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Comparison of slope length Factor Extraction in Hillslope Soil Erosion Model with Different DEM Resolutions

Agricultural Biotechnology 2020年第1期9卷 89-95页

作者： Feng KONG School of Public Policy and Management Tsinghua University Center for Crisis Management Research Tsinghua University Training Center China Meteorological Administration

In this study, non-cumulative slope length(NCSL) calculation method and spatial analytical calculation(SAC) method were respectively applied to extract slope length and slope length factor from 10 sample areas, which are located in Ansai County, north Shaanxi Province. The comparison of computation precision between variable DEM resolutions showed that NCSL was superior to SAC entirely. And the results were best when the DEM resolutions were 5 and 10 m. Besides, the results of slope length factor were nearly the same under the two conditions. So DEM of 10 m resolution can be used to extract slope length.

关键词： DEM Resolution slope length Precision differentiation Soil erosion model

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Rangeland hillslope lengths:A case study at the Walnut Gulch Experimental Watershed,southeastern Arizona

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International Soil and Water Conservation Research 2022年第4期10卷 597-609页

作者： Li Li Mark A.Nearing Philip Heilman Mary H.Nichols D.P.Guertin C.J.Williams School of Natural Resources and the Environment University of ArizonaTucsonAZ85705USA USDA-Agricultural Research Service Southwest Watershed Research CenterTucsonAZ85719USA

Rangeland hillslopes provide much of the sediment supplied to channel systems and their lengths exert a fundamental constraint on hillslope diffusive ***,information regarding lengths of rangeland hillslopes,and how best to estimate them,is *** this study,three groups of watersheds(10 in total)were selected from the Walnut Gulch Experimental Watershed according to their geology,soil and vegetation *** 1 watersheds were at lower elevations dominated by shrubs,Group 3 were at high elevations dominated by grass,and Group 2 were mixed shrub and *** hillslope lengths were calculated from 1 m-resolution DEMs using three methods:a flow routing algorithm,slope-area relationships,and inverted relationship with drainage *** that characterize the current watersheds,including Hack's exponent and coefficient,watershed shape coefficient,channel concavity and steepness,and surface roughness,were quantified and related to hillslope *** shows:(1)estimated hillslope lengths were different for the three methods and between the three groups of watersheds;(2)hillslope lengths that measured from the flow routing algorithm for the ten selected watersheds primarily ranged from 30 to 100 m,with a median value of 63.0 m,which was 20%e50%greater than those derived from slope-area plots or drainage densities;(3)hillslope lengths estimated from the flow routing method were greater in Group 3 watersheds than in Group 2 and then in Group 1 *** attributed these differences in hillslope lengths to the historic epeirogenic pulses,watershed and drainage network morphology,and differences in vegetation characteristics;(4)measured hillslope lengths from the flow routing algorithm were best correlated with hillslope relief,then surface roughness,channel steepness and *** results would benefit the applications of hydrological and erosion models in rangelands.

关键词： Rangeland hillslope slope length Drainage density slope-area relationship Hillslope hydrology

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Organic carbon losses by eroded sediments from sloping vegetable fields in South China

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Journal of Mountain Science 2017年第3期14卷 539-548页

作者： QIAN Jing ZHANG Li-ping WANG Wen-yan LIU Qiao Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition College of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China

Soil Organic Carbon （SOC） is the most important component of soil. Though small, it determines soil fertility and prevents soil losses. In this study, we examined relationships between the Particle-Size Distribution （PSD） of the eroded sediment and SOC loss, and evaluated the effects of plant coverage ratios （0%, 15%, 30%, 45%, 60% and 90%）, slope lengths （2 m, 4 m）, fertilizer treatments （unfertilized control （CK）, compound N-P-K fertilizer （CF）, and organic fertilizer （OF）） on SOC loss and the SOC enrichment ratio （ERsoc） in the eroded sediments. The experimental results showed that longer slope length and lower surface cover ratios produced larger surface runoff and the eroded sediments, resulting in larger SOC losses. The average SOC loss was greatest in the OF treatment and SOC loss was mainly associated with the eroded sediment. Surface runoff, which causes soil erosion, is a selective transportation process, hence there were more clay- sized particles （〈2 μm） and silt-sized particles （2-50μm） in the eroded sediments than in the original soils. SOC was enriched in the eroded sediments relative to in the original soil when ERsoc 〉 1. ERsoc was positively correlated with ERclay （〈2 pro）（R^2 = o.68） and ERie at （2-20 μm）（R2 = 0.63）, and from all the size particle categories of the original soil or the eroded sediments, more than 95% of SOC was concentrated in small-sized partieles （〈50 μm）. The distribution of SOC in different-sized particles of the original soil and the eroded sediment is primarily associated with clay-sized part-ides and fine silt-sized particles, thus we eonelude that as the eroded sediment partieles became finer, more SOC was absorbed, resulting in more severe SOC loss.

关键词： Fertilizer treatment Particle-sizedistribution Vegetation cover ratio Sediment yields slope length Soil organic carbon Surface runoff

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FREEZE/THAW EFFECTS ON RILL AND GULLY EROSION IN THE NORTHWESTERN WHEAT AND RANGE REGION

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International Journal of Sediment Research 2005年第3期20卷 48-56页

作者： D. K. MCCOOL,J. D. WILLIAMS Supervisory Agricultural Engineer Land Management and Water Conservation Research USDA-ARS Pullman WA USA Hydrologist Columbia Plateau Conservation Research Center USDA-ARS Pendleton OR.

Hydrology of the Northwestern Wheat and Range Region (NWRR) of the Pacific Northwest USA is dominated by winter events. Fifty-five to sixty-five percent of the precipitation occurs from November through March, and formation of impermeable frost, intensified by excessive tillage and tillage pans, has long been a major factor in rill and gully formation in the region. Saturated zones can form above tillage pans, freeze solid, and significantly reduce infiltration. Frost heaved surface soils thaw and weaken with warming temperatures or rain. Under these conditions, runoff from rain or snowmelt or a combination of the two is inevitable, concentrating in rills and channels, and carrying with it the loosened soil. slopes are frequently quite steep and there may be little deposition above the toe slope. Classical over-fall head-cut gullies are uncommon. Concentrated flow channels form because of collection of water from impervious areas such as conventionally tilled fall seeded small grains and bare grass seed fields. In some soils, gullies are created by seepage from saturated layers above permanent restrictive layers in the soil. Gullies can also result from terrace failures due to rodent burrows and low compaction at the time of construction. In naturally unconsolidated soil, rodent activity can lead to piping failures that remove large quantities of subsurface soil and can become gullies. Rill measurements on conventionally tilled fields in Oregon, Washington, and Idaho were used to determine coefficients for relationships between slope length and steepness and size of rills. This paper describes these studies and the results as well as analysis of long-term erosion and weather records from southeastern Washington.

关键词： Erosion slope length slope steepness Topography Pacific Northwest Frozen soil Thawing soil

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