José Ribeiro de Araújo Neto

Land use and trophic state dynamics in a tropical semi-arid reservoir

Water body eutrophication process has been a serious problem around the world, especially in semiarid and arid region where main approach to storage water is reservoir. The aim of this work was to investigate the spatial and seasonal variability in water quality of a reservoir in a semi-arid tropical region with regards to its trophic state, and to identify the sources of nutrient input to the reservoir. Essa pesquisa foi realizada no reservatorio Oros, segundo maior do estado do Ceara-Brasil. This research was developed in the Oros reservoir, the second one most important reservoir in Ceara State, Brazil. Samples were collected bimonthly during the period April 2008 to April 2010, from sex sampling points representing the outlet of tributaries, and one point down of the dam. The study included the following variables: total phosphorus, transparency and chlorophyll-a. Trophic state was evaluated by application of the Carlson modified Trophic State Index (TSI). Maps of the spatial and seasonal dynamics of the water quality in the reservoir were constructed using GIS soft. According to the average values of total phosphorus (> 0.050 mg L -1 ), the waters can be classified as eutrophic. The highest concentrations of chlorophyll-a were found during the dry season, with values ranging from 3.8 to 26.5 µg L -1 , showing high temporal and spatial variations. The waters presented as eutrophic regarding average TSI, at all points sampled. The results indicate a deterioration in water quality and the need for intervention to reduce the release of waste, and thus improve the trophic state of the waters of the Oros reservoir.Water body eutrophication process has been a serious problem around the world, especially in semiarid and arid region where main approach to storage water is reservoir. The aim of this work was to investigate the spatial and seasonal variability in water quality of a reservoir in a semi-arid tropical region with regards to its trophic state, and to identify the sources of nutrient input to the reservoir. Essa pesquisa foi realizada no reservatorio Oros, segundo maior do estado do Ceara-Brasil. This research was developed in the Oros reservoir, the second one most important reservoir in Ceara State, Brazil. Samples were collected bimonthly during the period April 2008 to April 2010, from sex sampling points representing the outlet of tributaries, and one point down of the dam. The study included the following variables: total phosphorus, transparency and chlorophyll-a. Trophic state was evaluated by application of the Carlson modified Trophic State Index (TSI). Maps of the spatial and seasonal dynamics of the water quality in the reservoir were constructed using GIS soft. According to the average values of total phosphorus (> 0.050 mg L -1 ), the waters can be classified as eutrophic. The highest concentrations of chlorophyll-a were found during the dry season, with values ranging from 3.8 to 26.5 µg L -1 , showing high temporal and spatial variations. The waters presented as eutrophic regarding average TSI, at all points sampled. The results indicate a deterioration in water quality and the need for intervention to reduce the release of waste, and thus improve the trophic state of the waters of the Oros reservoir.

Runoff and soil and nutrient losses in semiarid uncultivated fields

Although water erosion is the principle agent responsible for soil degradation, field data on the impacts of erosion, due to high operational costs and measurement difficulties, are scarce, especially in semiarid regions. In this context, the aim of this study was to evaluate runoff and soil and nutrient losses in uncultivated areas in the semiarid region of the state of Ceara in Brazil. The experiment was conducted in a 20 m2 erosion plot that was uncultivated and populated with herbaceous plants. Data were collected during the rainy season from January to May 2009. Monthly water losses from overland flow ranged from 3.4 to 168.9 mm, representing 1.8 to 42.3% of the total monthly rainfall for January and April, respectively. Soil loss from erosion totaled 2,166.6 kg ha-1. In February, soil losses were 834.3 kg ha-1, corresponding to 38.5% of the total value. The rainfall erosivity index (EI30) was 5,716.4 MJ mm ha-1 h-1. The observed high variability of soil losses in individual events was influenced mainly by the antecedent soil water content. Although this study used only one year of observations, the findings are important for land use planning, especially in the semiarid region of Brazil, where datasets are scarce.

Similaridade e fatores determinantes na salinidade das águas superficiais do Ceará, por técnicas multivariadas

Tecnicas de estatistica multivariada foram empregadas com o objetivo de identificar a similaridade dos reservatorios superficiais do Ceara, com relacao a salinidade das aguas e identificar os fatores determinantes da qualidade das aguas. Os dados utilizados foram provenientes do banco de dados da Companhia de Gestao dos Recursos Hidricos do Ceara, no periodo de 1998/2009, no total de 807 amostras de 48 reservatorios. Os parâmetros considerados foram: Cl-, Ca2+, Mg2+, Na+, HCO3 -, CE e RAS. A analise de agrupamento hierarquico formou quatro grupos distintos, sendo determinantes os tipos e concentracoes dos sais analisados. Nos grupos 1 e 2 a salinidade da agua e definida principalmente pelas condicoes naturais de solo e clima da regiao e nos grupos 3 e 4, alem desses fatores, a influencia antropica. O emprego da analise de fator/analise de componente principal promoveu a reducao de sete caracteristicas das aguas superficiais do Estado Ceara, para dois componentes, sendo que o primeiro componente explicou 57,28% e o segundo, 26,77% da variância contida nas sete variaveis. Os parâmetros mais representativos na variabilidade da salinidade das aguas foram Cl-, CE, Na+ e Mg2+, relacionados com a solubilidade dos sais.

Influence of land use/occupation on water quality in the Trussu river valley, Ceará, Brazil

The growing pressure on water resources has reduced its availability as regards quality. Data was investigated for two different periods, with the aim of evaluating the influence of the use and occupation of space on the temporal dynamics of the quality of surface and groundwater in the perennialised valley of the Trussu River in the State of Ceara, Brazil. The first period was from September 2002 to February 2004 and the second from April 2013 to April 2014. Twenty-two water samples were taken from nine sampling stations, five on the surface and four underground. The same stations were considered, monitoring 12 attributes of water quality for a total of 2,376 analyses. Temporal dynamics were characterised employing a technique of multivariate statistics: hierarchical cluster analysis (HCA). The three groups formed by the surface water were independent of collection time, indicating that there was no significant change at a level of 1%. The main differences between the periods of monitoring were seen in the groundwater, with a reduction in the values of EC, Na+, Cl- and HCO3-, and an increase in the concentrations of the PO43- and NO3- ions during the second period, forming two distinct groups: group 1 comprising the water collected during the first period, and group 2 the water collected from April 2013 to April 2014. These results reflect changes in the quality of the groundwater due to an increase in agricultural area, and show that the change in land use had a greater impact on the groundwater.

FATORES DETERMINANTES DA QUALIDADE DAS ÁGUAS EM DOIS PERÍODOS DISTINTOS SEPARADOS POR DEZ ANOS SEM MONITORAMENTO NO SEMIÁRIDO BRASILEIRO

A pressao crescente das praticas agropecuarias e da urbanizacao sobre o recurso agua vem reduzindo a sua disponibilidade sobre o aspecto qualitativo. Com o objetivo de identificar os fatores determinantes da qualidade das aguas superficiais e subterrâneas no vale perenizado do rio Trussu, Ceara, Brasil, investigou-se dados em dois periodos distintos separados por 10 anos sem monitoramento, 2002-2004 e 2013-2014, aplicando a tecnica de estatistica multivariada Analises de Componentes Principais-ACP. Foram realizadas 22 coletas em 9 estacoes (5 superficiais e 4 subterrâneas), nos diferentes periodos, monitorando 12 parâmetros de qualidade de agua totalizando 2376 analises. Foi identificado um modelo de melhor ajuste composto por 3 componentes, explicando 76,93% da variância total no primeiro periodo e por 2 componentes explicando 69,40% da variância no segundo periodo de monitoramento. As principais mudancas verificadas foram os ions PO43- e NO3-, que no primeiro periodo apresentaram maior significância no segundo e terceiro componente, respectivamente, enquanto que no segundo periodo de monitoramento apresentaram maior significância no primeiro componente.

CARACTERIZAÇÃO DAS VARIÁVEIS HIDROQUÍMICAS NA SUB-BACIA DO ALTO JAGUARIBE, CEARÁ UTILIZANDO ANÁLISE MULTIVARIADA E SIG

Evaluation of surface water quality and detection of possible degradations of fundamental importance for the monitoring of river basin management. Thereby the objective of this work was to evaluate the quality of surface water reservoirs in the basin of the Alto Jaguaribe, Ceara as the chemical parameter for irrigation purposes. The study was conducted in 10 reservoirs that are part of sub-basin of the Alto Jaguaribe. the data of chemical concentrations of the reservoir water were used in a period from 2001 to 2015 the following parameters: electrical conductivity (EC), chloride (Cl-), sodium (Na+), calcium (Ca2+) and magnesium (Mg2+), totaling 750 samples. The data came from the company’s database Water Management (COGERH) available to the Federal Institute of Education, Science and Technology of Ceara state, campus Iguatu. The statistical technique was applied Multivariate Hierarchical Cluster Analysis (HCA) for formation of the similarity between the reservoirs. According to results, the waters of the Alto Jaguaribe sub-basin reservoirs have so far, moderate risk to salinity in general, with the exception of shells of Inhamuns region, in which were found high concentrations of salts. The Broco and Favelas weirs obtained the highest concentrations of salts from the study, with the upper limit for human consumption and irrigation, fact occurred by the low capacity of the reservoirs, high evaporation and low rainfall, resulting in increased concentration of body salts water.

VARIAÇÃO ESPACIAL DA PRECIPITAÇÃO DAS CIDADES DO CENTRO DO SUL DO ESTADO DO CEARÁ, BRASIL

A quantidade de chuva representada em uma regiao e um dos fatores mais importantes para a caracterizacao do clima e, por conseguinte, nas relacoes de consumo da mesma. E importante tambem para o desenvolvimento socioeconomico de uma regiao, tendo em vista o seu diverso uso em todos os setores. Analis ou -se, neste trabalho, a espacializacao da variabilidade da precipitacao media num periodo de 10 anos das cidades do Centro Sul do Ceara com o objetivo de caracterizar quais cidades estao sofrendo com a estiagem/seca e o que deve ser feito para que este cenario mude. Os resultados obtidos foram de que numa pequena regiao ha bastantes oscilacoes quanto a precipitacao, que grandes partes dos municipios estudados estao abaixo da media gerada e que eventos como El Nino, La Nina e Zona de Convergencia Intertropical (ZCIT) podem influenciar no regime pluviometrico quando sendo analisadas em conjunto, nao separadamente. Tambem se concluiu que a espacializacao tem serventia de maneira geral para fins de dimensionamento agronomicos e armazenamento de agua em lugares estrategicos.

ESTRATO HERBÁCEO E FATORES HIDROSEDIMENTOLÓGICOS EM MICROBACIAS EXPERIMENTAIS COM DIFERENTES MANEJOS NO SEMIÁRIDO CEARENSE

Objetivou-se com o presente trabalho avaliar o efeito do bosque herbaceo sobre as respostas hidrosedimentologicas de microbacias localizadas no semiarido cearense. Foram avaliadas duas microbacias, uma apresentando cobertura vegetal caatinga nativa e a outra foi submetida ao raleamento das plantas cujo diâmetro do caule era inferior a 10 cm. As variaveis hidrosedimentologicas estudadas foram: precipitacao pluviometrica, umidade do solo, escoamento superficial e perda de solo. As variaveis foram monitoradas em escala temporal de 24 horas por um periodo de dois anos (Jan/2010 a Dez/2011). As coletas do estrato herbaceo foram coletadas mensalmente para o mesmo periodo. A producao de biomassa no manejo raleado chegou a ser superior em 90%, quando comparada com o manejo de caatinga nativa para o ano de 2010. Esse maior desenvolvimento da vegetacao herbacea na microbacia raleada promoveu um aumento na taxa de infiltracao da agua no solo, com consequente reducao da lâmina escoada e das perdas de solo, tal fato promoveu uma maior umidade do solo na microbacia raleada em mais de 89% dos eventos, quando comparada com a microbacia nativa. Do ponto de vista de conservacao de agua e solo, o manejo do raleamento se mostra bastante adequado para o bioma caatinga.

Measurement of soil erosion on different spatial scales with vegetation cover of caatinga in the northeast of Brazil

Erosion is a phenomenon whose impact on renewable natural resources has been worrying governments and institutions in different parts of the world. To this effect, this study aimed to generate and analyze information obtained in the field, involving the main processes and sources of variation in soil-loss data on different spatial scales in a semi-arid region with a vegetation cover of native caatinga. The study area is located in the semi-arid region of the state of Ceara in Brazil, in the watershed of the upper Jaguaribe River. Studies of erosion and runoff were conducted on three different levels: a watershed with an area of 2.06 ha, an erosion plot of 20 m2 and a plot of 1 m2, all under natural-rainfall conditions. The vegetation of the study area is made up of native caatinga. The study was carried out from 2009 to 2011, with rainfall concentrated in the period of January to June, corresponding to the rainy season in the region. The highest coefficients of runoff were recorded on the scale of the 20m2 plot in relation to the scales of 1m² and the watershed, with the exception of 2009. The highest soil loss in the first two years studied occurred in the watershed in relation to the 20m2 scale. These results were due to the special characteristics of the watershed, where there are places of high sediment yield, these barely being found on the scale of the smaller plot. The transfer soil-loss data measured for small plots, to larger scales cannot be made in a linear fashion.

Emergy Evaluation of Semi-Arid Watersheds Under Different Management Strategies

Due to the environmental impacts generated by economic activities and faced with the challenge of producing food for an increasing population, the sustainability of production methods should be analyzed to determine those with the highest relative yield and the least degradation of the environment. Seeking alternatives for sustainable use of the caatinga biome, this research tested two types of management strategies in watersheds of the semi-arid region in Iguatu, Ceara, Brazil, and compared them to a preserved area of caatinga. To evaluate the performance of the systems, an emergetic methodology, suggested by H. T. Odum, was used. The thinned area showed the best emergy results, with a transformity of 12,975 seJ J -1 , while the preserved area and that planted with grass presented transformities of 14,477 and 22,062 seJ J -1 , respectively. Through the activity of thinning, where the energy produced was 45% higher, the transformity was lower than that of the unchanged caatinga, showing that the investment in labor for thinning was offset by an increase in energy production. The high transformity of the untouched caatinga indicates that better use could be made of the available resources. This system could be used for beekeeping, ecological tourism, or any other activity that, as with thinning, would not alter the system beyond its capacity for tolerance but that would allow a more efficient use of the natural resources.