Erosion and soils

EPIC is designed to simulate relevant biophysical processes simultaneously and realistically, using readily available input data and accepted methods. It is capable of simulating plant and soil response for hundreds of years, and it is applicable to a wide range of soils, climates, and plants. EPIC also simulates soil erosion and soil chemical and physical property changes over centuries. The time limit for simulation of hydrologic parameters is restricted only by the availability of high-quality climate input data. 

Tardy Y, Bustillo V, Boeglin JL (2004) Geochemistry applied to the watershed survey hydrograph separation, erosion and soil dynamics. A case study the basin of the Niger River, Africa. Appl Geochem 19 469-518... 

Williams JR, Jones CA, Dyke PT. A modeling approach to determining the relationship between erosion and soil productivity. Trans ASAE 1984 27 129-44. 

Gypsum stops water runoff and erosion and soil crusting... 

Colombia is a fortunate country in terms of its rich variety of plants, most of which are found in the Amazon Region but, unfortunately, some spedes have disappeared and others will follow the same path, in the name of progress, due to the indiscriminate felling of our primary forests, wich will keep us from knowing the metabolites of these species. Besides, the effects of erosion and soil degradation will convert our jungles into deserts. 

A Semi-quantitative Approach Erosion and Deposition. Over the centuries the primary impact of human activity has been to deforest the surrounding countryside and increase the rate of erosion and deposition into rivers. This results primarily from the destruction of vegetation cover which stabilizes soil systems on gradient. The ecological impact of erosion has at present reached catastrophic proportions. The magnitude of continental erosion into rivers is illustrated in Figure 3. 

In developing and applying the erosional-depositional system, careful consideration was given to the environmental factors which influence the potential for erosion, transport and deposition climate, topography, geology and soils, as well as human activity. 

Lai, R. In World Soil Erosion and Conservation Pimentel, D., Ed. Cambridge University Press Cambridge, UK, 1991. 

Much of the surface soil erosion and hence nutrient loss occurs when deforestation and biomass burning removes and/or consumes the organic materials that protect the soil surface. Significant losses may occur by dry ravel or overland water erosion associated with precipitation events. Under a shifting cultivation system in a tropical deciduous forest ecosystem in Mexico, Maass et al. 61) reported first year losses of N, P, K, and Ca were 187, 27, 31, and 378 kg ha" respectively. In contrast, losses in adjacent undisturbed forests were less than 0.1 kg ha for all nutrients except Ca (losses were 0.1-0.5 kg ha for Ca). 

DeBano, L.F. Rice, R.M. Conrad, C.E. Soil heating in chaparral fires Effects on soil properties, plant nutrients, erosion, and runoff. Berkeley, Calif. Pac. Southwest For. and Range Exp. Stn., Forest Service, USDA 1979, Res. Pap. PSW-145. 21 p. 

Soil is a key component of the rock cycle because weathering and soil formation processes transform rock into more readily erodible material. Rates of soil formation may even limit the overall erosion rate of a landscape. Erosion processes are also a key linkage in the rock cycle... 

Fig. 9-3 Conceptual model to describe the interaction between chemical weathering of bedrock and down-slope transport of solid erosion products. It is assumed that chemical weathering is required to generate loose solid erosion products of the bedrock. Solid curve portrays a hypothetical relationship between soil thickness and rate of chemical weathering of bedrock. Dotted lines correspond to different potential transport capacities. Low potential transport capacity is expected on a flat terrain, whereas high transport is expected on steep terrain. For moderate capacity, C and F are equilibrium points. (Modified with permission from R. F. Stallard, River chemistry, geology, geomorphology, and soils in the Amazon and Orinoco basins. In J. I. Drever, ed. (1985), "The Chemistry of Weathering," D. Reidel Publishing Co., Dordrecht, The Netherlands.)...

Many important erosion-related phenomena are episodic and infrequent, such as flash floods, landslides, and glaciations, while others such as orogenesis and soil formation involve time scales that exceed those of major climate fluctuations. In either case, the time scale of human existence is too short to make adequate observations. Consequently, it is difficult to directly estimate the rates or characterize the effects of such phenomena on erosion products. The key to understanding weathering and erosion, on a continental scale, is to decipher the relationship between landforms, the processes that produce them, and the chemistry and discharge of river-borne materials. 

Site topography Exclusion Must have slope <1% Site must not be susceptible to flooding Shallow water table or tile drains must not interfere with sampling These are exclusion criteria that have to be carefully determined during on-site inspection Site must be level to prevent losses of agrochemical due to surface run-off and soil erosion Site must not be susceptible to runoff from other areas higher than test site... 

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