Thin, overlapping section, contrast-enhanced, axial and coronal CT, with additional high-resolution (HR) treatment of the sections through the internal auditory canal, was performed on 31 patients clinically suspected of acoustic neuroma. With this technique 13 acoustic neuromas protruding more than 10 mm and eight acoustic neuromas protruding between 2 and 10 mm outside the internal auditory canal were unequivocally diagnosed. O2CT cisternography was performed on ten patients. An intracanalicular neuroma was diagnosed in three cases with this technique, also a small extracanalicular neuroma in one case, and an acoustic neuroma was definitely excluded in six cases. It is concluded that O2CT cisternograhy is the diagnostic procedure of choice for the detection of purely intracanalicular neuromas and the definite exclusion of acoustic neuroma. HR CT proved superior to polytomography for the evaluation of the internal auditory canal and should be performed in every case suspected of acoustic neuroma. A protocol for the radiological investigation of patients suspected of acoustic neuroma is given.

In semiarid regions, dams are useful for surface water storage, sediment sequestration, and aquifer recharge. Built in 1987 on the Cap Bon peninsula (in northeastern Tunisia), the Lebna Dam is considered a good example of a multifunctional reservoir. The dam feeds two important irrigation networks, stores large sediment quantities, and allows a significant recharge flow to the underlying aquifer. This work suggests new leakage flow and dam-aquifer interaction characterizations through the development of an approach that combines a water balance calculation, geological field observations, groundwater monitoring, and geophysical research.The hydrological balance calculation performed over the monitoring period ,shows that an estimated water volume of 3.7 Mm 3 y -1 has leaked from the Lebna reservoir to the coastal aquifer. Geological mapping of the Lebna Dam basin in summer 2019 revealed the existence of permeable layers of sands to sandstones exposed along the southern banks of the reservoir and extending to an elevation that included the water level when the dam is full; these rocks outcrop at approximately 16 m.a.s.l.A geophysical survey based on 67 vertical electrical soundings and 8 electrical resistivity tomography profiles in the area downstream of the reservoir was carried out to identify the lateral continuity of the recharge zones. Piezometric campaigns consisting of four field surveys in 2019 and 2020 were conducted in the region downstream of Lebna Dam, consisting of 71 water well samples.The collected evidence led to the conclusion that concentrated recharge occurs in the downstream bank of the dam.

<p>Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. In this study, we investigated how synoptic atmospheric patterns (i.e. weather types, Wts), and their distribution throughout the year, affect the intra-catchment rainfall variability and the temporal variability of runoff and sediment yield (SY). The analyse was based on a long-term database of rainfall, runoff and sediment yield acquired in a tunisian rural catchment (Kamech, OMERE observatory). The results first confirmed that most of runoff and SY occurred during a small number of rainfall events. They also indicated that just a few WTs accounted for large percentages of the total runoff amounts and SY, but with a large difference between the atmospheric circulation patterns relating to each of them as most of SY occurred during south (S) and south-east (SE) atmospheric circulation patterns, whereas most of runoff and rainfall occurred during the predominant north (N) and north-west (NW) atmospheric circulation patterns. Such a result suggest that synoptic WT may improve understanding of the general conditions under which runoff and SY occur. The approach used here could be useful to aid of the design of water management and soil conservation measures tailored for the local conditions of the Cap Bon region, where many reservoirs constructed for surface water mobilisation are highly affected by siltation issues. The relationships between synoptic atmospheric circulations and the runoff and erosive response can also help to anticipate adaptations measures to climate change. Future works are required to explore if the rainfall properties (e.g. raindrop size and energy) can explain the differences in the erosive response observed in the studied catchment between the S and SE flows and the N and NW flows.</p>

In semiarid regions, dams are useful for surface water storage, sediment sequestration, and aquifer recharge. Built in 1987 on the Cap Bon peninsula (in northeastern Tunisia), the Lebna Dam is considered a good example of a multifunctional reservoir. The dam feeds two important irrigation networks, stores large sediment quantities, and allows a significant recharge flow to the underlying aquifer. This work suggests new leakage flow and dam-aquifer interaction characterizations through the development of an approach that combines a water balance calculation, geological field observations, groundwater monitoring, and geophysical research. The hydrological balance calculation performed over the 27-year monitoring period, from 1990 to 2017, shows that an estimated water volume of 3.7 Mm3y-1 has leaked from the Lebna reservoir to the coastal aquifer. Geological mapping of the Lebna Dam basin in summer 2019 revealed the existence of permeable layers of sands to sandstones exposed along the southern banks of the reservoir and extending to an elevation that included the water level when the dam is full; these rocks outcrop at approximately 16 m.a.s.l. A geophysical survey based on 67 vertical electrical soundings and 8 electrical resistivity tomography profiles in the area downstream of the reservoir was carried out to identify the lateral continuity of the recharge zones. Piezometric campaigns consisting of four field surveys in 2019 and 2020 were conducted in the region downstream of Lebna Dam, consisting of 71 water well samples. An interpretation of these geophysical data coupled with available borehole logging and piezometric measurements was used to define the leakage geometry from the reservoir dam to the coastal aquifer. The collected evidence led to the conclusion that concentrated recharge occurs in the downstream sections, especially on the right bank of the aquifer.