The construction of four large reservoirs for hydroelectric power generation in the main channel of the Paraná River and many others in the tributaries has eliminated important wetlands, except over an area of ∼2000 km² between the reservoirs of the UHE Engenheiro Sérgio Motta (Porto Primavera) and the Itaipu. The up-river reservoirs created large changes in the river's hydrology and in its loads of suspended, bed and dissolved material. A detailed assessment of the impact of these changes requires a description and classification of the floodplain's different subunits, called macrohabitats, according to hydrological, hydromorphological, and vegetational parameters. The classification system presented herein is hierarchical and is embedded in the classifications of Brazilian wetlands. The system differentiates the Paraná River floodplain into 6 functional units, 13 subclasses, and 23 macrohabitats, which are presented in this paper. Changes in hydrology have reduced the flood amplitude, frequency and permanence, and thus confined the macrohabitats to an area currently subjected to a regular flood pulse of ∼3 m rather than the previous ∼6 m. The gradual terrestrialization of macrohabitats at the upper end of the flood gradient is expected, accompanied by a loss of macrohabitats at its lower end because of long-term flooding. The retention of sediments and dissolved nutrients in the reservoirs will lead to the oligotrophication of aquatic macrohabitats, the degradation of near-channel hydromorphic structures and their vegetation, and a general reduction of overall primary production in the floodplain, which may extend also to higher trophic levels.

四个大型水库水电发电在巴拉那河和许多其他的在支流的主要渠道建设已经消除了重要湿地，除了超过〜2000公里，面积²UHE Engenheiro Sérgio Motta (Porto Primavera) 和 Itaipu 的水库之间。上游水库使河流的水文及其悬浮物、河床和溶解物质的负荷发生了巨大变化。对这些变化的影响的详细评估需要根据水文、水文形态和植被参数对洪泛区的不同亚单位（称为大栖息地）进行描述和分类。这里介绍的分类系统是分层的，并嵌入到巴西湿地的分类中。该系统将巴拉那河漫滩区分为 6 个功能单元、13 个亚类和 23 个大型栖息地，这些在本文中进行了介绍。水文变化降低了洪水的幅度、频率和持久性，从而将大栖息地限制在当前遭受约 3 m 的常规洪水脉冲而不是之前的约 6 m 的区域。预计洪水梯度上端的大型栖息地将逐渐陆地化，同时由于长期洪水，其下端的大型栖息地也会丧失。水库中沉积物和溶解养分的滞留将导致水生大型栖息地的贫营养化、近河道水形结构及其植被的退化，以及泛滥平原整体初级生产的普遍减少，这也可能扩展到更高的营养水平。由于长期洪水，伴随着低端大型栖息地的丧失。水库中沉积物和溶解养分的滞留将导致水生大型栖息地的贫营养化、近河道水形结构及其植被的退化，以及泛滥平原整体初级生产的普遍减少，这也可能扩展到更高的营养水平。由于长期洪水，伴随着低端大型栖息地的丧失。水库中沉积物和溶解养分的滞留将导致水生大型栖息地的贫营养化、近河道水形结构及其植被的退化，以及泛滥平原整体初级生产的普遍减少，这也可能扩展到更高的营养水平。