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Browsing by Author "Caiado, M. A. C."

Now showing 1 - 3 of 3
  • Improved nutrient parameters for modeling diffuse pollution in the tropics
    Caiado, M. A. C.; Heatwole, Conrad D. (St. Joseph, MI: ASABE, 2009)
    Review of literature to determine appropriate parameters for nutrient relationships in tropical conditions. Comparison specifically to the GLEAMS model. Recommendations of parameter values and new relationships for modeling nitrogen dynamics in tropical environment.
  • Rural roads and trails as a source of sediment: Preliminary results from the Alegre watershed in Eastern Brazil
    Duff, M. J.; Heatwole, Conrad D.; Caiado, M. A. C. (St. Joseph, MI: ASABE, 2010)
    Extensive networks of unpaved roads and trails often exist in rural areas. These particular routes of transportation can be significant sources of sediment in a tropical watershed. Past research has offered little insight on comparisons between erosion prediction models. The purpose of this preliminary assessment was to offer a comparison between seven erosion prediction models (KINEROS2, SEDD model, WARSEM, ROADMOD, STJ-EROS, WEPP, and SEDMODL) in order to determine their suitability for assessment of an Eastern Brazil tropical watershed. The seven models were evaluated based upon ease of use, considerations of erodible features and processes, data requirements, temporal and spatial scales, ability to simulate management practices, level of output, and applicability to tropical environments. This comparison also employed a 13 km2 mixed land use watershed as a case study. Three models (SEDMODL, STJ-EROS, and WEPP) were selected for future application to the erosion analysis of the Alegre watershed and will be compared to field observations in order to identify roads of high erosion potential and true applicability to this particular watershed.
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    Technical Note: Improved nutrient parameters for modeling diffuse pollution in the tropics
    Caiado, M. A. C.; Heatwole, Conrad D. (American Society of Agricultural and Biological Engineers, 2009)
    Nonpoint-source (NPS) or diffuse pollution is a major environmental problem in developed countries, and modeling is an important tool used to evaluate the effectiveness of pollution control measures. The use of NPS models in the tropics usually involves the application of models developed for temperate regions with little, if ally, adaptation to tropical conditions. In this article, we provide a synthesis of the literature values from studies in the tropics, using the GLEAMS model as a reference for the comparable values used in representing temperate conditions. We found that values for the carbon to nitrogen (C:N) ratio, potentially mineralizable nitrogen to total nitrogen ratio (N(0)/N(total)), and base NO(3)-N and NH(4)-N concentrations representative of tropical soils were all different from the values considered appropriate for temperate soils. Relationships between phosphorus pools in tropical soils and in phosphorus sorption parameters likewise were different from those used in GLEAMS, with the exception that the GLEAMS ratio between labile and organic phosphorus in highly weathered soils was found to be comparable to data specific for tropical soils.