Land reclamation and transformation of floodplain-channel complexes at the Middle Amur lowland

Due to the specifics of climate, geology and relief of the Russian Far East, extensive land reclamation has been carried out in this region for more than sixty years in order to create the necessary conditions for agricultural production. The purpose of this land reclamation is heavy soils drainage in Primorye and the Amur Region. An extensive network of reclamation systems of open and closed types was created. This paper presents the results of studying the effect of land reclamation on floodplain-channel complexes (FCC) of the Middle Amur Lowland. It was found that construction and subsequent operation of reclamation systems (water receivers, main canals, regulating dehumidifiers) led to general degradation of FCC with full cessation in development of channel and riverine forms at micro- and meso- relief, and their complete silting. The concentration and seasonal dynamics of heavy metals in the soils of meliorated lands, in bottom sediments and water of small rivers and main canals at FCC was estimated. The content of heavy metals in the soils of meliorated lands’ decreased in comparison with unaffected environment. At the same time, accumulation of heavy metals took place in the waters and bottom sediments of main canals and water receivers. In addition, the paper presents data on the impact of catastrophic and unfavorable hydrological phenomena (floods, freshets) on the dynamics and state of agrocenoses within the boundaries of FCC.