The flood disaster in the Yangtze River basin and the heroic deeds of millions of soldiers and civilians in fighting floods have touched the hearts of hundreds of millions of people across the country. Reflecting on the causes of the flood, it is not difficult to find that, in addition to the relatively large precipitation in the Yangtze River basin in that year, the serious ecological imbalance caused by the destruction of ecological resources over the years is also an important factor for the aggravation of the flood.

1998 After the Yangtze River entered the main flood season, rainfall occurred in the upper reaches and the middle and lower reaches at the same time, and the floods in the upper, middle and lower reaches were concurrent, which made the flood volume surge, exceeding previous years. This is the main cause of the flood. Comparing the historical hydrological records, it can be found that the flood discharge of 1998 is not the largest in history. Taking Yichang as an example, the maximum discharge of the first three flood peaks was 56,400 cubic meters per second, while the maximum flood peak discharge in hydrological records exceeded 60,000 cubic meters per second for at least 23 years. It is directly related to the long-term man-made destruction of the ecological environment in the Yangtze River basin that the water level record is refreshed again and again when the flood is not at the maximum flow. There are two main aspects: First, the vegetation in the Yangtze River basin is destroyed; The second is the unreasonable use of lakes and rivers.

Vegetation has always been called "green reservoir", which has the function of water conservation. According to experts' investigation, the storage capacity of 6.5438+0 million mu of forest is equivalent to a reservoir with a storage capacity of 6.5438+0 million cubic meters. In the past, the Yangtze River basin has always been a region with high forest coverage, but since the 1950s, forests have been cut down in large areas, especially in the upper reaches of Jinsha River, Minjiang River and Jialing River.

The destruction of vegetation not only reduces the ability of water conservation, but also makes the surface runoff directly formed by precipitation increase the flood discharge pressure of rivers, which also leads to serious soil erosion. According to statistics, the area of soil erosion in the Yangtze River basin has increased by more than 50% in the past 30 years, and a large amount of sediment has flooded into the river, raising the riverbed and aggravating the siltation of rivers and lakes, so that even if the water volume is not large, a higher water level will be formed.

The reduction of wetland area is also an important aspect of ecological resources destruction in the Yangtze River Basin. Wetland is an important natural ecosystem on the earth, which has important functions such as water storage and flood regulation, climate regulation, soil and water conservation, water purification and biodiversity protection. Unfortunately, due to the reclamation of lakes, wetlands in the Yangtze River basin are decreasing, and the capacity of water storage and flood regulation is greatly reduced. The middle and lower reaches of the Yangtze River are the concentrated distribution areas of freshwater lakes in China, and many lakes have become natural regulation areas of Yangtze River water. However, blind reclamation around the lake leads to lake shrinkage and ecological degradation. Since the founding of the People's Republic of China, the water surface of Dongting Lake has decreased by 46%, the water surface of Poyang Lake by 40%, and the lake area in the middle and lower reaches of the Yangtze River has decreased by about 1.2 million hectares, with a loss rate of 34%, resulting in less and less water storage and reduced flood control capacity.