岔巴沟流域汛期径流模拟及地表产流特征分析

气候变化是影响流域水文循环过程的重要驱动因素,近年来,气候变化导致极端降雨—径流事件的频繁发生对人类社会经济发展构成了严重的威胁。因此,迫切需要开展流域水文模拟和产流特征分析。土壤和水评估工具(SWAT)是一种具有物理机制的分布式水文模型,已被广泛用于评价变化环境下的水文过程。以黄土高原岔巴沟流域为研究区,通过利用与黄土高原地区产流模式更为接近的Green-Ampt下渗法驱动SWAT模型模拟了岔巴沟流域日尺度的水文过程,并以水文响应单元为分析对象,结合4个降雨—径流事件的地表产流量和地表径流系数分析了降雨强度和前期土壤含水量对不同土地覆被产流特征的影响。结果表明：(1)基于Green-Ampt下渗法驱动的SWAT模型率定期和验证期E_NS为0.76,0.74,R²为0.78,0.75,模型能够较好地模拟日尺度流域水文过程;(2)流域不同土地覆被下地表径流系数随最大雨强的增加呈显著上升趋势,且最大降雨强度大于16 mm/h后地表径流系数显著增加,当土地覆被为耕地时降雨转化为地表径流的比例最大,其次为草地和林地;(3)前期土壤含水量的大小可以揭示大...     

SWAT模型及其应用研究

利用数学模型来模拟水文、泥沙、非点源污染过程是流域管理中对特定管理措施的效果进行评估的重要工具,也是研究环境变化条件下水资源管理的重要手段。SWAT(Soil and Water Assessment Tool)模型是一个集成了遥感(RS)、地理信息系统(GIS)和数字高程模型(DEM)技术的目前国际流行分布式水文模拟工具。介绍了SWAT模型的发展历程、原理及特点,概述了SWAT模型目前在径流模拟、非点源污染模拟与控制、气候变化对水文响应的影响、模型参数敏感性分析方面的进展情况,并对SWAT模型今后的应用和改进方向作了初步探讨。     

岷江上游流域不同土地利用与气候变化的径流响应研究

土地利用和气候变化对流域水循环和水资源的影响已经引起社会的广泛关注。以岷江上游流域为研究对象,以分布式水文模型SWAT（Soil and Water Assessment Tool）为研究工具,建立不同土地利用和气候变化情景,通过模型的校准与验证,模拟不同土地利用和气候变化的径流响应。模拟结果表明随着森林植被面积的减小径流量增大,且裸地增加对径流影响最显著。模拟径流量随着降水的增加而增大,且增加量主要产生于雨季。     

基于SWAT模型的长江源土地利用/土地覆被情景变化对径流影响研究

土地利用/土地覆被变化对流域水资源循环过程及配置影响显著。为了研究土地利用/土地覆被情景变化对径流影响情况,以长江源流域为例,构建了适合该流域的分布式水文模型(SWAT),并模拟了不同土地利用/土地覆被情景下的流域年均径流量和径流深。模拟结果如下:当流域林地和草地面积增加到最大,径流量减少了16.7%,达到304.12m3/s,径流深减少14.02mm;当林地和草地面积减少,并逐步变为沙地、裸地,流域径流量增加16.1%,达到424.32m3/s,径流深也增加了13.49mm;当林地和草地面积减少到无植被覆盖,将使流域径流量增加28.4%,达到469.67m3/s,径流深增加23.88mm;在草地覆被最佳状况下,径流量有所增加,但增加幅度不大,只有5.6%,达到385.98m3/s,径流深增加4.72mm。综上所述,长江源流域林地和草地面积增加,导致径流减少,而沙地和裸地面积增加导致径流量增加。     

不同气候变化情景模式对大凌河流域径流的影响研究

为定量研究不同气候变化情景对大凌河径流的影响,探索气候变化下大凌河径流响应规律,基于分布式水文模型SWAT模型,通过设定不同气候变化情景(假定气温±2℃,降水量变化±10%),定量分析不同气候变化情景对大凌河径流的影响。研究成果表明:模型适合于大凌河径流模拟,模型参数率定期和验证期年径流模拟相对误差均在10%以内,确定性系数均达到0.8以上;气温升高2℃,流域径流增加5.8%,降雨量减少10%,流域径流量减少4.7%;降雨量增加10%,流域径流量增加4.3%。研究成果对于大凌河应对气候变化下水资源保护以及利用可提供参考。     

SWAT径流模拟及其对流域内地形参数变化的响应研究

SWAT(soil and water assessment tool)模型是一个集成遥感(RS)、地理信息系统(GIS)和数字高程模型(DEM)技术的基于水文过程的、具有较强物理机制的先进的分布式流域水文模型。为了进一步研究流域尺度内水文过程的时空变化规律,深入了解流域水文时空过程与气象、地—气界面条件及流域地貌特征间的关系,选取汉江上游马道流域,运用AVSWAT2000版模型进行1981—1985年间的年、月径流模拟,以月径流模拟的N—S模型效率系数为主要指标,率定出月模拟效果最佳时的各参数值。在此基础上从马道出水站点沿主河道往上游再选取6个控制点,运用River Tools软件提取出各个控制点控制流域和地形参数,分析参数变化情况,并在此基础上用前面率定好的参数来模拟各个控制点处的出口流量,分析径流对地形参数变化的响应关系,并提出了归一化径流—河道总长比指数。该指数受到河源密度的影响,在流域内的变化趋于常数1。     

HEC-HMS水文模型系统在汉江褒河流域的应用研究

基于地理信息系统和遥感技术的水文模型集成系统将成为未来水文循环过程研究的发展趋势。基于HEC-HMS水文模型系统,采用多种方案对位于汉江上游的褒河流域进行了降雨径流模拟。研究结果表明:基于DEM、遥感影像和土壤资料,并结合GIS技术推求反映流域下垫面特征的关键水文参数的方法可以与HEC-HMS水文模型系统很好地耦合。该模型对于我国湿润、半湿润山区的次洪模拟具有较好的适用性。     

土地利用和气候变化对流溪河水库流域径流的影响

[目的]探究径流对土地利用与土地覆被变化(LUCC)和气候变化的响应，为华南地区流溪河水库流域未来水资源的合理利用开发及社会经济可持续发展提供依据。[方法]通过构建分布式生态水文模型CHESS和设置情景模式，定量分析了土地利用和气候变化对径流的影响，同时结合CA-Markov模型，对流域未来径流变化进行了预测。[结果]CHESS模型在流溪河水库流域径流模拟中有很好的适用性，率定期的纳什系数(NS)为0.82,R²为0.91,验证期的NS为0.74,R²为0.86;土地利用变化方面，耕地转化为林地或草地会导致年均径流量减少，林地或草地转化为耕地会导致年均径流量的增大，耕地、林地、草地对径流形成的贡献能力为耕地>草地>林地；气候变化方面，年均径流量与降水量成正比，与温度成反比；2000—2020年，流域年均径流量逐渐增大，气候变化促进了径流的形成，土地利用变化抑制了径流的形成，且气候变化的影响占主要地位；未来预估情景下，2030年、2050年流域内建筑用地面积会增大，林地、草地面积会减小，耕地、水体面积变化不大，且在2040—2050...     

基于径流模拟的分布式水文模型参数的空间响应研究

SWAT（Soil and Water Assessment Tool）模型是一个集成遥感（RS）、地理信息系统（GIS）和数字高程模型（DEM）技术的基于水文过程的、具有较强物理机制的先进的分布式流域水文物理模型。为了进一步研究流域尺度内水文过程的时空变化规律,深入了解流域水文时空过程与气象、地-气界面条件及流域地貌特征间的关系,选取汉江上游马道流域,运用AVSWAT2000版模型进行1981-985年间的年、月径流模拟,以月径流模拟的N-S模型效率系数为主要指标,率定出月模拟效果最佳时（N-S模型效率系数达0.9427）的各参数值。在此基础上从马道出水站点沿主河道往上游再选取6个控制点,用前面率定好的参数来模拟各个控制点处的出口流量,并研究径流模拟的空间响应,提出归一化径流面积比指数。分析指出当蒸发量小于月平均降水量时,马道流域不同面积研究区的归一化径流面积比指数趋于稳定值,当蒸发量接近或者大于月平均降水量的时候,随着研究区面积由大到小的变化,归一化径流面积比指数波动加剧,研究区面积越小,归一化径流面积比指数值的偏移量越大。     

分布式水文模型的误差分析

分布式水文模型以其具有明确物理意义的参数结构和对空间分异性的全面反映,能够准确详尽地捕述和模拟流域内真实的降水径流过程而被广泛需求和关注。在模拟土地利用、土地覆盖、水土流失等各种变化过程的水文响应,面源污染、陆面过程、气候变化影响评价等诸多领域都有广泛的应用。模型的预报精度和误差至关重要．决定了模型的应用和推广。在分析分布式水文模型建立和验证过程的基础上,提出了模型的4类误差来源：被排除往外的因素引起的误差,实测历史记录资料的随机或系统误差,参数误差和模型结构误差,讨论了各类误差的分析与计算方法,为模型的发展和成长提供了依据。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.