Land Cover Changes Based on Maps and Satellite Images Along the Croatian–Hungarian Section of the Drava River's Active Floodplain

Despite regulations, dam and embankment constructions upstream, the Drava is among Europe's most preserved near-natural rivers in the Croatian-Hungarian section. We examined how land cover in the active floodplain changed between the date of the first military survey (1783) and 2018. We delimited the study area, which is the area between the flood protection embankments. We did not deal with the flood-protected areas (former floodplain). We georeferenced and vectorized military and civilian topographic maps from the following years: 1783- 84, 1859, 1880, 1950-52, and 1990-2000. We also classified a Sentinel satellite image from 2018. We identified the following land cover categories: water area of river channel and standing waters, waterlogged areas (marshes), forest, bush, grassland (meadow, pasture), orchard and vineyard, built-up area. We found that the proportion of near-natural areas (water, marsh, forest) decreased significantly between 1783-84 and 1880, and then increased from then on. The trend of spatial change in agricultural areas was the opposite. Among the landscape ecology indicators, the Number of Patches (NP), Shannon Diversity Index (SHDI), and Edge Density (ED) were lower at the beginning and end of the study period, while they were higher in its middle. The Mean Patch Fractal Dimension (MFRACT) showed an increasing trend.