author = "Martins, Vitor S. and Kaleita, Amy and Barbosa, Cl{\'a}udio 
                         Clemente Faria and Fassoni-andrade, Alice C. and Lobo, Felipe de 
                         Lucia and Novo, Evlyn M{\'a}rcia Le{\~a}o de Moraes",
          affiliation = "{Iowa State University (ISU)} and {Iowa State University (ISU)} 
                         and {Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Universidade Federal do Rio Grande do Sul (UFRGS)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)}",
                title = "Remote sensing of large reservoir in the drought years: 
                         Implications on surface water change and turbidity variability of 
                         Sobradinho reservoir (Northeast Brazil)",
              journal = "Remote Sensing Applications: Society and Environment",
                 year = "2019",
               volume = "13",
                pages = "275--288",
                month = "Jan.",
             keywords = "inland water, Surface water change, Drought e\ff,,ects, 
                         Atmospheric correction, Landsat-8.",
             abstract = "Sobradinho reservoir has been suffering a severe water loss caused 
                         by multi-year drought in the Northeast Brazil. This reservoir 
                         contributes to the socio-economic development of the semi-arid 
                         region, and the monitoring of water shortage is crucial for people 
                         living in this climate-vulnerable region. In this study, we 
                         evaluate the surface water change and turbidity variability of 
                         Sobradinho reservoir during recent drought years (20132017). A 
                         time-series dataset was created using 109 Landsat-8 OLI images for 
                         mapping the water extent in the reservoir. A non-linear regression 
                         between measured turbidity and surface reflectance (red band) was 
                         developed and applied for turbidity retrievals. Additionally, we 
                         performed a long-term precipitation analysis (17-year) to assess 
                         the rainfall deficit over the catchment area. Our results show 
                         that the annual precipitation regimes are below the long-term 
                         average during 20122017 period, except 2013. We also found that 
                         negative anomalies occur during 26 out of 36 months between 2014 
                         and 2016, mostly in the rainy season. Since the rainfall regimes 
                         and river discharges are the major drivers for water recharge, 
                         these drought years have a critical impact on the reservoir level. 
                         According to our results, the water surface receded about 2073 km2 
                         (out of total 3303 km2) during September 2017; this represents a 
                         reduction of 62.8% in the total water extent. The surface water 
                         change is spatially distinct across the reservoir. For instance, 
                         the upper section of the reservoir was almost totally dried during 
                         September 2017, and the water coverage was ~8% (91.25 km2 out of 
                         1128 km2). Although other sections had a relatively low water 
                         change (reduction of ~40%), the losses are significant in terms of 
                         area (~1035.5 km2). The receding of water extent affects the 
                         people living near to the reservoir, and local communities are 
                         more distant from water (up to 13 km). We also observed that the 
                         turbidity is seasonally dependent, and water clarity presents a 
                         strong variability between rainy and dry seasons. In general, the 
                         turbidity levels vary from clear water (020 NTU) during the dry 
                         season to turbid condition (>50 NTU) during the rainy season. A 
                         lack of access to clean and safe drinking water in some periods 
                         might be harmful to humans, livestock and domestic animals. 
                         Finally, this research contributes to the assessment of 
                         drought-related impacts in the Sobradinho, the largest reservoir 
                         in the Northeast Brazil. The water shortage is a recurring concern 
                         in the semi-arid region, and the remote sensing techniques provide 
                         spatially explicit information to enhance the livelihood 
                         resilience during drought years.",
                  doi = "10.1016/j.rsase.2018.11.006",
                  url = "http://dx.doi.org/10.1016/j.rsase.2018.11.006",
                 issn = "2352-9385",
             language = "en",
           targetfile = "martins_remote.pdf",
        urlaccessdate = "23 abr. 2021"