship between fluctuations in suspended sediment concentration and turbidity and the calibration procedure that relates suspended sediment concentration to the turbidity meter's signal. This study assesses the relationship between suspended sediment concentration and turbidity for a small (1·19 km2) rural catchment in southern Brazil and evaluates two calibration methods by comparing the estimates of suspended sediment concentration obtained from the calibrated turbidity readings with direct measurements obtained using a USDH 48 suspended sediment sampler. With the first calibration method, the calibration relationship is derived by relating the turbidity readings to simultaneous measurements of concentration obtained from suspended sediment samples collected from the vicinity of the turbidity probe during flood events. With the second method, the calibration is based on the readings obtained from the turbidity meter when the probe immersed in samples of known concentration prepared using soils collected from the catchment. Overall, there was a close link between fluctuations in suspended sediment concentration and turbidity in the stream at the outlet of the catchment, and the estimates of sediment concentration obtained using the first calibration method corresponded closely with the conventionally measured sediment concentrations. However, use of the second calibration method introduced appreciable errors. When the estimated sediment concentrations were compared with the measured values, the mean errors were ± 122 mg l?1 and + 601 mg l?1 for the first and second calibration procedures respectively. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
5.
Ana L. Londero Jean P. G. Minella Fabio J. A. Schneider Dinis Deuschle Danrlei Menezes Olivier Evrard Madalena Boeni Gustavo H. Merten 《水文研究》2021,35(3):e14094
No-till (NT) is a conservation system that improves the hydrological regime of agricultural slopes by providing greater surface protection and benefits to the physical and hydrological properties of soils. However, the isolated use of NT is not enough to control runoff and its associated degradation processes. Therefore, this study aimed to evaluate the runoff of agricultural slopes under NT under different runoff control conditions by monitoring 63 rainfall events in two 2.4-ha zero-order catchments and 27 rainfall events in four 0.6-ha macroplots. The catchments are paired and similar in terms of the type of soil and relief, but different regarding the presence of terraces. The macroplots have different soil and crop management systems. By using monitoring techniques, the hyetographs and hydrographs revealed the influence of the different types of management on the catchments and macroplots and allowed rainfall characteristics, runoff volume, runoff coefficients, water infiltration, peak runoff, response times, and curve number to be analysed. The terraces positively affected the NT and controlled runoff and related variables, in addition to infiltration significantly increasing and runoff reducing in the terraced catchment. All the hydrological information assessed pointed to the positive effects provided by the presence of the terraces. The results in the macroplots showed that high amounts of phytomass and/or chiselling do not control runoff and its correlated variables in medium and high magnitude events. The study concludes by underlining the need for additional measures to control runoff (terraces), even in areas under NT and with high phytomass production. Additionally, the study emphasizes the importance of monitoring at the catchment scale to better understand the hydrological behaviour of agricultural areas and provide the necessary parameters to effectively control runoff. 相似文献
6.
Eric Christopher Merten Jacques Finlay Lucinda Johnson Raymond Newman Heinz Stefan Bruce Vondracek 《水文研究》2011,25(4):593-602
Wood deposited in streams provides a wide variety of ecosystem functions, including enhancing habitat for key species in stream food webs, increasing geomorphic and hydraulic heterogeneity and retaining organic matter. Given the strong role that wood plays in streams, factors that influence wood inputs, retention and transport are critical to stream ecology. Wood entrapment, the process of wood coming to rest after being swept downstream at least 10 m, is poorly understood, yet important for predicting stream function and success of restoration efforts. Data on entrapment were collected for a wide range of natural wood pieces (n = 344), stream geomorphology and hydraulic conditions in nine streams along the north shore of Lake Superior in Minnesota. Locations of pieces were determined in summer 2007 and again following an overbank stormflow event in fall 2007. The ratio of piece length to effective stream width (length ratio) and the weight of the piece were important in a multiple logistic regression model that explained 25% of the variance in wood entrapment. Entrapment remains difficult to predict in natural streams, and often may simply occur wherever wood pieces are located when high water recedes. However, this study can inform stream modifications to discourage entrapment at road crossings or other infrastructure by applying the model formula to estimate the effective width required to pass particular wood pieces. Conversely, these results could also be used to determine conditions (e.g. pre‐existing large, stable pieces) that encourage entrapment where wood is valued for ecological functions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
Ana L. Londero Jean P. G. Minella Fabio J. A. Schneider Dinis Deuschle Gustavo H. Merten Olivier Evrard Madalena Boeni 《水文研究》2021,35(7):e14286
No-till (NT) is a soil management system designed to protect soil resources from water erosion and provide numerous benefits compared to conventional tillage through the increase of organic matter inputs into the soil. However, NT in isolation is not sufficient to control erosion processes caused by an excessive production of surface runoff. This study evaluated soil losses on agricultural hillslopes under no-till characterized by contrasted water, soil, and crop management conditions. To this end, water and soil losses were monitored between 2014 and 2018 at two scales, including four macroplots (0.6 ha; 27 events) and two paired zero-order catchments (2.4 ha; 63 events). The resulting dataset covered a wide range of rainfall conditions that occurred in contrasted soil, crop, and runoff management conditions. Hyetographs, hydrographs, and sedigraphs were constructed, and these data were used to evaluate the impact of management on sediment yields, including that of terraces, scarification, and phytomass on sediment yield. The installation of terraces reduced sediment yield by 58.7%, mainly through surface runoff control. Crop management including an increased phytomass input efficiently controlled soil losses (63%), although it did not reduce runoff volume and peak flow. In contrast, scarification had no impact on runoff and soil losses. The current research demonstrated the need to combine the installation of terraces and leaving a high amount of phytomass on the soil to control surface runoff and erosion and reduce sediment yield. The current research therefore reinforces the relevance of the monitoring strategy conducted at the scale of macroplots and zero-order catchments to evaluate the impact of contrasted water, soil, and crop management methods and select the most effective conservation agriculture practices. 相似文献
8.
Stable isotopes, 2Hwater, 18Owater as well as 18Osulphate and 34Ssulphate, were used to study the flow system of shallow groundwater and soil water at the base area of a former leaching heap at the uranium mining area of Ronneburg, Germany. The flow paths and water‐retention times were estimated by comparison of δ2H and δ18O values in groundwater and soil water to the δ2H and δ18O signature of precipitation, giving distinctive inputs of summer or winter precipitation. The points of measuring the groundwater were divided into three categories with different flow conditions: rapid flow, stagnant conditions and a transition zone by hierarchical cluster analysis of δ2H and δ18O values of groundwater. The transit time of groundwater in the rapid flow area is less than 6 months, whereas water in the stagnant zone is stored for at least 1 year. In soil water, a clear response to different input signals is detectable only in the 30‐cm horizon (retention time is about 6 months), whereas at deeper levels a mixing with older water is taking place. The isotopic composition of the dissolved sulphate was used to identify oxidation of sulphides as the source of sulphate. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
9.
Anika Kötschau Georg Büchel Jürgen W. Einax Wolf von Tümpling Dirk Merten 《Environmental Earth Sciences》2014,72(6):2023-2031
On an uranium-mining-influenced area, sunflowers (Helianthus annuus) were grown on a small-scaled plot. Subsamples of sunflowers were harvested 34, 66, 96, 108, 140, and 170 days after sowing. Contents of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Th, U, Zn, and rare earth elements (REEs, La–Lu) were determined in the sunflower shoots, as well as total and bioavailable contents of these 25 elements in the soil taken on the day of sowing and after the last harvest. Shoot contents alone were not sufficient to evaluate the extraction capacity of the sunflowers. Instead total extracted masses (product of biomass and element content) had to be calculated. The total extracted mass increased for most of the elements until 140 days after sowing. Bioconcentration factors (BCFs) as ratio between element content in shoot and soil, were calculated for this time to evaluate the phytoextraction efficiency. BCFs ≥1 (relating total soil contents) and thus a very effective extraction was calculated for Cd. The BCFs, based on mobile soil contents, were ≥1 for all elements, except for U and REEs (La–Lu). Consequently, the sunflower is able to extract many elements effectively from the direct harmful soil fraction. To reduce the contents of Cd and Ni down to levels, where the mining-influenced area could be classified as arable land would require 55 and 207 sunflower growth cycles. Although this is quite a long time, the uranium-mining-influenced area could be successively remediated, while growing biofuel crops, without interfering with food production. 相似文献
10.
S. G. Tessema D. Mirgorodsky D. Merten A. Hildebrandt S. Attinger G. Büchel 《Environmental Earth Sciences》2013,70(2):821-837
Hydrochemical modeling, graphical methods, and different statistical techniques were applied to understand the nature of geological and hydrochemical processes in a shallow groundwater aquifer of the Jena biodiversity experimental field. Factor and cluster analyses were used to identify the governing underlying processes and to detect the spatial similarity between the sampling points. The hydrochemical modeling, using PHREEQC, was used to interpret the reactive minerals. Results of factor analysis indicated that there are five dominant factors which account for about 90 % of the variance of the chemical dataset in the cold season (March, April, November) and warm season (June, August). Factor analysis showed that 43 % of the variation in the cold season and 53 % of the variation in the warm season of the groundwater hydrochemical data are due to major cations and anions which reveals groundwater-geological matrix interaction. Redox and redox-sensitive elements are the next important factors and account for 15 % and 19 % variation in the cold season and warm season, respectively. The hydrochemical modeling using PHREEQC and X-ray diffraction results showed that calcite, dolomite, quartz, and siderite are reactive minerals and are responsible for changes in chemical composition. The hydrochemical data of the two seasons were also compared and the results showed that the groundwater chemistry of the study area varied seasonally in terms of some parameters such as mainly heavy metals (Ba, B, Fe, Mn, U, V, Zn, Sr, Ni), HCO3 ?, and DOC. 相似文献