River harnessing and flood control have been carried out on an unprecedented scale since the foundation of the People’s Republic of China in 1949. As a result, flood disasters were preliminarily brought under control: 85,000 reservoirs of various kinds with a total storage capacity of 520 billion cubic metres have been constructed; 270,000 kilometres of dykes have been built along the major rivers and lakes; and hundreds of flood detention and storage zones have been developed. All these achievements have attracted world attention.

Since the 1990s, China has again entered a period of frequent floods. Although the total affected area is reduced, the losses are huge due to social and economic development in the flood zone. Urbanization is bound to speed up in the 21st century and thus raise higher the requirements for flood control and disaster reduction.

Strategies for mitigation
Against this background, flood control and disaster mitigation have become significant issues for sustainable development in China. Readjusting the strategies for achieving them is absolutely crucial.

Over the past 2,000 years or so, the main strategy in China has been to regulate and restrict floods with all sorts of structural measures. Historical experiences have told us that it is difficult to eliminate flood disasters completely. Humankind must learn to live with the floods and enjoy harmonious co-existence with nature.

As early as 6 B.C., a Chinese scholar called Jia Rang proposed, in the History of the Han Dynasty, that river harnessing should adapt to the laws of floods and that human production and settlements should avoid them by resiting to unaffected areas. This is similar to today’s philosophy of combining both structural and non-structural measures, reflected in the revised Water Law of the People’s Republic of China, passed in October 2002. Article 15 of the Law emphasizes that regional social development should be in accordance with flood control planning. In other words, it is imperative to change from just preventing water harming humankind to paying special attention to preventing humankind harming water, and thus being harmed by it.

Flood disasters have both natural and social attributes: if one is missing there is no disaster. This duality has led to coordinated management, using structural measures to harness floods while at the same time readjusting social and economic development to adapt to them.

Adaptation does not mean passive avoidance. It involves respecting nature and human society with the aim of achieving sustainable social development. People have increasingly realized that ‘natural’ disasters are not all natural. Human activities have been the main cause of increasing flood disasters and losses during the past hundred years or so.

These dual attributes have led to a change in philosophy. Since the devastating Yangtze River floods in 1998, the Chinese Government has given in-depth thought to the issue and readjusted its work on flood control strategies. The major breakthroughs in this readjustment include both an emphasis on planning flood control projects under the greater framework of basin-wide ecosystem rehabilitation, and applying systematic theories and risk management. This demonstrates a transition from flood control to flood management.

Significant progress
Over the past five years, significant progress has been made in flood control and disaster mitigation. Structural measures provide the basic guarantee for social stability and development. During this period the Chinese Central Government has spent around $21.7 billion in the water sector, focusing on reinforcing dykes along the major rivers and lakes. By the end of 2002, 3,500 kilometres of dykes on the middle and lower reaches of the Yangtze River and nearly 1,000 kilometres of dykes on the Yellow River had reached design standards. To minimize negative impacts, an overall economic and environmental impact assessment is encouraged in planning and design, and the concept of green GDP is introduced.

Behavioural change
The social behaviour of overexploiting the land, and thus making the flood situation worse, has been regulated. For example, polder fields affecting flood release along the Yangtze River and other major rivers have been abandoned. At present, 3,000 square kilometres of polder fields have been turned back into lakes to restore the ecosystem of the Dongting and Poyang Lakes and others; this has increased the regulating capacity of the rivers and lakes by 13 billion cubic metres. As part of this process, the Government allocated funds to relocate 2.4 million people to safe, nearby areas.

Resolving the relationship between humankind and nature is a precondition for the progress of human society

Flood control has changed from emphasizing capital construction, such as building dykes and reservoirs, to developing an integral flood control system. There have been large-scale ecosystem rehabilitation campaigns in the middle and upper reaches of the rivers, including turning farmland into forests, planting trees and grass, and conserving water and soil. A total of 120 million cubic metres of sediment have been dredged from the beds and estuaries of major rivers. Information systems for flood control have provided advanced measures for scientific decision. Social management of flood control areas, dyke protection areas and flood plains has been strengthened, various kinds of economic and social activities have been regulated, and compensation policies for the use of flood detention and storage areas have been formulated.

As a departure from attempting to eliminate flood disasters completely and release the water into the sea, efforts have been made to bear a certain degree of risk, to formulate feasible flood control standards and flood regulating schemes, and to make comprehensive use of various measures to ensure safety within set standards and minimize losses when the floods exceed them.