Dam Construction and Loss of Geodiversity in the Araguari River Basin, Brazil

The Araguari River is located in the central uplands of Brazil. Over the past 40 years, the region has undergone considerable change in its economy because of the green revolution and urban development that followed the construction of Brasilia in the 1960s, the new capital of Brazil. The main changes in the landscape were the construction of two hydroelectric power plants across the main valley, resulting in ~95 per cent loss in the natural features of the lower 200 km of the Araguari course. The inundation of the river valley has dramatically modified the landscape, with submersion of many locations, especially gorges, islands as well as tributary valleys and historic sites. The concept of geodiversity implies that abiotic elements of nature have unique qualities that are not uniformly distributed and include geomorphic, geologic and pedologic qualities within the context of their location. The concept of geodiversity is used to understand and assess losses from the Araguari River Valley landscapes. In this research, we present the total quantity of geosite types occurring for our Araguari River Valley study site. Twelve complex sites were identified, with six transformed to simple geosites because of inundation associated with formation of two reservoirs. The major changes caused by river impoundment resulted in a reduction in the richness of geosites and a reduction in their complexity by 50 per cent. The study results find that 14.3 per cent of the original geodiversity was lost after valley inundation. Quantification of changes in geodiversity is essential to comprehensively characterize the environmental impact of dams.