The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully(EG).Vegetation suffers from rain erosion an...The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully(EG).Vegetation suffers from rain erosion and damage during the growth stage,which brings serious problems to the restoration of grass in the early stage.Therefore,effects of coir geotextile and geocell on EG erosion under four confluence intensities were researched in this study.Results of the simulated water discharge erosion test showed that when the confluence strength was less than 30 L/min,geocell and coir geotextile had a good effect on controlling EG erosion,and sediment yield of geocell and coir geotextile was reduced by 25.95%–37.82%and 73.73%–88.96%,respectively.However,when confluence intensity increased to 40 L/min,protective effect of coir geotextile decreased,and sediment yield rate increased sharply by 189.03%.When confluence intensity increased to 50 L/min,the protective effect of coir geotextile was lost.On the other hand,geocell showed that the greater the flow rate,the better the protective effect.In addition,with the increase in confluence intensity,erosion pattern of coir geotextile developed from sheet erosion to intermittent fall and then to completion of main rill,and the protective effect was gradually weakened.In contrast,the protective effect of EG under geocell was gradually enhanced from the continuous rill to the intermittent rill and finally to the intermittent fall.This study shows that coir geotextile and geocell can prevent EG erosion,and the effect of geocell is better than that of coir geotextile on the surface of EG.展开更多
Investigating the effect of geocells on the erosion and deposition distribution of ephemeral gullies in the black soil area of Northeast China can provide a scientific basis for the allocation of soil and water conser...Investigating the effect of geocells on the erosion and deposition distribution of ephemeral gullies in the black soil area of Northeast China can provide a scientific basis for the allocation of soil and water conservation measures in ephemeral gullies.In this study,an artificial simulated confluence test and stereoscopic photogrammetry were used to analyze the distribution characteristics of erosion and deposition in ephemeral gullies protected by geocells and the effect of different confluence flows on the erosion process of ephemeral gullies.Results showed that when the confluence flow was larger,the effect of geocell was more evident,and the protection against ephemeral gully erosion was stronger.When the confluence flow rates were 0.6,1.8,2.4,and 3.0 m^(3)/h,ephemeral gully erosion decreased by 37.84%,26.09%,21.40%,and 35.45%.When the confluence flow rates were 2.4 and 3.0 m^(3)/h,the average sediment yield rate of the ephemeral gully was close to 2.14 kg/(m^(2)•min),and the protective effect of ephemeral gully erosion was enhanced.When the flow rate was higher,the surface fracture of the ephemeral gully was more serious.With an increase in confluence flow rate,the ratio of erosion to deposition increased gradually,the erosion area of ephemeral gullies was expanded,and erosion depth changed minimally.In conclusion,geocell measures changed erosion patterns by altering the rill erosion/deposition ratio,converting erosion from rill erosion to sheet erosion.展开更多
Short,momentary,temporary,transient,precarious,and labile are adjectives that the current post-pandemic,ecological,climatic,war,political,economic,and social contingencies have accustomed us to employ almost compulsiv...Short,momentary,temporary,transient,precarious,and labile are adjectives that the current post-pandemic,ecological,climatic,war,political,economic,and social contingencies have accustomed us to employ almost compulsively and indiscriminately by now,and that,beyond everything,are synonyms inter-implicit with and in the ephemerality,which deserves reconsideration in its literalness as epìheméra(for a day),that can take place through a sort of its“double”,not quite mainstream but nonetheless suggestive and perhaps even effective,such as the artistic one of dance.Therefore,it is worth pausing to try and see which streaks/implications of the ephemerality itself the dance-ephemeral conveys and/or produces:the neuralgic concretions that the latter seems to me to involve and permeate,in a perspective of re-cognition/re-discovery/awareness,are time,space and the body,evidently inter-implicated.展开更多
To clarify the characteristics of photoinhibition and the primary defense mechanisms of ephemeral plant leaves against photodestruction under high temperature stress,inhibitors and the technology to determine chloroph...To clarify the characteristics of photoinhibition and the primary defense mechanisms of ephemeral plant leaves against photodestruction under high temperature stress,inhibitors and the technology to determine chlorophyll fluorescence were used to explore the protective effects of D1 protein turnover and the lutein cycle in the high temperature stress of the leaves of three ephemeral plants.The results showed that the maximum light conversion efficiency(Fv/Fm)of the ephemeral plant leaves decreased,and the initial fluorescence(Fo)increased under 35℃±1℃ heat stress for 1-4 h or on sunny days in the summer.Both Fv/Fm and Fo could be recovered after 8 h of darkness or afternoon weakening of the external temperature.Streptomycin sulfate(SM)or dithiothreitol(DTT)accelerated the decrease of Fv/Fm and the photochemical quenching coefficient(qP)in the leaves of three ephemeral plants at high temperature,and the decrease was greater in the SM than in the DTT treatment.When the high temperature stress was prolonged,the Y(II)values of light energy distribution parameters of PSII decreased,and the Y(NPQ)and Y(NO)values increased gradually in all the treatment groups of the three ephemeral plants.The results showed that the leaves of the three ephemeral plants had their own highly advanced mechanisms to protect against photodamage,which inhibited the turnover of D1 protein and xanthophyll cycle.This can damage the PSII reaction center in the leaves of the three ephemeral plants under high temperature.The protective effect of D1 protein turnover on heat stress in Erodium oxyrrhynchum and Senecio subdentatus was greater than that of the lutein cycle,while the protective effect of lutein cycle was greater than that of D1 protein turnover in Heliotropium acutiflorum subjected to heat damage.展开更多
Previous studies documented that most desert plants can be colonized by arbuscular mycorrhizal (AM) fungi, however, little is known about how the dynamics of AM fungi are related to ephemerals in desert ecosystems. ...Previous studies documented that most desert plants can be colonized by arbuscular mycorrhizal (AM) fungi, however, little is known about how the dynamics of AM fungi are related to ephemerals in desert ecosystems. The dynamics of AM fungi with desert ephemerals were examined to determine the effects of host plant life stages on the development of AM fungi. Mean colonization of ephemeral annual plants was 45% lower than that of ephemeral perennial plants. The colonizations were much higher in the early part of the growing season than in later parts, peaking at flowering times. The phenology of AM fungi in root systems varied among different ephem- erals. The density of AM fungal spores increased with the development of ephemeral annual plants, reached its maximum at flowering times, and then plateaued about 20 days after the aboveground senescence. A significant positive correlation was found between AM fungi spore density and biomass of ephemeral annual plants. The life cycles of AM fungi associated with desert ephemerals were very shod, being about 60-70 days. Soil temperature and water content had no direct influence on the development of AM fungal spores. We concluded that the development of AM fungi was in response to desert ephemeral phenology and life history strategy.展开更多
Water and nitrogen (N) inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influen...Water and nitrogen (N) inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influencing biodiversity and ecosystem function.Snowfall is a form of precipitation in winter,and snow melting can recharge soil water and result in a flourish of ephemerals during springtime in the Gurbantunggut Desert,China.A bi-factor experiment was designed and deployed during the snow-covering season from 2009 to 2010.The experiment aimed to explore the effects of different snow-covering depths and N addition levels on ephemerals.Findings indicated that deeper snow cover led to the increases in water content in topsoil as well as density and coverage of ephemeral plants in the same N treatment; by contrast,N addition sharply decreased the density of ephemerals in the same snow treatment.Meanwhile,N addition exhibited a different effect on the growth of ephemeral plants:in the 50% snow treatment,N addition limited the growth of ephemeral plants,showing that the height and the aboveground biomass of the ephemeral plants were lower than in those without N addition; while with the increases in snow depth (100% and 150% snow treatments),N addition benefited the growth of the dominant individual plants.Species richness was not significantly affected by snow in the same N treatment.However,N addition significantly decreased the species richness in the same snow-covering depth.The primary productivity of ephemerals in the N addition increased with the increase of snow depth.These variations indicated that the effect of N on the growth of ephemerals was restricted by water supply.With plenty of water (100% and 150% snow treatments),N addition contributed to the growth of ephemeral plants; while with less water (50% snow treatment),N addition restricted the growth of ephemeral plants.展开更多
Based on systematically monitoring plants on dune ridges in the southern part of the Gurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation, describes ...Based on systematically monitoring plants on dune ridges in the southern part of the Gurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation, describes the temporal and spatial distribution patterns of ephemeral plants on isolated sand dunes, analyses the natural invasion processes of ephemeral plants on human-disturbed sand surface and expounds the importance of ephemeral plants in stabilizing sand dune surface. A total of 45 plant species were identified in the study area, 29 of which are ephemeral plants. Ephemeral plants sprouted in early April and completed their life-circle within about two months. Just as aeolian sand activities came to the strongest stage from April to June in desert regions of northern Xinjiang, the total coverage of trees, shrubs and herbs of long vegetational period on most dune ridges was less than 10%, while the mean coverage of ephemeral plants reached 13.9% in April, 40.2% in May and 14.1% in June. Therefore ephemeral plants acted as the major contributor to dune surface stabilization in the Gurbantunggut Desert. Investigations of vegetation restoration on engineering-disturbed dune surface show that ephemeral plants first recolonized the disturbed dune surface.展开更多
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 quanti...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 (I30), 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 I30 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 Iso 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 Izo) was selected as the key index of rainfall characteristics to fit soil loss equations. Two sets of linear regression equations between soil loss and Plzo 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.展开更多
Research on germination strategies has been proposed as a tool for understanding the evolutionary patterns of plant species living in extreme climate conditions. Previous research has concentrated on spring-germinated...Research on germination strategies has been proposed as a tool for understanding the evolutionary patterns of plant species living in extreme climate conditions. Previous research has concentrated on spring-germinated plants, while there has been little investigation on the ecological significance of ephemeral plants that germinate in both autumn and spring. The biological characteristics and life history strategies of autumn-and spring-germinated plants of Hypecoum erectum L. that belongs to Hypecoum in Papaveraceae family in the southern part of the Gurbantunggut Desert, China, were investigated from 2016 to 2017. Results showed that:(1) the interval from seedling emergence to the end of the life cycle in autumn-germinated plants(202–208 d) was significantly longer than that in spring-germinated plants(53–65 d);(2) the height, crown, principal axis and the number of leaves of autumn-germinated plants were much greater than those of spring-germinated plants;(3) allocation of dry mass to reproduction was 30.24%(±2.41%) and 10.12%(±0.68%) in autumn-and spring-germinated plants, respectively. Autumn-germinated seedlings of H. erectum had an advantage in avoiding the competition between annual and perennial herbs that had longer periods of vegetative growth.Spring-germinated seedlings need to ensure the survival of population when only a fewer autumn-germinated seedlings successfully overwinter. In an unpredictable environment, the germination strategy of bet hedging not only utilizes the resources and reduces the competition intensity in offspring,but also ensures the survival of the plant population.展开更多
Ephemeral gullies,which are widely developed worldwide and threaten farmlands,have aroused a growing concern.Identifying and mapping gullies are generally considered prerequisites of gully erosion assessment.However,e...Ephemeral gullies,which are widely developed worldwide and threaten farmlands,have aroused a growing concern.Identifying and mapping gullies are generally considered prerequisites of gully erosion assessment.However,ephemeral gully mapping remains a challenge.In this study,we proposed a flow-directional detection for identifying ephemeral gullies from high-resolution images and digital elevation models(DEMs).Ephemeral gullies exhibit clear linear features in high-resolution images.An edge detection operator was initially used to identify linear features from high-resolution images.Then,according to gully erosion mechanism,the flow-directional detection was designed.Edge images obtained from edge detection and flow directions obtained from DEMs were used to implement the flow-directional detection that detects ephemeral gullies along the flow direction.Results from ten study areas in the Loess Plateau of China showed that ranges of precision,recall,and Fmeasure are 6 o.66%-90.47%,65.74%-94.98%,and63.10%-91.93%,respectively.The proposed method is flexible and can be used with various images and DEMs.However,analysis of the effect of DEM resolution and accuracy showed that DEM resolution only demonstrates a minor effect on the detection results.Conversely,DEM accuracy influences the detection result and is more important than the DEM resolution.The worse the vertical accuracy of DEM,the lower the performance of the flow-directional detection will be.This work is beneficial to research related to monitoring gully erosion and assessing soil loss.展开更多
Desert ephemeral plants play an important role in desert ecosystem.Soil water availability is considered as the major restrictive factor limiting the growth of ephemeral plants.Moreover,arbuscular mycorrhizal fungi(A...Desert ephemeral plants play an important role in desert ecosystem.Soil water availability is considered as the major restrictive factor limiting the growth of ephemeral plants.Moreover,arbuscular mycorrhizal fungi(AM fungi) are widely reported to improve the growth of desert ephemerals.The present study aimed to test the hypothesis of that AM fungi could alleviate drought stress of desert ephemeral Plantago minuta,and AM fungal functions reduced with the improvement of soil water content.A pot experiment was carried out with three levels of soil water contents(4.5%,9.0%,and 15.8%(w/w)),and three AM inoculation treatments(Glomus mosseae,Glomus etunicatum and non-inoculation).The results indicate that mycorrhizal colonization rate decreased with the increase of soil water availability.Inoculation improved plant growth and N,P and K acquisition in both shoots and roots regardless water treatments.When comparing the two fungi,plants inoculated with G.mosseae performed better than those inoculated with G.etunicatum in terms of plant growth and nutrient acquisition.These results showed that ameliorative soil water did not suppress arbuscular mycorrhizal fungal functions in improving growth and nutrient acquisition of desert ephemeral Plantago minuta.展开更多
Ephemeral and perennial streams of mountainous catchments in Sabaragamuwa Province of Sri Lanka and Hong Kong of China were studied for two years on vegetation dynamics.Each year,sampling was conducted during a period...Ephemeral and perennial streams of mountainous catchments in Sabaragamuwa Province of Sri Lanka and Hong Kong of China were studied for two years on vegetation dynamics.Each year,sampling was conducted during a period when ephemeral streams had low surface flows.Sampling was realized contiguously using belt transects.The standing crop biomass(hereafter biomass)of herbaceous vegetation in ephemeral channels was comparatively lower than perennials and so was the herb diversity.Herb diversity showed a peak from 1.5 to 4.5 m from the centerline/thalweg of ephemeral and perennial streams.Out of 24 herbs,only three were common for both.A peak herb biomass zone was observed in perennials in the same region where diversity peaked.In ephemerals,herb biomass increased laterally up to^1.5 m,and was constant thereafter.Seedling experiment results tallied with the field diversity observations of both stream types,and suggested that seed dispersion was the main reason for herb colonization.Furthermore,it showed sapling emergence to be significantly higher in perennials than ephemerals.Return period of annual maximum monthly rainfall was a strong indicator of age of trees in ephemeral streams,and elucidated the possibility of hindcasting past flow episodes.Electrical conductivity was significantly high in ephemeral streams among all the water quality parameters.The contents of the water nutrients were approximately the same in both stream types.While recommending further studies on eco-hydrology of ephemerals,we recognize ephemeral streams to be valuable references in climate change studies due to their responsiveness and representativeness in long term hydrological changes.展开更多
The results of a study conducted by light microscopy of the anatomical structure of the leaf in ephemeral species from the family Brassicaceae growing under the conditions of Kyzylkum (Uzbekistan) are presented. The f...The results of a study conducted by light microscopy of the anatomical structure of the leaf in ephemeral species from the family Brassicaceae growing under the conditions of Kyzylkum (Uzbekistan) are presented. The following diagnostic, structural adaptive features were revealed: a leaf lamellar, dentate (Diptychocarpus strictus), in Leptaleum filifolium—valky. It is pubescent with various types of trichomes: stellate, dendroid (Meniocus linifolius), equilateral (Streptoloma desertorum) and unequal (Strigosella, Leptaleum filifolium species), unicellular hooked (Leptaleum filifolium). Epidermal cells flattened with wavy or winding walls. The stomata are numerous, not submerged, anomocytic, hemiparacytic, anisocytic types are noted. In all species, the isolate-palisade type of leaf mesophyll predominates. Vascular bundles of all species are sclerified. The main protective features of the leaf of species of the family Brassicaceae are pubescence and sclerification of vascular bundles. We consider the mesomorphic and xeromorphic lines of development ancient and independent. Identified and described signs that can be used in taxonomy and ecology.展开更多
Gully erosion can account for significant volumes of sediment exiting agricultural landscapes, but is difficult to monitor and quantify its evolution with traditional surveying technology. Scientific investigations of...Gully erosion can account for significant volumes of sediment exiting agricultural landscapes, but is difficult to monitor and quantify its evolution with traditional surveying technology. Scientific investigations of gullies depend on accurate and detailed topographic information to understand and evaluate the complex interactions between field topography and gully evolution. Detailed terrain representations can be produced by new technologies such as terrestrial LiDAR systems. These systems are capable of collecting information with a wide range of ground point sampling densities as a result of operator controlled factors. Increasing point density results in richer datasets at a cost of increased time needed to complete field surveys. In large research watersheds, with hundreds of sites being monitored, data collection can become costly and time consuming. In this study, the effect of point sampling density on the capability to collect topographic information was investigated at individual gully scale. This was performed through the utilization of semi-variograms to produce overall guiding principles for multi-temporal gully surveys based on various levels of laser sampling points and relief variation (low, moderate, and high). Results indicated the existence of a point sampling density threshold that produces little or no additional topographic information when exceeded. A reduced dataset was created using the density thresholds and compared to the original dataset with no major discrepancy. Although variations in relief and soil roughness can lead to different point sampling density requirements, the outcome of this study serves as practical guidance for future field surveys of gully evolution and erosion.展开更多
In this text, we seek to present and analyze artistic works that were part of the exhibition Visual Music: interactions between music and image. This exhibition was held for a period of one month at Brazilian Bank Cu...In this text, we seek to present and analyze artistic works that were part of the exhibition Visual Music: interactions between music and image. This exhibition was held for a period of one month at Brazilian Bank Cultural Center and integrated III Understanding Visual Music Symposium (2015). This international event brought together artists from four continents and has been considered one of the most important academic forums dedicated to the study of the relationship between music and image. The works presented in the exhibition dealt with different possibilities of and the need for interaction with the public. Further, interesting discussions were raised, especially related to the possibilities and need for preservation of these works. These debates were unfolded to the plan of artistic dissemination; moreover, have embraced considerations about ephemeral art.展开更多
Pop-up stores present many advantages to brands and customers.They take advantage of seasonality and events and manifest themselves in a relevant way in front of the targeted customer.Following a mixed-method approach...Pop-up stores present many advantages to brands and customers.They take advantage of seasonality and events and manifest themselves in a relevant way in front of the targeted customer.Following a mixed-method approach,semi-structured interview outcomes were used to enrich the proposed research model,which was then tested by a questionnaire.Our research’s results highlighted interesting components respective to the Lebanese market’s pop-up stores;test and experimentation,collection presentation,communication and buzz creation.Test results showed that Lebanese pop-up store atmospheres are characterized by their social dimension;customers are less affected by the aesthetics and more affected by the crowd who frequents the pop-up.Results showed that customers feel happier and are more likely to stay and to spend time in the store than to make purchases.展开更多
Ephemeral gullies are widely distributed in the hilly and gully region of the Loess Plateau and play a unique role in the slope gully erosion system.Rapid and accurate identification of ephemeral gullies impacts the d...Ephemeral gullies are widely distributed in the hilly and gully region of the Loess Plateau and play a unique role in the slope gully erosion system.Rapid and accurate identification of ephemeral gullies impacts the distribution law and development trend of soil erosion on the Loess Plateau.Deep learning algorithms can quickly and accurately process large data samples that recognize ephemeral gullies from remote sensing images.Here,we investigated ephemeral gullies in the Zhoutungou watershed in the hilly and gully region of the Loess Plateau in China using satellite and unmanned aerial vehicle images and combined a deep learning image semantic segmentation model to realize automatic recognition and feature extraction.Using Accuracy,Precision,Recall,F1value,and AUC,we compared the ephemeral gully recognition results and accuracy evaluation of U-Net,R2U-Net,and SegNet image semantic segmentation models.The SegNet model was ranked first,followed by the R2U-Net and U-Net models,for ephemeral gully recognition in the hilly and gully region of the Loess Plateau.The ephemeral gully length and width between predicted and measured values had RMSE values of 6.78 m and 0.50 m,respectively,indicating that the model has an excellent recognition effect.This study identified a fast and accurate method for ephemeral gully recognition in the hilly and gully region of the Loess Plateau based on remote sensing images to provide an academic reference and practical guidance for soil erosion monitoring and slope and gully management in the Loess Plateau region.展开更多
Evaluation of prediction models is crucial to achieving valid information on erosion processes and their management choices.WEPP model efficiency in predicting ephemeral gully(EG)erosion was recently tested and compar...Evaluation of prediction models is crucial to achieving valid information on erosion processes and their management choices.WEPP model efficiency in predicting ephemeral gully(EG)erosion was recently tested and compared with both EGEM and empirical models.The models abilities to predict EG erosion were validated using measured estimates at the 6 eroding locations around Mubi area in Northeast Nigeria between April 2008 and October 2009.Each location consisted of 3 watersheds where data on soils,climate,slope,management practices,EG shapes and dimensions were collected.Data on relevant soil properties were collected in the field and then analyzed in laboratory.The mass of soil loss(MSL)predicted by empirical,EGEM and WEPP models were compared with the measured using paired T-test,regression graphs(r^(2)-values),error analysis,and analysis of variance(ANOVA)in a completely ran-domized design.The EG erosion losses varied significantly(P≤0.05)between sites and years.No sig-nificant(P≤0.05)differences were observed between measured and the empirically predicted aggregate MSL.The measured aggregate MSL strongly correlated with those predicted by empirical(r^(2)=0.67),than with EGEM(r^(2)=0.57),and WEPP(r^(2)=0.53)models.Slight over and under-prediction instances against the measured erosion were noted with all the models.The WEPP model was found to slightly over-predict MSL when compared to either the empirical or EGEM model.The prediction quality of the models was generally impressive.Future works should focus more on local inputs such as climate,plants,management,and tillage data for use with WEPP.展开更多
A field adaptation test of the Ephemeral Gully Erosion Model(EGEM)to predict ephemeral gully(EG)erosion was carried out in the 2008 and 2009 farming seasons in the Mubi area,NE Nigeria.Land use,conservation practices,...A field adaptation test of the Ephemeral Gully Erosion Model(EGEM)to predict ephemeral gully(EG)erosion was carried out in the 2008 and 2009 farming seasons in the Mubi area,NE Nigeria.Land use,conservation practices,and EG channel features were measured and/or noted at each site.Soil loss varied among the sites and seasons.The measured area,volume,and mass of soil loss were used to test the standard EGEM_(std),and the adapted models'(EGEM_(Ad) and EGEM_(Al))prediction efficiencies.The result showed that EGEM_(std) could not predict the area of soil loss adequately.Both EGEM_(Ad) and EGEM_(Al) were efficient and better adapted to predicting area,volume,and mass loss from EG erosion.The adapted models are therefore strongly recommended for implementation in the study area.展开更多
A field study was carried out to assess soil loss from ephemeral gully(EG)erosion at 6 different locations(Digil,Vimtim,Muvur,Gella,Lamorde and Madanya)around the Mubi area between April,2008 and October,2009.Each loc...A field study was carried out to assess soil loss from ephemeral gully(EG)erosion at 6 different locations(Digil,Vimtim,Muvur,Gella,Lamorde and Madanya)around the Mubi area between April,2008 and October,2009.Each location consisted of 3 watershed sites from where data was collected.EG shape,land use,and conservation practices were noted,while EG length,width,and depth were measured.Physico-chemical properties of the soils were studied in the field and laboratory.Soil loss was both measured and predicted using modeled empirical equations.Results showed that the soils are heterogeneous and lying on flat to hilly topographies with few grasses,shrubs and tree vegetations.The soils comprised of sand fractions that predominated the texture,with considerable silt and clay contents.The empirical soil loss was generally related with the measured soil loss and the predictions were widely reliable at all sites,regardless of season.The measured and empirical aggregate soil loss were more related in terms of volume of soil loss(VSL)(r^(2)=0.93)and mass of soil loss(MSL)(r^(2)=0.92),than area of soil loss(ASL)(r^(2)=0.27).The empirical estimates of VSL and MSL were consistently higher at Muvur(less vegetation)and lower at Madanya and Gella(denser vegetations)in both years.The maximum efficiency(M_(se))of the empirical equation in predicting ASL was between 1.41(Digil)and 89.07(Lamorde),while the M_(se) was higher at Madanya(2.56)and lowest at Vimtim(15.66)in terms of VSL prediction efficiencies.The M_(se) also ranged from 1.84(Madanya)to 15.74(Vimtim)in respect of MSL predictions.These results led to the recommendation that soil conservationists,farmers,private and/or government agencies should implement the empirical model in erosion studies around Mubi area.展开更多
基金supported by the National Natural Science Foundation of China(41907047)the China Scholarship Council(202106515016)the Strategic International Collaboration of Scientific and Technological Innovation for the National Key Research and Development Plan(2016YFE0202900).
文摘The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully(EG).Vegetation suffers from rain erosion and damage during the growth stage,which brings serious problems to the restoration of grass in the early stage.Therefore,effects of coir geotextile and geocell on EG erosion under four confluence intensities were researched in this study.Results of the simulated water discharge erosion test showed that when the confluence strength was less than 30 L/min,geocell and coir geotextile had a good effect on controlling EG erosion,and sediment yield of geocell and coir geotextile was reduced by 25.95%–37.82%and 73.73%–88.96%,respectively.However,when confluence intensity increased to 40 L/min,protective effect of coir geotextile decreased,and sediment yield rate increased sharply by 189.03%.When confluence intensity increased to 50 L/min,the protective effect of coir geotextile was lost.On the other hand,geocell showed that the greater the flow rate,the better the protective effect.In addition,with the increase in confluence intensity,erosion pattern of coir geotextile developed from sheet erosion to intermittent fall and then to completion of main rill,and the protective effect was gradually weakened.In contrast,the protective effect of EG under geocell was gradually enhanced from the continuous rill to the intermittent rill and finally to the intermittent fall.This study shows that coir geotextile and geocell can prevent EG erosion,and the effect of geocell is better than that of coir geotextile on the surface of EG.
基金supported by the National Natural Science Foundation,China(41907047)the National Key Research and Development Program of China(2016YFE0202900)the Natural Science Foundation of Tianjin,China(18JCZDJC39600).
文摘Investigating the effect of geocells on the erosion and deposition distribution of ephemeral gullies in the black soil area of Northeast China can provide a scientific basis for the allocation of soil and water conservation measures in ephemeral gullies.In this study,an artificial simulated confluence test and stereoscopic photogrammetry were used to analyze the distribution characteristics of erosion and deposition in ephemeral gullies protected by geocells and the effect of different confluence flows on the erosion process of ephemeral gullies.Results showed that when the confluence flow was larger,the effect of geocell was more evident,and the protection against ephemeral gully erosion was stronger.When the confluence flow rates were 0.6,1.8,2.4,and 3.0 m^(3)/h,ephemeral gully erosion decreased by 37.84%,26.09%,21.40%,and 35.45%.When the confluence flow rates were 2.4 and 3.0 m^(3)/h,the average sediment yield rate of the ephemeral gully was close to 2.14 kg/(m^(2)•min),and the protective effect of ephemeral gully erosion was enhanced.When the flow rate was higher,the surface fracture of the ephemeral gully was more serious.With an increase in confluence flow rate,the ratio of erosion to deposition increased gradually,the erosion area of ephemeral gullies was expanded,and erosion depth changed minimally.In conclusion,geocell measures changed erosion patterns by altering the rill erosion/deposition ratio,converting erosion from rill erosion to sheet erosion.
文摘Short,momentary,temporary,transient,precarious,and labile are adjectives that the current post-pandemic,ecological,climatic,war,political,economic,and social contingencies have accustomed us to employ almost compulsively and indiscriminately by now,and that,beyond everything,are synonyms inter-implicit with and in the ephemerality,which deserves reconsideration in its literalness as epìheméra(for a day),that can take place through a sort of its“double”,not quite mainstream but nonetheless suggestive and perhaps even effective,such as the artistic one of dance.Therefore,it is worth pausing to try and see which streaks/implications of the ephemerality itself the dance-ephemeral conveys and/or produces:the neuralgic concretions that the latter seems to me to involve and permeate,in a perspective of re-cognition/re-discovery/awareness,are time,space and the body,evidently inter-implicated.
基金This work was supported by the Open Foundation of the State Key Laboratory of Desert and Oasis Ecology(KH0054).
文摘To clarify the characteristics of photoinhibition and the primary defense mechanisms of ephemeral plant leaves against photodestruction under high temperature stress,inhibitors and the technology to determine chlorophyll fluorescence were used to explore the protective effects of D1 protein turnover and the lutein cycle in the high temperature stress of the leaves of three ephemeral plants.The results showed that the maximum light conversion efficiency(Fv/Fm)of the ephemeral plant leaves decreased,and the initial fluorescence(Fo)increased under 35℃±1℃ heat stress for 1-4 h or on sunny days in the summer.Both Fv/Fm and Fo could be recovered after 8 h of darkness or afternoon weakening of the external temperature.Streptomycin sulfate(SM)or dithiothreitol(DTT)accelerated the decrease of Fv/Fm and the photochemical quenching coefficient(qP)in the leaves of three ephemeral plants at high temperature,and the decrease was greater in the SM than in the DTT treatment.When the high temperature stress was prolonged,the Y(II)values of light energy distribution parameters of PSII decreased,and the Y(NPQ)and Y(NO)values increased gradually in all the treatment groups of the three ephemeral plants.The results showed that the leaves of the three ephemeral plants had their own highly advanced mechanisms to protect against photodamage,which inhibited the turnover of D1 protein and xanthophyll cycle.This can damage the PSII reaction center in the leaves of the three ephemeral plants under high temperature.The protective effect of D1 protein turnover on heat stress in Erodium oxyrrhynchum and Senecio subdentatus was greater than that of the lutein cycle,while the protective effect of lutein cycle was greater than that of D1 protein turnover in Heliotropium acutiflorum subjected to heat damage.
基金funded by the National Natural Science Foundation of China (30770341)the International Fund for Agricultural Development (the WATERCOPE project,I-R-1284)
文摘Previous studies documented that most desert plants can be colonized by arbuscular mycorrhizal (AM) fungi, however, little is known about how the dynamics of AM fungi are related to ephemerals in desert ecosystems. The dynamics of AM fungi with desert ephemerals were examined to determine the effects of host plant life stages on the development of AM fungi. Mean colonization of ephemeral annual plants was 45% lower than that of ephemeral perennial plants. The colonizations were much higher in the early part of the growing season than in later parts, peaking at flowering times. The phenology of AM fungi in root systems varied among different ephem- erals. The density of AM fungal spores increased with the development of ephemeral annual plants, reached its maximum at flowering times, and then plateaued about 20 days after the aboveground senescence. A significant positive correlation was found between AM fungi spore density and biomass of ephemeral annual plants. The life cycles of AM fungi associated with desert ephemerals were very shod, being about 60-70 days. Soil temperature and water content had no direct influence on the development of AM fungal spores. We concluded that the development of AM fungi was in response to desert ephemeral phenology and life history strategy.
基金funded by the National Basic Research Program of China(2009CB825102)the National Basic Research Program of China(2009CB421102E)+1 种基金the International Science & Technology Cooperation Program of China(2010DFA92720)the Natural Science Foundation of China(4117049)
文摘Water and nitrogen (N) inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influencing biodiversity and ecosystem function.Snowfall is a form of precipitation in winter,and snow melting can recharge soil water and result in a flourish of ephemerals during springtime in the Gurbantunggut Desert,China.A bi-factor experiment was designed and deployed during the snow-covering season from 2009 to 2010.The experiment aimed to explore the effects of different snow-covering depths and N addition levels on ephemerals.Findings indicated that deeper snow cover led to the increases in water content in topsoil as well as density and coverage of ephemeral plants in the same N treatment; by contrast,N addition sharply decreased the density of ephemerals in the same snow treatment.Meanwhile,N addition exhibited a different effect on the growth of ephemeral plants:in the 50% snow treatment,N addition limited the growth of ephemeral plants,showing that the height and the aboveground biomass of the ephemeral plants were lower than in those without N addition; while with the increases in snow depth (100% and 150% snow treatments),N addition benefited the growth of the dominant individual plants.Species richness was not significantly affected by snow in the same N treatment.However,N addition significantly decreased the species richness in the same snow-covering depth.The primary productivity of ephemerals in the N addition increased with the increase of snow depth.These variations indicated that the effect of N on the growth of ephemerals was restricted by water supply.With plenty of water (100% and 150% snow treatments),N addition contributed to the growth of ephemeral plants; while with less water (50% snow treatment),N addition restricted the growth of ephemeral plants.
基金The National Key Project for Basic Research No. G1999043504National Natural Science Foundation of China+3 种基金 No.90202019 The "Light of West China" Project for Talent Training CAS No. 20032057
文摘Based on systematically monitoring plants on dune ridges in the southern part of the Gurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation, describes the temporal and spatial distribution patterns of ephemeral plants on isolated sand dunes, analyses the natural invasion processes of ephemeral plants on human-disturbed sand surface and expounds the importance of ephemeral plants in stabilizing sand dune surface. A total of 45 plant species were identified in the study area, 29 of which are ephemeral plants. Ephemeral plants sprouted in early April and completed their life-circle within about two months. Just as aeolian sand activities came to the strongest stage from April to June in desert regions of northern Xinjiang, the total coverage of trees, shrubs and herbs of long vegetational period on most dune ridges was less than 10%, while the mean coverage of ephemeral plants reached 13.9% in April, 40.2% in May and 14.1% in June. Therefore ephemeral plants acted as the major contributor to dune surface stabilization in the Gurbantunggut Desert. Investigations of vegetation restoration on engineering-disturbed dune surface show that ephemeral plants first recolonized the disturbed dune surface.
基金supported by the National Natural Science Foundation of China(Grant No.41271299)by the Opening Fund of MWR Laboratory of Soil and Water Loss Process and Control in the Loess Plateau of China(Grant NO.2017001)
文摘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 (I30), 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 I30 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 Iso 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 Izo) was selected as the key index of rainfall characteristics to fit soil loss equations. Two sets of linear regression equations between soil loss and Plzo 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.
基金supported by the National Natural Science Foundation of China (31660061, 31460183, 31200417)the Corps Scientific Program Project (2015AD023)
文摘Research on germination strategies has been proposed as a tool for understanding the evolutionary patterns of plant species living in extreme climate conditions. Previous research has concentrated on spring-germinated plants, while there has been little investigation on the ecological significance of ephemeral plants that germinate in both autumn and spring. The biological characteristics and life history strategies of autumn-and spring-germinated plants of Hypecoum erectum L. that belongs to Hypecoum in Papaveraceae family in the southern part of the Gurbantunggut Desert, China, were investigated from 2016 to 2017. Results showed that:(1) the interval from seedling emergence to the end of the life cycle in autumn-germinated plants(202–208 d) was significantly longer than that in spring-germinated plants(53–65 d);(2) the height, crown, principal axis and the number of leaves of autumn-germinated plants were much greater than those of spring-germinated plants;(3) allocation of dry mass to reproduction was 30.24%(±2.41%) and 10.12%(±0.68%) in autumn-and spring-germinated plants, respectively. Autumn-germinated seedlings of H. erectum had an advantage in avoiding the competition between annual and perennial herbs that had longer periods of vegetative growth.Spring-germinated seedlings need to ensure the survival of population when only a fewer autumn-germinated seedlings successfully overwinter. In an unpredictable environment, the germination strategy of bet hedging not only utilizes the resources and reduces the competition intensity in offspring,but also ensures the survival of the plant population.
基金funded by the National Natural Science Foundation of China (Grant No. 41930102, 41971333, 41771415, and 41701449)the Priority Academic Program Development of Jiangsu Higher Education Institutions (Grant No. 164320H116)the Open Fund of Key Laboratory for Synergistic Prevention of Water and Soil Environmental Pollution (Grant No. KLSPWSEPA04)。
文摘Ephemeral gullies,which are widely developed worldwide and threaten farmlands,have aroused a growing concern.Identifying and mapping gullies are generally considered prerequisites of gully erosion assessment.However,ephemeral gully mapping remains a challenge.In this study,we proposed a flow-directional detection for identifying ephemeral gullies from high-resolution images and digital elevation models(DEMs).Ephemeral gullies exhibit clear linear features in high-resolution images.An edge detection operator was initially used to identify linear features from high-resolution images.Then,according to gully erosion mechanism,the flow-directional detection was designed.Edge images obtained from edge detection and flow directions obtained from DEMs were used to implement the flow-directional detection that detects ephemeral gullies along the flow direction.Results from ten study areas in the Loess Plateau of China showed that ranges of precision,recall,and Fmeasure are 6 o.66%-90.47%,65.74%-94.98%,and63.10%-91.93%,respectively.The proposed method is flexible and can be used with various images and DEMs.However,analysis of the effect of DEM resolution and accuracy showed that DEM resolution only demonstrates a minor effect on the detection results.Conversely,DEM accuracy influences the detection result and is more important than the DEM resolution.The worse the vertical accuracy of DEM,the lower the performance of the flow-directional detection will be.This work is beneficial to research related to monitoring gully erosion and assessing soil loss.
基金funded by the Foundation for University Key Teacher by Henan Educational Committee (2013GGJS070)the National Basic Research Program of China (2014CB954202)+1 种基金the National Natural Science Foundation of China (40971150)the China Scholarship Council (201208410020)
文摘Desert ephemeral plants play an important role in desert ecosystem.Soil water availability is considered as the major restrictive factor limiting the growth of ephemeral plants.Moreover,arbuscular mycorrhizal fungi(AM fungi) are widely reported to improve the growth of desert ephemerals.The present study aimed to test the hypothesis of that AM fungi could alleviate drought stress of desert ephemeral Plantago minuta,and AM fungal functions reduced with the improvement of soil water content.A pot experiment was carried out with three levels of soil water contents(4.5%,9.0%,and 15.8%(w/w)),and three AM inoculation treatments(Glomus mosseae,Glomus etunicatum and non-inoculation).The results indicate that mycorrhizal colonization rate decreased with the increase of soil water availability.Inoculation improved plant growth and N,P and K acquisition in both shoots and roots regardless water treatments.When comparing the two fungi,plants inoculated with G.mosseae performed better than those inoculated with G.etunicatum in terms of plant growth and nutrient acquisition.These results showed that ameliorative soil water did not suppress arbuscular mycorrhizal fungal functions in improving growth and nutrient acquisition of desert ephemeral Plantago minuta.
基金funded by the Research Grants Council Fund of Hong Kong(Project number:Poly U152161/14E)Environment and Conservation Fund,Hong Kong(Project number:39/2011)。
文摘Ephemeral and perennial streams of mountainous catchments in Sabaragamuwa Province of Sri Lanka and Hong Kong of China were studied for two years on vegetation dynamics.Each year,sampling was conducted during a period when ephemeral streams had low surface flows.Sampling was realized contiguously using belt transects.The standing crop biomass(hereafter biomass)of herbaceous vegetation in ephemeral channels was comparatively lower than perennials and so was the herb diversity.Herb diversity showed a peak from 1.5 to 4.5 m from the centerline/thalweg of ephemeral and perennial streams.Out of 24 herbs,only three were common for both.A peak herb biomass zone was observed in perennials in the same region where diversity peaked.In ephemerals,herb biomass increased laterally up to^1.5 m,and was constant thereafter.Seedling experiment results tallied with the field diversity observations of both stream types,and suggested that seed dispersion was the main reason for herb colonization.Furthermore,it showed sapling emergence to be significantly higher in perennials than ephemerals.Return period of annual maximum monthly rainfall was a strong indicator of age of trees in ephemeral streams,and elucidated the possibility of hindcasting past flow episodes.Electrical conductivity was significantly high in ephemeral streams among all the water quality parameters.The contents of the water nutrients were approximately the same in both stream types.While recommending further studies on eco-hydrology of ephemerals,we recognize ephemeral streams to be valuable references in climate change studies due to their responsiveness and representativeness in long term hydrological changes.
文摘The results of a study conducted by light microscopy of the anatomical structure of the leaf in ephemeral species from the family Brassicaceae growing under the conditions of Kyzylkum (Uzbekistan) are presented. The following diagnostic, structural adaptive features were revealed: a leaf lamellar, dentate (Diptychocarpus strictus), in Leptaleum filifolium—valky. It is pubescent with various types of trichomes: stellate, dendroid (Meniocus linifolius), equilateral (Streptoloma desertorum) and unequal (Strigosella, Leptaleum filifolium species), unicellular hooked (Leptaleum filifolium). Epidermal cells flattened with wavy or winding walls. The stomata are numerous, not submerged, anomocytic, hemiparacytic, anisocytic types are noted. In all species, the isolate-palisade type of leaf mesophyll predominates. Vascular bundles of all species are sclerified. The main protective features of the leaf of species of the family Brassicaceae are pubescence and sclerification of vascular bundles. We consider the mesomorphic and xeromorphic lines of development ancient and independent. Identified and described signs that can be used in taxonomy and ecology.
文摘Gully erosion can account for significant volumes of sediment exiting agricultural landscapes, but is difficult to monitor and quantify its evolution with traditional surveying technology. Scientific investigations of gullies depend on accurate and detailed topographic information to understand and evaluate the complex interactions between field topography and gully evolution. Detailed terrain representations can be produced by new technologies such as terrestrial LiDAR systems. These systems are capable of collecting information with a wide range of ground point sampling densities as a result of operator controlled factors. Increasing point density results in richer datasets at a cost of increased time needed to complete field surveys. In large research watersheds, with hundreds of sites being monitored, data collection can become costly and time consuming. In this study, the effect of point sampling density on the capability to collect topographic information was investigated at individual gully scale. This was performed through the utilization of semi-variograms to produce overall guiding principles for multi-temporal gully surveys based on various levels of laser sampling points and relief variation (low, moderate, and high). Results indicated the existence of a point sampling density threshold that produces little or no additional topographic information when exceeded. A reduced dataset was created using the density thresholds and compared to the original dataset with no major discrepancy. Although variations in relief and soil roughness can lead to different point sampling density requirements, the outcome of this study serves as practical guidance for future field surveys of gully evolution and erosion.
文摘In this text, we seek to present and analyze artistic works that were part of the exhibition Visual Music: interactions between music and image. This exhibition was held for a period of one month at Brazilian Bank Cultural Center and integrated III Understanding Visual Music Symposium (2015). This international event brought together artists from four continents and has been considered one of the most important academic forums dedicated to the study of the relationship between music and image. The works presented in the exhibition dealt with different possibilities of and the need for interaction with the public. Further, interesting discussions were raised, especially related to the possibilities and need for preservation of these works. These debates were unfolded to the plan of artistic dissemination; moreover, have embraced considerations about ephemeral art.
文摘Pop-up stores present many advantages to brands and customers.They take advantage of seasonality and events and manifest themselves in a relevant way in front of the targeted customer.Following a mixed-method approach,semi-structured interview outcomes were used to enrich the proposed research model,which was then tested by a questionnaire.Our research’s results highlighted interesting components respective to the Lebanese market’s pop-up stores;test and experimentation,collection presentation,communication and buzz creation.Test results showed that Lebanese pop-up store atmospheres are characterized by their social dimension;customers are less affected by the aesthetics and more affected by the crowd who frequents the pop-up.Results showed that customers feel happier and are more likely to stay and to spend time in the store than to make purchases.
基金This research was supported by the National Natural Science Foundation of China(41977064)the Fundamental Research Funds for the Central Universities(2452021158+1 种基金2452021036)the 111 Project of the Ministry of Education and the State Administration of Foreign Experts Affairs(B12007)。
文摘Ephemeral gullies are widely distributed in the hilly and gully region of the Loess Plateau and play a unique role in the slope gully erosion system.Rapid and accurate identification of ephemeral gullies impacts the distribution law and development trend of soil erosion on the Loess Plateau.Deep learning algorithms can quickly and accurately process large data samples that recognize ephemeral gullies from remote sensing images.Here,we investigated ephemeral gullies in the Zhoutungou watershed in the hilly and gully region of the Loess Plateau in China using satellite and unmanned aerial vehicle images and combined a deep learning image semantic segmentation model to realize automatic recognition and feature extraction.Using Accuracy,Precision,Recall,F1value,and AUC,we compared the ephemeral gully recognition results and accuracy evaluation of U-Net,R2U-Net,and SegNet image semantic segmentation models.The SegNet model was ranked first,followed by the R2U-Net and U-Net models,for ephemeral gully recognition in the hilly and gully region of the Loess Plateau.The ephemeral gully length and width between predicted and measured values had RMSE values of 6.78 m and 0.50 m,respectively,indicating that the model has an excellent recognition effect.This study identified a fast and accurate method for ephemeral gully recognition in the hilly and gully region of the Loess Plateau based on remote sensing images to provide an academic reference and practical guidance for soil erosion monitoring and slope and gully management in the Loess Plateau region.
文摘Evaluation of prediction models is crucial to achieving valid information on erosion processes and their management choices.WEPP model efficiency in predicting ephemeral gully(EG)erosion was recently tested and compared with both EGEM and empirical models.The models abilities to predict EG erosion were validated using measured estimates at the 6 eroding locations around Mubi area in Northeast Nigeria between April 2008 and October 2009.Each location consisted of 3 watersheds where data on soils,climate,slope,management practices,EG shapes and dimensions were collected.Data on relevant soil properties were collected in the field and then analyzed in laboratory.The mass of soil loss(MSL)predicted by empirical,EGEM and WEPP models were compared with the measured using paired T-test,regression graphs(r^(2)-values),error analysis,and analysis of variance(ANOVA)in a completely ran-domized design.The EG erosion losses varied significantly(P≤0.05)between sites and years.No sig-nificant(P≤0.05)differences were observed between measured and the empirically predicted aggregate MSL.The measured aggregate MSL strongly correlated with those predicted by empirical(r^(2)=0.67),than with EGEM(r^(2)=0.57),and WEPP(r^(2)=0.53)models.Slight over and under-prediction instances against the measured erosion were noted with all the models.The WEPP model was found to slightly over-predict MSL when compared to either the empirical or EGEM model.The prediction quality of the models was generally impressive.Future works should focus more on local inputs such as climate,plants,management,and tillage data for use with WEPP.
文摘A field adaptation test of the Ephemeral Gully Erosion Model(EGEM)to predict ephemeral gully(EG)erosion was carried out in the 2008 and 2009 farming seasons in the Mubi area,NE Nigeria.Land use,conservation practices,and EG channel features were measured and/or noted at each site.Soil loss varied among the sites and seasons.The measured area,volume,and mass of soil loss were used to test the standard EGEM_(std),and the adapted models'(EGEM_(Ad) and EGEM_(Al))prediction efficiencies.The result showed that EGEM_(std) could not predict the area of soil loss adequately.Both EGEM_(Ad) and EGEM_(Al) were efficient and better adapted to predicting area,volume,and mass loss from EG erosion.The adapted models are therefore strongly recommended for implementation in the study area.
文摘A field study was carried out to assess soil loss from ephemeral gully(EG)erosion at 6 different locations(Digil,Vimtim,Muvur,Gella,Lamorde and Madanya)around the Mubi area between April,2008 and October,2009.Each location consisted of 3 watershed sites from where data was collected.EG shape,land use,and conservation practices were noted,while EG length,width,and depth were measured.Physico-chemical properties of the soils were studied in the field and laboratory.Soil loss was both measured and predicted using modeled empirical equations.Results showed that the soils are heterogeneous and lying on flat to hilly topographies with few grasses,shrubs and tree vegetations.The soils comprised of sand fractions that predominated the texture,with considerable silt and clay contents.The empirical soil loss was generally related with the measured soil loss and the predictions were widely reliable at all sites,regardless of season.The measured and empirical aggregate soil loss were more related in terms of volume of soil loss(VSL)(r^(2)=0.93)and mass of soil loss(MSL)(r^(2)=0.92),than area of soil loss(ASL)(r^(2)=0.27).The empirical estimates of VSL and MSL were consistently higher at Muvur(less vegetation)and lower at Madanya and Gella(denser vegetations)in both years.The maximum efficiency(M_(se))of the empirical equation in predicting ASL was between 1.41(Digil)and 89.07(Lamorde),while the M_(se) was higher at Madanya(2.56)and lowest at Vimtim(15.66)in terms of VSL prediction efficiencies.The M_(se) also ranged from 1.84(Madanya)to 15.74(Vimtim)in respect of MSL predictions.These results led to the recommendation that soil conservationists,farmers,private and/or government agencies should implement the empirical model in erosion studies around Mubi area.