Spatio-temporal variation in stream water chemistry in a tropical urban watershed

Abstract

ABSTRACT. Urban activities and related infrastructure alter the natural patterns of stream physical and chemical conditions. According to the Urban Stream Syndrome, streams draining urban landscapes are characterized by high concentrations of nutrients and ions, and might have elevated water temperatures and variable oxygen concentrations. Here, we report temporal and spatial variability in stream physicochemistry in a highly urbanized watershed in Puerto Rico. The main objective of the study was to describe stream physicochemical characteristics and relate them to urban intensity, e.g., percent impervious surface cover, and watershed infrastructure, e.g., road and pipe densities. The Río Piedras Watershed in the San Juan Metropolitan Area, Puerto Rico, is one of the most urbanized regions on the island. The Río Piedras presented high solute concentrations that were related to watershed factors, such as percent impervious cover. Temporal variability in ion concentrations lacked seasonality, as did all other parameters measured except water temperature, which was lower during winter and highest during summer, as expected based on latitude. Spatially, stream physicochemistry was strongly related to watershed percent impervious cover and also to the density of urban infrastructure, e.g., roads, pipe, and building densities. Although the watershed is serviced by a sewage collection system, illegal discharges and leaky infrastructure are probably responsible for the elevated ion concentration found. Overall, the Río Piedras is an example of the response of a tropical urban watershed after major sewage inputs are removed, thus highlighting the importance of proper infrastructure maintenance and management of runoff to control ion concentrations in tropical streams.

Nutrient export and elemental stoichiometry in an urban tropical river

“…The effects of these leaks on stream chemistry have recently been described by Ramírez et al. () and Potter et al. (), who both documented the spatial variability in nitrogen, phosphorus, and major ion concentrations with extensive sampling throughout the Río Piedras basin.…”

Urban Evolution: The Role of Water

“…For example, research has characterized ecosystem functions such as nitrogen uptake, denitrification, and ecosystem metabolism in buried streams, storm drains, and stormwater management controls [37,42,[48][49][50]. Other work has investigated broader spatial patterns in transport and transformation of materials along natural and engineered hydrologic flowpaths of the urban watershed continuum [45,51,52]. Finally, recent work has also proposed that the urban watershed continuum can be a useful tool for guiding watershed management and ecosystem restoration by recognizing a distinct hydrology and ecology along urban hydrologic flowpaths [50,53].…”

Relação entre padrões de uso e ocupação do solo e qualidade da água em uma bacia hidrográfica urbana

“…Relação do uso e ocupação do solo com a qualidade da água em uma bacia urbana LEE et al, 2009;LI et al, 2009;WALKER et al, 2009;FIA et al, 2015;RAMIREZ et al, 2014 Com relação às áreas agrícolas, não foram observados incrementos de nutrientes durante a estação chuvosa, como citado por outros autores (LI et al, 2009;TRAN et al, 2010). Provavelmente, a baixa precipitação acontecida de forma anormal durante o ano avaliado não proporcionou escoamento superficial suficiente para que houvesse o transporte de nutrientes.…”