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 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
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 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.
