The northern and western regions of the Netherlands were flooded again due to heavy rains. The Meteorological Agency issued an orange warning, and precipitation in some areas exceeded 100 mm.
Rainstorms occur frequently in summer, which can easily cause floods. This year alone, China and Western Europe have suffered many floods. But among them, the Netherlands is the least affected. What is worth learning in this city that coexists with water?
This article will introduce you:
Control measures and risk assessment
July 2021 in southeastern Netherlands Limburg threat of flooding, evacuation of at least 15,000 people. Extremely high water levels appeared on the Maas and Rhine rivers, the highest on record in 1911. In recent years, the summer in the Netherlands is usually dry, and this summer is accompanied by a lot of precipitation. The water levels of the Rhine and Maas rivers have risen sharply, and the water levels in the tributaries have also risen as a result.
Maas River Hongfan District
In 1993 and 1995, continuous rains once caused huge floods in Limburg Province, and a large number of people and livestock were sparsely distributed. Due to the many ecological problems caused by the early flood control dyke construction, the Dutch government later proposed rain and flood prevention measures and a risk assessment mechanism: the emergency intensity of the plan is equal to the product of the probability of a disaster and the consequences of the disaster. The Netherlands has changed from completely resisting floods to allowing floods in certain areas. In addition to reducing the probability of floods by artificially building and strengthening embankments, it also uses ecological measures of “soil and water integration” to mitigate the impact of disasters.
The Netherlands has adopted a strategy of resilient planning. In the “zoning flood detention” strategy, the fenced area is divided into several sub-regions. When a storm occurs, the flooding sequence of different sub-regions is determined according to the current land use type to achieve the flood detention effect. The gradient of fortification standards in the downstream increases, and the overall planning of land use in sensitive areas must meet the needs of flood control, so as to ensure the safety of high-density built-up areas.
The village of Itron (Limburg) during the flooding of the Maas River in 1995
The polder and Hongfan districts are full of water when the water level is high
In the “Green River” strategy, the corridors and patches of the nature reserves and agricultural areas along the river are sorted out. They are used for temporary recreational purposes during normal periods, and emergency flood discharge areas during extraordinary periods. In addition, the Netherlands will activate an emergency defense system to avoid systemic paralysis of water conservancy infrastructure in extreme situations such as dams collapse, water shortages, and catastrophic floods. During the heavy rainfall season, the city reduces the impact of floods through low-impact development planning and design. During the dry season, the priority of water supply is determined according to factors such as the degree of irreversible disasters, the effects of intensive use of water resources, and socio-economic impacts.
It can be seen that in the process of using water and fighting against floods in the 20th century, the Netherlands experienced land development by impounding water by engineering means, building canals for transportation; Waterfront areas in cities and towns; and then to the change of thinking of adjusting the relationship between urban construction and nature through ecological measures of “soil and water integration”.
The Dutch “Resilience Planning” ideology recognizes the environmental dynamic characteristics of periodic floods, and relies on the floodability of cities to actively adapt to floods instead of passively resisting floods. Therefore, unlike previous engineering measures to increase the height of dams to prevent floods, the “Expanding River Space” project emphasizes the realization of the function of natural floodplains, and through ecological interventions such as widening river space and redevelopment of coastal land consolidation, it reduces the impact of river high water level periods. Due to environmental and human impacts, the method of strengthening the dam should be adopted only when the coastal land consolidation is extremely difficult.
Canoeing on the Maas River
The dense vegetation in the Hongfan district of the Mas River will be removed
High-water floodplain near Nijmegen
Floodplain management: build a safe and natural river area
The area between the river and the embankment is a floodplain. The floodplains along the main rivers play an important role in the safety of residents; discharge of river water at high water levels is usually an important habitat for plants and animals. In essence, rivers are constantly changing, changing their routes in the changing times, and the forests on the banks of the river, and the sediments of sand, clay and gravel on the riverbed are all changing accordingly. In the Netherlands, this natural process is restricted for shipping and the safety of residents in the area. And this restriction is accumulated to a certain extent, and then encounter extreme weather, there is a risk of flooding.
Currently, the Dutch Ministry of Water Affairs manages more than 70,000 hectares of floodplains in a sustainable manner
In recent years, rivers in the Netherlands have been widened in many places to allow more water to be discharged. According to the statutory tasks of the Water Framework Directive, the Dutch Ministry of Water Affairs is responsible for the management and maintenance of all floodplains. The Ministry of Water Affairs is committed to the sustainable management of more than 70,000 hectares of floodplains, covering more than 12,000 landowners. Dutch forestry, agriculture, businesses and residents all own land along the river. The government owns more than 11,000 hectares of land. All these different owners and interests need to be well coordinated.
Maintenance and natural development
For each floodplain, the Dutch Ministry of Water will check which vegetation is allowed to use, and where high water levels hinder the flow of the river, it will ensure that overgrowth of vegetation is restricted. Vegetation level Vegetatielegger is the basis of floodplain management, and the Ministry of Water Affairs determines which types of vegetation are allowed to be used in each area. Vegetatielegger is part of Legger Rijkswaterstaatwerken, which determines the ideal state of all water management work in the Netherlands. Major flood control facilities, such as dikes, dams, and storm surge barriers, have their own system level.
Different uses of floodplains
Floodplains are not only important for flood control, but also have other uses. As a grassland pasture, or as a natural and recreational area. Numerous interests and needs sometimes put pressure on limited space. Therefore, the Ministry of Water Affairs coordinates the management of the floodplain with partners in the area (such as municipalities, interest groups, provincial landscapes, and national parks).