scholarly journals THE INFLUENCE OF CONVERSION MODEL CHOICE FOR EROSION RATE ESTIMATION AND THE SENSITIVITY OF THE RESULTS TO CHANGES IN THE MODEL PARAMETER

2010 ◽  
Vol 6 (2) ◽  
pp. 199-204
Author(s):  
Nita Suhartini

A study of soil erosion rates had been done on a slightly and long slope of cultivated area in Ciawi - Bogor, using 137Cs technique. The objective of the present study was to evaluate the applicability of the 137Cs technique in obtaining spatially distributed information of soil redistribution at small catchment. This paper reports the result of the choice of conversion model for erosion rate estimates and the sensitive of the changes in the model parameter. For this purpose, small site was selected, namely landuse I (LU-I). The top of a slope was chosen as a reference site. The erosion/deposit rate of individual sampling points was estimated using the conversion models, namely Proportional Model (PM), Mass Balance Model 1 (MBM1) and Mass Balance Model 2 (MBM2). A comparison of the conversion models showed that the lowest value is obtained by the PM. The MBM1 gave values closer to MBM2, but MBM2 gave a reliable values. In this study, a sensitivity analysis suggest that the conversion models are sensitive to changes in parameters that depend on the site conditions, but insensitive to changes in  parameters that interact to the onset of 137Cs fallout input.   Keywords: soil erosion, environmental radioisotope, cesium

2007 ◽  
Vol 50 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
Avacir Casanova Andrello ◽  
Carlos Roberto Appoloni ◽  
Virgílio Franco do Nascimento Filho

The aim of this work was to assess the soil erosion process in native forest by the 137Cs methodology. The mass balance model was applied to assess the rates of soil loss in three native forests around of Londrina city, Paraná, Brazil. 137Cs distribution depth was of exponential type for the three forests and 137Cs inventory was 241 Bq m-2 for Mata 1, 338 Bq m-2 for Mata 2 and 325 Bq m-2 for Mata UEL. The soil loss value calculated for three native forests was: 6,684 kg ha-1 yr-1 for Mata 1, 1,788 kg ha-1 yr-1 for Mata 2 and 4,524 kg ha-1 yr-1 for Mata UEL.


2006 ◽  
Vol 86 (1) ◽  
pp. 77-87 ◽  
Author(s):  
K. Hassouni ◽  
S. Bouhlassa

Despite the seriousness of the erosion problem in the Nakhla watershed, there are still only limited data on the rates of soil loss on cultivated land on steep slopes. Thus, there is a need for more information for optimizing strategies for soil conservation. Recent concern over problems of soil degradation and the off-site impacts of accelerated erosion has highlighted the need for improved methods of estimating rates and patterns of soil erosion by water. In this paper, soil erosion and deposition rates have been studied using the 137Cs technique in upstream part in the Nakhla watershed on cultivated soils (Larbaa Beni Hassan area), which is known to suffer soil erosion. Multiple transect sampling was established parallel to the slope, and 137Cs inventories were determined for the sampling points. After establishing the local reference inventory (3073 Bq m-2), soil erosion and deposition rates were estimated using the 137Cs inventories on all the transects with three calibration models: proportional model (PM), mass balance model 1 (MBM1) and mass balance model 2 (MBM2). The magnitude of the soil erosion rates depends on many factors, including the location of sampling, the local topography, and the soil properties. Estimated soil erosion rates for the study area varied from 0.4 to 28.9 t ha-1 yr-1 using PM; from 0.5 to 66.9 t ha-1 yr-1 using MBM1; and from 0.4 to 56.4 t ha-1 yr-1 using MBM2. The deposition ranged, respectively, from 0.3 to 8.0 t ha-1 yr-1 for PM, from 0.4 to 14.5 t ha-1 yr-1 for MBM1, and from 0.3 to 11.5 t ha-1 yr-1 for MBM2. The sediment delivery ratio is about 98%. For one selected plot, L11, the erosion rates show a clear relationship with the range of slopes in its three different horizontal parts. Estimates of soil redistribution rates were interpolated by means of kriging, using Surfer 7.0 software. Two representative transects were selected to identify the contribution of tillage on 137Cs redistribution by using mass balance model 3. It is observed that the pattern of 137Cs redistribution is dominated by water erosion and that the contribution of tillage redistribution remain is smaller. Key words: 137Cs method, soil erosion, erosion rate, soil redistribution, conversion models


Author(s):  
Linden B. Huhmann ◽  
Charles F. Harvey ◽  
Ana Navas-Acien ◽  
Joseph Graziano ◽  
Vesna Slavkovich ◽  
...  

1990 ◽  
Vol 26 (5) ◽  
pp. 1079-1092 ◽  
Author(s):  
Richard Barry ◽  
Marcel Prévost ◽  
Jean Stein ◽  
Andre P. Plamondon

1999 ◽  
Vol 45 (151) ◽  
pp. 559-567 ◽  
Author(s):  
Rijan Bhakta Kayastha ◽  
Tetsuo Ohata ◽  
Yutaka Ageta

AbstractA mass-balance model based on the energy balance at the snow or ice surface is formulated, with particular attention paid to processes affecting absorption of radiation. The model is applied to a small glacier, Glacier AX010 in the Nepalese Himalaya, and tests of its mass-balance sensitivity to input and climatic parameters are carried out. Calculated and observed area-averaged mass balances of the glacier during summer 1978 (June-September) show good agreement, namely -0.44 and -0.46 m w.e., respectively.Results show the mass balance is strongly sensitive to snow or ice albedo, to the effects of screening by surrounding mountain walls, to areal variations in multiple reflection between clouds and the glacier surface, and to thin snow covers which alter the surface albedo. In tests of the sensitivity of the mass balance to seasonal values of climatic parameters, the mass balance is found to be strongly sensitive to summer air temperature and precipitation but only weakly sensitive to relative humidity.


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