# Before and After: A Multiscale Remote Sensing Assessment of the Sinop Dam, Mato Grosso, Brazil
## 2 Materials and Methods  
### Study Area  
The Teles Pires river forms the major eastern branch of the Tapajos river basin and is also the administrative border between the states of Mato Grosso and Para. The most recent hydropower plant in the Teles Pires river complex, HPP Sinop (HPPS), is in the state of Mato Grosso, 70 km north of Sinop, serving the municipalities of Claudia, Itauba, Ipiranga do Norte, Sinop, and Sorriso. The HPPS is in the middle-upper portion of the Teles Pires river drainage within the Arc of Deforestation [51] where the landscape consists of large patches of deforestation mainly due to large scale commercial agricultural activities and was formerly referred to as the epicenter of deforestation in Brazil [52] (Figure 2). The HPPS began operations in September 2019. Its reservoir had a planned impoundment of 342 km\({}^{2}\) with an installed capacity of 401.88 MW. The actual area flooded by the Teles Pires following operationalization of the HPPS was considered as the study area for the satellite imagery analysis.  
At a smaller scale, for UAS SfM-MVS photogrammetry, two sites on the Teles Pires were chosen: the fast-flowing rapids of the Corredeira do Sulplicio and the shallow, high flow, sand, and rubble zone on the upstream (north) side of Ilha do Lair (Figure 2). At the Corredeira do Sulplicio prior to inundation, white water rapids dropped in elevation by \(\sim\)1 m and the Teles Pires is also narrower (\(\sim\)15 m wide) than elsewhere along the main channel. The substrate is composed of sand, stone, and large boulders. Due to the intense flow, only macrophytes of the Podostemaceae family that adhere directly on the rocks were present. In contrast, at Ilha do Lair, prior to the inundation there was a rapid current, but not as strong as at Corredeira do Sulplicio. This sector of the river is both wider (\(\sim\)150 m wide) and shallower than elsewhere in the main channel. Several species of macrophytes were present in a substrate composed of sand, stone, and small boulders. These two sites are part of the largest continuous stretch of rapids in the sector flooded by the HPPS reservoir. Prior to inundation the main channel had a pH ranging from 5.1-7.7, and average temperature of 24.5-29.3 \({}^{\circ}\)C.  
In addition to the overall impact of the lenti zone on the landscape, changes to the biodiverse small Creek tributaries during and after inundation were also examined from  
Figure 2: Sector of the Teles Pires river (Mato Grosso, Brazil) impacted by the HPPS reservoir. The river’s course is shown in blue prior to the construction of the dam. The red dot indicates the location of the UAS study areas: (**A**) Corredeira do Sulplicio, photograph facing South and (**B**) Ilha do Lair, photograph facing North.  
satellite imagery. These small tributaries, often only 1-3 m wide, flow into the Teles Pires river from the surrounding valleys and are especially vulnerable to change. They are found within riparian zones where the riverbanks retain a thin band of trees and palms. Water in these creeks was usually clear and fast-flowing (Figure 3). The streams in the region have acidic waters, with an average pH of 4-5.4, average temperature of 22.8-24.6 \({}^{\circ}\)C and mean conductivity of 7.52 \(\pm\) 2.8 \(\mu\)S/cm (5.36-15.44 \(\mu\)S/cm).