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Due to limitations of hydrometeorological monitoring network related to spatial station distribution and extension of historical series, tools that aim to improve consistency and optimize available data analysis have become essential. In this context, regionalization techniques stand out, once the main focus is the delimitation of hydrologically homogeneous regions with the subsequent spatial transposition of hydrological variables of interest. Regional indicators, defined as the mean values of hydrological variables and characteristics of a homogeneous region, constitute an expeditious approach to hydrological regionalization. The main perspective of the study was to evaluate the use of regional indicators when quantifying reference flows associated with average flow, drought, or flood conditions. The study area selected was the Manhuaçu River basin, a major Doce River tributary, located in the state of Minas Gerais, Brazil. The results showed that the regional indicators allow estimates of diverse reference flows with mean errors lower than 30%, considered satisfactory for the study area. However, the conventional method of flow regionalization presented more consistent results, with mean errors usually lower than 20%, regardless of the reference flow analyzed. It was also observed that adopting historical flow series with varied extensions did not produce relevant differences when appropriating the diverse reference flows for the Manhuaçu River basin, with none exceeding 3%., Em função das limitações da rede de monitoramento hidrometeorológico, tanto do ponto de vista da distribuição espacial quanto da extensão das séries históricas, ferramentas que busquem dar consistência e otimizar a análises dos dados disponíveis vêm ganhando espaço. Neste contexto, destacam-se as técnicas de regionalização, cujo principal foco é a delimitação de regiões hidrologicamente homogêneas com a subsequente transposição espacial de variáveis hidrológicas de interesse. Os indicadores regionais, definidos como valores médios de uma variável hidrológica e característicos de uma região homogênea, constituem abordagem expedita de regionalização hidrológica. O presente estudo teve como principal perspectiva avaliar o emprego de indicadores regionais quando da quantificação de vazões de referência associadas às condições médias de escoamento, estiagens ou cheias. A área de estudo selecionada para a condução do estudo foi a bacia hidrográfica do rio Manhuaçu, importante afluente do rio Doce, Minas Gerais, Brasil. Os resultados demonstraram que os indicadores regionais permitem estimativas de diferentes vazões de referências com erros médios inferiores a 30%, considerados satisfatórios para a área de estudo. No entanto, o método convencional de regionalização de vazões apresentou resultados mais consistentes, com erros médios usualmente inferiores a 20%, independentemente da vazão de referência analisada. Observou-se, adicionalmente, que a adoção de séries históricas de vazões com diferentes extensões não produziu diferenças relevantes quando da apropriação das diferentes vazões de referência para a bacia hidrográfica do rio Manhuaçu, com diferenças que não superaram 3%.

Due to limitations of hydrometeorological monitoring network related to spatial station distribution and extension of historical series, tools that aim to improve consistency and optimize available data analysis have become essential. In this context, regionalization techniques stand out, once the main focus is the delimitation of hydrologically homogeneous regions with the subsequent spatial transposition of hydrological variables of interest. Regional indicators, defined as the mean values of hydrological variables and characteristics of a homogeneous region, constitute an expeditious approach to hydrological regionalization. The main perspective of the study was to evaluate the use of regional indicators when quantifying reference flows associated with average flow, drought, or flood conditions. The study area selected was the Manhuaçu River basin, a major Doce River tributary, located in the state of Minas Gerais, Brazil. The results showed that the regional indicators allow estimates of diverse reference flows with mean errors lower than 30%, considered satisfactory for the study area. However, the conventional method of flow regionalization presented more consistent results, with mean errors usually lower than 20%, regardless of the reference flow analyzed. It was also observed that adopting historical flow series with varied extensions did not produce relevant differences when appropriating the diverse reference flows for the Manhuaçu River basin, with none exceeding 3%., Em função das limitações da rede de monitoramento hidrometeorológico, tanto do ponto de vista da distribuição espacial quanto da extensão das séries históricas, ferramentas que busquem dar consistência e otimizar a análises dos dados disponíveis vêm ganhando espaço. Neste contexto, destacam-se as técnicas de regionalização, cujo principal foco é a delimitação de regiões hidrologicamente homogêneas com a subsequente transposição espacial de variáveis hidrológicas de interesse. Os indicadores regionais, definidos como valores médios de uma variável hidrológica e característicos de uma região homogênea, constituem abordagem expedita de regionalização hidrológica. O presente estudo teve como principal perspectiva avaliar o emprego de indicadores regionais quando da quantificação de vazões de referência associadas às condições médias de escoamento, estiagens ou cheias. A área de estudo selecionada para a condução do estudo foi a bacia hidrográfica do rio Manhuaçu, importante afluente do rio Doce, Minas Gerais, Brasil. Os resultados demonstraram que os indicadores regionais permitem estimativas de diferentes vazões de referências com erros médios inferiores a 30%, considerados satisfatórios para a área de estudo. No entanto, o método convencional de regionalização de vazões apresentou resultados mais consistentes, com erros médios usualmente inferiores a 20%, independentemente da vazão de referência analisada. Observou-se, adicionalmente, que a adoção de séries históricas de vazões com diferentes extensões não produziu diferenças relevantes quando da apropriação das diferentes vazões de referência para a bacia hidrográfica do rio Manhuaçu, com diferenças que não superaram 3%.

BACKGROUND: To report patients with age-related macular degeneration and atypical central retinal pigment epithelium (RPE) defects not attributable to geographic atrophy (GA) or RPE-tears with overlying preserved photoreceptor layers.METHODS: Multimodal imaging case-series evaluating the course of atypical RPE- defects in patients with AMD using Color fundus images, Optical coherence tomography (OCT), OCT-Angiography, fundus autofluorescence (FAF) and fluorescein-angiography (FA).RESULTS: Ten patients were identified. Three patients had a prior RPE-rip and were excluded. Seven patients with a mean follow-up period of 47 ± 38 months after the occurrence of the RPE-defect were included (age range 71-87 years). Mean distance Best corrected visual acuity (BCVA) at initial presentation was 0.36 ± 0.29logMAR and at last follow-up visit 0.51 ± 0.43logMAR. Patients presented with clinically apparent GA on funduscopy and FAF, but preserved photoreceptor layers on optical coherence tomography (OCT). On FA there was early hyperfluorescence and late pooling visible. Over time, migration of RPE/drusenoid material right above the Bruch's membrane with concomitant decrease of hypoautofluorescence was detectable in 4 cases. An enlargement of the RPE-defect was apparent in the remaining 3 cases. The majority (n = 4) showed a drusenoid pigment epithelium detachment (PED) preceding the lesion.CONCLUSIONS: Beside GA and characteristic RPE-tears, another atypical form of RPE-defect with overlying preserved photoreceptor layers are found in AMD. This so far disregarded subgroup of patients present with reasonable visual function and long-term survival of photoreceptors layers. Repair mechanisms such as ingrowth of RPE/drusenoid material and persistent subretinal fluid (SRF), but also a RPE-independent visual cycle for cone photopigment within the neurosensory retina may contribute to their favorable course.

BACKGROUND: To report patients with age-related macular degeneration and atypical central retinal pigment epithelium (RPE) defects not attributable to geographic atrophy (GA) or RPE-tears with overlying preserved photoreceptor layers.METHODS: Multimodal imaging case-series evaluating the course of atypical RPE- defects in patients with AMD using Color fundus images, Optical coherence tomography (OCT), OCT-Angiography, fundus autofluorescence (FAF) and fluorescein-angiography (FA).RESULTS: Ten patients were identified. Three patients had a prior RPE-rip and were excluded. Seven patients with a mean follow-up period of 47 ± 38 months after the occurrence of the RPE-defect were included (age range 71-87 years). Mean distance Best corrected visual acuity (BCVA) at initial presentation was 0.36 ± 0.29logMAR and at last follow-up visit 0.51 ± 0.43logMAR. Patients presented with clinically apparent GA on funduscopy and FAF, but preserved photoreceptor layers on optical coherence tomography (OCT). On FA there was early hyperfluorescence and late pooling visible. Over time, migration of RPE/drusenoid material right above the Bruch's membrane with concomitant decrease of hypoautofluorescence was detectable in 4 cases. An enlargement of the RPE-defect was apparent in the remaining 3 cases. The majority (n = 4) showed a drusenoid pigment epithelium detachment (PED) preceding the lesion.CONCLUSIONS: Beside GA and characteristic RPE-tears, another atypical form of RPE-defect with overlying preserved photoreceptor layers are found in AMD. This so far disregarded subgroup of patients present with reasonable visual function and long-term survival of photoreceptors layers. Repair mechanisms such as ingrowth of RPE/drusenoid material and persistent subretinal fluid (SRF), but also a RPE-independent visual cycle for cone photopigment within the neurosensory retina may contribute to their favorable course.