Now showing 1 - 10 of 50
  • Publication
    Catchment Management Support Tools for Characterisation and Evaluation of Programme of Measures
    (Environmental Protection Agency, 2018-05) ;
    Nutrient enrichment and eutrophication can negatively impact on freshwater ecosystems, estuarine and coastal waters. As a result of improvements in nutrient management and regulation, there has been a large reduction in total phosphorus, total ammonia and total nitrogen emissions from Irish catchments in recent decades. However, half of Irish river water bodies still require improvements to bring them to Good status, as required by the Water Framework Directive (WFD) (2000/60/EC). The Catchment Management Support Tools for Characterisation and Evaluation of Programme of Measures project, or CatchmentTools project, developed data analysis tools and models for assessing nutrients in Irish catchments to support catchment scientists and managers to (1) characterise nutrient sources, pathways and receptors in catchments and (2) assess potential mitigation measures.
  • Publication
    Assessment of factors affecting flood forecasting accuracy and reliability. Carpe Diem Centre for Water Resources Research : Deliverable 10.3
    (University College Dublin. Departmetn of Civil Engineering, 2004-12) ; ; ;
    In Deliverable 10.1, a optimal methodology for combining precipitation information from raingauges, radar and NWP models (in this case HIRLAM) was described. It was based on an artificial neural network combination model, fitted to historic data, and operating on one-dimensional time-series of discharges. In this report, this new methodology is tested by applying it to (i) a rural catchment (Dargle)and (ii) a small urban catchment (CityWest). The results are compared with measured discharge series in both cases. Various measures of performance, applied to both the entire discharge series and also to the peaks-only are reported for various combinations of lead-time, spatial resolution and numbers of neurons in the hidden layer of the ANN model.
  • Publication
    Comparison of physically based catchment models for estimating Phosphorus losses
    (IWA publishing, 2003-08) ;
    As part of a large EPA-funded research project, coordinated by TEAGASC, the Centre for Water Resources Research at UCD reviewed the available distributed physically based catchment models with a potential for use in estimating phosphorous losses for use in implementing the Water Framework Directive. Three models, representative of different levels of approach and complexity, were chosen and were implemented for a number of Irish catchments. This paper reports on (i) the lessons and experience gained in implementing these models, (ii) compares the performances of the individual models and (iii) assesses their sensitivities to the main parameters and to spatial scales.
  • Publication
    The significance of the differences in soil phosphorus representation and transport procedures in the SWAT and HSPF models and a comparison of their performance in estimating phosphorus loss from an agriculture catchment in Ireland
    Phosphorus transported from agriculture land has been identified as a major source of water pollution in a large number of Irish catchments. Models of this process are required in order to design and assess management measures. This paper reports on the comparison and assessment of two of the most promising physically-based distributed models, SWAT and HSPF, with particular emphasis on their suitability for Irish conditions. The representation of the overall soil phosphorus cycle is similar in both models but there is a significant difference in the level of detail in describing the chemical and biochemical processes in each model. Also there are differences in modeling the mechanisms by which phosphorus is removed from the soil column and either transported in dissolved form with the runoff water or in particulate form attached to eroded or detached sediment. These differences could have a significant influence on performance when using either of the models to simulate phosphorus loss from any catchment. Both models are applied to estimating the phosphorus concentration at the outlet of the Clarianna catchment in north Tiperrary (Ireland). This catchment is small (23km2) and the landuse is mainly pasture on grey brown podozilic soils. The results of model calibration are presented along with an assessment of the usefulness of the model outputs as a water quality management tool.
  • Publication
    Developing an independent, generic, phosphorus modelling component for use with grid-oriented, physically-based distributed catchment models
    Grid-oriented, physically based catchment models calculate fields of various hydrological variables relevant to phosphorous detachment and transport. These include (i) for surface transport: overland flow depth and flow in the coordinate directions, sediment load, and sediment concentration and (ii) for subsurface transport: soil moisture and hydraulic head at various depths in the soil. These variables can be considered as decoupled from any chemical phosphorous model since phosphorous concentrations, either as dissolved or particulate, do not influence the model calculations of the hydrological fields. Thus the phosphorous concentration calculations can be carried out independently from and after the hydrological calculations. This makes it possible to produce a separate phosphorous modelling component which takes as input the hydrological fields produced by the catchment model and which calculates, at each step the phosphorous concentrations in the flows. This paper summarise the equations and structure of Grid Oriented Phosphorous Component (GOPC) developed for simulating the phosphorus concentrations and loads using the outputs of a fully distributed physical based hydrological model. Also the GOPC performance is illustrated by am example of an experimental catchment (created by the author) subjected to some ideal conditions.
  • Publication
    FloodWarnTech: Flood warning technologies for Ireland
    (Environmental Protection Agency, 2019-04) ;
    Flooding occurs when a body of water rises to overflow land that is not normally submerged (Ward, 1978). While this definition explicitly includes all types of surface inundation, floods are typically classified into four categories, viz., riverine (fluvial), coastal, groundwater and urban (often called pluvial) flooding. This study is limited to riverine floods, which occur when a river discharge exceeds its bankfull capacity (Leopold et al., 1964).
  • Publication
    ESManage Programme: Irish Freshwater Resources and Assessment of Ecosystem Services Provision
    Freshwater is vital for all forms of life and it is a key requirement in almost all human activities. The societal importance of water has been highlighted by the United Nations, with access to clean water and sanitation regarded as a universal human right. Consequently, the sustainable management of freshwater resources has gained importance at regional, international and global scales. However, the activities of humankind affect freshwater resources extensively, in terms of both quantity and quality, through a variety of activities ranging from abstraction of water for drinking and irrigation to waste disposal. Today, worldwide freshwater ecosystems are undergreat pressure and are one of the most endangered ecosystems. Furthermore, climate change, especially in relation to precipitation patterns and flooding, will result in the traditional norms being replaced with increased variability and unpredictability, with knock-on effects for human societies and well-being.
  • Publication
    CCT: A simple prioritisation tool for identifying critical source areas for managing waterborne pollutants
    Catchment characterisation integrates an understanding of the physical characteristics, sources, pathways and pressures in a catchment, and provides a scientific basis for evaluation of mitigation measures required by the EU Water Framework Directive. In Ireland, the Catchment Characterisation Tool (CCT) has been developed to assess the potential risk posed by nitrate and phosphate from diffuse agricultural sources to surface and groundwater receptors, and to delineate critical source areas in Irish sub-catchments (typically from 10 – 200 km2 in size) as a means of facilitating the targeting of mitigation measures. The CCT for nitrate, which is presented in this paper, is a steady-state model based on annual average nitrate loadings transported from their land sources along near surface and subsurface pathways to each receptor. The GIS-based model links spatial datasets, such as land-use, soil and geological properties with transport and delivery factors derived from field and literature data. The model can distinguish between the contaminant loads transported through each of the major hydrological pathways. The CCT calculates the nitrate loading to surface waters following the source-pathway-receptor methodology, and results are displayed in pollution impact potential maps. A key issue with such export models is how they can be validated. This paper describes the validation methodology which compared a national dataset of measured nitrate concentrations in Irish water bodies with values predicted by the CCT. More detailed comparisonswith local test catchments that are more intensively monitored showed satisfactory correlation between the CCT predictions and measured concentrations. This paper thus shows both the potential of the CCT approach, the likely range of the uncertainty to be expected, and the issues that arise from its validation.
  • Publication
    Improving national mapping of critical source areas of phosphorus and nitrogen losses in Irish agricultural catchments to support policy
    Policymakers, farm advisors and water agencies require up-to-date national maps of critical source areas (CSAs) of nitrogen (N) and phosphorus (P) losses from agricultural land to improve catchment management decisions. The DiffuseTools project aimed to achieve this in Ireland by updating the existing Catchment Characterisation Tool and sub-model NCYCLE_IRL, which predicts environmental losses of N and P from the farm via surface runoff, leaching, denitrification and volatilisation. Updates included (i) using improved national maps of farm-scale source loadings as inputs, (ii) sub-field scale modelling of surface transport risk using soil topographic indices derived from 1 m and 5 m NEXTMap digital elevation models (DEMs), (iii) modelling hydrological disconnectivity from microtopography (HSA Index) and reinfiltration (SCIMAP), (iv) improving the national ditch and stream channel network used by the model by DEM extraction, and (v) using SCIMAP to improve predictions of erosion risk. The improved national source loading maps included mean nationally weighted farm-gate N and P imports (fertilizer, feed and livestock) and balance surpluses (kg/ha) calculated for each stocking rate and soil group (land use potential) category within each sector type (dairy, mixed livestock, suckler cattle, non-suckler cattle, sheep and tillage), using annual Teagasc National Farm Survey data (2008-15). Furthermore, updated national maps of soil P and atmospheric N and P deposition inputs were also used within the national source loading maps to improve model performance. National CSA maps for N and P for each pathway were then produced and evaluated using water quality monitoring data and field observations from the Environmental Protection Agency and Teagasc Agricultural Catchments Programme. These maps will be able to support sustainable intensification by informing farm and catchment management decisions such as where to cost effectively target mitigation measures to reduce environmental losses, where to distribute nutrient surpluses (to non-CSAs in nutrient deficit), and improving functional land management.