Effects of land use and seasonality on stream water quality in a small tropical catchment: The headwater of Córrego Água Limpa, São Paulo (Brazil)

Abstract

Stream water quality is controlled by the interaction of natural and anthropogenic factors over a range of temporal and spatial scales. Among these anthropogenic factors, land cover changes at catchment scale can affect stream water quality. This work aims to evaluate the influence of land use and seasonality on stream water quality in a representative tropical headwater catchment named as Córrego Água Limpa (Sao Paulo, Brasil), which is highly influenced by intensive agricultural activities and urban areas. Two systematic sampling approach campaigns were implemented with six sampling points along the stream of the headwater catchment to evaluate water quality during the rainy and dry seasons. Three replicates were collected at each sampling point in 2011. Electrical conductivity, nitrates, nitrites, sodium superoxide, Chemical Oxygen Demand (DQO), colour, turbidity, suspended solids, soluble solids and total solids were measured. Water quality parameters differed among sampling points, being lower at the headwater sampling point (0m above sea level), and then progressively higher until the last downstream sampling point (2500m above sea level). For the dry season, the mean discharge was 39.5ls (from April to September) whereas 113.0ls were averaged during the rainy season (from October to March). In addition, significant temporal and spatial differences were observed (P<0.05) for the fourteen parameters during the rainy and dry period. The study enhance significant relationships among land use and water quality and its temporal effect, showing seasonal differences between the land use and water quality connection, highlighting the importance of multiple spatial and temporal scales for understanding the impacts of human activities on catchment ecosystem services.

Assessing Anthropogenic Impacts on Chemical and Biochemical Oxygen Demand in Different Spatial Scales with Bayesian Networks

“…The research implied that anthropogenic activities had the most significant impacts on the oxygen-consuming organic matter indicators (COD and BOD) at the EUC scale in the HRB. It was consistent with previous research that focused on other river basins, such as the Dongjiang River basin in China, the Adour-Garonne basin in southwestern France and the Córrego Água Limpa in Brazil [16,19,61]. However, some studies suggested that the land use in relative finer scales had more effects on water quality [62,63].…”

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“…The human influence on the coast is stronger than in other regions of the Earth given that more than 40% of the world population lives in coastal neighbourhoods (Small and Nicholls, ; Ouillon, ). It is indeed recognized that human activities can be a morphogenetic process (Marriner et al ., ; Kołodyńska‐Gawrysiak and Poesen, ; Poesen, ) and can influence the main characteristics of an estuarine environment such as the tidal prism (Kerner, ; Winterwerp et al ., ), the turbidity (Rapaglia et al ., ; Winterwerp et al ., ; Rodrigues et al ., ), the sediment budget (Syvitski et al ., ; Wang et al ., ; Sarretta et al ., ; Zhu et al ., ), the erosion rate (De Roo and Troch, ; Zaggia et al ., ) and the morphodynamics itself (Jeuken and Wang, ; Monge‐Ganuzas et al ., ).…”

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