Technological platform for catchment water safety planning

Technological platform for catchment water safety planning J.M.P. Vieira*, J.L.S. Pinho*, B.F.V. Vieira* * Centre for Territory, Environment and Construction, Department of Civil Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal, j[email protected] Abstract: Water safety plans is a concept proposed by the World Health Organisation for risk assessment and risk management in drinking water systems. This concept includes the identification of hazards and control points throughout the water cycle from the catchment to the point of consumption. Deterioration in surface and groundwater quality due to sources of pollution impacting the water intake should be identified and monitored allowing effective management and operation of drinking water systems. Land use information, monitoring databases, and hydrodynamics and water quality river modelling can be used to estimate and forecast the spatial and temporal mass transport and attenuation hazards that impact a given drinking water intake. This work presents a technological platform based on the Delft-FEWS software in which databases and models were implemented for supporting catchment water safety plans in different river basins of the NW region of Portugal. Keywords: catchment water safety plan; technological platform; water quality modelling Introduction Water safety plans (WSP) is a concept introduced by the World Health Organisation (WHO, 2004) for risk assessment and risk management in drinking water systems. This approach has been increasing embraced by water suppliers, governments and other stakeholders. Raw water quality is a key factor for ensuring good and safe drinking water. Water use, land use and polluting human activity in the catchment area all have significant impacts on surface and groundwater quality, and thus the level and complexity of treatment plants necessary to ensure that the water leaving the works is safe and acceptable to consumers. Protection of raw water sources should be seen as the first, and often the most important, barrier to prevent microbial, chemical and radiological contamination of drinking water sources (Vieira et al., 2011). Due to continuously emerging threats to the drinking water quality from organic matter, pesticides, fertilizers, pharmaceuticals, trace metals, and other types of contaminants, much effort has been put in the development of knowledge that is capable to effectively identify potential risks. Information on catchment characteristics (e.g. geology, hydrology, meteorology, land use, competing water uses), surface water bodies (e.g. flow rate, water quality and seasonality) and groundwater (e.g. aquifer flow rate, flow direction and aquifer vulnerability to pollution) and application of models to quantify the spatial and temporal dynamics of transport and attenuation of hazards that arise from the pollution sources across a catchment are of paramount importance for evaluating and prioritizing risks in raw water sources (Vieira & Pinho, 2014; WHO, 2016). This paper presents the use of the Delft-FEWS platform (Werner et al., 2012) in implementing an early warning system supported by proper hydrodynamics and water quality models for supporting catchment water safety plans in two river basins of the NW region of Portugal. Methodology Rivers Cávado and Ave basins are located in the north-western region of Portugal (Figure 1). At these basins important water treatment plants are installed abstracting water both from river Cávado and river Ave. At the same time, the same rivers are used as receiving waters of waste water treatment plants discharges. Water safety plans identified different threats that needs proper early warnings for effective action to avoid the interruption of public water supply. This is achieved recurring to a technological platform that is being implemented using Delft-FEWS software. The platform was implemented based on rivers and WWTP hydrodynamic and water quality data. It is also based on a modelling system that simulates rivers network hydrodynamics and the transport of substances or properties that are used as water quality indicators. A set of water quality processes were selected, considering either simple processes (such as accidental discharges simulations considering conservative pollutants) or more complex processes (such as organic matter degradation). Bacterial contamination resulting from urban wastewater discharges or diffuse pollutant sources were simulated by taking a 1st - order decay approach. Models were implemented using Sobek software and calibrated using available measured data (Figure 2). Results and Conclusion The implemented early warning tool constitutes a robust and efficient technological platform to support the operational implementation of catchment safety plan. Forecasts of water quality along the main rivers allow predicting that this new tool will be extremely effective and important to achieve the objectives of keep in a safety operational status the main water treatment plants installed within the basins. In the next years, the use of all the potentialities of this platform in practical situations under different water management problems constitutes a major challenge for the evaluation of the developed tool. Moreover, water authorities once decide to use this kind of management tools will certainly see improved their analysis capabilities, strengthening their technological skills for the adoption of more sustainable water management policies. Figure 1 Catchment water safety planning: A) location of river basins, B) Main pollutant point sources and subbasins of Cavado river basin. Valor médio monitorizado (mg/L) Valor simulado (mg/L) Estação 0.9 0.3 10 1.4 0.8 2 1.3 0.8 1 1.2 0.9 3 1.0 1.1 4 0.9 1.2 5 1.2 1.2 6 1.0 1.0 7 0.9 0.9 8 1.3 1.3 9 0.9 0.5 11 0.8 0.8 12 Carência Bioquímica de Oxigénio (5 dias) Cenário 1 Figure 2 Results of water quality model calibration for water quality model of river Cavado used in the implementation of the early warning system for catchment safety planning. REFERENCES Vieira J.M.P.; Breach B.; Hirata R. 2011 Developing a Catchment Water Safety Plan. In: Drinking Water Quality Management from Catchment to Consumer (B. Breach ed.). IWA Publishing, London. Vieira, J.M.P.; Pinho, J.L.S. 2014 River Water Quality Modelling in Developing a Catchment Water Safety Plan. 11th International Conference on Hydroinformatics, HIC 2014, New York, USA. Werner, M.; Schellekens, J.; Gijsbers, P.; Dijk, M. Van; Akker, O. Van Den; Heynert, K. 2012 The Delft-FEWS flow forecasting system. Environmental Modelling & Software, pp. 1-13. WHO 2016 Protecting surface water for health. Identifying, assessing and managing drinking-water quality risks in surface-water catchments. World Health Organization, Geneva. WHO 2004 Guidelines for Drinking-water Quality (3rd Edition). World Health Organization, Geneva. BOD5 (mg/L) Scenario 1