This, land subsidence, and increased storms make further upgrades to the flood control and water management infrastructure necessary. The sea defenses are continuously being strengthened and raised to meet the safety norm of a flood chance of once every 10,000 years for the west, which is the economic heart and most densely populated part of the Netherlands, and once every 4,000 years for less densely populated areas. The primary flood defenses are tested against this norm every five years. In 2010 about 800 km of dikes out of a total of 3,500 km failed to meet the norm. This does not mean there is an immediate flooding risk; it is the result of the norm's becoming more strict from the results of scientific research on, for example, wave action and sea level rise. The amount of coastal erosion is compared against the so-called "reference coastline" (BasisKustLijn), the average coastline in 1990. Sand replenishment is used where beaches have retreated too far. About 12 million m3 of sand are deposited yearly on the beaches and below the waterline in front of the coast. The Stormvloedwaarschuwingsdienst (SVSD; Storm Surge Warning Service) makes a water level forecast in case of a storm surge and warns the responsible parties in the affected coastal districts. These can then take appropriate measures depending on the expected water levels, such as evacuating areas outside the dikes, closing barriers and in extreme cases patrolling the dikes during the storm. The Second Delta Committee, or Veerman Committee, officially Staatscommissie voor Duurzame Kustontwikkeling (State Committee for Durable Coast Development) gave its advice in 2008. It expects a sea level rise of 65 to 130 cm by the year 2100. Among its suggestions are: to increase the safety norms tenfold and strengthen dikes accordingly, to use sand replenishment to broaden the North Sea coast and allow it to grow naturally, to use the lakes in the southwest river delta as river water retention basins, to raise the water level in the IJsselmeer to provide freshwater. These measures would cost approximately 1 billion Euro/year. Room for the River Global warming in the 21st century might result in a rise in sea level which could overwhelm the measures the Netherlands has taken to control floods. The Room for the River project allows for periodic flooding of indefensible lands. In such regions residents have been removed to higher ground, some of which has been