Resilience to Land Use Induced Impacts A Contribution To Improve Precautionary Ecological Management In Coastal Ecosystems

• Main Author: Teixeira, Zara Fani Gonçalves
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2015
• Subjects: Agriculture; Aquatic sciences; Area planning & development; Area Planning and Development; Basins; Biogeochemistry; Biology; Biomass; Chemistry; Communication; Community; Computer science; Ecology; Economic development; Economics; Ecosystems; Environmental impact; Environmental management; Environmental policy; Estuaries; Eutrophication; Geomorphology; Hydrologic sciences; Hydrology; Land use; Land Use Planning; Management; Nitrates; Public policy; River ecology; Society; Software; Water Resources Management; Water treatment; Watersheds
• ISBN: 9798837576553

The European Water Framework Directive enhances the role of land use in determining water quality of all waters, but the use of land cover data, regarding surface waters, is restricted to the estimation of land use patterns for the identification of pressures on surface waters from diffuse source pollution.The main goal of this study is to uncover specificities of land cover in the assessment of state changes (Chapter I), pressures (Chapter I and II) and drivers (Chapter III and IV) of water quality of surface waters.For this purpose, we use data from the Mondego river basin, a coastal watershed in Portugal, where socio-economic changes observed since the 1990s resulted in the loss of representativeness from the agricultural sector and gain from the construction sector. Despite the observed changes, agriculture remained a source of pressure on surface waters which, associated with hydro-morphological modifications, caused a decline of the ecological quality of the Mondego estuary. In 1998, the implementation of mitigation measures enabled the recovery of the system but routine monitoring identified high concentrations of nutrients deserving further assessment to understand its sources. For this reason, the Mondego river basin, as a case study, provided conditions to reveal wider applications of land cover data within the assessment of drivers and pressures of water quality.Chapter I establishes the baseline for our research applying indicators of nutrients and oxygenconsuming-substances to analyze progress in the concentrations of ammonia, nitrate and phosphate in the Mondego estuary from a former period (2003-2007) to a recent period (2012) - 2013) (ANOVA in R software); to analyze differences between the annual mean concentrations of nutrients in the tributary rivers in 2012-2013 and the average annual mean concentrations found in European rivers in three different periods (1992, 2000, 2012); and to evaluate differences in the variability of nutrient concentrations between the estuary and the tributaries in 2012-2013 (ANOVA in R software). Additionally, Chapter I evaluates the dependency of estuarine nutrient concentrations on riverine freshwater inputs in two different periods. A linear relationship between the nutrient concentrations and salinity, precipitation and temperature was sought (linear regression in R software). Altogether the results indicate differences between time intervals and are able to establish a dependency of nutrient concentrations on riverine freshwater inputs, indicating pressure from nutrient loadings on the estuary.In Chapter II pressure from nutrient flushing on the river basin is evaluated using land cover data as an indicator. The suitability of landscape metrics to describe the spatial variability of nitrate across the Mondego river basin is assessed using seasonal data from the years 2001 and 2006 (linear mixed model - R software). The results reveal that land cover patterns are weak descriptors of nitrate spatial variability in the Mondego river basin.In Chapter III driving forces of water quality are characterized using processes of landscape change as proxy. CORINE Land cover maps at 1990, 2000 and 2006 are used to analyze changes among eight categories through an extended analysis of transition matrices. The magnitude of change and consistency of transitions reveal that the most relevant driving forces from land transitions include categories with low percentage of occupation but high potential effect on hydrological processes.