20. 11. 2019
SOME INSIGHTS ON THE PORTUGUESE NATIONAL STRATEGY OF ADAPTATION TO CLIMATE CHANGE AND THE URBAN WATER SERVICES
BY JOSÉ SALDANHA MATOS, HIDRA
The predicted increase in the seasonal asymmetry of the rainfall regime, with the concentration of precipitation in winter, combined with the reduction in annual precipitation and increased evapotranspiration rates, will accentuate the difficulty of meeting water needs during spring, summer and autumn, especially if the foreseen scenarios of increase in water demand by several sectors are confirmed.
For instance, the increasing decarbonisation objectives and the consequent growth in energy production from renewable sources, namely hydropower, will lead to a greater demand for water volumes for the energy sector. Additionally, the trend towards a reduction of the amount of available water with adequate quality to meet the public supply will lead to an increased risk of critical situations and will increase the pressure for adequate water resources planning. These risks and pressures lead to the need for a more careful management of the water supply systems, from abstraction to distribution.
Wastewater drainage and treatment systems will also suffer the impacts of climate change, in particular, stormwater and combined drainage systems in urban areas. The confirmation of scenarios of increased risk of extreme rainfall events, which will lead to an increase in the peak rainfall flow that may exceed the drainage systems capacity, will result in urban floods.
Coastal systems located at low elevations will also have to take into account the increase in the mean sea level and the tidal amplitudes, with the consequent reduction in the drainage transport capacity of the final sections. Additionally, the tendency to increase the duration of dry periods may also limit the effectiveness of self-cleaning of sewers, which, together with the increase in air temperature, may lead to additional risks. The pressure will also increase for the wastewater treatment plants which, if adaptation measures are not implemented, will be required to treat larger volumes of polluted stormwater in short periods.
The framework of uncertainty associated with climate change, in terms of magnitude and impact on the various sectors, results in the need of having flexible, multidisciplinary and consistent adaptation strategies that include structural and non-structural measures and adaptive management procedures. In Portugal, the National Strategy of Adaptation to Climate Change establishes six structural programmes or axes to be considered in relation to urban water services:
- Promotion of efficient water use
- Reinforcement and diversification of water sources
- Control of the water supply quality
- Adequacy of the operating conditions of drainage and wastewater treatment systems;
- Control of the risk of urban floods
- Knowledge augmentation and dissemination.
These axes contemplate a total of 17 measures which differ on the action type (planning, management or monitoring), costs, impact magnitude, priority (from short-term, 5 years, to long-term, 20 years) and scope (from local to national).
The success of the urban water services adaptation programme is closely linked to the processes of continuous review of the operational management plans of all water cycle managing bodies. If these plans take a comprehensive and long-term view and periodic vulnerability assessment exercises of each system, as new data becomes available, the most appropriate adaptation measures will be triggered.
The methodology followed on RESCCUE is corroborating the path to achieve better decision-making processes not only through the research and dissemination of determinant information, such as downscale climate projections (WP1) and urban services’ hazard and risk assessments (WP2 and WP3), but also through the involvement of key stakeholders on the evaluation of the city performance (WP4) and on the definition of specific adaption strategies (WP5), leading to a real, concrete and tangible planning of urban resilience (WP6).