Geography of the European Netherlands European part of the country can be split into two areas: the low and flat lands in the west and north, and the higher lands with minor hills in the east and south. The former, including the reclaimed polders and river deltas, make up about half of its surface area and are less than above sea level, much of it actually below sea level. An extensive range of seawalls and coastal dunes protect the Netherlands from the sea, and levees and dikes along the rivers protect against river flooding. The rest of the country is mostly flat; only in the
Delta Works Law (Dutch: "Deltawet"). This required the government to keep risks of catastrophic flooding within these limits and to upgrade defences should new insights into risks require this. The limits have also been incorporated into the new Water Law ("Waterwet"), effective from 22 December 2009. The Delta Project (of which the Delta Works are a part) has been designed with these guidelines in mind. All other primary defences have been upgraded to meet the norm. New data elevating the risk assessment on expected sea level rise due to global warming has identified ten 'weak points.' These have been upgraded to meet