Modelling the impacts of subsurface drainage on surface runoff and sediment yield in the Le Sueur Watershed,Minnesota, USA     

F. K. Maalim 《水文科学杂志》2013,58(3):570-586

Abstract

Tile drainage influences infiltration and surface runoff and is thus an important factor in the erosion process. Tile drainage reduces surface runoff, but questions abound on its influence on sediment transport through its dense network and into the stream network. The impact of subsurface tiling on upland erosion rates in the Le Sueur River watershed, USA, was assessed using the Water Erosion Prediction Project (WEPP) model. Six different scenarios of tile drainage with varying drainage coefficient and management type (no till and autumn mulch-till) were evaluated. The mean annual surface runoff depth, soil loss rate and sediment delivery ratio (SDR) for croplands, based on a 30-year simulation for the watershed with untiled autumn mulch-till (Scenario 1), were estimated to be 83.5 mm, 0.27 kg/m² and 86.7%, respectively; on no-till management systems (Scenario 4), the respective results were 72.3 mm, 0.06 kg/m² and 88.2%. Tile drains reduced surface runoff, soil loss and SDR estimates for Scenario 1 by, on average, 14.5, 8.1 and 7.9%, respectively; and for Scenario 4 by an estimated 31.5, 22.1 and 20.2%, respectively. The impact of tile drains on surface runoff, soil loss and SDR was greater under the no-till management system than under the autumn mulch-till management system. Comparison of WEPP outputs with those of the Soil Water Assessment Tool (SWAT) showed differences between the two methods.

Editor Z.W. Kundzewicz

Citation Maalim, F.K. and Melesse. A.M., 2013. Modelling impacts of subsurface drainage on surface runoff and sediment yield in the Le Sueur Watershed in Minnesota, USA. Hydrological Sciences Journal, 58 (3), 570–586.  相似文献   

Seismic stability analysis of piled embankments: A multiphase approach     

Quang Thai Son  Ghazi Hassen  Patrick de Buhan 《国际地质力学数值与分析法杂志》2010,34(1):91-110

The seismic stability analysis of an embankment lying over a soft foundation soil reinforced by a group of vertical piles is performed within the framework of the upper bound kinematic approach of yield design. The analysis is based on a previously developed ‘multiphase’ model of the reinforced ground, which explicitly accounts for the shear and bending resistances of the piles. Making use of appropriate failure mechanisms involving shear zones across which the reinforcements are continuously deforming, along with ‘plastic hinge’ surfaces, upper bound estimates to the critical seismic coefficient of the structure are derived. The results, which are confirmed by the simulations obtained from a finite element elastoplastic code, give clear evidence of the key role played by the bending strength capacities of the piles in ensuring the stability of the pile reinforced embankment. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Predicting the dependency of a degree of saturation on void ratio and suction using effective stress principle for unsaturated soils     

David Mašín 《国际地质力学数值与分析法杂志》2010,34(1):73-90

The paper presents an approach to predicting variation of a degree of saturation in unsaturated soils with void ratio and suction. The approach is based on the effective stress principle for unsaturated soils and several underlying assumptions. It focuses on the main drying and wetting processes and does not incorporate the effects of hydraulic hysteresis. It leads to the dependency of water retention curve (WRC) on void ratio, which does not require any material parameters apart from the parameters specifying WRC for the reference void ratio. Its validity is demonstrated by comparing predictions with the experimental data on four different soils taken over from the literature. Good correlation between the measured and predicted behaviour indirectly supports applicability of the effective stress principle for unsaturated soils. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Sensitivity of soil parameters in unsaturated zone modelling and the relation between effective,laboratory and in situ estimates     

J. Mertens  H. Madsen  M. Kristensen  D. Jacques  J. Feyen 《水文研究》2005,19(8):1611-1633

Simulation of soil moisture content requires effective soil hydraulic parameters that are valid at the modelling scale. This study investigates how these parameters can be estimated by inverse modelling using soil moisture measurements at 25 locations at three different depths (at the surface, at 30 and 60 cm depth) on an 80 by 20 m hillslope. The study presents two global sensitivity analyses to investigate the sensitivity in simulated soil moisture content of the different hydraulic parameters used in a one‐dimensional unsaturated zone model based on Richards' equation. For estimation of the effective parameters the shuffled complex evolution algorithm is applied. These estimated parameters are compared to their measured laboratory and in situ equivalents. Soil hydraulic functions were estimated in the laboratory on 100 cm³ undisturbed soil cores collected at 115 locations situated in two horizons in three profile pits along the hillslope. Furthermore, in situ field saturated hydraulic conductivity was estimated at 120 locations using single‐ring pressure infiltrometer measurements. The sensitivity analysis of 13 soil physical parameters (saturated hydraulic conductivity (K_s), saturated moisture content (θ_s), residual moisture content (θ_r), inverse of the air‐entry value (α), van Genuchten shape parameter (n), Averjanov shape parameter (N) for both horizons, and depth (d) from surface to B horizon) in a two‐layer single column model showed that the parameter N is the least sensitive parameter. K_s of both horizons, θ_s of the A horizon and d were found to be the most sensitive parameters. Distributions over all locations of the effective parameters and the distributions of the estimated soil physical parameters from the undisturbed soil samples and the single‐ring pressure infiltrometer estimates were found significantly different at a 5% level for all parameters except for α of the A horizon and K_s and θ_s of the B horizon. Different reasons are discussed to explain these large differences. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Staurolite porphyroblast controls on local bulk compositional and microstructural changes during decompression of a St–Bt–Grt–Crd–And schist (Ancasti metamorphic complex,Sierras Pampeanas,W Argentina)     

S. O. VERDECCHIA  J. RECHE  E. G. BALDO  E. SEGOVIA‐DIAZ  F. J. MARTINEZ 《Journal of Metamorphic Geology》2013,31(2):131-146

The staurolite–biotite–garnet–cordierite–andalusite–plagioclase–muscovite–quartz metapelitic mineral assemblage has been frequently interpreted in the literature as a result of superimposition of various metamorphic events, for example, in polymetamorphic sequences. The assemblage was identified in schists from the Ancasti metamorphic complex (Sierras Pampeanas of Argentina) where previous authors have favoured the polymetamorphic genetic interpretation. A pseudosection in the MnNCKFMASH system for the analysed XRF bulk composition predicts the stability of the sub‐assemblage staurolite–biotite–garnet–plagioclase–muscovite–quartz, and the compositional isopleths also agree with measured mineral compositions. Nevertheless, the XRF pseudosection does not predict any field with staurolite, andalusite and cordierite being stable together. As a result of more detailed modelling making use of the effective bulk composition concept, our interpretation is that the staurolite–biotite–garnet–plagioclase–muscovite–quartz sub‐assemblage was present at peak metamorphic conditions, 590 °C and 5.2 kbar, but that andalusite and cordierite grew later along a continuous P–T path. These minerals are not in mutual contact and are observed in separate microstructural domains with different proportions of staurolite. These domains are explained as a result of local reaction equilibrium subsystems developed during decompression and influenced by the previous peak crystal size and local modal distribution of staurolite porphyroblasts that have remained metastable. Thus, andalusite and cordierite grew synchronously, although in separate microdomains, and represent the decompression stage at 565 °C and 3.5 kbar.  相似文献   

Using modified state surface approach to select parameter values in the Barcelona basic model     

Xiong Zhang  Ming Xiao 《国际地质力学数值与分析法杂志》2013,37(12):1847-1866

The Barcelona basic model (BBM) successfully explained many key features of unsaturated soils and received extensive acceptance. It is also one of the few elastoplastic constitutive models for unsaturated soils that have been implemented within finite element codes and applied to the analysis of real boundary value problems. The BBM was proposed in incremental forms according to theories of soil plasticity in which individual aspects of the isotropic virgin behavior are controlled by multiple parameters, whereas at the same time, a single parameter controls more than one aspect of soil behavior. Although a variety of methods have been recently developed for calibrating model parameters for elastoplastic soil models, at present, there are no well‐established, simple, and objective methods for selecting parameter values in the BBM from laboratory tests. This has been one of the major obstacles to the dissemination of this constitutive model beyond the research context. This article presents an optimization approach especially developed for simple and objective identification of material parameters in the BBM. This is achieved by combining a modified state surface approach, recently proposed to model the elastoplastic behavior of unsaturated soils under isotropic stress conditions, with the Newton or quasi‐Newton method to simultaneously determine the five parameters governing isotropic virgin behavior in the BBM. The comparison between results using the proposed method and an existing method for the same laboratory tests was discussed from which the simplicity and objectivity of the proposed method were evaluated. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Improvement in the calculation of anti-Stokes energy transfer and experimental justification based on Er_0.01Yb_xY_{1 - 0.01 - x}VO₄ crystal     

陈晓波  卢建  张蕴芝  徐小灵  冯宝华  王策  Gregory J. Salamo  杨国建 《海洋学报(英文版)》2010,29(9)

The improvement on the calculation of anti-Stokes energy transfer rate is studied in the present work. The additional proportion coefficient between Stokes and anti-Stokes light intensities of quantum Raman scattering theory as compared with the classical Raman theory is introduced to successfully describe the anti-Stokes energy transfer. The theoretical formula for the improvement on the calculation of anti-Stokes energy transfer rate is derived for the first time in this study. The correctness of introducing coefficient exp{ΔE / kT} from well-known Raman scatter theory is demonstrated also. Moreover, the experimental lifetime measurement in Er_0.01Yb_xY_{1 - 0.01 - x}VO₄ crystal is performed to justify the validity of our important improvement in the original phonon-assisted energy transfer theory for the first time.  相似文献   

Introducing a transferable fishing day management regime for Pacific Island countries     

Steven Shanks 《Marine Policy》2010

On 1 December 2007, eight ‘Small Island Developing States’ in the Western and Central Pacific Ocean implemented a management regime restricting the total number of days fished by tuna purse seine vessels within their waters, commonly referred to as the Vessel Day Scheme (VDS). The VDS is seen as one component of management arrangements to reduce fishing mortality on bigeye and yellowfin tuna, constrain fishing effort, and increase the rate of return from access fees by Distant Water Fishing Nations.  相似文献   

Faithful quantum secure direct communication protocol against collective noise     

杨静  王川  张茹 《海洋学报(英文版)》2010,29(11)

An improved quantum secure direct communication (QSDC) protocol is proposed in this paper. Blocks of entangled photon pairs are transmitted in two steps in which secret messages are transmitted directly. The single logical qubits and unitary operations under decoherence free subspaces are presented and the generalized Bell states are constructed which are immune to the collective noise. Two steps of qubit transmission are used in this protocol to guarantee the security of communication. The security of the protocol against various attacks are discussed.  相似文献   

A record of Lateglacial/Holocene environmental change from a high‐elevation site in the Intermountain West,USA     

Andrea Brunelle  Thomas A. Minckley  Elliott Lips  Paul Burnett 《第四纪科学杂志》2013,28(1):103-112

Records of past vegetation and fire history can be complicated by changes in the depositional environment of a sampling location. However, these changes can alternatively be used as a measure of climate variability. Our study site, ca. 18.0 cal. ka BP record from Little Brooklyn Lake, Wyoming, located near the crest of the Snowy Range, records three moisture states. Initially, the lake was likely a glacier‐fed pond indicated by the presence of Pediastrum algae colonies. Around 13.0 cal. ka BP this pond transitioned to a meadow environment, suggested by the loss of Pediastrum algae colonies and slow sedimentation rates. Meadow conditions were maintained until ca. 5.0 cal. ka BP when Pediastrum algae colony abundance increased,indicating the formation of a shallow lake. From 18.0 to ca. 5.0 cal. ka BP, the pollen record is suggestive of alpine vegetation conditions with relatively high spruce and herbaceous taxa. Low charcoal influx also characterizes the period between 18.0 and 5.0 cal. ka BP. After 5.0 cal. ka BP, the coincidence of the formation of shallow lake and pollen data, indicating a shift to a spruce and fir forest, suggests an increase in effective moisture. Fire remained rare in this basin over the entire record, however, once the lake established sedimentation rates and charcoal influx increased. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献