WEFTEC®.06 EFFECTS OF CLIMATE CHANGE ON WATER MANAGEMENT IN THE NETHERLANDS Arie van der Vlies, Kees Stoutjesdijk, Hans Waals Water authority Hollandse Delta P.O. box 469 3300 AL Dordrecht, the Netherlands ABSTRACT The climate is changing; the first indications are already apparent. The consequences for water and flood management are evident, especially in the Netherlands. The country has the highest population density in Europe, with the most economic centers and major cities below Mean Sea Level, so it is an absolute necessity to anticipate future changes. The development of both the necessary water burden for the regional waters and the floodwater program has led to the imposition of standards. The application of these standards has led to a series of measures that have been or are to be implemented in the period 2003 - 2015. These are very radical measures and the associated costs are considerable. Nevertheless, there is support for continuing, sustainable water management. This approach will lead to continuing a safe, healthy living environment in which the Dutch population as well as many foreigners can live, work and enjoy their leisure. KEYWORDS Climate change, flood defense, water management, regional water burden, safety, water is life program. INTRODUCTION Is climate change a challenge or a threat to water management? This question is acutely relevant in light of the extremely high river levels and floods that have occurred since the end of the 1990s in the Netherlands. These drastic occurrences, coupled with the predicted changes in the Earth's climate and rising sea levels, led the national government towards the end of the last century to mandate a committee to formulate a policy for "Water Management in the 21st Century". The committee came to be called WB21. Safety and the quantity of water are once again high on the government agenda in the Netherlands. This was reinforced once again last year thanks to the consequences of the hurricanes Katrina and Rita in New Orleans and this region. The parallel between New Orleans and the Netherlands holds to a degree, but the comparison does not hold in some respects. During WEFTEC 2005, in the session "In the wake of Hurricanes Katrina and Rita: where we go and what we know", one of the speakers called New Orleans "an 'evitable' city on an Copyright © 2006 Water Environment Foundation. All Rights Reserved 7213 WEFTEC®.06 impossible site". Can we say the same of the Netherlands, that it is an 'evitable' country on an impossible site? This paper discusses the statement. KEY DATA ON WATER MANAGEMENT Geographic location Water management in the Netherlands cannot be understood without some knowledge of the geographic situation. The country, with a land area of 36,000 square km, is situated along the North Sea. The Netherlands lies in the delta formed by the international rivers Rhine, Meuse and Scheldt. The country is sometimes viewed as the drainage sink of these major rivers. The Netherlands can be characterized as a wet country, if one looks at the mean annual rainfall of 750 mm. The climate is moderate, evaporation and transpiration together amount to 500 mm. There is a deficit of water in summer. About 25% of the land Figure 1 - The Netherlands influenced by the sea consists of polders which lie (brown) or rivers (blue) below Mean Sea Level. Figure 1 shows the division of the country into low and high areas. If the lower parts of the country were not protected by dunes or dikes, 65% of the country would be flooded when sea and river levels are high. The provinces of South Holland (with large cities like Rotterdam, The Hague and Dordrecht and with main industrial areas) and North Holland (with Amsterdam and its main airport Schiphol) are especially endangered by the rivers and the sea. A polder is a typical characteristic of the Dutch landscape. The word indicates a low-lying area, isolated from the surrounding hydrological Copyright © 2006 Water Environment Foundation. All Rights Reserved 7214 WEFTEC®.06 regime. The safety of the typical "polder" territories depends on the alertness of the water authorities, which are responsible for land drainage and flood control. Figure 2 illustrates the principle of a polder. Figure 2 - Typical water management in low-lying areas in the Netherlands In a polder the water levels are controlled by pumping excess water into the storage canals. In dry periods it may be necessary to reverse the direction of water flow, transfering water from the canals or rivers into the polders. In the low parts of the country most of the surface waters are stagnant. Eutrophication problems occur almost everywhere, run-off of nutrients from agricultural land and the intake of river water are responsible for excessive algal and duckweed growth in canals and smaller waterways. Managing the water in the major rivers and sea inlets is the responsibility of the Dutch Government. The management of the smaller rivers, the canals and the drainage ditches is the responsibility of the water authorities. Demographic situation The growth of the population is steady: from 8 million in 1930 to the present figure of more than 16 million. The population density of 450 persons per square km is the highest in Europe. The province of South Holland contains the cities of Rotterdam and The Hague, which are situated in the lowest-lying part of the province, the most densely populated in the country. In economic terms, a significant fraction of the most important industries and activities are also located in this province. One of the water authorities in this province is the Hollandse Delta water authority. Copyright © 2006 Water Environment Foundation. All Rights Reserved 7215 WEFTEC®.06 Table 1 - Population density Province of South Holland The Netherlands USA Population (x 106) 3.4 16.3 294 Area (km2) 2,880 36,000 9,373,000 Population density (inh/km2) 1,180 450 31 Hollandse Delta water authority The Hollandse Delta water authority is one of the 25 Dutch water authorities and is located in the province of South Holland in the neighborhood of the city of Rotterdam and in the western part of the Netherlands. This water authority takes care of safe dikes and dunes, treats the waste water, and ensures that the water in the ditches, ponds, lakes and other waterways is clean. In wet periods the water authority takes measures to prevent flooding. In dry periods, Hollandse Delta ensures that there is sufficient water in canals, ditches, ponds and lakes, so people can live, work and spend their leisure time safely and well, now and in the future. Table 2 - Hollandse Delta water authority in figures Total area under management 85,000 hectares Municipalities in area 23 Resident population 825,000 Dikes and dunes 650 kilometers Waste water treatment plants (wwtp) 23 Capacity wwtp 1,600,000 p.e. Regional monitoring areas 600 Roads 1,300 kilometers Cycle paths 170 kilometers Water pumping stations 150 Sewage pumping stations 63 Copyright © 2006 Water Environment Foundation. All Rights Reserved 7216 WEFTEC®.06 Outside the built-up areas, the water authority maintains the roads and cycle paths, mowing the verges in the summer and de-icing busy roads in the winter. The water authority works for everyone who lives, has a business, or owns land in southern South Holland. Hollandse Delta can only keep the area safe, clean and inhabitable with the help of society at large, which is why rules have been laid down in the Regulations (Keur) and the Surface Water Pollution Act. It is under these regulations that the water authority grants under restrictions permits to private persons, municipalities and businesses. WATER MANAGEMENT IN THE PAST Partly due to the country's location, water management has received a great deal of attention for centuries. Some of the water authorities in the west of the Netherlands have been performing this task for ab 800 years. A great deal has improved in many areas in recent decades. Safety For centuries the safety of the dikes and dunes has been an important responsibility of the authorities. The Dutch water authorities were the first democratic institutions, dating back to the 13th century. The construction and maintenance of dikes was an important task of the first water authorities. Everyone within the jurisdiction of the water authority had to pay taxes according to his interests within the region. This, however, also gave him proportional control over the water authority. This "interest", related to "tax", related to "control" has been in use for more than eight centuries for flood defense and water management Figure 3 - The Delta Works by the water authorities in the western part of the Netherlands. Despite the work of the water authorities there have been major floods throughout the country's history: • November 18, 1421: The Saint Elisabeth Flood destroyed more than 20 villages in the southwestern part of the Netherlands, causing over 2,000 casualties; • November 1, 1570: The All Saints Flood flooded large parts of the coastal area between Belgium and the northern parts of Germany and more than 20,000 people died; • December 24, 1717: The Christmas Flood. Again the northern coastal areas between Copyright © 2006 Water Environment Foundation. All Rights Reserved 7217 WEFTEC®.06 Denmark and the Netherlands were flooded and 14,000 people were killed; • January 31, 1953: A storm flood caused breaches in several dikes in the southwestern part of the Netherlands, in Belgium and southeast England. In total 1836 casualties were counted in the Netherlands. This flood is known as "de Ramp" (the Disaster). As a result of this last disaster the "Delta Law" was implemented by the Dutch government.