Modelling macronutrient dynamics in the Hampshire Avon river: A Bayesian approach to estimate seasonal variability and total flux

Abstract

The macronutrients nitrate and phosphate are aquatic pollutants that arise naturally, however, in excess concentrations they can be harmful to human health and ecosystems. These pollutants are driven by river currents and show dynamics that are affected by weather patterns and extreme rainfall events. As a result, the nutrient budget in the receiving estuaries and coasts can change suddenly and seasonally, causing ecological damage to resident wildlife and fish populations. In this paper, we propose a statistical change-point model with interactions between time and river flow, to capture the macronutrient dynamics and their responses to river flow threshold behaviour. It also accounts for the nonlinear effect of water quality properties via nonparametric penalised splines. This model enables us to estimate the daily levels of riverine macronutrient fluxes and their seasonal and annual totals. In particular, we present a study of macronutrient dynamics on the Hampshire Avon River, which flows to the southern coast of the UK through the Christchurch Harbour estuary. We model daily data for more than a year during 2013-14 in which period there were multiple severe meteorological conditions leading to localised flooding. Adopting a Bayesian inference framework, we have quantified riverine macronutrient fluxes based on input river flow values. Out of sample empirical validation methods justify our approach, which captures also the dependencies of macronutrient concentrations with water body characteristics.

Land cover and nutrient enrichment regulates low‐molecular weight dissolved organic matter turnover in freshwater ecosystems

“…Samples were collected from 45 rivers across five contrasting land covers (arable, grasslands, conifer forests, peatland, and mixed agricultural) in the Conwy catchment, North Wales, and the Nadder Catchment, a subcatchment of the well‐researched Hampshire Avon catchment in Southern England (Jarvie et al 2005; Pirani et al 2016; Fig. 1).…”

Modelling the impact of river flow, macronutrients and solar radiation on the eutrophication status of small shallow estuaries

“…This has prompted much of the river/estuarine system to be designated a Special Area of Conservation (SAC) with many parts of the catchment classed as Sites of Special Scientific Interest (SSSI; Whitehead et al, 2014). Due to its protected status, it is necessary to ensure ecosystem health is maintained; however, nutrient pollution in the Avon has been a growing issue, resulting in the development of algae growth and consequently eutrophication (Whitehead et al, 2014;Pirani et al, 2016). From 2012 to 2017 the Christchurch Harbour Macronutrients Project was established to provide extensive monitoring of the system and thus improve understanding of macronutrient behaviour in the Hampshire Avon, River…”

Prediction of Water Quality in Riva River Watershed

“…This situation negatively affects water quality criteria, biodiversity and the ecological health of rivers. Particularly nitrate and phosphate damage aquatic life by reducing water quality when they are present in excessive amounts although they naturally exist in freshwaters [5,6].…”