The emergence of increasingly accurate, fast, and inexpensive tools in the acquisition of data for the management base suitable for each type of environment is fundamental in the development of sustainable engineering. Based on this, the evaluation of the accuracy of the volume calculation performed using Digital Terrain Models (DTM’s), generated by images of Unmanned Aerial Vehicle (UAV) was carried out. The study was conducted in the area of the new landfill in the municipality of Fortaleza, state of Ceará, in a waste stabilization pond. Two DTM’s were generated and evaluated. The first was generated by collecting points from a Global Navigation Satellite System (GNSS) receiver, using 445 points, whereas the second was generated by aerial images obtained through a multirotor UAV, with 17 checkpoints and 10 Ground Control Points (GCP’s). With the two DTM’s of the GNSS Receiver and the UAV, the volume of the stabilization pond was calculated using the TopoEVN and Pix4D software, respectively. The estimated pond volume obtained through the Global Positioning System (GPS) data was 48548,33 m³, while by the UAV DTM, it was 48504,9 m³. The accuracy of the volume data obtained by DTM generated by UAV, even with considerable flight height (120 m), presented a result with variation less than 1% compared to those arising from conventional topography, thus indicating high reliability and data accuracy.

Water is an important resource for life and as such, its monitoring is essential. The aim of this study therefore was to estimate concentrations of chlorophyll-a and total suspended solids (TSS) using orbital remote sensing data. The study area was the General Sampaio reservoir, located in the Curu River Basin, in the state of Ceará. The concentration of chlorophyll-a and sediments were mapped based on orbital images captured by the Operational Land Imager (OLI) sensor. The images were acquired on 14 September 2017 and 13 June 2018. The chlorophyll-a concentration was estimated using a model employing a ratio of the blue (450-510 nm) and green (530-590 nm) bands, and the TSS concentration was estimated from the red band (640-690 nm) of the OLI sensor. The chlorophyll-a concentration in September 2017 varied from 37.03 to 43.0 mg L-1, and in June 2018 it ranged from 42.9 to 62.2 mg L-1. The TSS concentration in September 2017 varied from 1.8 to 4.2 mg L-1, while in June 2018, a period that corresponded to the highest local rainfall, the variation was greater, between 2.1 and 17.73 mg L-1. The highest concentrations of suspended sediments were seen in the tributaries of the Curu River and the Salvação Stream. It was possible to estimate the concentrations of chlorophyll-a and TSS using orbital images. The reservoir water was classified as eutrophic throughout the study period.