Seasonal variations in the influence of vegetation cover on soil water on the loess hillslope

Soil water is the key factor that restricts the restoration of the local ecological systems in the Loess Plateau of China.Studying the effects of vegetation types on soil water and its seasonal variation helps to understand hydrological characteristics and provides insights into the sustainable restoration of vegetation.Therefore,the Caijiachuan watershed was chosen as the research object to investigate the water status of a 0-10 m soil layer under different vegetation types including Pinus tabulaeformis,Robinia pseudoacacia,Platycladus orientalis,apple orchard,natural forestland,farmland and grassland.By comparing the difference between soil water of different land use types and that of grassland during the same period,the seasonal changes of soil water status of different types were judged.The results show that(1)in the 0-10 m soil layer,the largest value of soil water content was in the0.3-0.4 m layer,and the lowest was in the 5.6-5.8 m layer.The depths at which the vegetation cover influenced the soil water were up to 10 m;(2)among summer,fall and spring,the soil water storage wasthe highest in the fall.In addition,the lowest value of relative accumulation was in the fall,which was the period in which the soil water recovered;(3)the soil water in the 0-10 m layer was in a relatively deficient state in the artificial forestlands,apple orchards and native forestlands,while the relative accumulation was in the farmland.In addition,the relative deep soil layers(8-10 m)had more serious deficits in the areas in which P.tabulaeformis,R.pseudoacacia and the apple orchard grew;(4)during the study period,the farmland in the summer had the largest relative accumulation(182.71 mm),and the land under R.pseudoacacia in the fall had the lowest relative deficit(512.20 mm).In the Loess Plateau,vegetation cover will affect the change of deep soil moisture and artificial forest will cause soil water loss in different degrees.

Effects of rainfall regime and its character indices on soil loss at loessial hillslope with ephemeral gully

Understanding the relationship between hillslope soil loss with ephemeral gully and rainfall regime is important for soil loss prediction and erosion control. Based on 12-year field observation data, this paper quantified the rainfall regime impacts on soil loss at loessial hillslope with ephemeral gully. According to three rainfall parameters including precipitation(P), rainfall duration(t), and maximum 30-minute rainfall intensity(I_(30)), 115 rainfall events were classified by using K-mean clustering method and Discriminant Analysis. The results showed that 115 rainfall events could be divided into three rainfall regimes. Rainfall Regime 1(RR1) had large I_(30) values with low precipitation and short duration, while the three rainfall parameters of Rainfall Regime 3(RR3) were inversely different compared with those of RR1; for Rainfall Regime 2(RR2), the precipitation, duration and I_(30) values were all between those of RR1 and RR3. Compared with RR2 and RR3, RR1 was the dominant rainfall regime for causing soil loss at the loessial hillslope with ephemeral gully, especially for causing extreme soil loss events. PI30(Product of P and I_(30)) was selected as the key index of rainfall characteristics to fit soil loss equations. Two sets oflinear regression equations between soil loss and PI_(30) with and without rainfall regime classification were fitted. Compared with the equation without rainfall regime classification, the cross validation results of the equations with rainfall regime classification was satisfactory. These results indicated that rainfall regime classification could not only depict rainfall characteristics precisely, but also improve soil loss equation prediction accuracy at loessial hillslope with ephemeral gully.

Effects of heterogeneity distribution on hillslope stability during rainfalls

The objective of this study was to investigate the spatial relationship between the most likely distribution of saturated hydraulic conductivity(Ks) and the observed pressure head(P) distribution within a hillslope. The cross-correlation analysis method was used to investigate the effects of the variance of ln Ks, spatial structure anisotropy of ln Ks, and vertical infiltration flux(q) on P at some selected locations within the hillslope. The cross-correlation analysis shows that, in the unsaturated region with a uniform flux boundary, the dominant correlation between P and Ksis negative and mainly occurs around the observation location of P. A relatively high P value is located in a relatively low Kszone, while a relatively low P value is located in a relatively high Kszone. Generally speaking, P is positively correlated with q/Ksat the same location in the unsaturated region. In the saturated region, the spatial distribution of Kscan significantly affect the position and shape of the phreatic surface. We therefore conclude that heterogeneity can cause some parts of the hillslope to be sensitive to external hydraulic stimuli(e.g., rainfall and reservoir level change), and other parts of the hillslope to be insensitive. This is crucial to explaining why slopes with similar geometries would show different responses to the same hydraulic stimuli, which is significant to hillslope stability analysis.

Temporal stability analysis of soil moisture along a coniferous forest hillslope with subtropical monsoon climate in southwest China

Soil water content(SWC)plays a crucial role in simulating hydrological process,guiding reforestation and controlling soil erosion in mountainous regions.Spatial-temporal variability of SWC increases the difficulty of quantifying SWC pattern in the prediction of soil moisture.Temporal stability analysis of SWC can reduce the labor consuming and simplify the costly field monitoring.This study aimed to evaluate the temporal stability of SWC at hourly,daily and monthly temporal periods and its controlling factors at a hillslope in the Three Gorges region.The SWC of five soil depths was monitored at 5 topographic locations(toe,lower,middle,upper and top slope positions)along a 170 m hillslope in the Three Gorges region(110°04'~112°04'E,29°53'~31°34'N),Yichang City,Hubei Province,China from May 4^(th),2018 to May 3^(rd),2019.The results showed thatthe coefficient of variation of SWC ranged from 4%to 49%,which increased with rising soil depth within 40 cm but thereafter decreased.However,the high Spearman's rank coefficients(P<0.05)indicated strong temporal stability at three temporal periods.Therepresentative locations(RLs)varied in the different soil depths,which weretoe,upper and middle slope positions at 0~40,40~60 and 60~80 cm depthsof the investigated hillslope,respectively.Saturated hydraulic conductivity served as adominant factor controlling the temporal stability of SWC.The result advances our thorough understanding of hydrology and soil water resource in the Three Gorges region.

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

Rangeland hillslopes provide much of the sediment supplied to channel systems and their lengths exert a fundamental constraint on hillslope diffusive processes.However,information regarding lengths of rangeland hillslopes,and how best to estimate them,is limited.In this study,three groups of watersheds(10 in total)were selected from the Walnut Gulch Experimental Watershed according to their geology,soil and vegetation characteristics.Group 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 grass.Their hillslope lengths were calculated from 1 m-resolution DEMs using three methods:a flow routing algorithm,slope-area relationships,and inverted relationship with drainage density.Parameters 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 lengths.Results 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 watersheds.We 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 concavity.These results would benefit the applications of hydrological and erosion models in rangelands.

Impact of hillslope vegetation restoration on gully erosion induced sediment yield

Facing the eco-environmental construction on the Loess Plateau, especially the vegeta-tion restoration in the semiarid areas, as well as the dam system engineering construction that is about to start, how can the vegetation restoration gain the optimum ecological benefits following the improvement of the preservation rates of trees and grass on the basis of guaranteeing water storage and silt trapping effects? What techniques should be taken to restore vegetation? These questions critical to environmental management on the Loess Plateau have to be settled urgently. According to the different macroscopic spatial distribution patterns of forest and grass on the Loess Plateau, this paper analyzes the macroscopic hillslope and gully management relationship in the middle Yellow River and weight of natural and human factors in erosion-induced sediment yield in the context of environmental background of the major silt producing areas. In light of the current status of the inte-grated management of small watersheds and soil and water conservation measure arrangement schemes of hillslopes and gullies on the Loess Plateau, this paper discusses the impact of vegetation restoration on gully erosion induced sediment yield and the effect of vegetation caused sediment re-duction. Studies indicate that there exists an erosional environmental background related to the natural and human activities in the sediment yield peak values of the sandy and coarse sandy areas in the middle Yellow River, sediment yield modulus is closely related to the synthetic effect of environ-mental elements, and the rainstorms, reclamation rate and forest coverage are the main factors af-fecting sediment yield modulus in the sandy and coarse sandy areas. The key to control soil erosion in the sandy and coarse sandy areas is the conversion of farmland into forestland and grassland, the reduction of reclamation rate and the increase of tree and grass vegetation. Small catchment man-agement should adhere to the principle of simultaneous control of hillslope and gully erosion and combination of biological measures with engineering measures. Engineering measures play an im-portant role in the hillslope vegetation restoration in the initial period. Vegetation restoration can result in a reduction of erosion induced sediment yield in gullies of Yangjiagou by over 75%.

Spatial distribution of surface rock fragment on hillslopes in a small catchment in wind-water erosion crisscross region of the Loess Plateau

The cover and size distributions of surface rock fragment in hillslopes were investigated by using digital photographing and treating technique in a small catchment in wind-water erosion crisscross region of the Loess Plateau. The results indicated that the maximal cover of rock fragment was pre-sented at mid-position in steep hillslope. Rock fragment presented a general decreasing-trend along the hillslope in gentle hillslope. Rock fragment cover was positively related to gradient, rock fragment size decreased generally along the hillslope, and the size reduced with the gradient. The mean size of rock fragment was at a range of 6―20 mm in the steep hillslope, rock fragment size > 50 mm was rarely presented. The covers of rock fragment at different positions were markedly related to the quantities of rock fragment < 40 mm. The area of rock fragment of 2―50 mm accounted for 60% or more of the total area, dominating the distribution of rock fragment in the hillslopes.

Effect of Hillslope Gradient on Vegetation Recovery on Abandoned Land of Shifting Cultivation in Hainan Island,South China

In the present study, we investigated the effect of hillslope gradient on vegetation recovery on abandoned land of shifting cultivation In Hainan Island, south China, by measuring community composition and structure of 25-year-old secondary forest fallows along a hillslope gradient （up-, middle-, and down-slope position）. A total of 49 733 free-standing woody plant stems higher than 10 cm and belonging to 170 species, 112 genera, and 57 families was found in the three l-hm2 investigation plots. Stem density was highest in the down-slope stand and lowest in the up-slope stand. Species richness and the Shannon-Wiener Index were both highest in the middle-slope stand, and lower In the down-slope and up-slope stands. The recovery forest fallows on different hiUslope positions were all dominated by a few species. The five most abundant species accounted for 70.1%, 58.8%, and 72.9% of total stem densities in stands in the up-, middle-, and down-slope positions, respectively. The five species with the greatest basal areas accounted for 74.5%, 84.3%, and 74.7% of total stem basal area for the up-, middle-, and down-slope positions, respectively. The number of low-density species （stem abundance less than five） Increased from the up-slope position downward. Of the nine local common species among three different functional groups, the short-lived pioneer species dominated the up-slope position, but long-lived pioneer species dominated the middle- and down-slope positions. The climax species of primary tropical lowland rain forest was found in the downslope position. Both the mean diameter at breast height （DBH） and mean height of the trees Increased with decreasing hillslope gradient. The stem density and basal area in different size classes were significantly different in stands In different slope positions. Our results indicated that the rate of secondary succession varies, even over small spatial scales caused by the hlllslope gradient, in early vegetation recovery.

Hydrological Responses and Flow Pathways in an Acrisol on a Forested Hillslope with a Monsoonal Subtropical Climate

The nature of subsurface flow depends largely on hydraulic conductivity of the vadoze zone, permeability of the underlying bedrock, existence of soil layers differing in hydraulic properties and macropore content, soil depth, and slope angle.Quantification of flow pathways on forested hillslopes is essential to understand hydrological dynamics and solute transport patterns.Acrisols, with their argic Bt horizons, are challenging in this respect.To further elucidate flow pathways of water and short-term variability of soil moisture patterns in Acrisols, a field study was conducted on a forested hillslope in a sub-catchment of the Tie Shan Ping(TSP)watershed, 25 km northeast of Chongqing City, China.This catchment is covered by a mixed secondary forest dominated by Masson pine(Pinus massoniana).Soil saturated hydraulic conductivity(K sat) was significantly reduced at the interface between the AB and Bt horizons(2.6 × 10^(-5) vs.1.2 × 10^(-6) m s^(-1)), which led to that the flow volume generated in the Bt horizon was of little quantitative importance compared to that in the AB horizon.There was a marked decrease in porosity between the OA and AB horizons, with a further decrease deeper in the mineral subsoil.Especially, the content of soil pores > 300 μm was higher in the AB horizon(14.3%)than in the Bt horizon(6.5%).This explained the difference in soil K sat values.This study showed that Bt horizon had limited water transport capability, forcing part of the infiltrated rainwater as interflow through the OA and AB horizons.Thus, the topsoil responded quickly to rainfall events, causing frequent cycles of saturation and aeration of soil pores.

A hillslope version of the revised Morgan,Morgan and Finney water erosion model

The revised Morgan,Morgan and Finney(rMMF)water erosion model calculates annual surface runoff and soil loss from field-sized areas.The original version of the rMMF is neither suited to calculate water erosion along irregular hillslopes,nor capable to allow infiltration of once generated surface runoff at places where the runoff speed slows down,and infiltration could occur under natural conditions.The aim of this article is to describe a new hillslope version of the rMMF model that allows infiltration of surface runoff,and to show examples of soil erosion modelling along real and hypothetical hillslopes.The new hillslope version(hMMF)splits the entire hillslope into a number of sections that have individual properties,such as slope angle,slope length,soil properties and vegetation characteristics.The surface runoff along the slope is calculated by summing the volume of surface runoff generated in a particular section with the surface runoff coming from the immediate upsiope section.The related sediment transport is calculated for each section using the calculated detachment for the section,the sediment coming from the upsiope section and the transport capacity.A new variable is introduced to account for infiltration of surface runoff and allows simulating the effects of soil and water conservation structures on water erosion.The model was tested using measured data from plots in Africa,Asia,the US and Europe,as well as for a surveyed hillslope in Tunisia(Barbara watershed).Overall,the performance of the hMMF was reasonable for surface runoff and poor for soil loss when recommended input variable values are used.Calibration of the model resulted in a good performance,which shows the capability of the hMMF model to reproduce measured surface runoff and erosion amounts.In addition,realistic water erosion patterns on hillslopes with soil and water conservation can be simulated.

Field experiments on quantifying the contributions of Coreopsis canopies and roots to controlling runoff and erosion on steep loess slopes

Grass recovery is often implemented in the loess area of China to control erosion.However,the effect mechanisms of grass cover on runoff erosion dynamics on steep loess hillslopes is still not clear.Taking the typical forage species(Coreopsis)in semiarid areas as subject,this study quantified the effects of canopies and roots on controlling slope runoff and erosion.A series of field experiments were conducted in a loess hilly region of China.Field plots(5 m length,2 m width,25°slope gradient)constructed with three ground covers(bare soil;Coreopsis with intact grass;only roots of Coreopsis),were applied with simultaneous simulated rainfall(60mm h^(-1))and upslope inflow(10,30,50,70,90L min^(-1)).The results showed that compared with bare soil,intact grass significantly reduced runoff and soil loss rates by 16.6% and 62.4% on average,and decreased soil erodibility parameter by 66.3%.As inflow rate increased,the reductions in runoff and soil loss rates increased from 2.93 to 14.00 L min^(-1)and 35.11 to 121.96 g m^(-2)min^(-1),respectively.Canopies relatively contributed 66.7% to lowering flow velocity,turbulence,weakening erosive force and increasing hydraulic resistance.Roots played a predominant role in reducing soil loss and enhancing soil antierodibility,with relative contributions of 78.8% and 73.8%.Furthermore,the maximum erosion depth reduced by Coreopsis was at the upper slope section which was previously eroded the most.These results demonstrated the efficiency of Coreopsis cover in controlling runoff and erosion on steep loess slopes,especially under large inflow rates and at upper slope sections.We suggest protecting Coreopsis with intact grass at upper slope sections,while the aboveground grass biomass can be used for grazing or harvesting at middle and lower slope sections,with roots reserved.

Effects of rainwater harvesting on herbage diversity and productivity in degraded Aravalli hills in western India

Over-exploitation and rural growth have severely damaged native vegetations of Aravalli hills in Rajasthan, India. This study was conducted to evaluate the effects of different restoration practices （i.e., rainwater harvesting （RWH） and planting of tree seedlings） on improve- ment in soil water and nutrients and growth and biomass of herbaceous vegetation. Contour trench （CT）, Gradonie （G）, Box trench （BT）, V-ditch （VD） and a control were imposed on 75 plots （each of 700 m 2 ） in natural slope gradient defined as 10%, 10% 20% and 20% slopes in 2005. Each plot had three micro-sites of 1-m 2 at up （USP）, middle （MSP） and lower （LSP） part of the plot for observation in 2008. The existed gradient （due to soil texture and topographic features） of soil pH, EC, SOC, NH 4 - N, NO 3 -N and PO 4 -P in June 2005 between 20% to 10% slopes were decreased in 2008 after applying RWH techniques. Such improvement in soil status promoted vegetation growth and biomass in higher slope gra- dients. Soil water, species diversity and herbage biomass increased from USP to LSP, and RWH techniques had positive role in improving SOC, nutrients, vegetation population, evenness and growth at MSP. Despite of lowest SWC, regular rain and greater soil water usage enhanced green and dry herbage biomasses in 10% 20% and 20% slopes, compared with 10% slope. The highest diversity in CT treatment was related to herbage biomass, which was enhanced further by highest concentrations of SOC and PO 4 -P. Further, CT treatment was found to be the best treat- ment in minimizing biomass variance in different slopes. Conclusively, soil texture and topographic features controlled soil water and nutrients availability. Rainwater harvesting techniques increased soil water storage and nutrient retention and also enhanced vegetation status and biomass by minimizing the effects of hillslopes. Thus depending upon the site conditions, suitable RWH technique could be adopted to increase herb- age biomass while rehabilitating the degraded hills.

Sediment generation and soil mound denudation in areas of high-density tree throw along a river valley in the Jura Mountains, Switzerland

A preliminary field-based investigation was undertaken in a small(<10 km^(2))river valley located in the mountainous Jura region of northwest Switzerland.The aims of the work were to assess sediment generation and annual sediment transport rates by tree throw on forested hillslopes,and to document surface hydrology characteristics on four fresh soil mounds associated with recent tree throws over a 24-day monitoring period.For the soil mounds,average sediment recovery ranged from 7.7-28.2 g(dry weight),equivalent to a suspended sediment concentration of 145.2-327.8 g L^(-1),and runoff coefficients ranged from 1.0%-4.2%.Based on a soil bulk density value of 1,044 kg m^(-3),upslope runoff generation areas were denuded by an average 0.14 mm by the end of the 24-day monitoring period,representing an erosion rate equivalent to 2.1 mm yr^(-1).A ca.50 cm high soil mound could therefore feasibly persist for around 200-250 years.For tree throw work,the dimensions of 215 individual tree throws were measured and their locations mapped in 12 separate locations along the river valley representing a cumulative area equivalent to 5.3 ha(av.density,43 per ha).Tree throws generated a total of 20.1 m^(3) of fine-sediment(<2 mm diameter),or the equivalent of 3.8×10^(-4) m^(3) m^(-2).The process of tree throw was originally attributed to two extreme weather events that occurred in west and central Europe in late December 1999.Taking the 18-year period since both storms,this represents an annual sediment transport rate of 2.7×10^(-5) m^(3) m^(-1) yr^(-1).Exploring the relationship with wind on fall direction,65.5%of tree throws(143)generally fell in a downslope direction irrespective of hillslope aspect on which they were located.This infers that individual storms may not have been responsible for the majority of tree throws,but instead,could be associated with root failure.Given the high density of tree throws and their relative maturity(average age 41 years),we hypothesise that once trees attain a certain age in this river valley,their physiognomy(i.e.height,mass and centre of gravity)compromises their ability to remain securely anchored.We tentatively attribute this possibility to the presence of bedrock close to the surface,and to the shallow soil profile overlaying steep hillslopes.

Short Report: Identifying Sources of Subsurface Flow—A Theoretical Framework Assessing Hydrological Implications of Lithological Discontinuities

An integrative theoretical concept—combining scientific approaches from soil science and slope hydrology—is given as a framework to study the influence of depth functions of geochemical concentrations for trace elements, dissolved organic carbon and stable isotopes in the soil pore water of stratified soils on the chemical composition of the hillslope runoff. Combining investigations at the point and hillslope scale opens the opportunity to identify sources of subsurface runoff components using geochemical depth functions as proxies.

Field experimental study on the effect of thawed depth of frozen alpine meadow soil on rill erosion by snowmelt waterflow

Soil erosion by snow or ice melt waterflow is an important type of soil erosion in many high-altitude and high-latitude regions and is further aggravated by climate warming.The snowmelt waterflow erosion process is affected by soil freeze-thaws and is highly dynamically variable.In this study,a methodology was developed to conduct in situ field experiments to investigate the effects of the thawed depth of the frozen soil profile on snowmelt waterflow erosion.The method was implemented on an alpine meadow soil slope at an altitude of 3700 m on the northeastern Tibetan Plateau.The erosion experiments involved five thawed soil depths of 0,10,30(35),50,and 80(100)mm under two snowmelt waterflow rates(3 and 5 L/min).When the topsoil was fully frozen or shallow-thawed(≤10 mm),its hydrothermal and structural properties caused a significant lag in the initiation of runoff and delayed soil erosion in the initial stage.The runoff and sediment concentration curves for fully frozen and shallow-thawed soil showed two-stage patterns characteristic of a sediment supply limited in the early stage and subject to hydrodynamic-controlled processes in the later stage.However,this effect did not exist where the thawed soil depth was greater than 30 mm.The deep-thawed cases(≥30 mm)showed normal hydrograph and sedigraph patterns similar to those of the unfrozen soil.The findings of this study are important for understanding the erosion rates of partially thawed soil and for improving erosion simulations in cold regions.

Geomorphic impacts of timber harvesting

Timber harvesting influences (a) forest hydrology; (b) fluvial geomorphology; (c) terrain stability; and (d) integrated watershed behavior. Impacts on forest hydrology are well understood and include increased average runoff, total water yield, increased storm runoff and advances in timing of floods. Stream channels and valley floors are impacted differently by fine sediment, coarse sediment and large woody debris transport. Terrain stability is influenced through gully and mass movement processes that are accelerated by timber harvesting. Impacts on integrated watershed behavior are assessed through disturbed sediment budgets and lake sediments.

Effects of land use patterns on slope soil water in the semiarid Loess Plateau,China

Land use patterns(LUPs)are the form in which various land use types are combined spatially,evidently impacting soil water.However,the influence mechanism by which LUPs form remains unclear.In this study,the soil water content(SWC)in the 0–160-cm soil depth was observed in shrubland(SL),mature forestland(MF),grassland(GL)and young forestland(YF)sites on four slopes with different LUPs in the Yangjuangou catchment of the Chinese Loess Plateau.The SWC in SL-YF-SL(13.28%)was significantly greater than that in YF-MF(9.93%),MF-GL-YF(10.38%)and SL-MF(10.83%)and was temporally stable during the study period.The spatial distribution of SWC along the slope differed among the four LUPs.Vegetation characteristics and soil texture mainly determined the spatial variations in SWC in the shallow soil layers(0–40 cm),while topographic factors were the determinants in the deep soil layers(60–160 cm)as well as in the entire soil profile(0–160 cm).The significance of SWC differences among the various land use patterns increased with decreasing precipitation during the growing seasons.YF-MF(77.8 mm)and SL-YF-GL(73.9 mm)required more rainwater than SL-MF(68.2 mm)and MF-GL-MF(67.5 mm)to compensate for the loss of soil water on the monthly scale during the rainy season.Therefore,vegetation restoration should consider land use patterns on hillslopes for soil water conservation.

Assessing spatial variability and erosion susceptibility of soils in hilly agricultural areas in Southern Italy

Soil erosion is one of the main environmental problems in the Mediterranean area.This problem is becoming even more important especially in Italy,in the Apennines,where severe erosive processes occur due to the action of concentrated running water.The erodibility(K-Factor)of a soil,estimated using the Revised Universal Soil Loss Equation(RUSLE),is a measure of its susceptibility to erosion and depends on several soil properties such as organic matter,texture and permeability and structure.To assess the spatial variability of soil properties and soil erodibility in hilly agricultural areas and to investigate the relationships between soil features and landscape morphodynamics,a detailed study in Molise region(southern Italy),in a small drainange basin located along its hilly Adriatic flank,was carried out.In this catchment,63 topsoil samples(A horizons)were collected and 10 soil profiles,forming a catena crossing 3 land units,were sampled.The calculated K-Factors ranges between 0.012 and 0.048 t ha h ha-1 MJ-1 mm-1 indicating a complex spatial distribution,due to the several local pedological and geomorphological factors affecting soil erodibility.The results give clear evidence about the relationships among soil characteristics,soil erodibility and landscape morpho-dynamics(land units).Comparing the soil loss rates estimated for the study area with those reported in literature,a good correspondence can be observed only for the more stable land unit,not characterized by intense erosive processes.The proposed methodology is suitable to highlight areas characterized by similar morphodynamics features,and comparable soil erodibility,for a more effective spatialization of K factor.