Large Drainage System Research Articles

Partial-composite behavior of sandwich beams composed of fiberglass facesheets and woven fabric core

In this study, thin-walled sandwich composites made of glass fiber-reinforced polymer (GFRP) facesheets and a three-dimensional (3D) woven fabric core were studied. A total of 30 small-scale sandwich beam specimens were manufactured across six unique beam varieties with dimensions of 50 mm in width, and 200 or 350 mm in length to be tested under four-point bending up to failure. The load-deflection behavior, load-strain behavior, moment-curvature behavior, and neutral axis location were analyzed. Based on the test results, the flexural stiffness, shear stiffness, core shear modulus of the sandwich beams were calculated. Also, an analytical model is presented to consider the effect of core shear modulus on deformation and composite action of the test specimens. The model is capable to quantify the degree of composite action based on the geometry and material properties of sandwich beams. Overall, the sandwich beams displayed a partial-composite behavior raging from 15% to 91% of full-composite behavior, which was a function of the relative stiffness of the facesheets and the core plus the length of the shear span. It was shown that compatibility between the mechanical properties of the facesheet and core is a key factor in optimizing sandwich panels made of the core. The results will be used for the design of thin-walled sandwich liners for the rehabilitation of underground infrastructure including existing highway culverts and large diameter drainage systems.

A harmony-based calibration tool for urban drainage systems

The US Environmental Protection Agency's storm water management model SWMM 5·1 is widely used to simulate urban drainage processes both for qualitative and quantitative analysis. In the present work, SWMM 5·1 was applied to the Fossolo urban sub-catchment in Bologna, Italy, and the geographic information system ArcGIS was adopted to reproduce the spatial distribution of rainfall. An innovative and original optimisation procedure was developed, coupling the jazz-music-based harmony search evolutionary algorithm with SWMM 5·1 for the estimation of runoff parameters. Seven historical storm events were taken into account for model calibration and validation. A careful sensitivity analysis highlighted the effectiveness of the calibrated parameters for simulations. The results obtained showed the proposed approach to be a useful tool for the calibration of hydrological parameters in large urban drainage systems, defining a satisfactory correlation between modelled and measured data.

Sediment provenance in contractional orogens: The detrital zircon record from modern rivers in the Andean fold-thrust belt and foreland basin of western Argentina

This study analyzes detrital zircon U–Pb age populations from Andean rivers to assess whether active synorogenic sedimentation accurately records proportional contributions from varied bedrock source units across different drainage areas. Samples of modern river sand were collected from west-central Argentina (28–33°S), where the Andes are characterized by active uplift and deposition in diverse contractional provinces, including (1) hinterland, (2) wedge-top, (3) proximal foreland, and (4) distal broken foreland basin settings. Potential controls on sediment provenance were evaluated by comparing river U–Pb age distributions with predicted age spectra generated by a sediment mixing model weighted by relative catchment exposure (outcrop) areas for different source units. Several statistical measures (similarity, likeness, and cross-correlation) are employed to compare how well the area-weighted model predicts modern river age populations. (1) Hinterland basin provenance is influenced by local relief generated along thrust-bounded ranges and high zircon fertility of exposed crystalline basement. (2) Wedge-top (piggyback) basin provenance is controlled by variable lithologic durability among thrust-belt bedrock sources and recycled basin sediments. (3) Proximal foreland (foredeep) basin provenance of rivers and fluvial megafans accurately reflect regional bedrock distributions, with limited effects of zircon fertility and lithologic durability in large (>20,000 km2) second-order drainage systems. (4) In distal broken segments of the foreland basin, regional provenance signatures from thrust-belt and hinterland areas are diluted by local contributions from foreland basement-cored uplifts.

First record of epizootic ulcerative syndrome from the Upper Congo catchment: An outbreak in the Bangweulu swamps, Zambia.

We report on the first outbreak of epizootic ulcerative syndrome (EUS) amongst wild fish populations in the Bangweulu swamps, an inland delta, in the north of Zambia during 2014. The area supports a large and diverse fish fauna related to, but distinct from, that of the Zambezi River system where EUS outbreaks have occurred since 2006. A sizeable artisanal fishery, based on extensive fish weirs, is sustained by the annual flooding of the swamps, and observations of the disease outbreak by fishermen were recorded. Signs typical of infection with Aphanomyces invadans were observed in a number of species. Clinical observations, histology and molecular diagnostic methods were used to confirm infection with A.invadans in two of the most commonly and severely affected species. Several features of the wetland may have contributed to the outbreak and the annual recurrence of the disease. Modes by which the disease may have been introduced into the swamps are discussed. The outbreak is of great significance as the Bangweulu swamps drain into the Congo River in neighbouring Democratic Republic of Congo, Africa's largest drainage system with an extensive and diverse fish fauna previously unaffected by EUS.

The environmental impact assessment of drainage systems: a case study of the Karun river sugarcane development project

ABSTRACTSaline water can be drained from the plant root zone by developing a drainage network; therefore, the lack of control strategies for soil salinity and the subsurface water level will result in high salinity and nutrient concentrations. In large drainage systems, this issue becomes more important due to the large amount of water drained into the environment. Therefore, an environmental impact assessment (EIA) should be conducted before undertaking such developments. Due to the importance of wetlands that may be affected by the sugar cane fields located in Khuzestan Province in Southern Iran, the EIA process was implemented to evaluate this project. Three scenarios of a pre-drainage system development, drainage system development without management issues, and drainage system development with management issues are considered to help reduce the amount of water drained and protect the wetland. The scaling weighting checklist method was used to categorize the data and to ensure that no potential influence was overestimated. The results show the necessity of the application of management practices and drainage system development to protect the Shadegan International Wetland. Development of the project in its current condition is not recommended. Applying wastewater management, including cultivating salinity-resistant plants, is recommended as the most effective method.

Phylogeography and Vicariant Separation of Two River Darters, Percina uranidea and Percina vigil, from rivers that drain the North American Interior Highlands

The phylogeography and separation of two river darters, Percina uranidea and P. vigil were investigated through sequencing of the mitochondrial Cytochrome B and Cytochrome Oxidase genes. These molecular markers revealed the darters exhibit moderate genetic divergence between two large river drainage systems within the Mississippi River basin associated with the Interior Highlands of midwestern North America. An additional haplotype network analysis also supported these trends. Phylogenetic divergence dating indicated that population separation between the river systems occurred after recent Pleistocene glacial events rather than an early Pleistocene separation.

Strong spatial turnover in cichlid fish assemblages in the upper río Madera (Amazon basin) despite the absence of hydrological barriers

In freshwater ecosystems, spatial turnover in fish assemblages is often attributed to dispersal limitation imposed by fragmentation of water bodies. Other factors like environmental properties or biotic interactions have often been assumed to be minute relative to dispersal limitation when hydrogeological barriers are abundant. This study aims to describe the spatial differentiation of cichlid fish assemblages in the upper rio Madera in Bolivia, Brazil and Peru, a large drainage system characterized by the absence of significant hydrogeological barriers. We assessed the relative importance of spatial, climatic and geological predictors in the observed biogeographic structure using an integrative combination of cluster analyses, elements of metacommunity structure analysis, variation partitioning, and network analysis. Our results show that distinct assemblages of cichlid fish species replace each other across the landscape and that this turnover is partially determined by climate and geological gradients. A considerable fraction of the cichlid assembly structure could not be assigned to either space, climate or geology and might be explained by unmeasured parameters such as habitat structure or biotic interactions. Incorporating knowledge on spatial turnover of species assemblages into conservation strategies will be essential for the biodiversity management of the diverse aquatic fauna of the upper rio Madera.

Plio–Pleistocene palaeogeography of the Llanura Costera del Caribe in eastern Hispaniola (Dominican Republic): Interplay of geomorphic evolution and sedimentation

This paper aims to reconstruct the palaeogeographic evolution of the Llanura Costera del Caribe (LCC) in eastern Hispaniola (Dominican Republic) during the Pleistocene, adding new insights to published information on Pliocene–Early Pleistocene deposits. The LCC is a generally flat region comprising the unfolded sedimentary cover of the Cordilleras Central and Oriental. Within this cover, the Pliocene–Early Pleistocene Yanigua Formation,mainly consisting of marl, changes seawards to the mainly limestone Los Haitises Formation. Both units formed in a shallow-water platform rimmed by a reef barrier at least in the latest depositional stages. The overlying Pleistocene La Isabela Formation consists of two major offlapping reef terraces, in which a reef core enclosed a lagoon, and prograded over forereef bioclastic debris. Two belts in LCC's morphostructure directly reflect its sedimentary evolution. The Inner Belt extends over the marly substrate of the Yanigua Formation and the Coastal Belt comprises three major surfaces corresponding to the depositional top of the Los Haitises Formation (Upper Surface), and to the Upper and Lower terraces of the La Isabela Formation (Intermediate and Lower Surfaces, respectively). The MIS 5e age of the 10–20 m high Lower Terrace implies a low uplift rate of 0.033–0.068 mm/yr for the Lower Surface. The Pliocene–Early Pleistocene platform was emergent in the Early–Middle Pleistocene. The Early Pleistocene reef barrier separated endorheic watersheds extending over the former shelf lagoon from the open ocean. Reefs built the Upper Terrace of the La Isabela Formation during one or several Middle Pleistocene highstands and the Lower Terrace during MIS 5e and previous highstands. Siliciclastic deposits in this terrace record the opening to the Caribbean Sea of watersheds in the eastern LCC. The Lower Terrace emersion and opening of the large drainage systems of the western and central LCC took place after MIS 5e. Relative sea level fall and emersion of a large area did not imply increased terrigenous sedimentation in the adjacent marine basin. Development of endorheic watersheds over most of the emergent surface delayed the diachronic arrival of siliciclastics into the marine basin for hundreds of thousands of years.

Seismic Stratigraphy of Pleistocene Deltaic Deposits in Bahía Blanca Estuary, Argentina

The Bahía Blanca estuary (Argentina) has a morphological configuration resulting from hydrological and sedimentary processes related to Late Quaternary sea level changes. This estuarine system occupies a large coastal plain with a dense net of tidal channels, low-altitude islands and large intertidal flats. Little is known about the sedimentary units of the marine subbottom. Therefore, a stratigraphical analysis of the northern coast of Bahía Blanca estuary was carried out using high resolution seismic (3.5 kHz) in order to: i) define Quaternary sequences, ii) describe sedimentary structures, and iii) determine the paleoenvironmental conditions of sedimentation. The seismic stratigraphic data collected and their correlation with drilling lithological data show five seismic sequences (S1, S2, S3, S4 and S5), of which S1-S2 were found to be associated with a continental paleoenvironment of Miocene-Pleistocene age. Sequences S3 and S4, whose lithology and seismic facies (paleochannel structures and prograding reflection configurations), were defined on these materials, to evidence the development of an ancient deltaic environment which was part of a large Pleistocene drainage system. The S5 sequence was formed during the Holocene transgressive-regressive process and complete the seismostratigraphic column defined in the present study.

Controls on Sr isotopic evolution in lacustrine systems: Eocene green river formation, Wyoming

Strontium isotopes from lacustrine carbonates record detailed weathering histories of exposed bedrocks, and thus are potentially useful for understanding interactions between tectonics and climate that may be driven by local or regional factors in basin-scale hydrologic systems. We combine extensive 87Sr/86Sr and δ18O datasets from the Green River Formation in order to identify environmental factors driving the evolution of Sr concentration and isotopic composition in lacustrine systems through the use of Sr mass balance modeling. Two models are developed. The first tests the effect of drainage capture that drove a constant-volume lake from balance-filled to overfilled conditions, and is applied to the Laney Member of the Green River Formation. The second model focuses on lacustrine evolution in response to changing the concentration, composition, and mass of water influx in a variable-size Sr reservoir (lake). This model is applied to the Wilkins Peak Member of the Green River Formation.87Sr/86Sr ratios are correlated with δ18O values only during the Laney Member, when both are readily explained by a common forcing mechanism (drainage capture). Modeling of Sr isotope compositions and concentrations indicates a short residence time for Sr (~103–104years or less) in both balance-overfilled and underfilled phases of the Green River Formation lacustrine system. This in turn suggests that paleo-lacustrine sediments in most lakes can preserve Sr isotope records with high-resolution (~102years) timescales. Rates of Sr sequestration in carbonate are shown to have a strong influence on lacustrine Sr concentration, and high Sr concentrations of lacustrine carbonate consistent with high salinity are observed in the underfilled Wilkins Peak Member and the balance-filled Tipton and lower Laney Members. In the Laney Member, 87Sr/86Sr mass-balance modeling results provide additional support for previous interpretations that the introduction of a large drainage system produced an isotopic shift across the lower LaClede/upper LaClede boundary. Major drainage reorganization is not required to drive high variability in 87Sr/86Sr ratios, however. Modeling shows that variability in 87Sr/86Sr ratios of ~0.004 observed in the Wilkins Peak Member can be explained by change in the characteristics of intrabasinal water sources during highstand vs. lowstand conditions.

Analysis of the flash flood occurred on 18 January 2010 in wadi El Arish, Egypt (a case study)

Wadi El Arish is the largest drainage system in Sinai Peninsula, Egypt. The wadi was subjected to severe thunderstorms on 17 and 18 January 2010 followed by extreme violent flood that had not been known in Sinai since 1980. The flood claimed six victims, injured tens and devastated vital infrastructure and hundreds of houses. Hydrologic characteristics of the wadi are not fully understood due to the great lack of the detailed hydro-meteorological information. Hence, remote sensing and geographic information system (GIS) techniques were widely used to provide better spatial understanding of storm rain characteristics and drainage basin response. The study was based on the analysis of the TRMM images and the averaged six hourly HYDIS data for storm rain analysis. Hydrological model was constructed using ASTER digital elevation models (DEMs). The empirical black model box was used depending on the curve number approach to predict stream runoff. Landcover and hydrological soil groups were identified from the Landsat ETM+ mosaic using multispectral supervised classification. The curve numbers were adjusted to ARC I (dry condition) as the total rain in five-day period preceding the storm was very low (≤5 mm). The study deduced that the wadi received a total rain volume of 665.4 × 106 m3. Most of the rain fell on 17 January with an intensity ranged between 4–8 mm/hr. The estimated total surface runoff Q was 123.3 × 103 mm and the total runoff volume was 124 × 106 m3 that constitutes 18.8% of the total rain volume. The results are in agreement with the observed values in the wadi, and highly required for many applications related to water harvesting and flood protection studies.

The Iváň Canyon, a large Miocene canyon in the Alpine-Carpathian Foredeep

During the latest Early Miocene a large drainage system developed in the Alpine-Carpathian Foreland transporting sediments through a prominent submarine canyon along the narrow corridor between the south-eastern Bohemian Massif and the Waschberg-Ždánice Unit. The canyon followed the Alpine-Carpathian Foredeep from Lower Austria towards the north and northeast into the Czech Republic. 3-D seismic data allow the mapping of this 600 m deep structure over a distance of 25 km and a width of 5 km. Despite its dimension, making it the largest submarine erosive and sedimentary structure of the Neogene Alpine-Carpathian Foredeep, this canyon has not been previously recognised. Herein, it is interpreted as shelf-indenting canyon that formed due to a combination of isostatic rebound along a terminating thrust front and sea-level change during the terminal Early Miocene.The canyon fill comprises reworked littoral deposits with a typical Early Miocene, tropical micro- and macrofauna. The exact timing of this refilling remains unclear. Smaller channel structures in surface outcrops, representing potential tributaries of the canyon, suggest a more or less synsedimentary filling soon after indention. Finally, the top part of the canyon was eroded around the Early/Middle Miocene boundary, probably related to a global 3rd order sea level drop, and caped by marine marls during the subsequent early Middle Miocene transgression. With the sudden onset of the subsidence of the Northern Vienna Basin during that time, the drainage system abruptly moved southward shedding its sediments into the newly opening Vienna Basin. This explains the rather abrupt abandonment of the huge canyon feature, whose fan deposits are unknown so far.

Contrasting habitat associations of imperilled endemic stream fishes from a global biodiversity hot spot

BackgroundKnowledge of the factors that drive species distributions provides a fundamental baseline for several areas of research including biogeography, phylogeography and biodiversity conservation. Data from 148 minimally disturbed sites across a large drainage system in the Cape Floristic Region of South Africa were used to test the hypothesis that stream fishes have similar responses to environmental determinants of species distribution. Two complementary statistical approaches, boosted regression trees and hierarchical partitioning, were used to model the responses of four fish species to 11 environmental predictors, and to quantify the independent explanatory power of each predictor.ResultsElevation, slope, stream size, depth and water temperature were identified by both approaches as the most important causal factors for the spatial distribution of the fishes. However, the species showed marked differences in their responses to these environmental variables. Elevation and slope were of primary importance for the laterally compressed Sandelia spp. which had an upstream boundary below 430 m above sea level. The fusiform shaped Pseudobarbus ‘Breede’ was strongly influenced by stream width and water temperature. The small anguilliform shaped Galaxias ‘nebula’ was more sensitive to stream size and depth, and also penetrated into reaches at higher elevation than Sandelia spp. and Pseudobarbus ‘Breede’.ConclusionsThe hypothesis that stream fishes have a common response to environmental descriptors is rejected. The contrasting habitat associations of stream fishes considered in this study could be a reflection of their morphological divergence which may allow them to exploit specific habitats that differ in their environmental stressors. Findings of this study encourage wider application of complementary methods in ecological studies, as they provide more confidence and deeper insights into the variables that should be managed to achieve desired conservation outcomes.

Palaeoenvironmental control on modern forest composition of southwestern Marajó Island, Eastern Amazonia

AbstractThis study focuses on a forested area from southwestern Marajó Island, mouth of Amazon River, aiming to analyse the relationship between plant composition and the latest Quaternary evolution of a land‐form with palaeochannel morphologies. A floristic survey aiming to characterize the inner and outer palaeochannel areas indicated similar phytossociological parameters. However, a large volume of species was exclusive to only one of these areas. Although the present‐day forest is fairly uniform, a significant variation in floristic composition was recorded according to differences in lithology, topography and hydrology. These were determined by the evolution of the physical environment associated with successive stages of abandonment of a large fluvial drainage system during the latest Pleistocene to Holocene. The results derived from this study indicate that reconstruction of a physical environment is an important parameter to be taken into account before establishing models aiming to explain the distribution of modern plant species in tropical areas.

Case Study: Influence of Morphological Changes on Flooding in Jingjiang River

The middle reach of the Yangtze River, customarily called the Jingjiang River, together with its diversion channels and Dongting Lake, form a large complicated drainage system. In the last five decades, significant geomorphological changes have occurred in the drainage system, including the shrinkage of diversion channels, contraction of Dongting Lake, changes in the rating curve at the Luoshan station, and cutoffs of the lower Jingjiang River. These changes are believed to be the cause of the occurrence of abnormal floods in the Jingjiang River. Qualitative analyses suggest that the first three factors aggravate the flood situation in the lower Jingjiang River, while the last factor seems beneficial for flood prevention. To quantitatively evaluate these conclusions, a finite-volume numerical model was constructed. A series of numerical simulations were carried out to test the individual and combined effects of the aforementioned four factors, and these simulations showed that high flood stages in the Jingjiang River clearly are related to the geomorphological changes.

Applications of network analysis for adaptive management of artificial drainage systems in landscapes vulnerable to sea level rise

The vulnerability of coastal landscapes to sea level rise is compounded by the existence of extensive artificial drainage networks initially built to lower water tables for agriculture, forestry, and human settlements. These drainage networks are found in landscapes with little topographic relief where channel flow is characterized by bi-directional movement across multiple time-scales and related to precipitation, wind, and tidal patterns. The current configuration of many artificial drainage networks exacerbates impacts associated with sea level rise such as salt-intrusion and increased flooding. This suggests that in the short-term, drainage networks might be managed to mitigate sea level rise related impacts. The challenge, however, is that hydrologic processes in regions where channel flow direction is weakly related to slope and topography require extensive parameterization for numerical models which is limited where network size is on the order of a hundred or more kilometers in total length. Here we present an application of graph theoretic algorithms to efficiently investigate network properties relevant to the management of a large artificial drainage system in coastal North Carolina, USA. We created a digital network model representing the observation network topology and four types of drainage features (canal, collector and field ditches, and streams). We applied betweenness-centrality concepts (using Dijkstra’s shortest path algorithm) to determine major hydrologic flowpaths based off of hydraulic resistance. Following this, we identified sub-networks that could be managed independently using a community structure and modularity approach. Lastly, a betweenness-centrality algorithm was applied to identify major shoreline entry points to the network that disproportionately control water movement in and out of the network. We demonstrate that graph theory can be applied to solving management and monitoring problems associated with sea level rise for poorly understood drainage networks in advance of numerical methods.

Land clearance and hydrological change in the Sahel: SW Niger

In the West African semiarid belt of the Sahel, for the second half of the XXth century, lasting droughts (1970s–1980s) and one of the World's highest population growths have resulted in major land cover and hydrological changes that can be quantified using aerial photographs. This paper aims to provide one of the longest combined observations of land cover and hydrological changes for semiarid areas using a time series of normalised mosaics of aerial photographs dating back from 1950, field inquiries, and updated groundwater data. The 500 km 2 study area in southwest Niger was chosen (i) for its rural environment representative of the rain-fed agriculture belt of the Sahel and (ii) to encompass the main hydrological study sites investigated in this region over the past two decades (Hapex-Sahel and AMMA experiments, 1990–2000s). Results have significant implications for future freshwater availability and food security in the Sahel. Between 1950 and 1992, ∼ 80% of the study area has been cleared, firstly to open new areas for agriculture and secondly for firewood supply (59% of the plateaux, 42% of the valley bottoms, and 87% of the hillslopes). Intermediate aerial photograph surveys (1960, 1975) attest an accelerated loss in the woody savannah that could not be recovered on the short term. A strong, indirect impact of land clearance is observed on the water resources. Land clearance has resulted in a modification of the soil properties and infiltration capacity and has led to an increase in Hortonian runoff collected in numerous gullies and ponds. Between 1950 and 1992, aerial photographs show a ∼ 2.5 fold increase of the drainage density with the development of large drainage systems and new ponds. Groundwater data also indicate a continuous rise in the water table, mostly noticeable since the 1980s with a mean groundwater level rise of ∼ 4 m for the 1963–2005 period (+ 15% in aquifer reserves). The relatively short ∼ 30 year time-lag between the onset of land clearance and the beginning of the water table rise is linked to the process of indirect groundwater recharge and is timed with the connectivity of the drainage network and the formation of new ponds. Finally, the sustained increase in surface runoff and groundwater recharge during the past four decades indicates that the indirect impact of land clearance on the terrestrial water balance has been stronger than that of the long-lasting Sahelian drought. As the rate of land clearance increased for the past century in semiarid Africa, its main hydrological effects may not yet be fully perceptible.

Mega capture of the Rio Negro and formation of the Anavilhanas Archipelago, Central Amazônia, Brazil: Evidences in an SRTM digital elevation model

In the Central Amazônia (Brazil), the Solimões River and the Negro River (“Rio Negro”) merge to form the Amazonas, the largest river in the world. Analysis of a digital elevation model produced by the Shuttle Radar Topographic Mission (SRTM) in that region reveals the relicts of a large ancient drainage system hidden by the tropical rain forest. Interpretation of this unreported terrain feature in the context of the regional geological framework indicates that the present lower course of the Rio Negro results from a mega fluvial capture driven by an active tectonic regime prevailing in the Amazonian basin. The diversion of the Rio Negro was controlled by pre-existing NW–SE structural features, in which the arrangement of fault blocks compelled the river to funnel down into a strait. Partially blocked by this natural barrier, the Rio Negro widens upstream, assuming a lake-like appearance (up to 20 km-wide). Free space availability and low energy favored the deposition of sediments to form the Anavilhanas Archipelago, the largest group of freshwater islands on the world, refuge of a diversified fauna and flora.

Economic incentives in land reclamation sector in Lithuania

The study presents the critical evaluation of existing drainage systems from legal, economical, environmental and technical viewpoints. Nearly 80% of agricultural land in Lithuania drained by underground drainage systems covers around 3 million hectares . The prevailing large scale drainage systems with a complex of engineering structures such as conducting ditches, drains and collectors, local roads, bridges or farm road-crossings, dikes, dams, water reservoirs, pumping stations for irrigation and for drainage need today an efficient management solution in a new economic situation. The detailed analysis of legal and economic instruments adopted in transferring the management responsibilities of drainage systems to users has been carried out. The study resulted in a number of practical contributions towards the amendments in the Law on Land Reclamation in Lithuania and the establishment of a system of indicators that would allow rationalisation of subsidy allocations for the maintenance and improvement of the drainage systems. These subsidies from the state budget make at the moment the largest share among the investment sources. The financial and in kind contribution of drainage users is permanently increasing as are the allocations of the structural funds for public projects. The EU pre-accession programme SAPARD started in 2000 has supported some investments in rural areas. Unfortunately, it did not support the drainage infrastructure properly. A critical review of previous measures allowed suggesting new actions within the framework of the actual support from EU structural funds.

Microcirculation in DIEP flaps: a study of the haemodynamics using laser Doppler flowmetry and lightguide reflectance spectrophotometry

This paper gives us some useful information on the dynamics of the microcirculation following flap transfer. It also complements what we know about the vascular anatomy, and more particularly the venous anatomy of the DIEP flap. 1 Blondeel P.N. Arnstein M. Verstraete K. et al. Venous congestion and blood flow in free transverse rectus abdominis myocutaneous and deep inferior epigastric perforator flaps. Plast Reconstr Surg. 2000; 106: 1295-1299 Google Scholar While some of these changes may be intuitive, this paper makes the important contribution of documenting those changes. For example, an initial reduction in blood flow is something that we have appreciated in flap transfer, whether pedicled or free. There are many potential explanations for this. Vessel spasm as well as the effects of vaso-active peptides can explain some of these changes. 2 Zhang J. Lipa J.E. Black C.E. Huang N. Neligan P.C. Ling F.T. et al. Pharmacological characterization of vasomotor activity of human musculocutaneous perforator artery and vein. J Appl Physiol. 2000; 89: 2268-2275 Google Scholar What is particularly interesting is that a difference was noted between the flaps that went on to uncomplicated wound healing and outcome versus those that got into trouble. There is the potential to use this information as a means of monitoring outcomes. There may also be the potential to use this information to help make the clinical decision, for example, to do another vein. Perhaps a critical drop in flow below an arbitrary number may be a useful indicator. Maybe we should be using LRS readings to guide us in this decision-making. The fact that the one flap in this series with a large caliber deep venous drainage system recovered more quickly shows the importance of venous drainage in the equation of microcirculatory circulation. The authors are to be congratulated for drawing our attention to this subject and it is hoped that further studies will help define the role this information may ultimately play in clinical decision making in flap surgery. Microcirculation in DIEP flaps: a study of the haemodynamics using laser Doppler flowmetry and lightguide reflectance spectrophotometryJournal of Plastic, Reconstructive & Aesthetic SurgeryVol. 59Issue 6PreviewThe deep inferior epigastric perforator (DIEP) flap is ideally suited for breast reconstruction. The DIEP flap reduces abdominal wall morbidity when compared to a transverse rectus abdominis (TRAM) flap, however, there maybe a compromise of the flap vascularity. Early venous problems and late fat necrosis in DIEP flaps can occur. There is a limited literature on the haemodynamic and microcirculation of the DIEP flap. Sixteen consecutive patients who underwent immediate breast reconstruction with DIEP flap were prospectively monitored during the post-operative time for a minimum period of 48 h using laser Doppler flowmetry (LDF) and lightguide reflectance spectrophotometry (LRS) to analyse blood flow and oxygenated haemoglobin percentage in the cutaneous microcirculation of the flap. Full-Text PDF