AMICE Adaptation of the Meuse to the Impacts of Climate Evolution

Transcription

1 AMICE Adaptation of the Meuse to the Impacts of Climate Evolution Sub report 1 BELGIAN SCENARIOS FOR THE MEUSE 710_14 WL Adviezen Vlaamse overheid

2 AMICE: Adaptation of the Meuse to the Impacts of Climate Evolution Sub report 1 Belgian scenarios for the Meuse revised for AMICE by Wouter Vanneuville and Katrijn Holvoet June 2009 WL2009A710_14_rev2_0

3 This publication must be cited as follows: Vanneuville, W.; Holvoet, K. (2009). AMICE: sub report 1 - Belgian scenarios for the Meuse. Version 2_0. WL Adviezen, 710_14. Flanders Hydraulics Research & Deltares: Antwerp, Belgium Waterbouwkundig Laboratorium Flanders Hydraulics Research Berchemlei 115 B-2140 Antwerp Tel. +32 (0) Fax +32 (0) waterbouwkundiglabo@vlaanderen.be Nothing from this publication may be duplicated and/or published by means of print, photocopy, microfilm or otherwise, without the written consent of the publisher.

4 Document identification Title: AMICE: Fout! Verwijzingsbron niet gevonden. Customer: Partner Steering Group AMICE Ref.: WL2009A710_14_rev2_0 Keywords (3-5): Meuse, climate change, hydrologic modelling, scenario Text (p.): 5 Tables (p.): / Appendices (p.): / Figures (p.): / Yes Customer Exceptions: Internal Confidentiality: Flemish government Released as from No Available online Approval Author Vanneuville, Wouter Reviser Holvoet, Katrijn Project leader Vanneuville, Wouter Division Head Mostaert, Frank Revisions Nr. Datum Omschrijving Auteur 1_0 14/05/2009 Concept version Vanneuville, W. 1_1 05/06/2009 Revision customer Vanneuville, W. 2_0 18/05/2009 Final version Vanneuville, W. Abstract This note is no original work. It is a summary and translation of the report Belgische scenario s voor de Maas made by Otto de Keizer and Jaap Kwadijk from Deltares (april 2009). This summary is made to communicate the results to the project partners of the AMICE project. Climate change impacts for three scenarios were made by KULeuven Hydraulics Laboratory for Flanders Hydraulics Research (FHR) based on the scientific results of the Belgian Science Policy (Belspo) project Climate Change Impacts on Hydrology (CCI-Hydr) and applied on the hydrologic models available at FHR for sub catchments in the river Scheldt district. In the AMICE project climate change impacts on the hydrology of the river Meuse are an important topic. FHR has no hydrologic models for the Meuse catchments and ordered a study at Deltares to define boundary conditions for the FHR hydrodynamic Meuse model based on the three scenarios for climate change defined for FHR by KULeuven, the hydrologic models of Deltares and the SOBEK 1D routing model for the part of the river Meuse upstream Flanders.

5 Contents Contents... I 1 Introduction Approach Models Data Results Analysis Peak discharge List of references... 5 Final version WL2009A710_14_rev2_0 I

6 1 Introduction At Flanders Hydraulics Research (FHR) a study is ordered at KULeuven Hydraulics Laboratory on the Effect of Climate Change on discharges in high and low water situations and total water availability. FHR has no hydrologic models for the Meuse catchments and the AMICE-project was a trigger to extend the study. Compared to the total area of the Meuse catchments, the Flemish part is relatively small and hydrologic models covering the whole international Meuse basin already exist in the Netherlands. The Dutch delegation of the International Meuse Commission brought researchers at FHR and Deltares together and a study to calculate the 3 Belgian climate change scenarios for hydrologic impact with the models from Deltares was ordered by FHR. The simulations are done with the hydrologic model HBV-Maas and the hydraulic model SOBEK 1D. The hydraulic model is used to incorporate wave damping for very large peak discharges. 1.1 Approach The climate scenarios are constructed with a transformation routine from Belgian Science Policy Project Climate Change Impact on Hydrology (CCI-Hydr, by the Hydraulics Laboratory from the KULeuven University and the Belgium Royal Meteorological Institute (KMI) for the period The Belgian climate change scenarios are time series on a daily base for precipitation, temperature and potential evaporation (ETo). For all three scenarios and a control period simulation is done with HBV-Maas by Deltares. The simulated discharges at Borgharen (boundary between Belgium and the Netherlands) are analysed. The three highest discharges are selected in each scenario and from 10 days before till 10 after the peak and simulated in SOBEK-Maas. HBV results are analysed based on average yearly and seasonal discharges and the 90% percentiles of the discharges of all simulation runs. An analysis is done to compare the highest discharge in the HBV- Maas and SOBEK-Maas models. 1.2 Models HBV is a conceptual rainfall-runoff model. Its structure allows deriving discharges based on meteorological data for catchments. The version of the HBV-Model used by Deltares is the original one calibrated for the period and validated for the period The reliability is based on Nash-Sutcliffe efficiencies, standard R2, accumulated difference and visual inspection. It has to be mentioned that Nash and R2 coefficients are more sensitive for deviations in high water periods. Influence of the parameters for low water situations is not researched during calibration as the model is primarily used for high discharge periods. SOBEK is a hydraulic software package able to simulate in 1D or 2D and based on Saint Venant equations. SOBEK-Maas is a 1D hydraulic model calibrated for the Meuse stream district. 1.3 Data Input data are the 30 year time series for precipitation, temperature and ETo on a daily base. For the control period ( ) the series from KNMI (Dutch Royal Meteorological Institute) for all sub catchments of the Meuse based on data from KMI and MeteoFrance. More information about this can be found in Leander et al. (2005). Based on the control run FHR developed climate change scenarios using the CCI-Hydr transformation routine for The three scenarios are called low, middle and high. In the low scenario precipitation is decreasing in summer and winter, in the middle scenario there s a limited reduction during summer and a limited increase during winter, and in the high scenario there s an important rainfall Final version WL2009A710_14_rev1_0 1

7 increase during winter and an important decrease in summer. In spring and autumn all scenarios are more or less identical. (Figure 1). For temperature and ETo the middle and high scenario are comparable. The low scenario has a limited temperature increase resulting in lower ETo. Figure 1 % Change in rainfall 2100 CCI-Hydr for low (laag), middle (gemiddeld) en high (hoog) scenarios compared to KNMI-06 scenarios W and W+ Final version WL2009A710_14_rev1_0 2

8 2 Results Model results are given in digital format to FHR. In Table 1 statistics for the control period and scenario s are summarized. The averages are the average over the 30 year period. Table 1 Average yearly and seasonal discharge (m³/sec)f Control period Scenario low middle high Average yearly discharge Average winter discharge (dec-feb) Average summer discharge (jul-sep) %-percentile of daily values %-percentile of daily values Figure 2 Monthly average discharge for control run (referentie) and scenarios Final version WL2009A710_14_rev1_0 3

9 2.1 Analysis The average yearly discharges for the low scenario are significantly lower for the low scenario and significantly higher for the higher scenario compared to the actual situation. All scenarios are unambiguous for future summer discharge. The average summer discharge becomes lower than half discharge in the control period. February has the highest monthly discharge, except for the low scenario where this is in March. Explanation can be the higher influence of the base flow in the low, dryer, scenario. The high scenario results in an average winter discharge are almost double of the discharge in the control period. Maximum average yearly discharge is 1335 m³/sec in the control period and 1040 m³/sec, 1428 m³/sec and 1938 m³/sec in the low, middle and high scenario respectively. In all scenarios September has the lowest discharge. The average is 15 m³/sec in the high and 18 m³/sec in the low scenario, in spite of a comparable reduction of rainfall during summer. The lower discharge in the high scenario is a result of the higher ETo which is a consequence of the higher temperature in the high scenario. Rainfall during winter is still contributing to discharge in April in the high scenario. Also dry periods affect the discharge where October is a low discharge month (< 100 m³/sec). An important remark has to be made for low flows: as indicated earlier the calibration of the HBV model is done with a focus on high water applications. De Wit et al. (2007) suggest that influence of winter rainfall in average summer discharge is underestimated. 2.2 Peak discharge Table 2 indicates the maximum daily discharge during the highest high water in each series for the control period and each of the scenarios with the HBV hydrological model and with SOBEK. The values clearly indicate the influence of wave damping which is realistically simulated with SOBEK. Table 2 Highest discharge for control period and scenarios with HBV and SOBEK and relative decrease of calculated discharge with SOBEK. Scenario HBV (m³/sec) SOBEK (m³/sec) Decrease (%) Reference (1995) ,6 Low ,5 Middle ,5 High ,5 Final version WL2009A710_14_rev1_0 4

10 3 List of references De Keizer, O.; Kwadijk, J. (2009). Belgische scenario s voor de Maas, Deltares, in opdracht van Waterbouwkundig Laboratorium Antwerpen, Delft, ZWS-0004, p. 15. De Wit, M.; van den Hurk, B.; Warmerdam, P.; Torfs, E.; Roulin, E.; van Deursen, W. (2007). Impact of climate change on low-flows in the River Meuse, Climatic Change, 82, pp Leander, R.; Buishand, T.; Aalders, P.; De Wit, M. (2005). Estimation of extreme floods of the River Meuse using a stochastic weather generator and a rainfall-runoff model, Hydrological Sciences Journal, 50(6), pp Final version WL2009A710_14_rev1_0 5

11 Waterbouwkundig Laboratorium Flanders Hydraulics Research Berchemlei 115 B-2140 Antwerpen Tel. +32 (0) Fax +32 (0)