Agricultural Land Use and Best Management Practices to Control Nonpoint Water Pollution

Abstract

In recent years, improvements in point-source depuration technologies have highlighted the problems regarding agricultural nonpoint (diffuse) sources, and this issue has become highly relevant from the environmental point of view. The considerable extension of the areas responsible for this kind of pollution, together with the scarcity of funds available to local managers, make minimizing the impacts of nonpoint sources on a whole basin a virtually impossible task. This article presents the results of a study intended to pinpoint those agricultural areas, within a basin, that contribute most to water pollution, so that operations aimed at preventing and/or reducing this kind of pollution can be focused on them. With this aim, an innovative approach is presented that integrates a field-scale management model, a simple regression model, and a geographic information system (GIS). The Lake Vico basin, where recent studies highlighted a considerable increase in the trophic state, mainly caused by phosphorus (P) compounds deriving principally from the intensive cultivation of hazelnut trees in the lake basin, was chosen as the study site. Using the management model Groundwater Loading Effects of Agricultural Management Systems (GLEAMS), the consequences, in terms of sediment yield and phosphorus export, of hazelnut tree cultivation were estimated on different areas of the basin with and without the application of a best management practice (BMP) that consists of growing meadow under the trees. The GLEAMS results were successively extended to basin scale thanks to the application of a purposely designed regression model and of a GIS. The main conclusions can be summarized as follows: The effectiveness of the above-mentioned BMP is always greater for erosion reduction than for particulate P reduction, whatever the slope value considered; moreover, the effectiveness with reference to both particulate P and sediment yield production decreases as the slope increases. The proposed approach, being completely distributed, represents a considerable step ahead compared to the semidistributed or lumped approaches, which are traditionally employed in research into tools to support the decision-making process for land-use planning aimed at water pollution control.

Relações entre qualidade da água e uso do solo em Goiás: uma análise à escala da bacia hidrográfica

“…Quanto ao contraste sazonal, este variou entre -38% e +45%, com um coeficiente de variação relativamente expressivo (0,761), o que sugere certa inconstância na variabilidade temporal dos parâmetros. (BENETTI e BIDONE, 2000;REED e CARPENTER, 2002;RIPA et al, 2006). Da mesma forma, o uso de indicadores de uso do solo na escala paisagística de zona ripária, mais afeitos ao aporte de matéria orgânica, por exemplo, pode influenciar significativamente a relação entre IQA 1 e NRVI (GERGEL et al, 2002;MEADOR e GOLDSTEIN, 2003;HOULAHAN e FINDLAY, 2004).…”

“…Em grandes extensões territoriais, o conhecimento de parâmetros que relacionem as condições da cobertura vegetal com a qualidade desejável das águas, conforme seu uso preponderante, pode embasar instrumentos de planejamento e padrões de uso do solo (RIPA et al, 2006). Em Goiás, uma das bases de dados de qualidade das águas superficiais de maior abrangência espacial é a de monitoramento de mananciais de abastecimento público operados pela Saneamento de Goiás S/A, Saneago.…”

Assessment of Agricultural Best Management Practices Using Models: Current Issues and Future Perspectives

“…High data requirement of those complex models may provide litter, if any, improvements, especially in large areas where sufficient data are not always available. By consequence, a meta-model, which is not only based on process oriented simulations but also extends the BMPs' effectiveness to a large scale using approximation methods, seems to be an alternative to better face NPSs' complex behavior in practical applications [89][90][91][92]. Land managers should keep these intrinsic characteristics in mind when adopting modelling methods for assessment of BMPs.…”

Construction of a Bayesian Network for the Assessment of Agri-Environmental Measures – The Case Study of the Venice Lagoon Watershed

“…Point sources imply the identification of discrete pollution sources, plainly detectable, while non-point sources are not clearly identifiable. This work deals with diffuse pollution (or non-point source pollution as defined by the EEA Glossary 1 ), a source that is strongly dependent on land use, with agriculture being commonly considered as the main cause of this pollution, and agrochemicals recognised as the main causes of water depletion (Ripa et al, 2006).…”