Characterization of reservoirs for water supply in Northeast Brazil using high resolution remote sensing

Abstract

This paper reports the application of information acquired by aerial survey to characterize water supply reservoirs in the Pajeú River Basin (Pernambuco State/Brazil). The survey was carried out with digital cameras of high spatial resolution and laser relief profiling (LiDAR technology). Two areas were selected to apply the remote sensing products. Small reservoirs in the Quixaba Creek Basin were identified based on their topographic characteristics. Given that the small reservoirs are "depressions" in the terrain, they can be "filled", resulting in a new Digital Terrain Model (DTM). The difference between the filled DTM and the original DTM makes it possible to identify the reservoirs. A summary of the results is: 61 reservoirs were correctly detected; 18 reservoirs were not detected; 13 reservoirs were detected erroneously. In another application, the storage capacity of the reservoirs belonging to the hydrosystems of Pajeú River Basin was estimated. The storage in these reservoirs and maximum surface area were estimated using DTM and geoprocessing tools. From the total of 31 reservoirs evaluated, eight were completely empty at the time of the LiDAR data collection. The official registers reported 83.83 million m 3 for the storage capacity of these eight reservoirs, whereas our applications estimated the value at 70.23 million m 3 . This difference is explained by the loss of volume in the reservoirs due to the process of sediment transport.Keywords: LiDAR; Semiarid; Water resources; Storage capacity. RESUMOEste artigo apresenta a aplicação de produtos adquiridos por levantamento aéreo para caracterização de reservatórios de abastecimento de água na Bacia do Rio Pajeú (Pernambuco/Brasil). O levantamento foi feito com câmeras digitais de alta resolução espacial e perfilamento de relevo a laser (tecnologia LiDAR). Foram selecionadas duas áreas para aplicação dos produtos de sensoriamento remoto. Pequenos reservatórios na Bacia do Riacho Quixaba foram identificados com base em suas características topográficas. Considerando que os pequenos reservatórios são "depressões" no terreno, eles podem ser "preenchidos" resultando em um novo MDT. A diferença entre o MDT preenchido e o MDT original torna possível a identificação dos reservatórios. O resumo dos resultados é: 61 reservatórios foram corretamente detectados; 18 reservatórios não foram detectados; 13 reservatórios foram detectados erroneamente. Em outra aplicação, foi estimada a capacidade de armazenamento dos reservatórios pertencentes aos hidrossistemas da Bacia do Rio Pajeú. O armazenamento nos reservatórios e a área superficial máxima foram estimados utilizando o MDT e ferramentas de geoprocessamento.

Are Brazilian catchments gaining or losing water? The effective area of tropical catchments

“…Those arid catchments are located along the northeast coast of Brazil (Caatinga and Atlantic Forest biomes) and share particular characteristics that influence the surface and subsurface hydrological processes. The semiarid region has a complex network of reservoirs (ANA, 2021; Nascimento & Neto, 2017) composed of more than 70 thousand reservoirs with an approximated capacity of 31.215 hm 3 (ANA, 2017; Gondim et al, 2017; Rebouças, 1997), which alters the local water budget by reducing flow downstream and increasing ET losses. ECI does not capture human hydrological disturbances and therefore does not reflect the actual deviation between topographic and effective areas.…”

Are Brazilian Catchments Gaining or Losing Water? The Effective Area of Tropical Catchments

“…Those arid catchments are located along the northeast coast of Brazil (Caatinga and Atlantic Forest biomes) and share particular characteristics that influence the surface and subsurface hydrological processes. They have a complex network of reservoirs (Nascimento & Neto, 2017;ANA, 2021), which alters the local water cycle by reducing flow downstream and increasing ET losses. In the ECI estimation, this disturbance exacerbates the deviation of the effective area from its corresponding topographic area.…”

Application of satellite imagery to update depth-area-volume relationships in reservoirs in the semiarid region of Northeast Brazil

“…Three-Dimensional Pernambuco (PE3D) was a project of the Government of Pernambuco state, which resulted in a database of DTM and orthophotos of high-resolution using LiDAR technique (here called DTM PE3D ). The survey was carried out between March 2014 and December 2016, and the final product had the following characteristics: a scale of 1:5000, a spatial resolution of 1 m, and an altimetric accuracy of 25 cm, covering the entire territory of the state (Nascimento & Ribeiro Neto, 2017). The PE3D is another data source for calculating the bathymetry and CAVs of reservoirs in Pernambuco state.…”

“…The PE3D is another data source for calculating the bathymetry and CAVs of reservoirs in Pernambuco state. This is possible in cases where the reservoir was empty on the date of the measurement, as demonstrated by Nascimento & Ribeiro Neto (2017). The Barra do Juá reservoir is one of these cases, allowing the updating of its bathymetry.…”

“…This exercise is particularly important in semiarid regions, where reservoirs are the main source of water. Accurate information about volume storage in the reservoir is essential for proper water allocation (Nascimento & Ribeiro Neto, 2017).…”