Delta Works needed level of flood protection and the resulting costs are a recurring subject of debate, and involve a complicated decision-making process. In 1995 it was agreed in the Delta Plan Large Rivers and Room for the River projects that about 500 kilometres of insufficient dyke revetments were reinforced and replaced along the Oosterschelde and Westerschelde between 1995 and 2015. After 2015, under the High Water Protection Program, additional upgrades are made. In September 2008, the Delta Commission presided by politician Cees Veerman advised in a report that the Netherlands would need a massive new building program to strengthen the country's
Indus River Delta-Arabian Sea mangroves time it reaches the delta, the flow of freshwater is down by more than 90% compared to historic levels. Active flow only lasts for about two months, and the sediment load is similarly diminished. Saline water intrudes upstream for about and this affects both the mangroves growing in the area and the agricultural land. Loss of sediment causes increased coastal erosion, and this is exacerbated by land subsidence and rising sea levels. Other factors affecting the mangrove areas are pollution from sewage and industrial effluent, and parts of the mangrove area have been lost to agriculture and urban development. The