River Boyne Water Quality Management Plan - EPA

Hivrr Boyor Wnlcr Quality Xlanagrnmt PlanDaily rainfall data is available for various locations throughout the catchment. This information ispublished for 30 year periods and at l0 year intervals by the Meteorological Service. Records for theperiod 195 1-1980 are tabulated in Appendix I and Isohyets of rainfall for the catchment are presentedin Map No.2.Rainfall in the Boyne catchment varies from approximately 830mm in the central area of thecatchment (Trim, Navan and Drogheda) to approximately 1,100mm per annum in theBailieboro areaof Cavan.In carrying out a water resource balance assessment, allowance must be made for uptake of rainfall inevaporaticn and transpiration. Estimates of evapotranspiration are also provided by theMeteorological Service and vary according to weather conditions including sunlight. Typical valuesof evapotmnspiration loss for the catchment would be in the order of 400-450mm per annum.Typical water resource balance calculations in the River Boyne catchment are summarised in Table2.5 based on data from the document "A Statistical Analysis of River Flows" produced by the WaterResources Section, Environmental Research Unit (now the EPA), for the Eastern Water ResourceRegion.TABLE 2.5 - BOYNE CATCHMENT WATER RESOURCES (0.&'tr,. GAUGING SITES),5,For inspection purposes only.Consent of copyright owner required for any other use.This table demonstrates a consistent net yield from theBoyne catchment in the order of 1611s per km2as average daily flow. Higher figures are indicated for the smaller Moynalty and Skane catchments aswould be expected, due to shorter times of concentration.These figures give an overall estimate of the average water resources available in the catchment.However, from a water use and water quality point of view, the low flow data (95 percentile andDWF) are more significant.EPA Export 26-07-2013:17:26:59