Large Catchment Area Research Articles

Geomorphology as an indicator of the biophysical vulnerability of estuaries to coastal and flood hazards in a changing climate

Climate change is increasing the need to characterise the vulnerability of coastal landscapes to coastal and flood hazards that result in erosion and inundation. Indices, such as the Coastal Vulnerability Index (CVI), have emerged as useful tools with which coastal managers can prioritise areas for further detailed assessment of vulnerability, risk, resilience and adaptation options. Approaches, such as the use of an index, efficiently characterise the vulnerability of linear, one-dimensional coastal features such as coastlines; however, they do not capture variability in coastal processes affecting more complex, non-linear features, such as estuaries, or interactive effects of coastal processes between linear (e.g. coastlines) and non-linear (e.g. estuaries) landforms. We present an approach that uses geomorphology to indicate biophysical vulnerability of estuaries to coastal and flood hazards. The approach is applied to the South Coast of NSW; a wave-dominated coastline of approximately 400 km length that contains more than 100 estuaries. We demonstrate the simplicity of the approach and its utility in identifying areas requiring higher resolution assessments. Although this approach does not include socio-economic factors, we demonstrate the capacity to incorporate socio-economic components of vulnerability using regional land use mapping. We infer that the most vulnerable estuaries are characterised by large catchment areas, broad estuarine valleys, mature stages of infill, or entrances oriented towards the prevailing wave direction. The area below 15 m elevation was identified as a robust indicator of the total area of vulnerability within a catchment. This approach can be applied to one-dimensional and more complex two-dimensional landscapes, such as estuaries; integrates varying sea-level rise projections; and incorporates a wider range of hazards that operate in the coastal zone.

Factors associated with exit block and impact on the emergency department

We used routinely available data to identify the likelihood of exit block within type 1 EDs across acute trusts in England. While the findings are based on exploratory work and...

Alluvial and fluvial fans on Saturn's moon Titan reveal processes, materials and regional geology

Abstract Fans, landforms that record the storage and transport of sediment from uplands to depositional basins, are found on Saturn's moon Titan, a body of significantly different process rates and material compositions from Earth. Images obtained by the Cassini spacecraft's synthetic aperture radar reveal morphologies, roughness, textural patterns and other properties consistent with fan analogues on Earth also viewed by synthetic aperture radar. The observed fan characteristics on Titan reveal some regions of high relative relief and others with gentle slopes over hundreds of kilometres, exposing topographic variations and influences on fan formation. There is evidence for a range of particle sizes across proximal to distal fan regions, from c. 2 cm or more to fine-grained, which can provide details on sedimentary processes. Some features are best described as alluvial fans, which implies their proximity to high-relief source areas, while others are more likely to be fluvial fans, drawing from larger catchment areas and frequently characterized by more prolonged runoff events. The presence of fans corroborates the vast liquid storage capacity of the atmosphere and the resultant episodic behaviour. Fans join the growing list of landforms on Titan derived from atmospheric and fluvial processes similar to those on Earth, strengthening comparisons between these two planetary bodies.

Impact of length of stay for first psychiatric admissions on the ratio of readmissions in subsequent years in a large Brazilian catchment area.

This study aims to verify the impact that the length of stay has on the rates of readmission for patients who were first admitted to various inpatient psychiatric units in a large catchment area in a middle-income country. The study included all patients who were first admitted to the 108 acute psychiatric beds available in the catchment area of Ribeirão Preto, Brazil, for a period of 8 years. Demographic features, inpatient unit of discharge, diagnosis and length of stay were assessed by bivariate analysis. An analysis of the time span between first admission and readmission was also conducted using survival curves estimated by the Kaplan-Meier formula. For the analyses of the risk of readmissions, a logistic regression analysis was conducted. From a total of 6261 patients admitted in the period of the survey, approximately one-third (2006) had at least one other readmission during the follow-up period. The rates per year of early readmission (within 90 days after discharge) varied from 16.1 to 20.9 %. The risk of readmission was higher immediately after discharge. The survival analysis showed that ultrashort length of stay (1-2 days) was associated with reduced odds of readmission, but multivariate logistic analysis showed no association between length of stay and the odds of readmissions. The predictors of early readmission included the diagnosis of depressive, bipolar, psychotic, and non-alcohol-related disorders, younger ages and unemployment. Duration of the first psychiatric admission was not associated with a higher risk of readmissions. Predictors for early readmissions of first-time-admitted psychiatric patients seem to be more related to the severity of the psychiatric diagnosis and demographic characteristics.

Potencial de aproveitamento de água de chuva na Universidade Federal do Pará - Belém/PA

O objetivo deste artigo é avaliar o potencial de aproveitamento de água de chuva na Universidade Federal do Pará (UFPA), assim como a economia de água potável a partir de seu uso, contribuindo para a gestão e o planejamento sustentável dos recursos hídricos da região. Para isso, foram levantadas as áreas dos prédios do Setor Básico e Profissional da UFPA. Uma série histórica de precipitação com 46 anos de observações para o município de Belém foi utilizada. Foi realizado o monitoramento do consumo de água nos principais banheiros coletivos e estimados nos demais prédios. Os resultados mostram que devido ao alto índice pluviométrico e as grandes áreas de captação, a UFPA possui um potencial real e favorável de aproveitamento de água de chuva como forma alternativa de abastecimento, uma vez que verificou-se que nos meses chuvosos a economia de água potável pelo uso de água de chuva disponível, apresentou porcentagens superiores a 100%, o que demostra uma ótima alternativa para a economia de água fornecida pelo sistema de abastecimento da universidade.

Моделирование пространственного распределения снегозапасов на крупном водосборе с применением спутниковой информации

Моделирование пространственного распределения снегозапасов на крупном водосборе с применением спутниковой информации

Biogenic components and trace elements in the sediments of river mouths and accumulation areas of the Curonian Lagoon (south-eastern Baltic Sea)

The main suppliers of sedimentary matter into the large coastal freshwater lagoon of the southeastern Baltic (Curonian Lagoon) are the Neman River including the sleeves Atmata, Skirvytė and Razliv, as well as Matrosovka and Deima rivers. Large catchment area of the rivers densely populated and characterized by intensive industrial and agricultural activities, which are regarded as potential suppliers of biogenic and chemical elements. Elevated amounts of biogenic components (nitrogen and phosphorus) as well as arsenic recorded in sediments from the river mouth areas suggest serious contribution of anthropogenic activities (use of fertilizers and pesticides in the agricultural activities) on the general sediment quality in the investigated area. Newly obtained data clarify the patterns of biogenic and trace element distribution in sediments located in close vicinity of potential pollution sources.

Specialised commissioning for severe asthma: oxymoron or opportunity?

In the UK, almost 15% of the annual healthcare budget is set aside by the National Health Service (NHS) for specialised services . This significant resource (£14 billion last year)...

Cultural, geographical and clinical challenges of working with eating disorders in South Auckland

The Eating Disorders Service in South Auckland has been running in its current clinical capacity since January 2014. It is a tertiary referral service offering a service to adults and young people across the CMDHB area. There are multiple challenges in offering a service across a culturally diverse; geographically widespread area as well as the recognised difficulties encountered engaging and treating this clinical group. The challenges specific to NZ such as staff recruitment, training, supervision and support for staff and promoting knowledge of the condition amongst clinicians are also present; alongside the specific nature of the presentations seen in generic services. This talk will aim to present the cultural challenge to offer an appropriate and respectful service to Maori, Pacific as well as other groups (eg Chinese, European, Indian). It will discuss the implications of offering a service to a large catchment area with pockets of high deprivation, rural areas and also those of high socio economic standing. Clinically the service works via multiple interfaces. The specifics of our service will be presented along with details of our clinical population, treatments offered and outcomes. The challenge of workforce recruitment, retention and CPD will also be discussed, along with ideas for further development of this exciting service.

Evaluating the hydrological, geothermal and anthropic factors in the Baños tarn (Spanish Pyrenees)

Baños tarn is a low-altitude Pyrenean glacial lake with both geothermal and surface influxes and significant local anthropic stressors. Its water was seasonally sampled from 2010 to 2013 to study its dynamics and evaluate the main factors affecting its hydrochemical trends. Main surface and thermal streams draining into the water mass were also assessed and a detailed characterisation of the study site was made. The large catchment area of the Baños tarn implies a huge water input, a short water retention time and a high water mass mixing that reduces the natural stratification of the lake. The hydrochemical features of the Baños tarn are primarily determined by a slightly alkaline pH and fluctuating medium–high ionic and nutrient contents. Hydrological changes affecting lake tributaries are the foremost factors driving seasonal changes in the ionic composition of the lake. Resuspension of organic matter and nutrients trapped in floor sediments by a century-long history of untreated waste water inputs is supposed to be the main nutrient source to the Baños water mass. Other anthropic activities, such as tourism, dam and withdrawal pipe management, as well as shoreline reforestation, also affect the trophic dynamics of the Baños tarn. These results present herein are scientifically novel because of the uncommon features of the Baños tarn and may broaden our understanding of factors affecting glacial lake dynamics on a global scale.

Mineralogical, Sedimentological and Chemical Relationships of Sediments in Lower Peneplain of the Kelani River

Kelani river is having second largest catchment area and considered as the fourth longest river of the country. The total length of the river is around 145 km with 2292 km2 of river basin area. In general, the river carries lot of sediments with important heavy minerals from upper regions and assumed to be deposited at the lower flat terrain and those sediment will reflect overall fluvial process of the river. Identification of mineral sources, weathering grade and geochemistry of sediments are important for a river and sediment characteristics can provide information about source materials and providing information on weathering and transport process. However, many studies are done on contaminations in river water. Conversely, few studies are attempted to analyze sediments of the Kelani river in order to study fluvial process. This study was carried out along the transported sediments deposited in the lower peneplain of the river and the main aim of this study is to investigate mineralogy, sedimentology and chemical relationships of the sediments in the lower Peneplain of the river. Sieve analysis was done on both sand and flood plain sediments for study particle size distribution of the river. Different fractions of the samples were examined using optical microscope for mineralogy and volumetric percentages were calculated. The mineralogical studies of the river bed sediments reflect quartz, biotite, feldspars, garnet and sapphire rich composition. The most common one is the quartz, however biotite, feldspar and garnet are also present. Mineral biotite and garnet are rich in small particle sizes such as 0.106 mm, 0.053 mm and 0.047 mm. Most of the smaller minerals are sub angular or angular in shape. This may reflect that the fine grained sediments of the river are transported short distance from the origin. Quartz is the most abundant mineral in the river bed and rounded in shape. This concluded that they are transported long distance from the origin. Primary minerals are not dominant in the studied fine grained flood plain sediments which may reflect accumulation of secondary clay minerals. Conversely, river bed sandy sediments are having very limited finer clay fraction. In general, enrichment of weathering resistant minerals such as quartz and biotite, feldspar and garnet in river bed and enrichment of secondary clay minerals in flood plain concluded the strong weathering during transportation. The flood plain sediments are further tested for physico-chemical parameters such as pH, Oxidized Reduction Potential (ORP) and Total Organic Carbon (TOC). Value of pH is in between 6.0 to 7.0, have positive ORP between 15 to 30 mV and TOC is 16-19 %. This may concluded that the flood plain fine grained sediments are having favorable conditions for accumulation of heavy metals added from possible point-sources. Conversely, river bed sediments are predominantly rich with primary mineral quartz which is having very low possibility for accumulation of heavy metals. Keywords: Kelani River, Sediment, Mineral

Spatiotemporal Variation and the Role of Wildlife in Seasonal Water Quality Declines in the Chobe River, Botswana

Sustainable management of dryland river systems is often complicated by extreme variability of precipitation in time and space, especially across large catchment areas. Understanding regional water quality changes in southern African dryland rivers and wetland systems is especially important because of their high subsistence value and provision of ecosystem services essential to both public and animal health. We quantified seasonal variation of Escherichia coli (E. coli) and Total Suspended Solids (TSS) in the Chobe River using spatiotemporal and geostatistical modeling of water quality time series data collected along a transect spanning a mosaic of protected, urban, and developing urban land use. We found significant relationships in the dry season between E. coli concentrations and protected land use (p = 0.0009), floodplain habitat (p = 0.016), and fecal counts from elephant (p = 0.017) and other wildlife (p = 0.001). Dry season fecal loading by both elephant (p = 0.029) and other wildlife (p = 0.006) was also an important predictor of early wet season E. coli concentrations. Locations of high E. coli concentrations likewise showed close spatial agreement with estimates of wildlife biomass derived from aerial survey data. In contrast to the dry season, wet season bacterial water quality patterns were associated only with TSS (p<0.0001), suggesting storm water and sediment runoff significantly influence E. coli loads. Our data suggest that wildlife populations, and elephants in particular, can significantly modify river water quality patterns. Loss of habitat and limitation of wildlife access to perennial rivers and floodplains in water-restricted regions may increase the impact of species on surface water resources. Our findings have important implications to land use planning in southern Africa’s dryland river ecosystems.

Influence of bedrock groundwater on streamflow characteristics in a volcanic catchment

AbstractGroundwater movements in volcanic mountains and their effects on streamflow discharge and representative elementary area (REA) have remained largely unclear. We surveyed the discharge and chemical composition of spring and stream water in two catchments: the Hontani river (NR) catchment (6.6 km2) and the Hosotani river (SR) catchment (4.0 km2) at the southern part of Daisen volcano, Japan. Daisen volcano is a young volcano (17 × 103 years) at an early stage of erosion. Our study indicated that deep groundwater that moved through thick lava and pyroclastic flows and that could not be explained by shallow movements controlled by surface topography contributed dominantly to streamflow at larger catchment areas. At the NR catchment, the deep groundwater contribution clearly increased at a catchment boundary defined by an area of 3.0 km2 and an elevation of 800 m. At the SR catchment, the contribution deep groundwater to the stream also increased suddenly at a boundary threshold of 2.0 and 700 m. Beyond these thresholds, the contributions of deep bedrock groundwater remained constant, indicating that the REA is between 2 and 3 km2 at the observed area. These results indicate that the hydrological conditions of base flow were controlled mainly by the deep bedrock groundwater that moved through thick lava and pyroclastic flows in the undissected volcanic body of the upper part of the catchment. Our study demonstrates that deep and long groundwater movements via a deep bedrock layer including thick deposits of volcanic materials at the two catchments on Daisen volcano strongly determined streamflow discharge instead of the mixing of small‐scale hydrological conditions. Copyright © 2015 John Wiley &amp; Sons, Ltd.

근린단위 방과후 학습 교육기반에 관한 연구

As verifying the right scale of a learning community unit, making after-school facilities as a part of local learning communities in urban areas, and utilizing collective schools in which participants can access to customized programs, this research is to define the concept of local education community(LEC) which provides various programs of life-long learning. A survey of practical cases of the LEC in the district of Gangnam-Gu is to analyze proximity of the current after-school activities between students and schools and then it can address the potential coalition among education communities in terms of remote participation, learning network, and open-to-public school. In typological approach to the LEC, the case study developed the interactive overlap in the layout of 30 local schools that displays the inter-relation of adjacent schools. The graphs of school ranks based on the national evaluation of 'Student Performance Test' can address the preferred schools that has a larger catchment area in the local district. Reorganizing the learning community consisting of participant oriented schools in a regional society will be a critical agenda that can be achieved by both public and private supports. To verify the practical approach of urban types of the LEC, case studies of the research include a conceptual analysis of community clusters in terms of high-performing schools based on national exam ranks, after-school learning programs, and inhabitants pathways to alternative schools. Findings over the cases insinuate not only how to organize the LEC by public transit with hypothetical issues relating to urban renewal but also enhance active participation with social networks.

Modifications to a rainfall-streamflow model to handle &amp;quot;non-stationarity&amp;quot;

Abstract. This paper explores the variation in hydrological response (often termed as non-stationarity, though this is not necessarily the correct use in the statistical meaning of this term) through time for the Bani catchment in Africa (mostly located in Mali). The objective is to identify deficiencies in the ability of the model to capture the variation in the hydrologic response of the catchment, and modify the model to capture this variation. Due to the large catchment area (approximately 103 000 km2), the unit hydrograph component of the model was modified to permit the model to be used at a daily timescale. Further, an additional driver (population growth) needed to be included in order to adequately capture the transition from a perennial to an ephemeral river.

Sedimentary records of past earthquakes in Boraboy Lake during the last ca 600 years (North Anatolian Fault, Turkey)

Abstract Multiproxy sedimentological analyses along 4.9 m-long sequence of Boraboy Lake, which is located on the central eastern part of the North Anatolian Fault (NAF), reveal the sedimentary traces of past large earthquakes in the region. The lake has a relatively large catchment area (10 km2) compared to its size (0.12 km2), which renders sedimentation sensitive to heavy rain/storm events. Accordingly, the background sedimentation, which is composed of faintly laminated reddish/yellowish brown clayey silt, is frequently interrupted by organic-rich intercalations probably due to heavy rain/storm events transporting terrestrial plant remains from the densely vegetated catchment. In addition to frequent organic-rich intercalations, the background sedimentation is interrupted by four mass-wasting deposits (MWD) of which thickness range is between 15 and 50 cm. High-resolution ITRAX μXRF data confirms higher homogeneity along the MWDs (E1–E4) compared to the background sedimentation. Based on 137Cs and 210Pbxs dating and radiocarbon chronology, three MWDs detected in Boraboy sequence (E2, E3 and E4) temporally correlate with large historical earthquakes along the NAF; the 1943 Tosya (Ms = 7.6) and/or 1942 Niksar-Erbaa (Ms = 7.1), the 1776 Amasya-Merzifon and the 1668 North Anatolian (Ms = 7.9) earthquakes. The youngest MWD in the sequence (E1), which is dated to early 2000s, does not correlate with any strong earthquake in the region. This MWD was probably a single mass-wasting event due to routine overloading and oversteepening on the delta front formed by the main inlet of the lake. In subaqueous paleoseismology, coevality of multi-location mass-wasting events is used as a criterion to assign a seismic triggering mechanism, and to rule out mass-wasting events due to routine overloading/oversteepening of subaqueous slopes. Within this context, Boraboy sequence provides a valuable example to discuss sedimentological imprints of single- vs. multi-source MWDs.

A combined geochemical and isotopic study of the fluids discharged from the Montecatini thermal system (NW Tuscany, Italy)

The thermo-mineral fluids discharges of Montecatini Terme (Northern Apennines, Tuscany, Italy) have been exploited since the Roman times and despite the fact that this thermal complex is one of the biggest in Europe, the most recent geochemical investigations were published almost 40years ago. To fill this gap, in this paper a detailed geochemical and isotopic investigation on the main thermal springs and wells from the Montecatini thermal system (MTS) is presented.The chemical and isotopic features of the Montecatini waters suggested that they are mainly controlled by water–rock interaction processes between meteoric water, permeating at depth from the surrounding reliefs (up to 800m a.s.l.), and the Triassic evaporites (Burano Formation) belonging to the Tuscan sedimentary series. The local stratigraphic and tectonic framework favors an efficient recharge of the hydrothermal reservoir by the meteoric precipitation from a large catchment area and this aspect plays a fundamental role for the longevity of the Montecatini thermal spas, notwithstanding the huge amount of thermal water exploited. The 3H values indicated that the thermal waters are likely related to a relatively long (>50years) fluid circulation pattern. Approaching the surface, thermal and saline waters mix with cold and low TDS (Total Dissolved Solids) waters hosted in short, shallow aquifer(s), whose chemistry is dictated by the interaction of rain waters with silico-clastic rocks of low solubility. Geothermometric estimations in the F−–SO42−–HCO3− system suggested the occurrence of a main fluid reservoir at T⩾80–95°C and PCO2 ∼0.5bars. Such CO2 pressure is consistent with values estimated for other thermal springs from central-southern Tuscany, being CO2 basically supplied by a deep source. Nevertheless, δ13C-CO2 and δ13C-TDIC values were lower than those expected for a mantle/thermometamorphic CO2 source. This can be explained by: (i) isotopic fractionation occurring during calcite precipitation and/or (ii) mixing with biogenically derived gases, occurring at relatively shallow depth.

Modeling microfracture geometry to the asses the function of a karst system (Vízfő spring catchment area, Western Mecsek Mountains, Hungary)

One of the current objectives of karst research is to understand the spatial dynamics of karstic processes that increase ordecrease pore volume. Although we can construct 3D numerical models, it is a complex, multi-step process. These modellingapproaches combine a dissolution algorithm, a flow and/or transport model and an algorithm to reconstruct thespatial geometry of fracture networks. The paper focuses on the last task, and does not consider the first two problems. We applied the RepSim code, a DFN (discrete fracture network) type fracture geometry modelling software that usesfractal behavior of fracture patterns, for simulations. This method simulates fracture systems at a reservoir scale. The input parameters (length distribution, aperture, orientation and fractal dimension of the fracture midpoints) weredetermined using field measurements and evaluation of digitized images. The primary images were of outcrops fromthe surface and from two caves. The examined area is the karstic block of the Mecsek Mountains in SW Hungary, which is one of the most exploredkarstic regions in that country. There are seven small and one relatively large (Vizfő) catchment areas in the mountains. The large catchment was used as the study area, which lithologically consists of sandstones and limestones,both intensely fractured by subsequent tectonic events. The spatial distribution of cave entrances and dolinas is unevenacross the study area. This phenomenon has not yet been investigated. Here, a relationship is inferred between the original (prekarstic) microfracture network geometry and the spatial distributionof the aforementioned karst forms. The results show that the region can be divided into two zones that fracturedin distinctly different ways. Their fracture network communication features, porosity and permeability differ.Additionally, sub-regions could develop inside the catchment area where dissolution-cementation processes couldhave been differently effective, determining the spatial distribution of the dissolution governed karstic forms (e.g.caves, dolinas).

Early detection of maternal deaths in Senegal through household-based death notification integrating verbal and social autopsy: a community-level case study

BackgroundReliable detection of maternal deaths is an essential prerequisite for successful diagnosis of barriers to care and formulation of relevant targeted interventions. In a community-level case study, the use of household-level surveillance in Senegal unveiled an apparent increase in maternal deaths, which triggered a rapid-cycle collaborative response to implement a multipronged set of quick-win and sustained interventions intended to improve quality care.MethodsPart of a multi-country effort, the Millennium Villages Project is implementing a routine community-level information system in Senegal, able to detect maternal deaths in real-time and uncover clinical and social factors contributing to mortality. Within this geographically demarcated area of approximately 32 000 inhabitants, with a well-structured health system with patient referral services, deaths were registered and notified by community health workers, followed by timely verbal and social autopsies. Using the Pathway to Survival conceptual framework, case analysis and mortality reviews were conducted for evaluation and quality improvement purposes.ResultsThe estimated maternal mortality rates rose from 67/100000 births in 2009 (1 death), to 202/100000 births in 2010 (3 deaths) and 392/100000 births (5 deaths) in 2011. Although absolute numbers of maternal deaths remained too small for robust statistical analysis, following verbal autopsy analyses in 2011, it became evident that an unexpectedly high proportion of maternal deaths were occurring at the referral hospital, mostly post-Caesarian section. Inadequate case management of post-partum haemorrhage at the referral hospital was the most frequently identified probable cause of death. A joint task team systematically identified several layers of inefficiencies, with a potential negative impact on a larger catchment area than the study community.ConclusionsIn this study, routine community-based surveillance identified inefficiencies at a tertiary level of care. Community-level surveillance systems that include pregnancy, birth and death tracking through household visits by community health workers , combined with verbal and social autopsy can identify barriers within the continuum of maternal care. Use of mHealth data collection tools sensitive enough to detect small changes in community-level mortality trends in real-time, can facilitate rapid-cycle quality improvement interventions, particularly when associated with social accountability structures of mortality reviews.

Structural and hydrological controls on the development of a river cave in marble (Tapagem Cave, SE Brazil)

Tapagem Cave (or Devil’s Cave) is a river cave developed in the dolomite marble karst of the Serra do André Lopes (State of São Paulo, southeastern Brazil). Although this region is a plateau with significant variation in elevation and a humid subtropical climate, the cave is an anomalous feature in the André Lopes karst because there are few other caves. The marble, which is in a synclinal structure with subjacent phyllites, is a karst aquifer perched above the regional base level (Ribeira River) and has little allogenic recharge. The cave developed on a secondary anticline on the northwest flank of the marble synform forming a blind valley, the Tapagem River sink, that is an underground tributary of Ostras River. Development of the cave is due to the entrenchment of the Ostras through-valley and the large allogenic catchment area of the sink. In plan view, the morphology of the cave can be divided into three different sectors. The first sector, known as the Tourist Sector, has extensive collapse rooms, fossil passages and a variety of speleothems of notable dimensions. The second and most extensive sector is the river passage, which is a sinuous gallery controlled by marble banding with NE-SW cleavage and NW-SE fractures. In cross-section, the passages are vadose canyons up to 70 m in height, controlled by the marble banding. Four NW-SE diabase dykes in this passage do not affect its direction in plan view. The third sector is an extensive network of passages and collapse rooms, which are interlaced in plan view and on different levels, forming a maze pattern. Initially, the Tapagem and Ostras Rivers developed on a gentle surface and flowed into the Ribeira River. With the entrenchment of the Ostras through-valley, the Tapagem River partially infiltrated via a paleosink into the upper passage of the “Erectus Room," remaining a half-blind valley. Following a series of collapses and obstructions, the River next infiltrated via the current sink, creating a fully blind valley. Currently, the cave has a difference in elevation of 120 m between the sink and the resurgence, which corresponds to the difference in entrenchment between the two valleys.