Improving the SWAT forest module for enhancing water resource projections: A case study in the St. Croix River basin     

Qichun Yang  Xuesong Zhang  James E. Almendinger  Maoyi Huang  Guoyong Leng  Yuyu Zhou  Kaiguang Zhao  Ghassem R. Asrar  Xia Li  Jiali Qiu 《水文研究》2019,33(5):864-875

Insufficiently calibrated forest parameters of the Soil & Water Assessment Tool (SWAT) may introduce uncertainties to water resource projections in forested watersheds. In this study, we improved SWAT forest parameterization and phosphorus cycling representations to better simulate forest ecosystems in the St. Croix River basin, and we further examined how those improvements affected model projections of streamflow, sediment, and nitrogen export under future climate conditions. Simulations with improved forest parameters substantially reduced model estimates of water, sediment, and nitrogen fluxes relative to those based on default parameters. Differences between improved and default projections can be attributed to the enhanced representation of forest water consumption, nutrient uptake, and protection of soil from erosion. Better representation of forest ecosystems in SWAT contributes to constraining uncertainties in water resource projections. Results of this study highlight the importance of improving SWAT forest ecosystem representations in projecting delivery of water, sediment, and nutrients from land to rivers in response to climate change, particularly for watersheds with large areas of forests. Improved forest parameters and the phosphorus weathering algorithms developed in this study are expected to help enhance future applications of SWAT to investigate hydrological and biogeochemical consequences of climate change.  相似文献   

2014年秋季我国华西地区降水异常的成因分析   总被引：4，自引：4，他引：0  

司东  邵勰  孙冷  王启祎  李多 《气象》2015,41(4):508-513

2014年秋季,全国平均降水量较常年同期偏多,其中华西地区降水偏多明显。季内,我国华西地区降水阶段性变化显著。分析表明,秋季华西地区降水偏多可能与热带印度洋海温偏高有关。印度洋海温偏高,一方面有利于西北太平洋地区对流层低层异常反气旋式环流的发展和东南水汽输送的加强,另一方面印度洋海温的偏高有利于印度洋地区对流的活跃和西南水汽输送的加强。在中高纬地区,贝加尔湖地区为异常低槽区,易引导冷空气南下影响我国华西地区。同时,西太平洋副热带高压强度偏强及西伸脊点的偏西,综合导致华西地区秋季降水偏多。而华西地区降水的季内变化与西太平洋副热带高压的异常活动有关。  相似文献   

四川东部和重庆西部一次ＭＣＣ致洪暴雨过程综合分析     

井喜  艾丽华  廖瑞德 《陕西气象》2011,(1):1-7

吕梁山区出现局地大暴雨为小概率事件,在县局的订正预报中有很大的难度。2010年8月11日位于吕梁市东北端的岚县出现了106．2mm的大暴雨,而吕梁的其它县、市只出现中雨以下量级降水。本文分析了造成本次强降雨的高低空环流形势、主要影响系统、水汽条件、云图与雷达回波资料以及本县特殊的地形特征等结果表明：本次局地大暴雨天气是由高空短波槽、中层切变线、副热带高压边缘西南暖湿气流共同作用产生的;对流层低层强盛的偏南气流为大暴雨提供了源源不断的水汽;地面弱低压加强了辐合上升运动,特殊地形的抬升与阻挡作用,使强回波雨团长时间在迎风坡下的平坦地段停留,从而造成局地性的强降水。  相似文献   

Paleogene carbon isotope excursions in the Bunkers Hill borehole: Hampshire Basin, UK     

Emma Hodgson  Stephen T. Grimes  Gregory D. Price  Meriel E.J. Fitzpatrick  Malcolm B. Hart  Melanie J. Leng 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(3):460-471

This study demonstrates that the Bunkers Hill borehole, which is located within the Hampshire Basin, contains a carbon isotope excursion (CIE) in the Upnor Formation followed by a positive recovery from another CIE within the overlying Reading Formation. This study has also shown that the CIE in the Upnor Formation predates the Paleocene/Eocene Thermal Maximum (PETM), while the carbon isotope recovery at the base of the Reading Formation is most likely related to it. The positive carbon isotope trend, before a return to more negative values, seen throughout the majority of the Reading Formation can also be seen in coeval deposits in the Jubilee 404T borehole in the London Basin and in the Tienen Formation in the Doel and Kallo boreholes from the Belgium Basin. This indicates that this post-PETM carbon isotope signal may, therefore, be regional if not global in nature.  相似文献   

A 500 yr speleothem-derived reconstruction of late autumn–winter precipitation, northeast Turkey     

Catherine N. Jex  Andy Baker  Jonathan M. Eden  Warren J. Eastwood  Ian J. Fairchild  Melanie J. Leng  Louise Thomas  Hilary J. Sloane 《Quaternary Research》2011,75(3):399-405

A verified instrumental calibration of annually resolved δ¹⁸O for a stalagmite from Gümü?hane in northeast Turkey is presented and cross-validated using a ‘leave-one-out’ technique. The amount of late autumn to winter precipitation is negatively correlated with stalagmite δ¹⁸O between AD 1938 and 2004. The observed relationship is extrapolated back to ~ AD 1500 leading to the first long winter precipitation reconstruction for this region. Modern day October to January precipitation is linked to pressure fields in Western Russia. Anomalously lower reconstructed rainfall is recorded in AD 1540–1560 at which time higher pressure over the Caspian Sea region is inferred.  相似文献   

Inter-laboratory comparison of oxygen isotope compositions from biogenic silica     

Bernhard Chapligin  Melanie J. Leng  Anne Alexandre  Akira Ijiri  Aldo Shemesh  Ulrike Herzschuh  Hanno Meyer  Yusuke Okazaki  Zachary D. Sharp  Corinne Sonzogni  Florence Sylvestre  Ruth Yam 《Geochimica et cosmochimica acta》2011,75(22):7242-7256

Several techniques have been introduced in the last decades for the dehydration and release of O₂ from biogenic silica (opal-A) for oxygen-isotope analysis. However, only one silica standard is universally available: a quartz standard (NBS28) distributed by the IAEA, Vienna. Hence, there is a need for biogenic silica working standards. This paper compares the existing methods of oxygen-isotope analyses of opal-A and aims to characterize additional possible working standards to calibrate the δ¹⁸O values of biogenic silica. For this purpose, an inter-laboratory comparison was organized. Six potential working standard materials were analysed repeatedly against NBS28 by eight participating laboratories using their specific analytical methods. The materials cover a wide range of δ¹⁸O values (+23 to +43‰) and include diatoms (marine, lacustrine), phytoliths and synthetically-produced hydrous silica. To characterize the proposed standards, chemical analyses and imaging by scanning electron microscopy (SEM) were also performed. Despite procedural differences at each laboratory, all methods are in reasonable agreement with a standard deviation (SD) for δ¹⁸O values between 0.3‰ and 0.9‰ (1σ). Based on the results, we propose four additional biogenic silica working standards (PS1772-8: 42.8‰; BFC: 29.0‰; MSG60: 37.0‰; G95-25-CL leaves: 36.6‰) for δ¹⁸O analyses, available on request through the relevant laboratories.  相似文献   

2011年度地理学基金项目评审与成果分析   总被引：1，自引：1，他引：0  

冷疏影  李本纲  赵小蓉  刘志刚  张运林  王君波  林耿  程昌秀 《地球科学进展》2011,26(12):1310-1321

着重分析2011年度面上项目、青年基金项目及地区基金项目的申请与资助情况,2010年度在研及结题项目的进展情况,以及2012年度地理学基金管理将重点关注的问题。  相似文献   

THE STRATEGIC STRAIT WITH SPECIAL REFERENCE TO THE MALACCA STRAITS1     

Allan Chia  Lee Yong Leng 《Singapore journal of tropical geography》1988,8(2):97-113

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New OSL dating of UK loess: indications of two phases of Late Glacial dust accretion in SE England and climate implications     

Michèle L. Clarke  Antoni E. Milodowski  Jon E. Bouch  Melanie J. Leng  Kevin J. Northmore 《第四纪科学杂志》2007,22(4):361-371

Windblown dust deposits or loess, locally known in the UK as brickearth, blanket many parts of southern England outside the limits of the British and Irish Ice Sheet. The best‐studied loess exposures occur in Kent, southeast England, where the deposits are believed to be Late Glacial in age. New sedimentological evidence is presented for phases of accretion with two distinct units, a calcareous brickearth exhibiting periglacial cryoturbation and a non‐calcareous, massive brickearth. Optically stimulated luminescence (OSL) dating has been applied to chemically isolated modal quartz silts to derive a chronology for sediment accretion and to better understand the palaeoclimatic significance of these deposits. © British Geological Survey/Natural Environment Research Council copyright 2007. Reproduced with the permission of BGS/NERC. Published by John Wiley & Sons, Ltd.  相似文献   

Synchronous climate anomalies in the western North Pacific and North Atlantic regions during the last 14,000 years     

Y.T. Hong  B. Hong  Q.H. Lin  Y. Shibata  Y.X. Zhu  X.T. Leng  Y. Wang 《Quaternary Science Reviews》2009,28(9-10):840-849

A peat cellulose δ¹⁸O record spanning around 14,000 years from the Hani peat mire in northeastern China reveals several abrupt temperature anomalies in the period from the last deglaciation through the Holocene. The timing of these anomalies coincides well with the notable cooling events recorded respectively using the GISP2 ice core and ice-rafted sediment of the North Atlantic Ocean, such as the Older Dryas, Inter-Allerød, Younger Dryas, and the nine ice-rafted debris events. The results demonstrate that this repeating pattern of abrupt temperature deterioration is not limited to the North Atlantic area at high latitude but also exists in the western North Pacific region at middle latitude. The synchronous temperature anomalies possibly are resulted from the joint effects of meltwater discharge into the North Atlantic Ocean and reduced solar activity. In the period from around 8600 to 8200 cal. yrs BP the Hani peat record shows a broad δ¹⁸O peak that may reflect compound climate signals resulting from the two kinds of forcing factors: the temperature drop related to reduced solar activity at around 8600–8250 cal. yrs BP, and the temperature anomaly attributed to the meltwater effect at around 8220 ± 70 cal. yrs BP. This result may provide palaeo-temperature evidence for existence of the sharp “8.2 k” event in the western North Pacific region. In addition, our results have revealed that in the period from the last deglaciation through the Holocene the synchronous temperature anomalies before and after the “8.2 k” event seem to be related to meltwater outflow and reduced solar activity, respectively. It is important that the all temperature anomalies—whether because of reduced solar activity in the late Holocene or from meltwater discharge in the early Holocene—are accompanied by an abrupt decline in the Indian Ocean summer monsoon and abrupt strengthening of the East Asian summer monsoon. It is likely that reduced solar activity and meltwater outflow appear to modulate Earth system changes in the same direction. The influences could be compounded. Reduced solar activity and meltwater outburst both appear to act as triggers for occurrence of the El Niño phenomenon in the equatorial Pacific Ocean, which may result in broad teleconnections between the temperature anomaly in the Northern Hemisphere and abrupt variation of the Asian monsoon.  相似文献