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Премия рунета 2017

Catastrophic flooding on Amur and its consequences

There has been catastrophic flooding of river Amur basin, which affected thousands of people and the economy of the region. Together with fellow countrymen we feel this disaster and sympathize with all who are in trouble. The Great River once again has shown its temper and proved that it requires serious attitude towards it; that humans must adapt to it. Free flowing Amur must have available floodplain so that water can spread out during the flood, causing minimal damage to people.

Assessing the consequences of floods, it is difficult to talk about damage to nature, as this is a natural process. For thousands of years ecosystems of Amur have adapted to a periodic rise in water levels and flooding of the floodplain. We need to talk about the damage to the population, the economy and of possibilities to avoid this damage in the future, adapting to the catastrophic natural phenomenon.

Today there is an increasing opinion that the only panacea for floods on the Amur River is the construction of new hydroelectric dam stations. However world experience has shown that only constructing flood control dams and reservoirs does not solve the problem entirely. Approximately once in 100 years such water volumes come, which dams cannot withstand, often provoking even more damage downstream. And sometimes they result in a catastrophe with the destruction of dams and overflow of water through dam’s crest.

Most vivid and sad example this is the Yangtze River flood in 1998. The amount of precipitation exceeded the volume of floodwater capacity of reservoirs, the dams collapsed, and the water suddenly poured onto densely populated floodplain. As a result, more than 100 million people were injured, thousands have died, and the damage amounted to 30 billion dollars. In 2010, despite the commission of the «Three Gorges» HPP and the reconstruction of flood control dams on the Yangtze River, once again flooding has not been prevented. The situation has been repeated, although experts believe this flood was not more powerful than in 1998.

In 2010, Europe suffered from flooding, despite a system of flood control dams protecting large settlements. In June 2013, due to the recurrence of floods on the Rhine and Elbe rivers, dams broke, the Danube overflowed its banks, Hungary, Austria, Germany and other countries have been affected. There were mortalities and missing persons. In the United States, in 2010, river Mississippi destroyed flood protection dams, flooded numerous towns and farms in the river’s floodplain, to a large extent destroying the city of New Orleans.

Given the experience of these floods and taking into account the lessons of current year situation on rivers Zeya and Amur, it is necessary to not only think about constructing new dams that can hold water, but also about the fact that an influx of very high-water rivers can exceed reservoirs’ flood control capabilities. Regulation of the use of the floodplain and the construction of protective hydraulic structures around populated areas should be the priority measure, which has a long-term positive result. Therein, it is necessary to distinguish flooding zones of various capabilities during high water and to determine possible types of economic and other uses for these zones. For example, a low floodplain of river Zeya is unsuitable for settlements, since it is flooded with a periodicity of about 25 years with serious damage to residents and economic entities. For the same reason, it is risky to situate capital production facilities in the vicinity of the river’s floodplain. Agriculture conduct on floodplain lands should also be regulated. Plowing of a floodplain up to the edge of small and large rivers should not be permitted due to the high risk of water saturation and flooding of river’s floodplains in high water years. At the same time, floodplain can be used for haymaking, as well as seasonal cattle pasture. And if a system of evacuating harvested fodder and animals to capital facilities on not flooded territories is anticipated, then they are also safe.

Works on zoning and regulating activities in the basin’s floodplain zone were actively conducted in the early 2000s. Even design works have been completed in the Jewish Autonomous Region, as well as in some areas of the Amur Region. It was already possible to prepare normative legal acts regulating economic and residential use of a floodplain. But all this turned out to be unnecessary when the new Water Code in 2006 has determined the width of water protection zone with limited economic activities; only 200 meters even for such large river as Amur. Moreover, it allows installment of economic facilities. Over the past years, housing has been erected on the territory, which will continue to be flooded in case of high floods.

It is necessary to be prepared for the fact that in case of a high flood the possibility of retaining water by shore-protecting dams will be forfeited, and there will be risk of their destruction. As a result, there will be a sharp rise in water level, and flooding will develop at a high rate. Taking this possibility into account, it can be concluded that, probably, a more effective measure is to move residents from the affected floodplain to not flooded areas during high water. It makes sense to build protective hydraulic structures only for large settlements located on high banks of river Amur. Such measures include the construction of a permanent dam in the village of Verkhne-Bogoschensky, the construction of locks in the mouth of the Burkhanovka and Chygyrynka Rivers in Blagoveshchensk, a dam in Khabarovsk from the mouth of the Ussuri and to Voronezh.

Of course, the construction of new hydro-electric power station dams, especially in the upper reaches of Amur tributaries, can also help to restrain part of the floods, but not catastrophic levels. For example, Zeyskaya hydro power plant has truly reduced and, most importantly, shifted times of flood crests. But we must admit that not a single hydrotechnical structure is capable of completely retaining a flood of rare occurrence (flood, characteristic of very high-water years). If we inspect the time table of water inflow into the reservoir and change in its level, it becomes clear that the Zeyskaya HPP has retained about a half of the flood volume of the upper reaches of the river Zeya (although not more than 10% of the general Amur flood and certainly not 6 meters of flood wave). Nevertheless, due to discharges in the second-third decade of August 2013, the level of river Zeya remained at a fairly high level. It is important that representatives of «RusHydro» have noted the lack of a technical opportunity to dump excess water when the reservoir is filled to a mark of a full reservoir level (FRL) of 315 meters. This was not permit to regulate the level of the reservoir in the interval between 315–317.5 m. According to the evaluation of hydropower specialists, expressed in the media, by August 22-23rd, Zeyskaya Hydroelectric Power Station withheld more than 6 cubic kilometers of water and, thereby, significantly reduced the flooding of the floodplain. By the time the discharge began to exceed 3000 cubic meters per second (01.08.2013), the reservoir has reached an excess of water (above the FRL) slightly more than 6 cubic kilometers. And if the owner of Zeyskaya HPP, the company «RusHydro», had the opportunity to discharge small volumes of water earlier, it is possible that flooded area would be much smaller.

Therefore, the reconstruction of Zeyskaya HPP, the creation of a bypass channel through which water can be discharged from a mark of 315 meters and lower, into the river channel downstream of the town of Zeya, can be one of the most significant ways to reduce flood damage. This is the most important task, since all the HPP proposed for construction will have little effect on the water level in case of a flood, due to either their position or technological features. The Gilyuiskaya HPP will be located above Zeyskaya and if the scenario of the 2013flooding is repeated, it will not be able to significantly influence the situation downstream of Zeyskaya HPP. The construction of the Nizhne-Zeiskaya HPP is important from the point of view of creating a counter regulator of Zeyskaya HPP, although its anti-flood properties will not be substantial. The counter regulator has a small water reservoir adapted to pass a spillway of the upstream dam to smooth out the diurnal and weekly fluctuations of the water level. Consequently, the dam of Nizhne-Zeiskaya HPP will only slightly delay the beginning of the flood, which is important for timely commencement of rescue operations, but will not affect the area of flooding. In a situation similar to that of 2013, the Nizhne-Zeyskaya water reservoir may be completely ineffective, since its vacant capacity will be quickly filled up with an inflow of rivers feeding into Zeya below Zeyskaya hydroelectric dam, such as Urkan and Tygda.

The construction of other hydroelectric dams does not exclude the possibility of flooding rivers’ floodplains, settlements and economic facilities located on this territory. Reconstruction of Zeyskaya and the construction of Nizhne-Zeyskaya HPPs should be accompanied by works to conserve and increase the flow of river channels and the surrounding area. An organization of environmental releases [1], which provide flooding of floodplain streams and lakes (natural flood control reservoirs) can help with this.

At the moment the Russian Scientific Research Institute of Integrated Use and Protection of Water Resources (RosNIIVH) is completing the development of a Scheme for an integrated use and protection of water bodies (SKIOVO) of the Amur River basin. The fact that a significant part of the Amur is on the Chinese side it is not taken into account during the development of the Scheme; it is not predicted that the river will affect two parts of the basin at the same time. SKIOVO does not specify issues related to the use of the floodplain.

WWF Russia suggests to:

  • develop a set of measures that removes people and capital structures from the zone of possible flooding;
  • adopt in each region normative legal acts regulating the use of floodplain lands located in the flood impact zone;
  • prevent the reduction of flood control capacity of large rivers by erecting structures directly in the river bed, as was done during the construction of a new embankment in Blagoveshchensk;
  • identify settlements where it is advisable to create flood control dams;
  • sign international agreements that will allow an exchange of operational information on the flood situation;
  • include in SKIOVO for Amur the development and further adoption of scientific and regulatory framework governing the use of the floodplain and the implementation of anti-flood measures.

SKIOVO of the Amur River Basin should be a tool that allows the usage of the floodplain only in a manner that allows avoiding damage due to any floods. Free flowing Amur is a guarantee of adaptation of humans and their economic activity to natural cycles of the great river of the world!

[1] Environmental discharge is a release from a reservoir that provides conditions for sustainable and safe functioning of aquatic ecosystems in the river section below the reservoir.