Raphael Abrahão

Impact of irrigation implementation on hydrology and water quality in a small agricultural basin in Spain

Abstract Irrigation practice has increased considerably recently and will continue to increase to feed a growing population and provide better life standards worldwide. Numerous studies deal with the hydrological impacts of irrigation, but little is known about the temporal evolution of the affected variables. This work assesses the effects on a gully after irrigation was implemented in its hydrological basin (7.38 km2). Flow, electrical conductivity, nitrate concentration and exported loads of salts and nitrates were recorded in Lerma gully (Zaragoza, Spain) for eight hydrological years (2004–2011), covering the periods before, during and after implementation of irrigation. Non-parametric statistical analysis was applied to understand relationships and trends. The results showed the correlation of irrigation with flow and the load of salts and nitrates exported, although no significant relationship with precipitation was detected. The implementation of irrigation introduced annual trends in flow (3.2 L s-1, +23%), salinity (–0.38 mS cm-1, –9%), and nitrate concentration (5.4 mg L-1, +8%) in the gully. In addition, the annual loads of contaminants exported increased (salts and nitrates, 27.3 Mg km-2 year-1, +19%, and 263 kg NO3–-N km-2 year-1, +27%, respectively). The trends presented a strong seasonal pattern, with higher and more significant trends for the irrigation season. The changes observed were different from those of larger irrigation districts or regional basins, due to the differences in land use and irrigation management. It is important to understand these changes in order to achieve an adequate management of the environment and water resources. Editor Z.W. Kundzewicz Citation Merchán, D., Causapé, J., and Abrahão, R., 2013. Impact of irrigation implementation on hydrology and water quality in a small agricultural basin in Spain. Hydrological Sciences Journal, 58 (7), 1400–1413.

Nitrate and salt water contamination associated with the transition of an agrarian basin into an irrigated area.

The introduction of irrigation to agrarian areas involves several environmental changes that can be aggravated by physical and agronomic factors. The aim of this study is to analyze the spatiotemporal dynamics of the environmental impact on water resources that result from the transition of an agrarian basin into an irrigated area. During five hydrological years, a spatiotemporal comparison was carried out on the quantity and quality of drainage from the four zones in which the study area was subdivided. Introduction of irrigation activities incorporated flows that lowered salinity and increased nitrate concentration in the basin. The zones/years with most irrigation showed the greatest exports of salts and nitrates, with temporal variations related to rainfall patterns and spatial variations related to soil salinity and nitrogenous fertilization. The agro-environmental impacts of the gradual introduction of irrigation into a previously non-irrigated area were congruent to that of established irrigation areas with similar characteristics.

Production and Bromatological Characteristics of Elephant Grass— Cenchrus purpureus (Schumach.) Morrone—Planted Under Application of Industrial Biosolid and Chemical Fertilization

Biosolid, i.e., dehydrated sludge from effluent treatment stations, has been progressively used as an agricultural fertilizer due to its high organic matter and nutrient contents. Elephant grass (Cenchrus purpureus (Schumach.) Morrone) presents easy adaptation and high yields, being used for animal feeding and for energy purposes. The objective of this work was to analyze the production and bromatological parameters of elephant grass with four different doses of biosolid, one of chemical fertilizer and a control plot, with two replicates each. A field experiment was carried out using a randomized block design with three blocks, totaling 18 plots, which received biosolid fertilization at 1×, 2×, 4×, and 8× the levels recommended by the Brazilian National Environment Council, along with conventional chemical fertilization and no fertilization, all under similar drip irrigation. Tukey’s test indicated a significant difference at p < 0.01 for total production in the first cut and acid detergent fiber in the second cut. At p < 0.05, significant differences were detected for total nitrogen and total protein in the first cut. The elephant grass yield under “1× biosolid” was similar to that reached with chemical fertilization. Physical and bromatological characteristics indicated potential use as animal feed and energy source. For doses higher than specified by Brazilian standards (2×, 4×, and 8×), further studies are required to verify possible contamination from heavy metals, pathogenic microorganisms, and n.

Assessment of Precipitation Trends in the Sertão Paraibano Mesoregion

The state of Paraíba, located in the northeastern region of Brazil, comprises 223 municipalities and covers an area of 56,469 km. Paraíba is divided into four major mesoregions: Zona da Mata, Agreste, Borborema and Sertão Paraibano. For this study, the Sertão Paraibano mesoregion, a semiarid area, was chosen to understand vulnerability to climate change, taking into account the region’s economic importance for water and energy supply. The Mann-Kendall non-parametric test was applied to evaluate trends in the historical series of monthly, trimestrial, biannual and annual precipitation data. The series utilized corresponded to the period 1912-2012 and were built from data generated by five meteorological stations distributed throughout the mesoregion. These stations are maintained by the Executive Agency for Water Management (AESA) and National Department of Works Against Drought (DNOCS). The results indicated increasing precipitation trends for the Sertão Paraibano mesoregion, especially in the annual evaluation, for the first semester of the year (January to June), for the trimester December-January-February and the month of January, with slopes between 2.67 mm/year and 5.45 mm/year. The results evidenced the need to deepen studies on the influence of climate change in the area, to promote prompt adaptation measures.

Trends in Temperature and Rainfall Extremes near the Artificial Sobradinho Lake, Brazil

The formation of artificial lake due construction of a hydroelectric plant causes irreversible environmental impacts. Studies associated with these artificial lakes for the Brazilian semiarid region are still insufficient. Thus, the objective of this study is to provide new information on the trends of climatic extremes, dependent on rainfall and air temperature, for the Sobradinho Hydroelectric Power Plant (SHPP) lake region, through the analysis of climate change indices. This study is particularly important for the SHPP region because microclimate changes have significant impacts on the natural, social and economic sectors. For the two analyzed stations (Bebedouro-PE and Mandacaru-BA), it is not possible to affirm that the construction of the SHPP artificial lake altered the local microclimate. Trends of increase in maximum temperature, the number of hot days and diurnal temperature range were noticed. However, the rise of these indices cannot be attributed to the formation of the SHPP lake. The influence of the SST of Tropical Oceans on the temporal behavior of some of the indices used in this study may have contributed to increases in hot days and nights, maximum temperature, diurnal temperature range and consecutive dry days over the region.

Effectiveness of nutrient remotion and cell physiology of Amphora sp. cultured in shrimp farm effluents

Shrimp farm effluents are one of the principal causes of eutrophication in coastal environments. Integrated processes of bioremediation involving the culturing of purifying organisms have been suggested, but very few studies have focused on microalgae. For that purpose evaluated the growth potential of Amphora sp. in the residual waters of shrimp farm activity fulfilled on the Paraíba State, Brazil. The experiments were performed using Conway medium as the control and wastewaters from shrimp farm at 100% concentrations. Amphora sp. demonstrated good growth in the shrimp farm effluents under test conditions, although less than that observed in the control medium. This diatom was found to removed 73.357 and 72.572% of PO4− and NO3−, respectively, demonstrating a high mitigation potential for this type of effluent. Comparisons of the physiological responses measured by flow cytometry demonstrated higher cell densities of Amphora sp. in the control medium, but a higher lipid content was observed in Amphora cultured in shrimp farm effluents.

TENDÊNCIAS CLIMÁTICAS NA MESORREGIÃO DA MATA PARAIBANA E SUA INFLUÊNCIA NA PRODUÇÃO DE ENERGIA FOTOVOLTAICA

Climate change can be damaging to all sectors of society, with possible permanent negative environmental impacts such as the extinction of different species from an ecosystem. Living things usually require an adaptation period to create mechanisms for survival to the new climate. Energy production follows a similar pattern, especially for renewable sources, which are closely related to the local climate. In this study, climatic data from the Mata Paraibana mesoregion were analyzed for the climatic characterization and understanding of trends in the parameters maximum, minimum and mean temperature, besides cloudiness. The evolution of these parameters in the mesoregion was understood to verify the estimation of electricity production for two ENCICLOPÉDIA BIOSFERA, Centro Científico Conhecer Goiânia, v.15 n.27; p. 2018 90 models of photovoltaic panels. In this way, impacts of climate change on the performance of the photovoltaic panels were measured.

Group Comparison, Trends and Cluster Analysis to Understand Historical Precipitation

Several studies alert about increasing temperatures in different sites of the world. Most of the studies are based on climate models, but the use of historical climate data also presents similar results. These increasing temperatures are not the only climate element suffering change. Shifting in precipitation patterns (frequency and intensity) is another important change that needs to be better understood, as it may result in different environmental and social impacts. Understanding how climate is changing, as well as the potential impacts of these climate changes, is crucial for the determination of adaptation policies towards mitigation of the impacts of climate change. Relatively long historical climate datasets are available for many cities and sites, but little use of this information is made towards a better understanding of climate change impacts. The high cost of installation and maintenance of the climate monitoring stations, throughout decades, could be better availed and deeper information about the dynamics of regional climate change could be obtained from the datasets. For this study, three different approaches were followed to understand local precipitation from historical data: (1) a general assessment of annual totals with comparison of past and recent periods; (2) trend analysis; and (3) the application of cluster analysis to analyze monthly and seasonal changes. Fifty-five years of monthly rainfall and snowfall data were obtained from Environment Canada (Canadian National Climate Data and Information Archive) for the municipality of Sudbury (Ontario, Canada). The dataset suggests that annual rainfall is increasing in Sudbury while annual snowfall is not changing significantly. Trend analysis detected annual, seasonal and monthly changes in rainfall, highlighting that the annual increasing trends observed for rainfall volumes were not uniform throughout the year. No significant trends were detected for snowfall. However, cluster analysis detected changes in snowfall distribution for December, January and February, the 3 months of higher snowfall values in the site. The clusters also evidenced that, despite the annual increases in rainfall, decreases could be observed in some months, especially in summer, the rainier season in Sudbury. This study did not intend, by any means, to prove that the methodology herein presented is better than the overspread use of climate models. The results highlighted the importance of also taking into account these different approaches, and combinations of the three methods should be considered to provide a more detailed perspective of monthly and seasonal changes that could be hidden in the usual high variability of some climate elements, such as precipitation.

Watershed Monitoring for the Assessment of Irrigation Water Use and Irrigation Contamination

One of the main current questions on the sustainability of life in our planet is if in the next years there will be sufficient water to satisfy the necessities of agriculture and of the other users of this important resource (urban, industrial, touristic and ecological uses). Irrigation activities allow for the increase of agrarian yields, also allowing for a greater stability in food supply, mainly in those regions where the development of crops is limited by rain. In this way, agriculture consumes 70% of all water extracted from natural courses, being considered the main responsible factor for global fresh water shortage (FAO, 2002). Nevertheless, although the volumes employed by the agrarian sector are high, at a global level it is estimated that only 50% of the water extracted is finally utilized by plants; the remaining share ends up in drainage and irrigation return flows in rivers and aquifers (FAO, 2003). These volumes returned to water systems could contribute to a reduction in the impact generated by the extraction of resources if the water quality was not very distant from that of the original water extracted, due to the transport of salts and agrochemicals from the soil profile. Regarding the presence of agrochemicals, nitrate is a very important issue for water quality, and above all, is associated with notable changes implemented in agriculture in the last decades (OMS, 2004). The problem of nitrate with respect to other agrochemicals is its effect on human health by the simple fact of being present in high concentrations in potable water. The consumption of water with high concentrations of nitrate causes the development of methemoglobinemia in the blood, making the blood stream incapable of transporting enough oxygen through the organism and leading to death of the individual (OMS, 2004). On the other hand, the occurrence of high concentrations of nitrate in rivers and oceans is causing serious environmental effects on aquatic plants and animals, leading to the occurrence of anoxic zones and eutrophication of water resources (Diaz, 2001), as is evidenced on the coast of the United States (Scavia and Bricker, 2006) and China (Wang, 2006). The impacts generated by irrigation can be aggravated by physical (geology and climate) and agronomic (management of irrigation and fertilization) factors. For example, the natural salinity of the area in which irrigation is implemented can contribute significantly to the

Water quality of a stream receiving industrial effluents, located in the Brazilian Northeast

Industries, as a source of pollution, have a considerable impact on water resources due to the diversity in the composition of their effluents. The Mussure Stream was chosen for this study because it flows across the industrial district of Joao Pessoa, in Northeast Brazil, and is the main receiver of liquid effluents, which are disposed into the stream almost exclusively without adequate treatment. The objectives of this study are to use the water quality index WQIB to give an overview of the impact of the industrial effluents on the quality of the water of the Mussure Stream, as well as the comparison of the content of dissolved oxygen found in the water with the minimum values required by the effective legislation. The results indicated that the water of the Mussure Stream presented levels of dissolved oxygen that were below that which could be considered satisfactory and the water was classified according to the WQIB, during the two years of the study, between 35 and 49, for all collecting stations, indicating low water quality and a potential risk for the population.