FLOODPLAIN LEVEL DEVELOPMENT INDUCED BY HUMAN ACTIVITY - CASE STUDY IN THE LOWER MAROS/MURES RIVER, ROMANIA AND HUNGARY

Multiple human impacts affect the development of the lowland section of the Maros/Mures River. Extensive channel and floodplain regulations implemented during the nineteenth century resulted in considerable shortened and straightened channel, and formation of a narrow artificial floodplain. Later, in the twentieth century, the construction of revetments and groynes, and in-channel gravel and sand mining influenced the channel morphology. These human activities triggered an increase in channel slope and stream power, thus significant incision took place. This paper aims (1) to determine the incision rate of the channel along the Maros/Mures River, and (2) to characterize the newly formed floodplain sections. The incision process varied temporally and spatially. The first stage of channel incision occurred between 1876 and 1912, and it was driven by channel regulation works. It was replaced by an aggradation stage (1913-1981), and finally, in the second half of the 20th century a new incision stage has started in connection with in-stream gravel mining. The incision rate was the highest upstream of Arad. The incision resulted in the development of floodplains levels, which have 65-644 cm height difference. Under these circumstances, the duration of floods decreased to one fifth of the original length.