Drought management and early warning in the Po River Basin

Transcription

1 Drought management and early warning in the Po River Basin Claudia Vezzani Po river basin Authority

2 Po Basin features The Po River is the major Italian river. The basin lies between the continental and the Mediterranean area and it covers almost the whole northern part of Italy. Small portions of the basin are located outside the national borders, in France and Switzerland. Po basin is classified as international district according to the Water Framework Directive.

3 Geographic and social features Basin area km 2 Mountains: 58% Alluvial plain: 42% Municipalities: Population: 17M Portion of NGDP: 38% Main geographical and social features of the Po basin. The 42% of the total area consists of floodplain, in which most of the social and economic activities take part. 17 million people live in more than 3000 municipalities and 3 metropolitan cities: Milano, Bologna e Torino. In this area the 38% of the national GDP is generated, and this have a direct influence on water use, fresh water availability and on the state of water and of water-related ecosystems.

4 Natural fresh-water availability Po river length: 652 km Min daily Q: 168 m 3 /s Mean daily Q: 1500 m 3 /s Max daily Q: m 3 /s Data on water volumes involved in the hydrological cycle of the Po. The main course length of the Po river is about 650 kilometres. The annual average flow is 1500 cubic meters per second. Flow-regime is extremely variable: it ranges from the minimum of 168 to the maximum of cubic meters per second. This feature is a peculiarity of the Po river within European main rivers. The total annual average surface flow volume is about 45 billion of cubic meters: 90% is concentrated from September to may, while only the 10% flows during late spring and summer. Other 9 billion of cubic meters are available as subsurface water. Average annual weather influx 78 * 10 9 m 3 /y Average annual surface flow 46,5 *10 9 m 3 /y Average via Garibaldi, 75 annual Parma - tel. groundwater *10 9 m 3 /y

5 Main pressures: focus on agriculture Source: INEA 2012 Spatial distribution of De Martonne meteorological aridity index, defined as the ratio between rainfall and temperature. On the left the situation during non irrigation period, on the right the situation during the irrigation period. In the Po district, the problem of efficient water use, water scarcity and drought is a seasonal problem, and the season in which there s a greater need of water corresponds to the season in which there is naturally fewer availability.

6 Main pressures: focus on agriculture Focus on agricultural use: it is the main water consuming use in the Po district. The extension of area devoted to agriculture is 4.5 million of hectares, and the irrigated portion is about 1.6 million of hectares. In light green is the extension of the district, and in dark green the area that falls under the administration of an irrigation-entity. Source: INEA 2012

7 Situation: water scarcity features Source: Situation presented in terms of water exploitation : the Po district is classified as moderately exploited at an annual range. A monthly water exploitation index calculated from 2007 to 2009 shows how it is little exploited during winter season, and highly exploited during summer. The last three slides considered together show the lack of temporal and spatial homogeneity, suggesting some key aspects that can be considered by a proper management policy.

8 DEWS-Po System Drought Early Warning system Po Developed Fews-System in the world General description: DELFT-FEWS is a free software: ARPA Emilia Romagna AIPO

9 DEWS-Po System DEWS-Po Drought Early Warning System for the Po River is a computer monitoring system, which comprises meteorological forecastings and hydrological/hydraulic simulations for discharge/level forecast. It allows a better understanding of the functioning of river basin with its hydraulic network. High density observational network: Rainfall Temperature Level/discharge (telemetry data) Meteorological input: Deterministic Model (15 days) (ECWM) Model ensemble (seasonal forecasting) Monitoring network: 588 water level gauges 1014 raingauges 756 thermometers

10 The radar network

11 Meteorological forecastings The input consists in meteorological data from the European Centre for Medium-Range Weather Forecasts

12 Modelling scheme Rainfall TEMPERATURE Discharge - Water level Observed, telemetry Weather Radar Meteorological models Forecasting +15 gg Seasonal forecasting Validation, interpolation and data processing (DEWS drought early warning system) Hydrological modelling Rainfall runoff model TOPKAPI Water balance model RIBASIM

13 Hydraulic balance model: RIBASIM (RIver BAsin SIMulation) (Deltares MITSIM MIT) The water balanc emodel principle is applied to divide flow at each node of a schematic network. Many components are represented: rivers, channel networks, groundwaters Modello di bilancio idrico RIBASIM

14 Hydraulic balance model: RIBASIM (RIver BAsin SIMulation) (Deltares MITSIM MIT) Basic components The river system is schematized into: nodes, branches or reaches, connections between reaches (diversions, junctions, withdrawals points, groundwater districts, irrigation districts, etc.). Rivers have been schematized in different reaches with homogeneous parameters.

15 Salt intrusion simulation % of sea water and of freshwater in the real time for each X- section A forecasting of the distance of salt intrusion is provided by the model in different tide condition

16 Salt intrusion simulation SOBEK DELWAQ

17 What we do with the system 1. Long term basin planning: data support for the developing of basin plans, through the simulation of what if scenarios. 2. Real time forecast and management of water resource: evaluation of options, decisional support. Proactive approach: 1. Assessing in advance impacts and vulnerability 2. Planning in advance suitable actions to be carried out.

18 Output Flow forecasting (+ 15 dd) 29/05/2012 Po a Cremona Stura di Lanzo a Torino

19 Statistics of minimum discharges Po a Pontelagoscuro 1-P Tr [anni] Portata al Portata al Portata minima Serie storica Weibull /11/ /18/201 2 prevista PORTATA PREVISTA [m 3 /s] [m 3 /s] [m 3 /s] Piacenza Tempo di ritorno, anni Cremona Tempo di ritorno, anni Boretto Tempo di ritorno, anni Borgoforte Q [m³/s] Tempo di ritorno, anni Pontelagoscuro Tempo di ritorno, anni

20 Output It is possible to go back to the origine of each portion of water arriving at the outlet Po a Cremona Contributo del Ticino Contributo dell Oglio Po a Pontelagoscuro Po a Crescentino Po a Boretto Po a Isola Sant Antonio

21 Output Simulation of a what if scenario considering different rate of restriction of abstraction (-10% )

22 Decisions based on impacts/vulnerability assessment actual discharge observed in some relevant cross-sections of the Po river, with meteorological forecasting on the short term (seven days), and water needs forecasts represent toghether the most important management indicators. The challenge is to connect this level with drought/water scarcity impacts over the territory, and then going ahead with vulnerability assessment. Discharge

23 Threshold Forecasts driven Forecasting Forecasts/observations Driven Actions Survellance Normal Pre-alert Threshold Threshold Emergency Alert Monitoring (level 2) Forecasts/observations Driven actions Threshold Monitoring (level 1) observations Driven actions

24 Thresholds definition Threshold type Values Assessement criteria Generic thresholds Flow value from: flow duration curves/statistics Indexes/indicators (spi, SFI ) Frequency Return time Hystorical thresholds Specifyc thresholds Levels/discharges in reference ponts Local known risks Hystorcal events Field surveys (questionnaires)

25 Climate change scenarios

26 Simulation of hydrologc impacts of climate change Vezzoli et al. (2014) - Hydrological simulations driven by RCM climate scenarios at basin scale in the Po river, Italy Evolving water resources systems: understanding, predicting and managing water society interactions - Proceedings of ICWRS2014, (IAHS publ. 364, 2014) Step 1 Model validation Step forecasts Use of DEWS-Po system for Po discharges projection until 2100 through climatic-hydrologic simulations Basin water balance s forecasts

27 Proiezioni Climatiche ( vs )

28 Impacts of cc on extreme low flows Climatic scenarios Duration curve Probability distribution Extremes variation (min and Max) Po a Pontelagoscuro 1-P Tr [anni] Serie storica magra ordinaria magra ordinaria 2030 magra ordinaria 2050 magra ordinaria trend s analirys Q [m³/s]

29 Thank you for your kind attention