14 th European Seminar on Geography of Water

1. Ente Acque della Sardegna ENAS Ente Acque della Sardegna 14th European Seminar on Geography of Water Facing climate change and desertification. Water Management in Sardinia Drought Watch System in Sardinia to Reduce Supply Vulnerability and Improve Water Resources Management During Periods of Drought Roberto Silvano (Director of Water Resources Management and Remote Control Service - ENAS) Presentedby: Andrea Virdis Water Resources Management and Remote Control Service ENAS, Ente Acque della Sardegna, Italy 1

2. Water Resources management in Italy Ente Acque della Sardegna The management of the water resources in Italy and in the other Countries of the European Union underwent during the past years through significant changes TheEU Water Framework Directive (WFD) (2000/60/EC)is the major piece of European Union (EU) legislation having environment at its core. The Directive provides for a legislative framework aiming to protect Community waters in qualitative as well as in quantitative terms What marks the Water Framework Directive out is that it defines the quality of surface waters in terms of ecology rather than chemistry or water pollution Main aim of Member States is to restore the good ecological status (chemical, biological, hydromorphological) of ground and surface water in the framework of the river basin producing the River Basin Management Plan, in each river basin district According to the devolution principle of the WFD, the environmental protection and monitoring, which was before a matter under the control of the Nation, fell on hands of the Regions by the mean of the Basin Authorities. These are Bodies created with the purpose of implementing, within their territory of competence, the Directive Rules In 2006, the Italian Government started up the process wanted by the WFD by promulgating the Legislative Decree 152/2006 titled “Environment Policies” (“Norme in MateriaAmbientale”), which reformed the entire body of environmental regulations in Italy The Decree 152/2006 lists eight river basin districts in Italy. The districts are: Serchio, Padano, Eastern Alps, Northern Apennines, Central Apennines, Southern Apennines, Sardinia, and Sicily. After the approval of the Legislative Decree 152/2006, the Sardinian Regional Authority reviewed competences and duties in the area of Water Resource, by means of the Regional Law 19/2006“Rules on Water Resources and Hydrographic Basins” “Disposizioni in materiadirisorseidriche e baciniidrografici” 2

3. Water Resources management in SardiniaRegional Law 19/2006 Ente Acque della Sardegna The Regional law introduces the concept of “multi purpose water system”. This system is created to deliver raw water to different categories of users, contributing to keep a balance between supply’s quantity and costs • In Sardinia, 80% of supplied water comes from artificial reservoirs (52 dams) • Main uses of dams in Sardinia are forirrigation and drinking water purposes 3

4. Institutional Flowchart of Sardinian Water System Regional Law n.19/2006 Sardinian Regional Authority Official assignment Regional Basin Authority Official assignment Institutional Committee River Basin District Agency ENAS is the Region’s operational agency tasked with managing the island’s multi-purpose water system It supplies the wholesale water for the principal macro demands of the region civil, irrigational and industrial Managing Body of the multi purpose water system: ENAS Raw water supply AbbanoaS.p.A. Integrated urban water Authority (ATO) Reclamation Consortia Industrial Consortia 4

5. ENAS - Ente Acque della Sardegna ... since 1946 EAF to-day ENAS ... Regional Law n.19/2006 transformed EAF into ENAS expanding and upgrading EAF by the addition of major water works for multi-purposes uses and the experience and skills of staff coming from the Land Reclamation Consortia At the same time, ENAS gave in to the Urban Water Service all the waterworks for civil uses • Currently, the system comprises • works and infra-structure for the • collection, storage and conveyance • of raw water for multi-purposes sectors • 34 dams (1.900 Mmc of storage capacity) • 24 diversion dams, • 850 km of aqueducts, • 209 km of conveyance canals, • 47 pumping plants (with 70 Megawatt of installed power) • 4 hydropower plants (13, 27.5, 1.3, 1.25 Megawatt)

6. ENAS – Distributed Volumes CIVIL: to AbbanoaSpA, which is the Water Purification Company who is in charge of the Integrated urban water management in Sardinia IRRIGATIONAL: to the nine Land Reclamation Consortia who have the management, at retail level, of raw water addressed to irriguous purposes INDUSTRIAL: to five Industrial Consortia

7. Hydrological features and droughts in Sardinia Ente Acque della Sardegna Sardinia is located in the centre of the western basin of the Mediterranean Sea and has a surface area of 24.000 km² with a population of 1.648.000 residents The climate is prevalently Mediterranean, characterized by a long period of drought in summer and mild and rainy winters with isolated frosts The amount of water resources available for civil, industrial and agricultural use contracted critically in Sardinia about ten years ago due to hydrological alterations which had occurred on the island over the last three decades, similarly to the rest of the Mediterranean basin 7

8. Hydrological features and droughts in Sardinia Ente Acque della Sardegna Mean water balance in Sardinia Analysis of the historical hydrological series in Sardinia over the past 90 years shows that both the rainfall and runoff are non-stationary in the mean Hydrological inflows display higher stochasticity and their behaviour is difficult to predict • Such variability, which is linked to the change in climatic conditions and has high repercussions on the volumes that can be supplied by water systems, and makes it necessary to manage resources using reliable and prudential operational rules The rainfall-runoff transformation in Sardinia proves that runoff is highly sensitive to any reduction in rainfall: 20% reduction in rainfall may produce a decrease of 40% in runoff and consequently in water resources available for human use. Mean water balance in Sardinia 8

9. DroughtManagement System in Sardinia Ente Acque della Sardegna In this type of context, the management of complex interconnected hydraulic systems, mainly based on large reservoirs regulating the water resources over multiannual periods, plays a strategic role A proactive action to be taken against droughts before they occur rather than simply reacting to them, must be the aim of the strategy It is crucial to define criteria and operational rules to minimizing water supply deficits and to guarantee the sustainable use of natural runoff on a multi-annual base The Region of Sardinia has in place since several years a drought alert and risk analysis system for the management of multi-purpose water supply systems, with the aim to reduce the vulnerability of supply and increase its reliability and avoid crisis situations 9

10. Hydrological and OperationalDroughts Ente Acque della Sardegna Hydrological droughts: random natural phenomena, revealed by analysis of the historical hydrological data series Operational droughts: lack of water supply available to users Hydrological droughts are transformed into Operational droughts by a transformation function that considers the physical and size characteristics of the water work system and the operational rules selected to manage such waterworks Drought is a phenomenon composed of both random natural aspects and important human component It is therefore essential to build a model that accounts for all such aspects and delivers effective decision support 10

11. Droughtindices Ente Acque della Sardegna An indicator that takes into account these aspects is the amount of water reserves held in the artificial reservoirs of the regional water system This parameter is influenced both by the characteristics of the hydrological inflows in the time and by the operational rules chosen to manage reservoirs and the main water conveyance lines The built model accounts for all such aspects by implementing a calculation method that measure the indicator at monthly intervals, so to make decisions based on such measurements 11

12. The model: Methodology Ente Acque della Sardegna This model, which is based on stochastic analysis principles, has two components: • a model to generate synthetic series of the runoff of Sardinian rivers which preserves: a) the basic statistics of the historical series in each relevant section of rivers of the regional territory; b) the time correlation structure; c) the spatial correlation structure; d) specific drought statistics (persistence, duration, intensity); • a simulation model for operating the water supply system using mathematical models to accurately represent both the functional characteristics of structural elements (reservoirs, pipes, open channels, pumping plant, hydroelectric plants, etc.) and the natural phenomena impacting the system, for instance evaporation from reservoirs and the operational rules adopted for optimum management of the resource • Using these two fundamental tools, a variable indicator is generated at monthly intervals for each reservoir or for two or more reservoirs forming a single water scheme 12

13. Ente Acque della Sardegna The model: Methodology The output of the model is a state indicator which as an excellent key factor to measure the condition of water storage in the artificial reservoirs It is named Storage Frequency Index: Index of the probability of not exceeding stored volumes, for each month of the year, in a single hydraulic system It represents the indicator adopted for the drought management system in the region of Sardinia This indicator summarizes both: - natural elements (rainfall reduction and, therefore, runoff which feeds artificial water basins) - anthropic elements (the demand for water from basins, the rules governing management of water resource transfer in complex hydraulic systems) 13

14. Applicationof the Drought Management System in Sardinia Ente Acque della Sardegna Curve of Storage Frequency Index for each month of the year, in a single hydraulic system Example: In April the probability of not exceeding a stored volume of 1100 Mmc in the system is 0.8 (low probability, 20%, of exceeding) Example: In April the probability of not exceeding a stored volume of 200 Mmc in the system is between 0.1 and 0.2 (high probability, 80-90% of exceeding) 14

15. Application of the Drought Management System in Sardinia Ente Acque della Sardegna The value of the drought state indicator, at monthly scale, can be determined by matching the curves of the storage frequency index with the current water storage in each system Example 1): In April if the currentstored volume is 200 Mmc The Storage Frequency Index is 0.1- 0.2 (that means that the model has forecast an high probability of exceeding 200 Mmc) Consequently it is evident a critical state of the hydraulic system Example 2): In April if the currentstored volume is 1000 Mmc The Storage Frequency Index is 0.5- 0.6 (that means that the model has forecast an low probability of exceeding 1000 Mmc) Consequently it is evident a non critical state of the hydraulic system 15

16. Applicationof the Drought Management System in Sardinia Ente Acque della Sardegna The values of the indicator have been grouped into four bands which, correspond to different state of the hydraulic system and consequently to different sets of decisions to be made and already identified in the water crisis management plan These four bands represent the four rules defined to implement specific actions for an effective short-term drought mitigation measure Definition of alert pointers 16

17. Alert pointers and drought mitigation actions Ente Acque della Sardegna • Ordinary regime: for stored volumes in excess of the value that has a 50% probability of not exceeding; Vigilance level: for stored volumes within the values having between 50% and 30% probability of not exceeding; It is necessary to monitor climate parameters to rapidly identify any further fluctuations which may reduce the mean resources available. Concurrently, consumption should be reduced to an amount that creates only limited discomfort for users Danger level: for stored volumes between the values with non-exceeding probability of 30% to 15%. Water supply must be reduced to a substantial degree, in order to face the possible persistence of the dry period, and the planned mitigation measures must be implemented; Emergency level: for stored volumes within 15% of the probability of not exceeding; This level should never be reached, since water supply should be restricted once the danger level is reached. However, should the emergency level be reached, this would mean that the statistical parameters of the series are continuing to change and therefore supply must be restricted further and the annual mean of water available for distribution must be reassessed. 17

18. Applicationof the Drought Management System in Sardinia Monti Pranu Tirso-Flumendosa System Ente Acque della Sardegna Series of the monthly drought indicator Storage Frequency Index 18

19. Applicationof the Drought Management System in Sardinia Ente Acque della Sardegna Drought indicators of Sardinian Reservoir June 2008 March 2010 More uniform and with indicators that show a general situation of normality Different characteristics of alert for the various water systems of the island 19

20. Remarks Ente Acque della Sardegna • The application of this method to Sardinian water system, over about three years, has given good results to identify crisis areas and enforce mitigation measures • This method can be more finely tuned and perfected • As experience has shown, some aspects require particularly careful assessment and monitoring: • it is preferable to anticipate shortages if the costs are not a linear function of the shortage; therefore it is preferable to have several years with a moderate shortage rather than a single year with a high shortage; • measures to meet an anticipated shortage generate costs even though such shortage may not occur; • the timescale of such costs may cover several months or even years: this is a tough decision to make; • risk perception: it is not easy to measure. Different individuals and organizations have different perceptions: conflict situations; • it is essential to pursue a technically balanced solution and seek agreement among stakeholders. • The tool implemented, identifies and describes crisis areas and situations by means of easy-to-read quantitative parameters that represents a highly effective aid to public participation and stakeholder consultation processes 20

21. Thank you very much for you kind attention ENTE ACQUE DELLA SARDEGNA Via Mameli, 88 - 09123 Cagliari Tel +39 070 - 60 21.1 Fax +39 070 – 670758 Water Resources Planning and Remote Control Service (ServizioProgrammazione e Telecontrollo) Ing. Roberto Silvano (Director) Ing. Andrea Virdis andrea.virdis@enas.sardegna.it roberto.silvano@enas.sardegna.it http://www.enas.sardegna.it