City Of Iquitos Research Articles

Spatial and temporal analysis on the impact of ultra-low volume indoor insecticide spraying on Aedes aegypti household density

BackgroundAedes aegypti is the primary mosquito vector for several arboviruses, such as dengue, chikungunya and Zika viruses, which cause frequent outbreaks of human disease in tropical and subtropical regions. Control of these outbreaks relies on vector control, commonly in the form of insecticide sprays that target adult female mosquitoes. However, the spatial coverage and frequency of sprays needed to optimize effectiveness are unclear. In this study, we characterize the effect of ultra-low-volume (ULV) indoor spraying of pyrethroid insecticides on Ae. aegypti abundance within households. We also evaluate the effects of spray events during recent time periods or in neighboring households. Improved understanding of the duration and distance of the impact of a spray intervention on Ae. aegypti populations can inform vector control interventions, in addition to modeling efforts that contrast vector control strategies.MethodsThis project analyzes data from two large-scale experiments that involved six cycles of indoor pyrethroid spray applications in 2 years in the Amazonian city of Iquitos, Peru. We developed spatial multi-level models to disentangle the reduction in Ae. aegypti abundance that resulted from (i) recent ULV treatment within households and (ii) ULV treatment of adjacent or nearby households. We compared fits of models across a range of candidate weighting schemes for the spray effect, based on different temporal and spatial decay functions to understand lagged ULV effects.ResultsOur results suggested that the reduction of Ae. aegypti in a household was mainly due to spray events occurring within the same household, with no additional effect of sprays that occurred in neighboring households. Effectiveness of a spray intervention should be measured based on time since the most recent spray event, as we found no cumulative effect of sequential sprays. Based on our model, we estimated the spray effect is reduced by 50% approximately 28 days after the spray event.ConclusionsThe reduction of Ae. aegypti in a household was mainly determined by the number of days since the last spray intervention in that same household, highlighting the importance of spray coverage in high-risk areas with a spray frequency determined by local viral transmission dynamics.Graphical abstract

FIRST RECORD OF THE BEETLE Trachyderes succinctus (CERAMBYCIDAE) ON THE PLANT Senna reticulata (FABACEAE) IN IQUITOS, PERU

This study documents for the first time the presence of the beetle Trachyderes succinctus (Cerambycidae) on the plant Senna reticulata (Fabaceae) in the city of Iquitos, Peru. The sample consisted of three beetle larvae collected from within the branches of the plant, which were reared in controlled environments until reaching adulthood. The adult beetle individuals and plant samples were identified using specialized keys. T. succinctus shows a preference for plant species in the Fabales order, and this finding expands our knowledge of its relationship with different species. This study provides valuable information about the interaction between the beetle and the plant in the Peruvian Amazon.

FISHES AT RISK: UNVEILING THE HIDDEN DIVERSITY OF A VULNERABLE LAKE IN THE PERUVIAN AMAZON REGION

The study focuses on the Huachana lake, a vulnerable ecosystem in the Peruvian Amazon region that receives wastewater from the city of Iquitos. Despite its significance in ichthyology and its role as a type locality for various species, water bodies near Iquitos face threats. While a portion of the ichthyological diversity in the Loreto region is known, the Huachana lake had never been subject to sampling, making this study the first to examine fish diversity in this aquatic environment. A total of 52 fish species from 5 orders, 20 families, and 39 genera were identified. The Characiformes present the greatest species richness (30 species), followed by Cichliformes (12 species). Cichlidae and Characidae are the families richest in species. No species are endangered according to the IUCN; the majority are considered of least concern. The study also identified ornamental and commercial species, providing crucial information about ichthyofauna in nearby urban areas and its potential long-term environmental impact.

Intestinal endoparasitism in Corydoras multiradiatus (Siluriformes: Callichthyidae) in Iquitos, Loreto-Peru

Corydoras multiradiatus (Orcés V.1960), commonly called “hog-nosed brochis” and popularly known in Peru as “coridora jumbo” is a species of commercial importance among the Amazonian ornamental fish. It is known that the integrity of the health of aquatic organisms positively increases the production and trade of quality products, however, the opposite negatively affects financial losses and production costs. Among the possible diseases, parasitism stands out, and there is still a lack of information, mainly about metazoans, parasitic species that infect C. multiradiatus. Therefore, this study aimed to identify the species of endoparasite metazoans in C. multiradiatus and evaluate the histological lesions present to provide information to ornamental fish producers about these pathologies. Thirty specimens of C. multiradiatus were collected by fishermen in the municipality of “Belén” in Iquitos, Peru. The results revealed the presence of Tylodelphys sp. and nematode larvae in the intestinal wall and Procamallanus (Spirocamallanus) pintoi (Kohn & Fernandes 1988) present in the intestine. The histopathological analysis of the intestine showed several lesions: necrosis; cell desquamation; infiltration of lymphocytes in the mucosa; transepithelial infiltration of lymphocytes; enterocyte hyperplasia; goblet cell hyperplasia and enterocyte desquamation. The study revealed the presence of endoparasites in C. multiradiatus collected in Iquitos, Loreto-Peru, and a moderate degree of damage caused by histological lesions in the intestine of infected fish. The results of this work will serve the fishermen, collectors and aquarists of the city of Iquitos, who, knowing the endoparasites present in C. multiradiatus and the damage they can cause to the fish, will be able to adopt prophylactic measures in order to guarantee the good condition of the fish for its consequent commercialization at a local, national and international level.

Cultural roles of primates in an Amazonian urban center

Primate species in the Neotropics are undergoing increasing anthropogenic threats, including unsustainable trade and consumption by rapidly urbanizing communities. Yet the diverse cultural and symbolic factors contributing to primate trade and consumption are understudied, which inhibits the design of sound conservation policies for regulating primate utilization. In this scoping study, we administered an online survey seeking to characterize the ecological, market-based, and symbolic roles of primates in Iquitos, Peru, a rapidly urbanizing center of the Peruvian Amazon. We assessed the salience of each inferred taxa and frequencies of respondents indicating different roles that primates play in the urban system. Results suggest that primate species across sixteen inferred genera and five families play diverse cultural roles in the city of Iquitos, including as food (subsistence and consumption as traditional practice), for use as body parts or live individuals, depictions in art and stories, and as symbols to attract tourists to businesses and to promote conservation. The most salient species based on survey responses also held high conservation value (i.e. were Endangered or Vulnerable on the IUCN Red List). These preliminary findings suggest that conservation measures aimed at reducing primate trade by targeting economic incentives and commercial flows alone may be ineffective in culturally diverse Amazon cities. Future research should assess the potential to leverage primate symbolic values and meanings in conservation efforts in light of increased rural–urban migration, infrastructure development, and tourism in the urbanizing Amazon.

Direct mosquito feedings on dengue-2 virus-infected people reveal dynamics of human infectiousness.

Dengue virus (DENV) transmission from humans to mosquitoes is a poorly documented, but critical component of DENV epidemiology. Magnitude of viremia is the primary determinant of successful human-to-mosquito DENV transmission. People with the same level of viremia, however, can vary in their infectiousness to mosquitoes as a function of other factors that remain to be elucidated. Here, we report on a field-based study in the city of Iquitos, Peru, where we conducted direct mosquito feedings on people naturally infected with DENV and that experienced mild illness. We also enrolled people naturally infected with Zika virus (ZIKV) after the introduction of ZIKV in Iquitos during the study period. Of the 54 study participants involved in direct mosquito feedings, 43 were infected with DENV-2, two with DENV-3, and nine with ZIKV. Our analysis excluded participants whose viremia was detectable at enrollment but undetectable at the time of mosquito feeding, which was the case for all participants with DENV-3 and ZIKV infections. We analyzed the probability of onward transmission during 50 feeding events involving 27 participants infected with DENV-2 based on the presence of infectious virus in mosquito saliva 7-16 days post blood meal. Transmission probability was positively associated with the level of viremia and duration of extrinsic incubation in the mosquito. In addition, transmission probability was influenced by the day of illness in a non-monotonic fashion; i.e., transmission probability increased until 2 days after symptom onset and decreased thereafter. We conclude that mildly ill DENV-infected humans with similar levels of viremia during the first two days after symptom onset will be most infectious to mosquitoes on the second day of their illness. Quantifying variation within and between people in their contribution to DENV transmission is essential to better understand the biological determinants of human infectiousness, parametrize epidemiological models, and improve disease surveillance and prevention strategies.

Dengue and COVID-19 Co-circulation in the Peruvian Amazon: A Population-Based Study.

The COVID-19 pandemic affected the main Amazon cities dramatically, with Iquitos City reporting the highest seroprevalence of anti-SARS-CoV-2 antibodies during the first COVID-19 wave worldwide. This phenomenon raised many questions about the possibility of a co-circulation of dengue and COVID-19 and its consequences. We carried out a population-based cohort study in Iquitos, Peru. We obtained a venous blood sample from a subset of 326 adults from the Iquitos COVID-19 cohort (August 13-18, 2020) to estimate the seroprevalence of anti-dengue virus (DENV) and anti-SARS-CoV-2 antibodies. We tested each serum sample for anti-DENV IgG (serotypes 1, 2, 3, and 4) and SARS-CoV-2 antibodies anti-spike IgG and IgM by ELISA. We estimated an anti-SARS-CoV-2 seroprevalence of 78.0% (95% CI, 73.0-82.0) and an anti-DENV seroprevalence of 88.0% (95% CI, 84.0-91.6), signifying a high seroprevalence of both diseases during the first wave of COVID-19 transmission in the city. The San Juan District had a lower anti-DENV antibody seroprevalence than the Belen District (prevalence ratio, 0.90; 95% CI, 0.82-0.98). However, we did not observe these differences in anti-SARS-CoV-2 antibody seroprevalence. Iquitos City presented one of the highest seroprevalence rates of anti-DENV and anti-SARS-CoV-2 antibodies worldwide, but with no correlation between their antibody levels.

Flooding risk of cropland areas by repiquetes in the western Amazon basin: A case study of Peruvian Tamshiyacu City

Study regionThe western Amazon basin at Tamshiyacu gauging station (near the Iquitos City) hosts floodplain agriculture that can be affected by the sudden reversal in direction of water levels known as “repiquetes” that produce intermittent flooding. Study focusThis study assesses repiquete flooding risk in riparian crop areas based on statistical analyses of repiquete events registered from 1996 to 2018, hydraulic modeling to estimate flooded extension, and assessment of climatological characteristics during the formation of repiquetes. New hydrological insightsFloods (≥ 20 cm) produced by repiquetes in riparian crop areas between 83.00 and 88.00 m above sea level (masl) occur 1.8 times per year. However, not all elevation ranges have the same flooding risk to crops. Terrain elevations between 85.31 and 87.00 masl have a reduced flooding risk of 0.35 per year. Likewise, areas with elevations between 87.00 and 88.00 masl (43% of the total area) were not affected by repiquetes. Extreme repiquetes (study cases of 2002 and 2008) have been influenced by the increase of atmospheric moisture flux convergence and precipitation over both the northern Ucayali and Marañón basins through the six previous days. Flood impacts from the extreme event of 2002 (2008) could have reached 40% (25%) of the available area for agriculture at the initiation of the repiquete.

The Rotting City: Surrealist Arts of Noticing the Urban Anthropocene

This article develops a surrealist approach to researching and writing about the urban Anthropocene, as a critical contribution to existing literatures on “arts of noticing” and “staying with the trouble.” Drawing on psychogeographical explorations of the city of Iquitos in the Peruvian Amazon and distancing itself from conventional modes of academic writing, the article presents a montage of surrealist images of this (post)apocalyptic metropolis. Iquitos emerges as a palimpsest of the wreckage of repeated resource booms, strewn with the ruins of a stillborn modernity and incubating an uncanny fusion of apocalyptic and utopian elements observable in the everyday practices of its subaltern inhabitants. Just as Paris was the capital of the 19th century for Walter Benjamin’s Arcades Project, so the interpretation of Iquitos as an extreme metaphor for our combined and uneven apocalypse designates it as the capital of the Anthropocene.

Apocalypse and utopia in the salvagepunk metropolis

This paper explores the nature of utopia in the context of our apocalyptic present. Drawing on Evan Calder Williams’ concepts of salvagepunk, it interprets the city of Iquitos in the Peruvian Amazon as a (post)apocalyptic metropolis. It excavates the origins of Iquitos in genocidal violence and extractivist destruction, deconstructs the modernising megaprojects designed to rescue the city from its isolated status, and explores the subaltern forms of its everyday production. In doing so, the paper problematises accelerationist and pluriversal fantasies of escape from planetary socioecological breakdown, and discerns an apocalyptic utopia emerging at the urban cutting edge of the Anthropocene.

Microplastic occurrence in fish species from the Iquitos region in Peru, western Amazonia

ABSTRACT The contamination of aquatic environments by microplastic has become a major threat to biodiversity. The presence of microplastic is documented in the aquatic fauna of the oceans, but, in the Amazon basin, reports on microplastic occurrence are few. The present study surveyed microplastic occurrence in fishes in an area of the Peruvian Amazon. We sampled 61 specimens of 15 commercial species from local markets in the city of Iquitos, Loreto Department. We detected a total of 2337 microplastic particles, 1096 in the gills and 1241 in the internal organs (esophagus, stomach, intestine, liver, gonads, pancreas, swim bladder and heart). The prevalence of microplastic particles was 100% and the overall average abundance was of 38.3 particles per individual (17.9 particles per individual in gills and 20.3 particles per individual in internal organs). Most particles were found in carnivorous fish. There was no correlation of particle abundance with fish standard length and weight. These results provided evidence of the degree of microplastic contamination of the fish fauna in the region of Iquitos.

Situación del narcotráfico y amenazas a la seguridad en el valle del Río Putumayo

is study analyzes the drug trafficking situation and security threats, seeks to determine the impact, consequences and possible scenarios; through a qualitative study for the design of a strategic route of security and development. The purpose is to contribute to the strengthening and improvement of the joint and integrated performance of the participation of the Law Enforcement Forces and other State institutions and to combat illegal activities in the national territory of the department of Loreto. The methodology used was prospective to study the historical, present and future behavior of a set of variables from the global and regional context on political, social, economic, health and national defense characteristics of the territory. The visit made tothe city of Iquitos, Loreto Region, helped to anticipate and identify dangers and opportunities of future situations. In this way, the main internal variables that characterize the territory and are representative of the regional reality have been recognized; concluding, among others, that the main cause of drug trafficking in the Putumayo river basin, as well as related crimes and the poor development and very low competitiveness of the Department of Loreto is its lack of terrestrial connectivity. This makes the logistics of maintaining a long-term presence of the State in that border region very complex and expensive. Loreto's connectivity with the rest of the country is only via air and river, the latter being cheaper than the former, but unfortunately dependent, so river transport of large volumes of cargo is only possible in certain periods of the year.

Resolving the enigma of Iquitos and Manaus: A modeling analysis of multiple COVID-19 epidemic waves in two Amazonian cities.

The two nearby Amazonian cities of Iquitos and Manaus endured explosive COVID-19 epidemics and may well have suffered the world's highest infection and death rates over 2020, the first year of the pandemic. State-of-the-art epidemiological and modeling studies estimated that the populations of both cities came close to attaining herd immunity (>70% infected) at the termination of the first wave and were thus protected. This makes it difficult to explain the more deadly second wave of COVID-19 that struck again in Manaus just months later, simultaneous with the appearance of a new P.1 variant of concern, creating a catastrophe for the unprepared population. It was suggested that the second wave was driven by reinfections, but the episode has become controversial and an enigma in the history of the pandemic. We present a data-driven model of epidemic dynamics in Iquitos, which we also use to explain and model events in Manaus. By reverse engineering the multiple epidemic waves over 2 y in these two cities, the partially observed Markov process model inferred that the first wave left Manaus with a highly susceptible and vulnerable population (≈40% infected) open to invasion by P.1, in contrast to Iquitos (≈72% infected). The model reconstructed the full epidemic outbreak dynamics from mortality data by fitting a flexible time-varying reproductive number [Formula: see text] while estimating reinfection and impulsive immune evasion. The approach is currently highly relevant given the lack of tools available to assess these factors as new SARS-CoV-2 virus variants appear with different degrees of immune evasion.

Quantifying heterogeneities in arbovirus transmission: Description of the rationale and methodology for a prospective longitudinal study of dengue and Zika virus transmission in Iquitos, Peru (2014-2019).

Current knowledge of dengue virus (DENV) transmission provides only a partial understanding of a complex and dynamic system yielding a public health track record that has more failures than successes. An important part of the problem is that the foundation for contemporary interventions includes a series of longstanding, but untested, assumptions based on a relatively small portion of the human population; i.e., people who are convenient to study because they manifest clinically apparent disease. Approaching dengue from the perspective of people with overt illness has produced an extensive body of useful literature. It has not, however, fully embraced heterogeneities in virus transmission dynamics that are increasingly recognized as key information still missing in the struggle to control the most important insect-transmitted viral infection of humans. Only in the last 20 years have there been significant efforts to carry out comprehensive longitudinal dengue studies. This manuscript provides the rationale and comprehensive, integrated description of the methodology for a five-year longitudinal cohort study based in the tropical city of Iquitos, in the heart of the Peruvian Amazon. Primary data collection for this study was completed in 2019. Although some manuscripts have been published to date, our principal objective here is to support subsequent publications by describing in detail the structure, methodology, and significance of a specific research program. Our project was designed to study people across the entire continuum of disease, with the ultimate goal of quantifying heterogeneities in human variables that affect DENV transmission dynamics and prevention. Because our study design is applicable to other Aedes transmitted viruses, we used it to gain insights into Zika virus (ZIKV) transmission when during the project period ZIKV was introduced and circulated in Iquitos. Our prospective contact cluster investigation design was initiated by detecttion of a person with a symptomatic DENV infection and then followed that person's immediate contacts. This allowed us to monitor individuals at high risk of DENV infection, including people with clinically inapparent and mild infections that are otherwise difficult to detect. We aimed to fill knowledge gaps by defining the contribution to DENV transmission dynamics of (1) the understudied majority of DENV-infected people with inapparent and mild infections and (2) epidemiological, entomological, and socio-behavioral sources of heterogeneity. By accounting for factors underlying variation in each person's contribution to transmission we sought to better determine the type and extent of effort needed to better prevent virus transmission and disease.

Inapparent infections shape the transmission heterogeneity of dengue.

Transmission heterogeneity, whereby a disproportionate fraction of pathogen transmission events result from a small number of individuals or geographic locations, is an inherent property of many, if not most, infectious disease systems. For vector-borne diseases, transmission heterogeneity is inferred from the distribution of the number of vectors per host, which could lead to significant bias in situations where vector abundance and transmission risk at the household do not correlate, as is the case with dengue virus (DENV). We used data from a contact tracing study to quantify the distribution of DENV acute infections within human activity spaces (AS), the collection of residential locations an individual routinely visits, and quantified measures of virus transmission heterogeneity from two consecutive dengue outbreaks (DENV-4 and DENV-2) that occurred in the city of Iquitos, Peru. Negative-binomial distributions and Pareto fractions showed evidence of strong overdispersion in the number of DENV infections by AS and identified super-spreading units (SSUs): i.e. AS where most infections occurred. Approximately 8% of AS were identified as SSUs, contributing to more than 50% of DENV infections. SSU occurrence was associated more with DENV-2 infection than with DENV-4, a predominance of inapparent infections (74% of all infections), households with high Aedes aegypti mosquito abundance, and high host susceptibility to the circulating DENV serotype. Marked heterogeneity in dengue case distribution, and the role of inapparent infections in defining it, highlight major challenges faced by reactive interventions if those transmission units contributing the most to transmission are not identified, prioritized, and effectively treated.

Factors and Economic Growth of Peruvian Mypes

Purpose: Describe the factors that promoted the economic growth of MSEs in the city of Iquitos in the year 2021.
 Theoretical framework: The world we know has many shortcomings, schools, hospitals, infrastructure necessary to provide essential services to the entire population, and that economic activities, production, transportation, etc., allow and contribute to the presence of upstream supply of goods and services that people require for their livelihood (Aguilar Zuluaga, 2016).
 Methodology: For the development of this study, the qualitative approach of phenomenological - hermeneutic design was used, the informants were entrepreneurs, microentrepreneurs, officials of the Chamber of Commerce and officials of the Municipal Economic Development Management.
 Findings: The study provides information about the intrinsic reality that Peruvian MSEs are going through, that which economic indicators and quantitative studies do not provide.
 Contributions: The present study provides an analysis of the reality about economic growth, making a study of the phenomenology that this represents, with the respective hermeneutic analysis that is required, which could serve as a basis for the promotion and design of public policies for the economic development of the sector.
 Originality/value: This study is innovative due to the absence of research that addresses the social phenomenon of economic growth and its factors from the perspective of its protagonists, the entrepreneurs, which will contribute to the analysis of decisions for the development of these economic sectors.

Epidemiological characteristics of P. vivax asymptomatic infections in the Peruvian Amazon.

IntroductionHerein, we tested the hypothesis that Asymptomatic P. vivax (Pv) infected individuals (Asym) feature different epidemiological, clinical and biochemical characteristics, as well as hematological parameters, potentially predictive of clinical immunity in comparison to symptomatic Pv infected individuals (Sym).MethodologyBetween 2018 - 2021, we conducted 11 population screenings (PS, Day 0 (D0)) in 13 different riverine communities around Iquitos city, in the Peruvian Amazon, to identify Pv Sym and Asym individuals. A group of these individuals agreed to participate in a nested case - control study to evaluate biochemical and hematological parameters. Pv Asym individuals did not present common malaria symptoms (fever, headache, and chills), had a positive/negative microscopy result, a positive qPCR result, reported no history of antimalarial treatment during the last month, and were followed-up weekly until Day 21 (D21). Control individuals, had a negative malaria microscopy and qPCR result, no history of antimalarial treatment or malaria infections during the last three years, and no history of comorbidities or chronic infections.ResultsFrom the 2159 individuals screened during PS, data revealed a low but heterogeneous Pv prevalence across the communities (11.4%), where most infections were Asym (66.7%) and submicroscopic (82.9%). A total of 29 Asym, 49 Sym, and 30 control individuals participated in the nested case - control study (n=78). Ten of the individuals that were initially Asym at D0, experienced malaria symptoms during follow up and therefore, were included in the Sym group. 29 individuals remained Asym throughout all follow-ups. High levels of eosinophils were found in Asym individuals in comparison to Sym and controls.ConclusionFor the first-time, key epidemiological, hematological, and biochemical features are reported from Pv Asym infections from the Peruvian Amazon. These results should be considered for the design and reshaping of malaria control measures as the country moves toward malaria elimination.

Two new surprising species of leaf-litter toad of the Rhinella margaritifera species group (Anura: Bufonidae) from the Peruvian Amazon, LoretoPeru.

We describe two new species of Rhinella (Anura: Bufonidae) from the department of Loreto, Peru. We integrate morphological and phylogenetic analyses to provide evidence of new species. R. angeli sp. nov. is diagnosable from all congeners by its pronounced fleshy proboscis and R. unapensis sp. nov. by the small size (mean snout-vent length=37.7 4.1 mm) of adult males, snout pointed in dorsal view, nearly acute in lateral view, and small bony protrusion at the angle of jaws among other characters. The two species are allopatric, where the first species is known to be associated inhabits upland (=terra firme) forests, while the second white sand forests (=varillales) around Iquitos city. The two new species represent the 20th and 21st species of the Rhinella margaritifera species group.

Occurrence of Eustrongylides sp. (Nematoda: Dioctophymatidae) in Fish Species Collected in the Peruvian Amazonia and Its Implications for Public Health.

The present study aims to report the occurrence of Eustrongylides sp. in some neotropical fish species commercialized in the Peruvian Amazonia. Samples of young farmed Arapaima gigas were collected from a fish farmer; young Brachyplatystoma tigrinum were acquired from a fish exporter and samples of adult specimens of Acestrorhynchus falcirostris, Pseudoplatystoma punctifer, Cichla monoculus, Hoplias malabaricus, Hydrolycus scomberoides, Raphiodon vulpinus, and Serrasalmus rhombeus were acquired from a fish market of Iquitos, Loreto-Peru. Samples were transported to the "Laboratorio de Parasiología y Sanidad Acuícola" from "Instituto de Investigaciones de la Amazonía Peruana" located in Iquitos, Peru. Larvae L4 of Eustrongylides sp. were found in the host body, in the muscle, and in the visceral cavity of studied fish species. Notorious damages were reported in young A. gigas (lumps in the muscle, inflammation and severe redness of the skin) and in young B. tigrinum (perforation of the abdominal cavity), while in adult specimens of the remaining species, no external damage was reported. The presence of Eustrongylides sp. in various fish species collected in the city of Iquitos-Peru contributes to the distribution of this parasite in the Peruvian Amazon, reporting it, for the first time in this country. Its presence in the muscle of various fish species commercialized in fish markets, warm a possible public health concern and implications for their marketability in the city of Iquitos, Peru.

Detecting the Planform Changes Due to the Seasonal Flow Fluctuation and 2012 Severe Flood in the Amazon River near Iquitos City, Peru Based on Remote Sensing Image Analysis

The Upper Amazon River forms an anabranching planform, which has been found to have significant changes in migration rate and river morphology. Previous studies have elaborated long-term evolution of the anabranching systems; however, research on the influence of the water level on temporal changes in anabranching is absent. According to the theory of river hydraulics, fluvial scour usually occurs when the shear force possessed by the high flow exceeds the resistance of the streambank. In contrast, deposition occurs when the tractive force of the low flow is insufficient to overcome the forces of gravity and friction. This study investigated the Muyuy anabranching planform change of the Upper Peruvian Amazon River due to the seasonal flow fluctuations and a severe flood in 2012. The Muyuy anabranching area is located 20 km upstream of Iquitos City, Peru. Landsat images from the wet and dry seasons in 2008, 2009, 2012, and 2013 were collected. The images were classified into three land cover classes (water, bare soil, vegetation and others) based on NDVI analysis. Quantitative analysis of the erosion/deposition shows that deposition is more noticeable than erosion in the Muyuy anabranching area. Considerable deposition can be found on the island of the anabranching system, and the streambank erosion occurred in the outer (concave) side of the main channel. This phenomenon of river erosion and deposition consistently occurred in 2008 and 2009 because of the periodical variation among the wet and dry seasons. However, prominent erosion was observed in 2012 and it was recognized to be caused by the severe flood. Furthermore, the extensive island was formed in 2013, which means substantial depositions accumulated in the recession of the 2012 flood.