Predicting Nitrate Concentrations in Northern Ireland Rivers Using Time Series Analysis
1997
Stronge, K. M. | Lennox, S. D. | Smith, R. V.
Lough Neagh is an important natural resource, being the largest single source of potable water for Belfast. Its catchment area covers about one-third of the land area of Northern Ireland. Six inflow rivers drain 88% of the total catchment, which has a land usage of grassland and rough grazing that is similar to Northern Ireland as a whole. This report examines the causes of the year-to-year variation in river NO⁻₃ concentrations that have been the focus of European Community (EC) legislation. A multiple regression model has been developed which explains 74% of the variation in NO⁻₃ concentrations for the time period 1974 to 1994. Based on a knowledge of the Northern Ireland annual utilized metabolizable energy (UME) for grazing livestock and N fertilizer sales, the model employs the efficiency of fertilizer usage as an independent variable. Additional independent variables are climatic: previous summer rainfall, sun hours in the winter and rainfall for the period January to June. Based on a worst case scenario, employing the extreme values for these climatic variables and the least fertilizer efficiency ratio, the predicted NO⁻₃ concentration is only 4.4 mg N L⁻¹, which is well below the EC maximum admissible level of 11.3 mg N L⁻¹ for drinking water.
显示更多 [+] 显示较少 [-]