Multitemporal analysis of estimated soil loss for the river Mourão watershed, Paraná – Brazil / Análise multitemporal da perda de solo estimada para a bacia hidrográfica do rio Mourão, Paraná – Brasil

The multitemporal behavior of soil loss by surface water erosion in the hydrographic basin of the river Mourão in the center-western region of the Paraná state, Brazil, is analyzed. Forecast was based on the application of the Universal Soil Loss Equation (USLE) with the data integration and estimates within an Geography Information System (GIS) environment. Results had shown high mean annual rain erosivity (10,000 MJ.mm.ha–1.h–1.year–1), with great concentration in January and December. As a rule, soils have average erodibilities, exception of Dystroferric Red Latisol (low class) and Dystrophic Red Argisol (high class). Although the topographic factor was high (>20), rates lower than 1 were predominant. Main land uses comprise temporal crops and pasture throughout the years. The watershed showed a natural potential for low surface erosion. When related to usage types, yearly soil loss was also low (<50 ton.ha–1.year–1), with more critical scores that reach rates higher than 150 ton.ha–1.year–1. Soil loss over the years did not provide great distinctions in distribution standards, although it becames rather intensified in some sectors, especially in the center-eastern and southwestern sections of the watershed.

Resumo Este estudo visa analisar o comportamento multitemporal da perda de solo por erosão hídrica laminar na bacia hidrográfica do rio Mourão, localizada na região centro-ocidental do Estado do Paraná – Brasil. A predição foi baseada na aplicação da Equação Universal de Perdas de Solo (USLE), com integração dos dados e estimativas realizados em ambiente SIG (Sistema de Informações Geográficas). Os resultados mostram elevada erosividade da chuva média anual (10.000 MJ.mm.ha–1.h–1.ano–1). Os solos apresentam, em geral, média erodibilidade, com exceções do Latossolo Vermelho Distroférrico (classe baixa) e o Argissolo Vermelho Distrófico (classe alta). O fator topográfico atingiu índices elevados (>20), no entanto, predominaram os valores inferiores a 1. Os tipos de usos principais são as lavouras temporárias e pastagem, para todos os anos. A bacia apresentou Potencial Natural a Erosão laminar predominante baixo, quando relacionado aos tipos de usos resultou numa perda de solo anual estimada também baixa (<50 ton.ha–1.ano–1), com pontos mais críticos que atingem valores superiores a 150 ton.ha–1.ano–1. A perda de solo entre os anos não apresentou grandes distinções nos padrões de distribuição, apenas intensificou-se em alguns setores, como nas porções centro-leste e sudoeste da bacia.

Multitemporal analysis of estimated soil loss for the river Mourão watershed, Paraná Brazil

The multitemporal behavior of soil loss by surface water erosion in the hydrographic basin of the river Mourão in the center-western region of the Paraná state, Brazil, is analyzed. Forecast was based on the application of the Universal Soil Loss Equation (USLE) with the data integration and estimates within an Geography Information System (GIS) environment. Results had shown high mean annual rain erosivity (10,000 MJ.mm.ha1.h1.year1), with great concentration in January and December. As a rule, soils have average erodibilities, exception of Dystroferric Red Latisol (low class) and Dystrophic Red Argisol (high class). Although the topographic factor was high (>20), rates lower than 1 were predominant. Main land uses comprise temporal crops and pasture throughout the years. The watershed showed a natural potential for low surface erosion. When related to usage types, yearly soil loss was also low ( 50 ton.ha1.year1), with more critical scores that reach rates higher than 150 ton.ha1.year1. Soil loss over the years did not provide great distinctions in distribution standards, although it becames rather intensified in some sectors, especially in the center-eastern and southwestern sections of the watershed.

Resumo Este estudo visa analisar o comportamento multitemporal da perda de solo por erosão hídrica laminar na bacia hidrográfica do rio Mourão, localizada na região centro-ocidental do Estado do Paraná Brasil. A predição foi baseada na aplicação da Equação Universal de Perdas de Solo (USLE), com integração dos dados e estimativas realizados em ambiente SIG (Sistema de Informações Geográficas). Os resultados mostram elevada erosividade da chuva média anual (10.000 MJ.mm.ha1.h1.ano1). Os solos apresentam, em geral, média erodibilidade, com exceções do Latossolo Vermelho Distroférrico (classe baixa) e o Argissolo Vermelho Distrófico (classe alta). O fator topográfico atingiu índices elevados (>20), no entanto, predominaram os valores inferiores a 1. Os tipos de usos principais são as lavouras temporárias e pastagem, para todos os anos. A bacia apresentou Potencial Natural a Erosão laminar predominante baixo, quando relacionado aos tipos de usos resultou numa perda de solo anual estimada também baixa ( 50 ton.ha1.ano1), com pontos mais críticos que atingem valores superiores a 150 ton.ha1.ano1. A perda de solo entre os anos não apresentou grandes distinções nos padrões de distribuição, apenas intensificou-se em alguns setores, como nas porções centro-leste e sudoeste da bacia.

Soil Erosion Mapping in Singhanhalli-Bogur Microwatershed in Northern Transition Zone of Karnataka Using Universal Soil Loss Equation and Geographic Information Systems.

Soil erosion which occurs at spatially varying rates is a widespread threat to sustainable resource management at watershed scale. Thus estimation of soil loss and identification of critical area for implementation of best management practices is central to a successful soil conservation programme. The present study was conducted to assess soil erosion using USLE and suggests possible intervention strategies to address soil loss in Singhanhalli-Bogur Microwatershed of Dharwad District in northern transition zone of Karnataka. The average annual soil loss was 27 tons ha-1yr-1. About 574 ha of the study area was under slight erosion, 118 ha under moderate erosion and 53 ha under severe erosion. The soil loss under different land uses ranged from 7 tons ha-1yr-1 under forest to 40 tons ha-1yr-1 under agriculture. The soil loss under plantation and open scrub land uses were 8 and 26 tons ha-1yr-1 respectively. Major causes of soil erosion were cultivation without proper soil and water conservation measures in area not suitable for crops, denuded areas without vegetation, cultivated fallow on moderate slopes, degraded forests/pastures on steep slopes and poorly managed forest cover. Appropriate soil conservation and land management techniques for the different soil erosion classes were suggested.