Investigation of First Flushes in a Small Rural-Agricultural Catchment

Abstract

The control of diffuse pollution requires information on the transport processes of those pollutants within a catchment. The characteristics of diffuse nitrogen and phosphorus discharged from a typical rural-agricultural catchment dominated by residential areas, sloping cropland, and forest land were monitored in the hilly area of the upper Yangtze River, China, and analyzed based on a total of eight rainfall-event runoff from August 2010 to September 2011. The results showed that the average of event mean concentrations (EMCs) of TN, DN, PN, TP, DP, and PP were 4.94, 3.18, 1.76, 1.11, 0.19, and 0.92 mg/L, respectively. The high EMCs demonstrated diffuse pollution of rural-agricultural catchment posing great pressure on receiving water. The first flush phenomenon for nitrogen and phosphorus was identified in rural-agricultural catchment, especially for the medium and heavy rainfall events, and a total of 36%, 44%, 46%, and 51% of the mass for TN, PN, TP, and PP, respectively, were discharged in the first 25% of the runoff. The first flush phenomenon suggested more attention should be paid on the management of the initial part of runoff in order to improve the efficiency of diffuse pollution control at catchment scale.

Hydrological controls on DOC : nitrate resource stoichiometry in a lowland, agricultural catchment, southern UK

“…Thus changing climate, with important, potential implications for rainfall patterns and hydrochemical responses in rivers, is adding a new urgency to understanding and managing the issue of excess nitrate in our agricultural-dominated landscapes (Howarth et al, 2012). In the UK, there is concern that warmer, drier summers and wetter winters may lead to increased nitrate export from lowland catchments (Whitehead et al, 2009), one scenario being an increased accumulation of nitrate in soils by mineralization in hot, dry summers followed by flushing of nitrate from soils during autumn at the end of the drought (Whitehead et al, 2006) especially in conjunction with first-flush responses (Jiang et al, 2010;Yang et al, 2015;Orr et al, 2016). However, considerable uncertainty exists around current predictions (Heathwaite, 2010), and policymakers lack results from studies at appropriate temporal and spatial scales for confident decision making (Watts et al, 2015).…”

The North Wyke Farm Platform: effect of temperate grassland farming systems on soil moisture contents, runoff and associated water quality dynamics

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