dataesr/scientific-paragraphs-categorization huggingface dataset:
2009). Over the last decade, there have been an increasing number of Earth Observation-based hydraulic modeling studies carried out on large African rivers that can be more easily observed from space. These models have been used to investigate inundation dynamics, map flood hazard, and to advance flood modeling methods in data sparse contexts. Generally, the models utilize a global DEM to represent terrain and map floodplain and main river channels and rely on remotely sensed observations of water surface elevation and/or extent for model calibration and validation. Typically, these models also involve estimation of river channel bathymetry, often by treating it as a parameter to be calibrated alongside the friction coefficient. While the representation of bathymetry is crucial to the hydraulic model performance, observed bathymetry data are seldom available, which presents a key challenge of modeling large rivers in this data sparse context.
The river flow data used to drive these models are acquired using a variety of methods, which are covered in the previous hydrological modeling section. The Niger River again is a prime example of an African river whose study has been significantly enhanced by satellite data, having been the subject of no less than four hydrodynamic modeling studies within the last decade. The upper Niger, including the Inner Niger Delta, has been simulated with multiple models all of which make extensive use of satellite-derived water surface elevation and extent data, as described in Sect. 2  (Neal et al. 2012; Fleischmann et al. 2018; Haque et al. 2019; Getirana et al. 2021). Landsat imagery of water extents was used to estimate river channel width and validate modeled flood extents. Neal et al. (2012)  also used water surface elevation observations from the Ice, Cloud, and land Elevation Satellite (ICESat) altimeter to calibrate their model's friction and bathymetry parameters and showed the model was able to predict water surface elevation at altimeter VSs with a RMSE of 1.
84 m). Landsat imagery was also used to obtain channel width estimates. Flood inundation fractions produced globally at 25 km spatial resolution from GIEMS  (Prigent et al. 2007)  were used to evaluate modeled flood extents, the dense rainforest here having prevented routine acquisition of higher resolution flood extents from satellite imagery. Also,  Paris et al. (2022)  presented the MGB hydrologic-hydraulic model for the whole Congo River basin, which was validated with several satellite-derived surface water elevation and extent datasets. Published Earth Observation-based hydraulic modeling studies of rivers other than the principal African rivers described above are scarce but do exist. For example,  Komi et al (2017)  used the Oti River, a tributary of the Volta River in West Africa, as a case study for flood modeling of mid-size rivers in data sparse contexts.
2021 ), which would not be possible without increasing availability of satellite-derived open datasets. These GFMs have been a valuable source of currently missing flood risk information in Africa, nonetheless, these methods are still relatively new and there is some way to go before models consistently predict similar areas of flood hazard  (Trigg et al. 2016; Bernhofen et al. 2018) , as demonstrated in Fig. 10. In many locations, GFMs provide the best available information on flood hazard. However, these models are applied in an automated fashion and are generally not calibrated or validated, and their coarse scale can miss many smaller rivers  (Bernhofen et al. 2021). Despite the current limitations of GFMs, they can be of use to decision-makers, as documented by  Emerton et al. (2020)  in their evaluation of the use of GFMs in the emergency response to cyclones in Mozambique.
This evaluation concluded that realtime hazard and risk information from a GFM provided a successful proof of concept with a positive real-world impact. Specifically, the emergency flood bulletins derived directly from the GFM supported critical actions such as sending an assessment team to the region most likely to be affected. These extreme hydrological events are likely to become more common with climate change, and while Earth Observation cannot predict future climate change, it has been crucial for the development of models for predicting future impacts and will also be essential for monitoring the changing impacts over the coming decades  (Guo et al. 2015). There is no doubt that Earth Observation data have transformed hydrology and hydrodynamic modeling across Africa in the last few decades.
Observational Challenges and Future Opportunities to Monitor African Surface Waters: Way Forward to Water Resources Management African surface hydrology and terrestrial water cycle have undoubtedly benefited from more than 30 years of developments and studies using Earth Observation and models, as demonstrated and discussed in the previous sections. The use of remote sensing data has helped to improve our overall knowledge and understanding of the variability and changes of surface water across the African continent, as well as the processes and mechanisms that drive them at various scales. Remote sensing data now represent a powerful complement to "classical" observations, and the synergy of both means is key to overcome difficulties in a region with sparse in situ networks and where many basins are still ungauged.
In addition, SWOT data will offer new opportunities in the fields of data assimilation into models  (Wongchuig-Correa et al. 2020)  or across interfaces to study land-ocean exchanges  (Stephens et al. 2020). Because SWOT data will be freely accessible, as altimetry has always been, a major advantage of SWOT mission will also reside in the possibility to propose an independent, reliable, and accurate measurement system to scientists and water management authorities over an entire basin. This is of particular importance in Africa given the transboundary character of many of its river basins making Earth Observation a fundamental tool to fulfill the disparity in data availability among countries. Nevertheless, it should also be noticed that the SWOT mission will still face some limitations, especially regarding its use for water resource management or when it comes to the monitoring of surface water bodies such as wetlands, floodplains or inundated area with vegetation.
This could be done thanks to the future capabilities of the next generation of radar altimetry mission aiming at daily revisit, such as the SMall Altimetry Satellite for Hydrology (SMASH) constellation currently under study by the scientific community with the support of CNES. In the future, we should consider to combine the strengths of SWOT swath global measurements with a high temporal sampling of SMASH-like constellation to define a new SWOT-like satellite constellation providing global and daily to sub-daily observations. An ongoing trend, motivated by the amount of satellite records, now covering multiple decades, along with advances in data storage and computation, has resulted in a more integrated use of satellite observations, based on synergy or data fusion techniques. A comprehensive monitoring of surface water could only benefit from integrating and merging various satellite observations with complementary strengths, such as proposed for instance in  Pham-Duc et al.
In the near future, this will probably push back the current spatiotemporal constraints and will deliver new hydrological process insights  (McCabe et al. 2017). Nevertheless, the unprecedented availability of information, with the possible production of petabytes of data will challenge the current storage and analysis capabilities. This will require new analytical approaches and capacities to interpret such massive data volumes. New tools or fusion techniques based on artificial intelligence and increased computing power will be needed. Such new opportunities will require the joint effort of space agencies, the commercial sector and start-up companies. Way forward Monitoring and modeling the components of the hydrological cycle with Earth Observation have now become a reality and this will be reinforced further in the coming years.
Thus, the remote sensing community is now facing real challenges as it needs to promote these new knowledges and datasets in a manner that is more useful for societies and to pave the way for innovation and decision support in Africa. Potential actions to take include to reducing the gap between scientific communities, by promoting interdisciplinary approaches toward more inclusive water systems, by training decision-makers to Earth Observation current progress and advances, by promoting open access datasets, tools and repositories. These actions should also include a better integration and support of African scientists in future programs related to water in order to reduce the disparity of opportunity and access to resources. Investment in science, from national and international communities, is also needed to fill these gaps, as demonstrated for the Congo Basin  (White et al.
Acknowledgements This work is partially funded by the  Centre National d'Etude Spatiale (CNES)  through the  TOSCA  project " DYnamique hydrologique du BAssin du CoNGO (DYBANGO) " (2020)(2021)(2022)(2023). BK is supported by a PhD grant from the  CNES, Agence Française du Développement (AFD)  and  Institut de Recherche pour le Développement (IRD). FP, AP, SC, BK and RT are supported by the  IRD Groupement De Recherche International SCaHyLab. The work on African Lakes by JFC, PGG and BC is supported by the  European Space Agency (ESA)  through project  Lakes of the Climate Change Initiative program. Funding for MT, AC and RT was provided by the  Royal Society-DFID Africa Capacity Building Initiative  (grants  AQ150005 ,  FLR\R1\192057 ,  FCG\R1\201027 ). This work was supported by the  French Centre National d'Etudes Spatiales (CNES)  through the  TELESSAO  project and the  SPLASH (APR TOSCA ).
Acknowledgements This work was financially supported by  ONERA  within the framework of the  PROMETE  project  2017-2021. MB acknowledges support from the  National Science Foundation  ( 1665456 ), the  Air Force Office of Scientific Research  ( FA9550-19-1-0078 ), and the  Army Research Office  ( W911NF2120053 ). The authors are grateful for advice from  Nicolas Riviere ,  Valérie Rialland ,  Thierry Huet ,  Charly Mandal ,  Gérald Lemineur ,  Gilles Roy ,  Grégoire Tremblay , and  William Heinson. The authors thank  Guillaume Huss  and  Paul-Henri Pioger from Leukos  for developing and proving the laser source. ONERA authors acknowledge the General Scientific Directorate (DSG), including  Riad Haidar  and  Laurent Jacquin , for their continued support.
04 ng/kg bw/day. However, as this opinion remains at this stage a draft, the risk assessment performed in this paper will still consider the t-TDI set in 2015. Bisphenol S (BPS) is used in a variety of industrial applications as a substitute for BPA, for example, as a wash fixative in cleaning products, or as a starting monomer for the synthesis of polyether sulfone specifically used in the manufacture of baby bottles and children's tableware. Available data on the presence of BPS in the environment are more limited than for BPA. In Europe, BPS was detected in the wastewater of industrial facilities  [20]  and canned food  [21]. BPS is also used as a developer in thermal paper, including in products marketed as "BPA-free paper"  [22]. A survey of manufacturers selling thermal paper in the EU conducted by ECHA indicates that the use of BPS as an alternative to BPA in the manufacture of thermal paper had not increased markedly for the period 2014-2016  [23].
No risk assessment has yet been published for BPS, but several initiatives are underway. The toxicological profile of BPS has however been studied by  Beausoleil et al. (2022)   [25]. There is a fairly large body of data on the toxicity of BPS, including repeated dose toxicity, reproductive toxicity and also specific effects on the endocrine system. Human biomonitoring (HBM) is a tool of growing importance for estimating internal aggregated exposure to chemicals and can therefore be used to improve human health risk assessment. The European Joint Programme on Human Biomonitoring (HBM4EU) is a joint effort of 30 countries and the European Environment Agency (co-funded by the European Commission within the framework of Horizon 2020) with the aim of advancing and harmonising human biomonitoring in Europe  [26].
One of the limitations for the use of HBM data in risk assessments (RA) is the lack of HBM guidance values (HBM-GV)  [27]  which represent the concentration of a biomarker of exposure in a human biological matrix at and below which no adverse effect for human health is expected according to current toxicological knowledge. Those values are useful to risk assessors and risk managers for comparing to the HBM data measured in biomonitoring studies. This paper aims to characterise the risks associated with BPS and BPA according to available HBM data in Europe. For this purpose, the derivation of HBM-GVs for exposure to BPS for both the general population (HBM-GVGenPop) and for workers (HBM-GVWorker) has also been performed, as has been done previously for BPA  [28].
For the General Population RCRs were calculated by comparing total BPA levels in urine from the HBM studies to the corresponding HBM-GVs derived for BPA (Table  2 ). The t-TDI based HBM-GVGenPop for total BPA in urine for adults was used for calculating RCRs for teenagers. For studies reporting results for children and teenagers in combination, the HBM-GV for children was used with a conservative approach. In all cases the calculated RCRs are significantly lower than 1, both for adults and for children, and for each set of data available, meaning that exposure levels reported are far lower than the HBM-GVGenPop. These results indicate that exposure to BPA for the populations sampled, according to current knowledge in a single substance-risk assessment approach, does not constitute a risk when taking into account the HBM-GVGenPop derived from the t-TDI established by EFSA in 2015.
Selection of the Methodological Approach for the Derivation of HBM-GVs for BPS The human data analysed by  Beausoleil et al. (2022)  were considered insufficient for establishing a relationship between internal concentrations and relevant health effects  [25]. In addition, neither toxicity reference values nor occupational exposure limits have been proposed by the EU or by any relevant non-EU organisations so far. Regarding workers, the scarcity of data on occupational exposure does not allow for assessment of the relationship between atmospheric concentrations of BPS and total urinary concentrations of BPS. Thus, the derivation method for HBM-GVs for BPS for both the general population and the workers was based on a point of departure (POD) identified from animal experimental studies, as tentatively proposed by  Beausoleil et al.
Selection of Key Studies and Choice of POD The first two options that, according to methodology developed within the HBM4EU programme and published by  Apel et al. (2020) , should be used to derive the HBM-GV when the data available allows it, could not be followed for BPS. Therefore, the third option is to derive an HBM-GV based on critical effects observed in animal studies. The choice of POD is based on the recommendation formulated by  Beausoleil et al. (2022)  who reviewed regulatory toxicology studies conducted in accordance with OECD Test Guidelines, as well as numerous academic studies investigating more specific parameters dedicated to endocrine disrupting effects  [25]. Adverse effects due to BPS exposure were reported in academic studies assessing male and female reproduction, mammary glands, neurobehavior and metabolism/obesity.
Assessment of Exposure to BPS The data from studies reporting total BPS levels in urine were used to calculate the RCRs with the corresponding HBM-GVs detailed above. For the risk assessment for the general population exposed to BPS, data from seven studies from six different European countries were compiled. RCRs were calculated for each available dataset, with the exception of studies for which P95 values were not reported. Some studies also reported results corrected by urine specific gravity. As with BPA, the results of those studies were used as is and even though they are close to the HBM-GVs this contributes to the uncertainty of the meaning of the corresponding RCRs calculated. In addition, unlike BPA, a specific HBM-GVGenPop value for children was not developed for BPS and a general value calculated based on adult weight was used.
Discussion The expanding database on BPS provides convincing evidence of adverse effects on neurodevelopment or mammary glands following exposure during early life. The sensitivity to BPS is clearly dependent on the timing of exposure with specific periods of development being critical. Disruption of estrogenic signalling is likely central in the mediation of these effects although other modes of action may be involved  [70] [71] [72]. The derived HBM-GVGenPop is applicable to the whole general population and thereby is protective for all. Nevertheless, we are also aware of the current assessment of BPS at the EU level, which may be finalised during the coming months. Depending on the conclusion of this assessment, the derivation of the HBM-GVs for BPS could be updated accordingly. Consideration of the type and time of sampling is crucial, because the proposed HBM-GVs should allow for direct comparison with urinary data on bisphenols collected from the general population or occupational biomonitoring studies.
The diversity of the subpopulations considered, the geographical sampling areas and the sampling years also contribute to the difficulty of comparing the reported data. We find a clear difference between risk assessments for BPA and BPS exposure according to our current HBM-GVs. Indeed, according to current knowledge, while risk could be ruled out for BPA with very low RCRs for the general population, this is not the case for BPS where RCRs are high for a large portion of the sampled population, and it appears that protective measures need to be taken regarding BPS exposure in the general and occupational population. This is because the HBM-GVs for BPS were established on the basis of endocrine disruption effects in animals at very low doses, in contrast to the HBM-GVGenPop for BPA. As mentioned in the introduction, the EFSA CEP Panel recently released a draft opinion for consultation regarding the re-evaluation of the t-TDI for BPA set in 2015 in light of the latest available data  [19].
Several initiatives are underway and, depending on their findings, the risk assessment proposed here may change. With respect to occupational populations, more studies need to be conducted to assess the risk of exposure to bisphenols for the European population for various occupational activities. This is true for BPA for which data are still limited. This is even more important for BPS and other BPA analogues in a context of BPA replacement in some products following the restriction of BPA in thermal papers, but also the evolution of societal concerns. Furthermore, there is a lack of knowledge at the international level regarding the actual exposure to BPA according to occupational activities, which triggers the need to perform biomonitoring studies for each activity. Calculating the difference in total BPA in urine from pre-and post-work samples may help to assess exposure resulting from workplace BPA ingestion at the individual level.
The EFSA Panel has recently reviewed new evidence of BPA toxicity, and if the effects of BPA at very low doses as suggested is confirmed in the near future, then most of the European population would be at risk. It is therefore necessary to continue to produce harmonised and accessible biomonitoring data both for the general population and according to different occupational activities. This is particularly relevant as regulatory action has been taken to reduce BPA, but an increase has been observed in the use and applications of BPS and other analogues. All of this highlights the importance of developing and harmonising the use of biomonitoring to inform public policy, as is done in European research projects such as the HBM4EU. The new European Partnership for the assessment of risks from chemicals (PARC) is also moving in this direction and is even more broadly involved in the development of all aspects of chemical risk assessment.
g. sampling density, noise, misalignment, holes). We used synthetic data to quantitatively evaluate the robustness of the selected approaches with respect to each criterion. In addition we evaluated the results of these approaches on five tree and crop datasets acquired with laser scanners or photogrammetry. This study allows us to highlight the benefits and drawbacks of each method and evaluate its appropriateness in a given scenario. Our main conclusion is that fitting a Bézier surface is the most robust and accurate approach to estimate plant leaf area in most cases.
The third approach constructs an implicit representation of the leaf from the point cloud  [22]. As in the previous case, the leaf area is estimated by meshing the resulting implicit surface. To the best of our knowledge, there is no consensus on whether one approach is better than the other. In this paper, we propose a thorough comparative study of eight methods selected from the three approaches described above. Rather than focusing on very specific methods, which would be hardly available, understandable and usable by plant biologists, we have chosen to select standard methods which are freely available in open-source software or libraries, except two of them for which we release a code. We also release our code to generate the synthetic datasets we used to evaluate the selected methods.
Related work Existing pieces of work have tackled similar problems, but only partially. Loch et al. compared two meshing approaches generating respectively (flat) Euclidean triangles and a smooth surface made of piecewise cubic (non-flat) Clough-Tocher triangles  [16]. More recently,  [18]  and  [20]  compared three parametric leaf surface models. In these studies, surface models were evaluated with respect to the maximum or root mean square distance between the computed parametric surface and the input point cloud, but no evaluation was given with respect to the leaf area. The most related work to our study is that of  [23]. As in  [16] , the authors compared a piecewise linear mesh model with a parametric surface, this time for leaf area estimation. The mesh was computed as a 2D triangulation of the data points projected onto the best fitting plane of the point cloud, and then lifted back to their original locations.
The parametric model chosen was a B-spline surface, which was trimmed according to the boundary of an alpha-shape  [24]. Both models were evaluated on point clouds acquired with a LiDAR from a flat gauge block. Only one parameter was tested: the thinness of the point cloud, which could be related to the noise level. Though Dupuis et al. only compared these models on simple, flat surfaces, they showed that the B-spline approach measures leaf areas with much greater accuracy than the direct triangulation approach. In our study, we have included the same meshing method, but a more advanced B-spline technique  [25]  is tested. It is also worth mentioning that a comparative analysis across five geometric models has also been proposed for tree branches  [26]. These models were evaluated on synthetic data with varying shape, length, noise level, sampling resolution and occlusion level.