bluuebunny/crossref_metadata_2025 huggingface dataset:
Sentidos e significados atribuídos por um grupo de estudantes às tarefas matemáticas
Authors: Torisu Edmilson Minoru
Published: October 2018

Sentido e significado são coincidentes? Partindo da discussão em torno dessa pergunta e de alguns dados de uma pesquisa qualitativa, realizada com um grupo de alunos do nono ano do ensino fundamental de uma escola pública de Minas Gerais, os construtos sentido e significado, definidos à luz da Teoria da Atividade são discutidos no contexto da pesquisa. O objetivo é mostrar, partindo das respostas dos estudantes, obtidas por meio de entrevistas semiestruturadas, uma não coincidência entre o significado social e o sentido que eles atribuem às suas participações nas tarefas matemáticas propostas pelo pesquisador, ao longo de um semestre letivo. Essa não coincidência, que costumamos compreender como uma ruptura na aula de Matemática, em nível micro, e na escola de modo geral, em nível macro, pode gerar uma atividade alienada. Os resultados mostram que o significado social da Matemática e da escola, de forma geral, não coincide com o sentido pessoal atribuído pelos estudantes a elas. Ao final, discutem-se algumas possibilidades para a práxis docente como auxiliares na tessitura de uma prática transformadora imbuída do desejo/dever de possibilitar aos estudantes atribuírem novos sentidos à escola.
Editorial
Authors: Fiorentini Dario , Dassie Bruno Alves
Published: October 2018

Este é o segundo número do volume 26 da revista Zetetiké (v. 26, n. 2), relativo ao ano de 2018. Neste segundo número, publicamos dez (10) artigos que foram produzidos por 22 autores, sendo três deles do exterior. A metade destes trabalhos tem o professor que ensina matemática como foco principal de estudo e análise, sendo três voltados à formação e aprendizagem docente e dois à prática pedagógica do professor que ensina matemática. Em relação aos trabalhos relativos à outra metade, há três artigos que têm como foco privilegiado de estudo o estudante da escola básica em relação à aprendizagem da matemática. Os dois últimos artigos têm como foco de análise e discussão as tendências curriculares do ensino da matemática, sendo um relativo à educação do campo e o outro ao ensino médio.
Parametric Optimization for Automatic Control System of 300 MW Power Units at a Constant Steam Pressure Upstream of the Turbine
Authors: Kulakov G. T. , Kulakov A. T. , Artsiomenka K. I.
Published: October 2018

The problem of parametric optimization of automatic control systems of power units (ACSPU) of 300 MW at the Lukoml’skaya GRES (Lukoml Condensing Power Plant) at a constant superheated steam pressure upstream of the turbine is under consideration. During 1974–1979, eight units of the Lukoml’skaya GRES implemented ACSPU with a leading boiler power control, which will be forced to work in a wide range of loads due to the planned commissioning of two power units of the Belarusian NPP: the first one – in 2019, and the second one – in 2020. The total capacity of the Belarusian Nuclear Power Plant will amount to 2400 MW. In addition, modern requirements for the regulation of the frequency and flows of active electric power in the power system have been tightened: the time to reach the half value of the required power alteration should be 10 seconds within the normal and emergency reserves; the time to reach the full value of the required power alteration should be 30 seconds within the range of the normal reserve and 2 minutes – within the range of the emergency reserve. With this regard, increasing the efficiency of the units operating in the variable part of the electric load schеdule by the use of modern methods of calculation of parameters of the dynamic adjustment of the regulating devices of ACSPU becomes an urgent problem. The methodology of parametric optimization of the typical ACSPU that make it possible to improve the quality of power regulation and the pressure of the superheated steam upstream of the turbine is presented. The described technique is illustrated by the results of computer simulation of transient processes in the system when the task and internal disturbances are worked out, which confirm the correctness of the proposed technique in comparison with the known methods of optimization of the typical ACSPU.
Selectivity of Very‐Long‐Chain Fatty Acid‐Inhibiting Herbicides in Rice as Influenced by Application Timing and Soil Texture
Authors: Godwin John , Norsworthy Jason K. , Scott Robert C.
Published: October 2018

Core Ideas

Alternative herbicide sites of action are desperately needed in US rice.

Rice exhibited tolerance to the currently non‐labeled herbicides acetochlor and pethoxamid when applied at the one‐ to two‐leaf growth stage on a silt loam and clay soil.

Delaying application of very‐long‐chain fatty acid‐inhibiting herbicides until drill‐seeded rice has completely emerged enhanced crop tolerance.

Very‐long‐chain fatty acid (VLCFA)‐inhibiting herbicides include pyroxasulfone, S‐metolachlor, acetochlor, and pethoxamid. Currently, no VLCFA‐inhibiting herbicides are labeled for use in US rice production; however, if rice tolerance can be established they would provide an alternative herbicide site of action (SOA). In 2015 and 2016, pyroxasulfone (Zidua) at 0.14 lb a.i. ac−1, S‐metolachlor (Dual Magnum) at 0.95 lb a.i. ac−1, acetochlor (Warrant) at 0.95 lb a.i. ac−1, and pethoxamid at 0.75 lb a.i. ac−1 were applied delayed preemergence (DPRE) and to spiking and one‐ to two‐leaf rice on a Dewitt silt loam and a Sharkey clay soil. Trials were conducted at separate locations to determine the effect differing soil properties may have on the tolerance of rice to VLCFA‐inhibiting herbicides. Substantial rice injury was observed on the Dewitt silt loam soil following all pyroxasulfone and S‐metolachlor treatments, ranging from 20 to 100% injury 3 weeks after rice flooding. On the Dewitt silt loam, treatments containing acetochlor and pethoxamid applied to one‐ to two‐leaf rice resulted in minimal injury and the highest yields observed among VLCFA‐inhibiting herbicides. In general, rice injury ratings were less on the Sharkey clay soil. Pethoxamid and acetochlor applied to rice at any application timing resulted in ≤ 1% injury 2 weeks after treatment. Hence, contingent on a label, pethoxamid and acetochlor can be applied under similar conditions as early as DPRE on the Sharkey clay soil and not until the one‐ to two‐leaf rice stage on the Dewitt silt loam at the rates assessed.
Two Aphid Species, Phorodon cannabis and Rhopalosiphum rufiabdominale, Identified as Potential Pests on Industrial Hemp, Cannabis sativa L., in the US Midwest
Authors: Lagos‐Kutz Doris , Potter Bruce , DiFonzo Christina , Russell Howard , Hartman Glen L.
Published: October 2018

Core Ideas

Two aphid species, Phorodon cannabis and Rhopalosiphum rufiabdominale, were identified as potential pests on industrial hemp, Cannabis sativa L., in the US Midwest.

Samples of aphids were obtained from field‐grown industrial hemp, hydroponic production, and suction traps in the US Midwest.

Morphological and molecular data were used to discriminate Phorodon cannabis from P. humuli.
Macro-scale grid-based and subbasin-based hydrologic modeling: joint simulation and cross-calibration
Authors: Chu Xuefeng , Lin Zhulu , Nasab Mohsen Tahmasebi , Zeng Lan , Grimm Kendall , Bazrkar Mohammad Hadi , Wang Ning , Liu Xingwei , Zhang Xiaodong , Zheng Haochi
Published: October 2018

Watershed hydrologic models often possess different structures and distinct methods and require dissimilar types of inputs. As spatially-distributed data are becoming widely available, macro-scale modeling plays an increasingly important role in water resources management. However, calibration of a macro-scale grid-based model can be a challenge. The objective of this study is to improve macro-scale hydrologic modeling by joint simulation and cross-calibration of different models. A joint modeling framework was developed, which linked a grid-based hydrologic model (GHM) and the subbasin-based Soil and Water Assessment Tool (SWAT) model. Particularly, a two-step cross-calibration procedure was proposed and implemented: (1) direct calibration of the subbasin-based SWAT model using observed streamflow data; and (2) indirect calibration of the grid-based GHM through the transfer of the well-calibrated SWAT simulations to the GHM. The joint GHM-SWAT modeling framework was applied to the Red River of the North Basin (RRB). The model performance was assessed using the Nash–Sutcliffe efficiency (NSE) and percent bias (PBIAS). The results highlighted the feasibility of the proposed cross-calibration strategy in taking advantage of both model structures to analyze the spatial/temporal trends of hydrologic variables. The modeling approaches developed in this study can be applied to other basins for macro-scale climatic-hydrologic modeling.
Evaluating remotely sensed monthly evapotranspiration against water balance estimates at basin scale in the Tibetan Plateau
Authors: Liu Wenbin
Published: October 2018

Global evapotranspiration (ET) products, as compensation for eddy-covariance observations, provide useful data sources for understanding terrestrial water-energy budgets at different scales, especially for data-sparse regions. Here, we evaluated three remotely sensed ET products against water balance-based reference ET () in 16 river basins across the Tibetan Plateau (TP) on a monthly time scale from 1983 to 2011. The results indicated that ET_GLEAM performed the best overall across the 16 TP river basins in terms of the multi-year average and the interannual variability of monthly , followed by ET_ZHANG and ET_CSIRO. The multi-year means of monthly were better estimated overall by the three remotely sensed ET products rather than their interannual variability. However, the performances of the three ET datasets varied among different TP basins based on various evaluation criteria. The seasonal cycle of was better captured by ET_GLEAM, ET_ZHANG and ET_CSIRO in the Yalong, Yangtze and Salween Basins and the upper Yellow River Basins rather than that in the Yulongkashi, Bayin and Brahmaputra River Basins. Overall, the ET_GLEAM performed relatively better than other datasets. The evaluation results will provide important references for us to select suitable datasets and to apply them in basin-scale water-energy budget studies in data-sparse regions.
How does a rubber plantation affect the spatial variability and temporal stability of throughfall?
Authors: Liu Jiaqing , Liu Wenjie , Li Weixia , Zeng Huanhuan
Published: October 2018

In Xishuangbanna, southwest China, the large-scale monoculture rubber plantation replaced the primary tropical forest, which changed the regional hydrology processes and biogeochemical cycles. As throughfall was an important component of the forest ecosystem water input, we researched the spatial variability and temporal stability of throughfall in the rubber plantation. We recorded 30 rainfall events by using 90 rain gauges during 2015–2016. We found a highly significant linear relationship between rainfall and throughfall, and a strong power correlation between the peak 30 min rainfall intensity and throughfall. The coefficient of variation for throughfall was significant and negatively correlated with rainfall and rainfall intensity. We also observed that throughfall had a strong spatial autocorrelation that would decrease during heavy rainfall events. The results indicate that the leaf area index did not have a significant relationship with throughfall. However, the lateral translocation of the throughfall in the canopy significantly affected the spatial distribution of the throughfall. Generally, the lower throughfall positions were close to the nearest rubber trunk, and the higher throughfall positions were mostly below the slope. This study contributes to the knowledge of the spatiotemporal heterogeneity of throughfall and helps elucidate the interception processes in the rubber plantation.
Flood mapping in small ungauged basins: a comparison of different approaches for two case studies in Slovakia
Authors: Petroselli Andrea , Vojtek Matej , Vojteková Jana
Published: October 2018

Flood mapping is a crucial element of flood risk management. In small and ungauged basins, empirical and regionalization approaches are often adopted to estimate the design hydrographs that represent input data in hydraulic models. In this study, two basins were selected in Slovakia and different methodologies for flood mapping were tested highlighting the role of digital elevation model (DEM) resolution, hydrologic modeling and the hydraulic model. Two DEM resolutions (2 m and 20 m) were adopted. Two hydrologic approaches were employed: a regional formula for peak flow estimation and the EBA4SUB model. Two hydraulic approaches (HEC-RAS and FLO-2D) were selected. Different combinations of hydrologic and hydraulic modeling were tested, under different spatial resolutions. Regarding the DEM resolution, results showed its fundamental importance in the low relief area while its effect was secondary in the moderate relief area. Regarding the hydrologic modeling, results confirmed that it affects the results of the flood areas in the same way independently of DEM resolution and that when using event-based models, the hydrograph shape determination is fundamental. Regarding the hydraulic modeling, this was the step where major differences in the flood area estimation were found.
Modelling the frequency distribution of inter-arrival times from daily precipitation time-series in North-West Italy
Authors: Baiamonte Giorgio , Mercalli Luca , Berro Daniele Cat , Agnese Carmelo , Ferraris Stefano
Published: October 2018

The discrete three-parameter Lerch distribution is used to analyse the frequency distribution of inter-arrival times derived from 26 daily precipitation time-series, collected by stations located throughout a 28,000 km2 area in North-West Italy (altitudes ranging from 113 m to 2,170 m a.s.l.). The precipitation regime of these Alpine regions is very different (latitude 44.5 to 46.5 N) from the typical Mediterranean precipitation regime of the island of Sicily (latitude 37 to 38 N), where the Lerch distribution has already been tested and whose results are compared. In order to verify the homogeneity of the precipitation time series, the Pettitt test was preliminarily performed. In this work, a good fitting of the Lerch distribution to NW Italy is shown, thus evidencing the wide applicability of this kind of distribution, also allowing to jointly model dry spells and wet spells. The three parameters of the Lerch distribution showed rather different values than the Sicily ones, likely due to the very different precipitation regimes. Finally, a relevant spatial variability of inter-arrival times in the study area was revealed from the regional scale application of the probability distribution here described. The outcomes of this study could be of interest in different hydrologic applications.
Multi-index data dimension reduction approach and its applicability in the calculation of indicators of hydrological alteration
Authors: Zhang Wenhai , Jia Yangwen , Ge Jinjin , Huang Xiaorong , Ni Guangheng , Hou Jiaming , Wang Hao
Published: October 2018

The length of record (LOR) method is an evaluation method that provides quantitative advice for the amount of computational data required for use of the indicators of hydrological alteration (IHA). The use of multi-index hydrological indicators to reflect river hydrological–ecological characteristics is the essence of the IHA method, while the LOR evaluation result using a single index does not have practical application value in the absence of IHA data volume. In this paper, we expand the LOR method from single index version into multi-index version, apply it to comprehensively analyze the credibility of hydrological alteration (HA) multi-indicators under different data volumes, and explore the relationship between multi-index LOR results and data requirements. Combined with the hydrological–ecological relationship, the practical application criteria of LOR dimension reduction under the condition of multiple HA indicators is given. The results show that the LOR results corresponding to each group of indicators in IHA have different data requirements, so an in-depth understanding of the hydrological–ecological relationship is the key to LOR's application of IHA data dimension reduction. In addition, we discuss the limitations of the LOR method of multi-index dimension reduction and its application value in IHA calculations.
ENSO modulated groundwater variations in a river basin of Central India
Authors: Rishma C. , Katpatal Yashwant B.
Published: October 2018

Several previous studies have examined the traceable regional impacts of El Niño Southern Oscillation (ENSO) on groundwater level (GWL) but it remains a question whether the ENSO impacts on groundwater can be established in smaller basins using statistical techniques. The present study attempts to record the ENSO impacts on the groundwater availability in Venna basin, Maharashtra by proposing a combination of statistical and spatial analysis. Utilizing the GWL, the study estimates the spatial variability of GWL, groundwater anomalies, groundwater recharge and discharge using geographic information system (GIS) and quantitative variations in groundwater using statistical techniques. The study also highlights the applicability of the Kolmogorov–Smirnov test in hydrometeorological studies. Analyses reveal the association of deeper GWLs and higher discharge with the El Niño, as opposed to shallower GWLs and higher recharge with La Niña. The two-sample Kolmogorov–Smirnov test confirms the discrepancy in the cumulative distribution of GWL between different ENSO phases. Mann–Kendall, Sen slope and Mann–Whitney tests ascertain the variation of GWL and recharge as well as ENSO impacts in the command area (area irrigated by reservoir using the canal networks) and non-command areas. A significant difference in recharge between El Niño and La Niña is observed in the command as well as in the non-command areas.
Comparison of runoff and river flow in two large northern basins
Authors: Woo Ming-ko , Thorne Robin , Brown Laura
Published: October 2018

The magnitude and timing of water delivery in two large northern basins are analysed to clarify where runoff is generated and how their rivers acquire comparable regimes (or seasonal rhythms) of flow. These two rivers, the Mackenzie in Canada and the Yenisei in Russia, traverse similar latitudes, physiographic provinces, vegetation zones and climatic regions. Within the basins, mountainous terrain and high-precipitation sections usually yield large runoff, but low runoff comes from the plains, low plateaus and areas of aridity. Winter runoff is commonly low and snowmelt is responsible for annual peak runoff in most parts of these basins, though rainfall is a prominent runoff source in southern Yenisei. Many rivers in the drainage networks display a seasonal pattern that suggests the dominance of snowmelt to produce a spring freshet followed by a general decline in summer that diminishes to winter low flows. Regulation of reservoir outflow greatly distorts the natural flow regime. Yet, along the main river downstream of the reservoirs, the influx of tributary discharge can dilute such human influence. To truly understand how water is produced and transferred in large northern rivers, the spatial and temporal complexity of flow-generation mechanisms and storage effects need to be unravelled.
Operating parameters for three resource recovery options from slow-pyrolysis of faecal sludge
Authors: Gold M. , Cunningham M. , Bleuler M. , Arnheiter R. , Schönborn A. , Niwagaba C. , Strande L.
Published: October 2018

Slow-pyrolysis is a treatment technology that is being explored for treatment of faecal sludge (FS) from onsite sanitation technologies. Next to pathogen inactivation, the technology produces treatment products. Revenues from these products could offset treatment costs and contribute to financially viable sanitation. In comparison to lignocellulosic biomass and other biowastes, little information is available on operating parameters for FS pyrolysis to produce char for different resource recovery options. In Kampala, Uganda, this bench-scale study investigated the influence of two major operating parameters, hold time (10, 20 and 40 minutes) and pyrolysis temperature (350, 450 and 600 °C) for pyrolysis of FS into char for solid fuel production, soil enhancement and carbon sequestration. Hold time: 10 min was the most suitable hold time for all resource recovery options as char characteristics had only minor variations between hold times. Temperature: Char characteristics identified 350 °C as the most suitable for fuel production and 450 or 600 °C for carbon sequestration. FS char had characteristics for soil enhancement comparable to biowaste and lignocellulosic biomass chars, with heavy metal concentration exceeding guideline concentrations. The most suitable temperature needs to be selected based on plant and soil type, and legal regulations.
Contributing to water security through water tariffs: some guidelines for implementation mechanisms
Authors: Pinto Francisco Silva , Tchadie Alain Michel , Neto Susana , Khan Shahbaz
Published: October 2018

The reform of water pricing practices and tariff mechanisms plays an important role in improving water supply services. However, setting tariff policies is a process that is rife with controversy. The current urban development rhythm and consequent challenges, in several developing cities, requires an urgent review and the establishment of an increasingly more ‘integrated’ management system with a suitable water tariff policy to promote water security. Many lessons can be learned from the successes and failures of water pricing policies in other countries and world regions, taking into account the context, status and development of the water supply sector. In this paper, several case studies are assessed throughout different countries or regions (South Africa, Vietnam, Malaysia, Singapore, Australia, and Europe) to provide key information able to support successful policy ‘transfer routes’. Based on those lessons, key policy recommendations are summarized to pave the way towards water security, particularly in rapidly growing urban centres that suffer already from water stress.
Consolidating the use of reclaimed water for irrigation and infiltration in a semi-arid agricultural valley in Mexico: water management experiences and results
Authors: Mendoza-Espinosa L. G. , Daesslé L. W.
Published: October 2018

The city of Ensenada (Baja California, Mexico) experiences severe water restrictions for urban and agriculture use, and reclaimed water (RW) for crop irrigation and aquifer infiltration has been identified as a promising water management option. This paper presents the path followed to consolidate the reclamation scheme that included monitoring programs on RW, groundwater, and agricultural soil. Seventy-nine percent of the RW samples complied with the particular discharge permit for El Naranjo wastewater treatment plant (WWTP), yet the local water utility has to have a better control of its wastewater treatment plant to avoid spikes of fecal coliforms. The presence of fecal coliforms in soil samples at surface and 30–60 cm depths indicates that farm workers could be at risk during the handling of the product, so it is highly recommended that workers be provided with clothes that will protect them from direct contact with water and soil. Results from monitoring wells adjacent to Las Ánimas and San Carlos creeks showed, on some occasions, the presence of fecal and total coliforms that could indicate infiltration of RW. In conclusion, technical aspects can be monitored and controlled yet the most challenging aspects that remain are social and political which require extensive negotiation and institutional arrangements.
In-vessel co-composting – a rapid resource recovery option for septage treatment in Indian cities
Authors: Thomas Anu Rachel , Kranert Martin , Philip Ligy
Published: October 2018

Septage management is a challenging task across India as more than 44% of the population depends on septic tanks for human waste management. Septage collected from Chennai city, India, was found to be rich in nutrients even though the total solids content (<2%) and C/N are low. The current practice of septage disposal in Chennai city is co-treatment in existing sewage treatment plants. The main drawback of this method is that treatment efficiency could deteriorate if the organic load increased much beyond the design load of the treatment plant and would result in poor treated-water quality. In this context, the present study focused on the potential of in-vessel co-composting as a sustainable treatment option. In order to enhance the co-composting process, suitable co-substrates were identified for making the process efficient and cost-effective. The area under the temperature profile during composting was used as an assessment tool for the identification of the proper mix. Addition of mixed organic waste and coir pith waste (bulking agent) to the dewatered septage gave the highest area among the different combinations. Different waste combinations were investigated in order to assess the suitability for field scale application.
Improving the use of qualitative comparative analysis for inferring complex causation in development and planning research
Authors: Thiem Alrik
Published: October 2018

Empirical research methods provide the necessary means to extract relevant information from data. Qualitative Comparative Analysis (QCA), one such method, is currently making first inroads into the development and planning (D&P) community. On the one hand, QCA is well suited for building empirically founded theories emphasizing causal complexity. On the other hand, however, current use of QCA in D&P research is marked by problematic applications of this method whose results misrepresent the empirical evidence marshaled to support them. Policy recommendations that stand on shaky grounds have been issued in consequence. By reanalyzing a recent empirical study on school sanitation maintenance in Belize, this method workshop article shows how the use of QCA can be improved, which should in turn lead to more solid, evidence-based policy recommendations for development interventions.
Forecasting extreme events: making sense of noisy climate data in support of water resources planning
Authors: Cox Timothy , Bywater Jenny , Heineman Mitchell , Rodrigo Dan , Wood Shayne
Published: October 2018

Global climate model (GCM) projections are generally considered the best source of information for predicting future climate and hydrologic conditions in the face of a changing climate. Understanding and interpreting GCM projections is therefore critical for water resources planning. Unfortunately, this can be a challenging task as climate model data, particularly precipitation data, are notoriously noisy with large scatter and lacking in apparent patterns or trends. There is also usually large projection variability between models and model scenarios. This paper demonstrates a simple, practical method for synthesizing climate model data into more informative metrics using case studies of Atlanta, Georgia and Austin, Texas. Monthly and daily GCM projections, as well as historical observations, were translated into commonly used summary metrics for extreme event planning: peak 24-hour storm events and the Palmer Drought Severity Index (PDSI). Statistical trend analyses on these two metrics were used as a simple means to better understand the data. As expected, results identified significant, increasing, trends in projected 21st century temperatures for most GCM projections. Less expectedly, significant trends were also identified for projected future monthly and 24-hour maximum precipitation and drought severity. Implications of this work for water resources planning are discussed.
Statistical analysis of rainfall and streamflow time series in the Lake Tana Basin, Ethiopia
Authors: Tigabu Tibebe B. , Hörmann Georg , Wagner Paul D. , Fohrer Nicola
Published: October 2018

This research focuses on the statistical analyses of hydrometeorological time series in the basin of Lake Tana, the largest freshwater lake in Ethiopia. We used autocorrelation, cross-correlation, Mann–Kendall, and Tukey multiple mean comparison tests to understand the spatiotemporal variation of the hydrometeorological data in the period from 1960 to 2015. Our results show that mean annual streamflow and the lake water level are varying significantly from decade to decade, whereas the mean annual rainfall variation is not significant. The decadal mean of the lake outflow and the lake water level decreased between the 1990s and 2000s by 11.34 m3/s and 0.35 m, respectively. The autocorrelation for both rainfall and streamflow were significantly different from zero, indicating that the sample data are non-random. Changes in streamflow and lake water level are linked to land use changes. Improvements in agricultural water management could contribute to mitigate the decreasing trends.
Automated procedure of real-time flood forecasting in Vu Gia – Thu Bon river basin, Vietnam by integrating SWAT and HEC-RAS models
Authors: Loi Nguyen Kim , Liem Nguyen Duy , Tu Le Hoang , Hong Nguyen Thi , Truong Cao Duy , Tram Vo Ngoc Quynh , Nhat Tran Thong , Anh Tran Ngoc , Jeong Jaehak
Published: October 2018

The precise and reliable simulation of hydrologic and hydraulic processes is important for efficient flood forecasting and warning. The study proposes a real-time flood forecasting system which integrates a coupled hydrological-hydraulic modeling system, weather station network, and stream gauges in a web-based visualization environment. An automated procedure was developed for linking dynamically terrestrial rainfall-runoff processes and river hydraulics by coupling the SWAT hydrological model and the HEC-RAS hydraulic model. The flood forecasting system was trialed in the Vu Gia – Thu Bon river basin, Quang Nam province, Vietnam. The results showed good statistical correlation between predicted and measured stream flow for a 10-year calibration period (R² = 0.95, NSI = 0.95, PBIAS = −1.54) and during the following 10-year validation period as well (R² = 0.93, NSI = 0.93, PBIAS = 6.18). A close-up analysis of individual storm events indicated that the magnitude and timing of peak floods were accurately predicted in 2015 (R² = 0.88, NSI = 0.69, PBIAS = 4.50) and 2016 (R² = 0.80, NSI = 0.93, PBIAS = 6.18). In addition, the automated procedure was demonstrated to be reliable with dependable computational efficiency of less than 5 minutes' processing time.
Effect of sustainable management of olive tree residues on soil fertility in irrigated and rain-fed olive orchards
Authors: Kavvadias V. , Papadopoulou M. , Vavoulidou E. , Theocharopoulos S. , Koubouris G. , Psarras G. , Manolaraki Chr. , Giakoumaki G. , Vasiliadis A.
Published: October 2018

Olive trees are a major source of agricultural residues. Strategies based on different management of organic amendments have been reported to increase soil fertility. The effect of sustainable organic matter input practices (application of shredded pruning residue and olive residue compost to soil) on soil properties in irrigated and rain-fed olive groves was investigated. The study took place in 40 olive groves in the region of Peza, island of Crete, Greece during a 5-year period (2012–2017). The results showed that olive trees play an important role in soil nutrient conservation under semi-arid conditions in the Mediterranean basin. The addition of olive tree residues, in combination with conservation tillage practices, improved soil fertility over the experimental period. Most of the soil properties were favored by irrigation. In olive soil parcels receiving organic materials the soil organic matter and the total nitrogen were increased in irrigated fields. The ability of surface soil to sequester carbon and nutrients beneath the tree canopy of olive groves was high. It is recommended that sustainable soil management practices should consider soil fertility variability of olive orchards.
A mini review of activated methods to persulfate-based advanced oxidation process
Authors: Song Wei , Li Ji , Wang Zhuoyue , Zhang Xiaolei
Published: October 2018

Persulfate-based advanced oxidation has been widely applied in environmental remediation for degrading contaminants. In recent years, numerous kinds of organic analytes including pesticides, dyes and pharmaceuticals, have emerged and related researches on the activation methods, the mechanism and the application have been performed. The activation is critical in persulfate-based advanced oxidation because the persulfate alone has a weaker oxidation potential to degrade these organic pollutants. Hence various activation methods have been extensively investigated to achieve a higher oxidation efficiency. These novel methods are gradually expanding the applicability and practicality. This review focuses on the classification of the different activation methods based on whether it is related to the substances or not. The effect of the environmental conditions (solution pH, dosage and the co-existing substance) on the oxidation capacity are also discussed.
An assessment of drought on maize cropping success in ancient Maya lowlands during the last half of the first millennium ce
Authors: Wong Alfred
Published: October 2018

Drought arising from a shift in intertropical convergence zone in the Yucatán peninsula during the last half of the first millennium is often cited as a determining cause in the collapse of ancient Maya polities. Some Mayanists have postulated that a small change in precipitation might have been sufficient to result in catastrophic cropping failure, with attendant large decline in population. The supporting data for this conjecture are essentially very weak. In particular, paleoclimatologists could provide only qualitative drier or wetter periods. The data resolution has not been at the level of daily or monthly precipitation in ancient times. It is well known in the cropping of maize that the pattern, frequency, and quantity of precipitation, among other things, during the growing period are of paramount importance. Present quantitative assessment suggests that a decrease of the order of 40%, uniformly over a 125-day growing season, from normal precipitation may not have an adverse impact on maize cropping success. This finding presents doubts in the hypothetical climate-based cause of catastrophic decline in population during the period of ‘Maya collapse’.
Research on spatial-temporal distribution characteristics of main pollutants of the rivers in the Linyi Development Zone
Authors: Liu Chao , Qian Binjie , Wang Liyuan , Miao Qun
Published: October 2018

The pollution issues with urban rivers is one of the key factors affecting the urban ecological environment, and water pollution control has become the top task for urban ecological construction. The first step of controlling water environment pollution is to have an objective knowledge of the water quality. This research selects the rivers in the Linyi Development Zone as the subject and analyzes the major pollution factors and the spatial-temporal distribution characteristics of the main pollutants in the river system based on routine monitoring data of the river system in the zone from August 2014 to May 2017, and also accurately judges the variation trend of the water quality with the time through the Spearman rank relational coefficient. The research result shows that NH3-N, TP, CODCr, CODMn, BOD5 are the main pollution factors. Between 2014 and 2017, the overall water quality variation trend of the river system in the development zone is very significant, and the water quality variation basically remains stable. The water quality variation and major pollution sources of the rivers in the development zone are judged, providing an important basis for the water ecology construction of the development zone.
The influence of silviculture investment in fixed assets on forest water conservation in China
Authors: Ying Zhang , Yi Aijun , Fang Lan
Published: October 2018

Forests play an important role in water conservation. It is important to study the relationship between forest water conservation (FWC) and forestry investment. Based on official statistics and ecological network observation data in China from 1999 to 2013, this paper for the first time uses correlation analysis and regression analysis methods to analyze the relationship between FWC and forest silviculture investment in fixed assets (FSIFA). Results show that FWC and FSIFA have a strong correlation and a strong influence, correlation coefficient is around 0.96. The amount of annual forest water conservation is increased with an increase in investment in fixed assets. The study also found that FSIFA affecting annual FWC lags more than 1 year, showing that FSIFA cannot play a role in water conservation immediately. The research also discussed other affecting factors on FWC, such as forest coverage rate, economic development level and forest quality improvement, etc. Their effects were also found to lag 1–5 years. Finally, the paper predicts the amount of annual FWC from 2014 to 2020 and gives some suggestions to strengthen investment in forest fixed assets and improve management of forest resources so as to promote the development of benefits of FWC.
Sustainability assessment of restoration plans under climate change by using system dynamics: application on Urmia Lake, Iran
Authors: Sarindizaj Elham Ebrahimi , Zarghami Mahdi
Published: October 2018

During the last decade, Urmia Lake has lost most of its surface area. As a result, finding management practices to restore the sustainable ecological status of Urmia Lake, the world's second largest hyper-saline lake, is imperative. In this study, the sustainability of different plans under climate change was assessed using system dynamics. The plans were evaluated with respect to sustainability criteria including reliability, resiliency, and vulnerability measures. According to the results due to different management practices, on average, water consumption should be reduced by at least 30% to restore the lake. The results revealed that only hybrid plans which incorporate multiple management practices, instead of focusing on just one approach, can be influential. Among the hybrid plans, that of increasing irrigation efficiency, reducing cultivated area, changing crop pattern, and inter-basin water transfer was identified as the most sustainable plan. About eight years after applying this plan, the lake will achieve its ecological level and will remain sustainable. Considering comprehensive factors, the proposed model can help watershed managers to take the necessary measures to restore this vital ecosystem. The results of this study can be applied to water resources systems with the same problem, especially those in semi-arid regions with multidisciplinary aspects.
Trend analysis of watershed-scale annual and seasonal precipitation in Northern California based on dynamically downscaled future climate projections
Authors: Ishida K. , Ercan A. , Trinh T. , Jang S. , Kavvas M. L. , Ohara N. , Chen Z. Q. , Kure S. , Dib A.
Published: October 2018

Impact of future climate change on watershed-scale precipitation was investigated over Northern California based on future climate projections by means of the dynamical downscaling approach. Thirteen different future climate projection realizations from two general circulation models (GCMs: ECHAM5 and CCSM3) based on four emission scenarios (SRES A1B, A1FI, A2, and B1) were dynamically downscaled to 9-km resolution grids over eight watersheds in Northern California for a period of 90 water years (2010–2100). Analysis of daily precipitation over the eight watersheds showed that precipitation values obtained from dynamical downscaling of the 1981 to 1999 control runs of ECHAM5 and CCSM3 GCMs compared well with the PRISM data. Long-term future trends of annual and seasonal basin-average precipitation were investigated. Although a large variability exists for the projected annual basin-average precipitation within each of the 13 individual realizations, there was no significant long-term trend over the eight study watersheds except for the downward trend in the A1FI scenario. On the other hand, significant upward and downward trends were detected in the seasonal basin-average precipitation except in the winter months (January, February, and March). The trend analysis results in this study indicated the importance of considering seasonal variability, scenario, and model uncertainty.
Joint effects of five environmental factors on the growth of cyanobacterium Microcystis aeruginosa
Authors: Hu Guikun , Zhang Qingtian
Published: October 2018

In many lakes and reservoirs, Microcystis aeruginosa is one of the dominant bloom species. Five environmental factors, including nutrients and physical factors, were selected to evaluate their effects and interactions on the growth of M. aeruginosa (FACHB-905) by joint analysis in a laboratory batch culture. The results indicated that all five factors affected the growth rate alone or in combination, and that their interactions were complex. This cyanobacterium strain preferred higher water temperature and alkaline conditions, while not requiring high illumination or high concentrations of nitrogen and phosphorus. Owing to these features the bloom of this cyanobacterium appears easily in nature. The form of nitrogen (nitrate or ammonium) also affected the assessment of M. aeruginosa bloom. The possibility of M. aeruginosa bloom would still exist even if the phosphorus concentration in the water column was very low. The result provided a good basis for the analysis and prediction of M. aeruginosa blooms in terms of environmental assessment, because the joint analysis of multiple factors would offer more valuable information than a univariate analysis.

This article has been made Open Access thanks to the kind support of CAWQ/ACQE (https://www.cawq.ca).
Assessing the impacts of changing climate and human activities on streamflow in the Hotan River, China
Authors: Fu Xiaohua , Shen Bing , Dong Zengchuan , Zhang Xiao
Published: October 2018

Climate change and intensified human activities are regarded as the two driving factors for most river systems having lost their connection with the Tarim River. The Hotan River is the second largest headstream of the Tarim River; therefore, it is important to determine the causes of its reduction in streamflow supply. Based on an analysis of changes in hydro-meteorological regime and the effects of direct human activities on streamflow, their contributions to the decrease in streamflow in different periods (natural period, 1964–1988; transition period, 1989–2002; post-transition period, 2003–2012) from the Hotan River to the Tarim River were quantified based on a double-mass curve of inflow and outflow in the Hotan River Basin. The results indicate that climatic changes reduced streamflow during the transition period yet increased streamflow during the post-transition period. Human activities reduced output by 73% in the transition period and by 127% in the post-transition period, which was significantly stronger than the contribution from the climate. Thus, human activities appear to be the main driving factor for the drop in streamflow from the Hotan River into the Tarim River. These results can be used as a reference for water resource planning and management.
Study on the hydro-chemistry process after mixing between water and rocks
Authors: Jing Xiuyan , Yang Hongbin , Wang Na
Published: October 2018

The chemical evolution of groundwater has received close attention from hydro-geologists. Northwest China largely consists of arid and semi-arid regions, where surface water and groundwater frequently exchange with each other, and where the mixing and water–rock interactions significantly affect the direction of water quality evolution. Based on experimental simulation, this paper investigates the interactions among the Yellow River water, groundwater and rocks in Yinchuan. The study found that when groundwater is mixed with the Yellow River water, the Yellow River water has a certain dilution effect on the hydro-chemical composition of groundwater; however, this effect is not simply diluted by proportion for no reaction between irons, but a portion of calcium, sulfur, and carbonate form precipitates. After mixing of the Yellow River water, groundwater and rocks, the pH increased, and the carbon dioxide system reached equilibrium again. In addition, CO32− was produced. While Na+ increase was mainly due to dissolution, SO42− decrease was because of precipitation. The precipitation or dissolution of Ca2+, Mg2+, and CO32− mainly depended on the mixing ratio between groundwater and river water, which suggested the reversible behavior of the dissolution-precipitation of carbonate minerals.
Natural organic matter as precursor to disinfection byproducts and its removal using conventional and advanced processes: state of the art review
Authors: Tak Surbhi , Vellanki Bhanu Prakash
Published: October 2018

Natural organic matter (NOM) is ubiquitous in the aquatic environment and if present can cause varied drinking water quality issues, the major one being disinfection byproduct (DBP) formation. Trihalomethanes (THMs) are major classes of DBP that are formed during chlorination of NOM. The best way to remove DBPs is to target the precursors (NOM) directly. The main aim of this review is to study conventional as well as advanced ways of treating NOM, with a broad focus on NOM removal using advanced oxidation processes (AOPs) and biofiltration. The first part of the paper focuses on THM formation and removal using conventional processes and the second part focuses on the studies carried out during the years 2000–2018, specifically on NOM removal using AOPs and AOP-biofiltration. Considering the proven carcinogenic nature of THMs and their diverse health effects, it becomes important for any drinking water treatment industry to ameliorate the current water treatment practices and focus on techniques like AOP or synergy of AOP-biofiltration which showed up to 50–60% NOM reduction. The use of AOP alone provides a cost barrier which can be compensated by the use of biofiltration along with AOP with low energy inputs, making it a techno-economically feasible option for NOM removal.
Assessment of the parasitological quality of water stored in private cisterns in rural areas of Tunisia
Authors: Ben Ayed Layla , Belhassen Khaoula , Sabbahi Sonia , Karanis Panagiotis , Nouiri Issam
Published: October 2018

Limited access to safe water enhances poverty, hunger and diseases. This study evaluated the drinking water quality stored in home-based systems, located in rural areas of Tunisia. Water management was also documented as an improvement of good practice as most of the water contamination could be related to behavioral patterns. Thirty-nine water samples from five different sources (rainwater, truck cistern, mix, etc.) were screened for enteric parasitic contamination with the modified Bailenger technique. This technique allowed the detection of three protozoa: Giardia spp.; Entamoeba histolytica/dispar/moshkovskii; Entamoeba coli and one helminth specie: Ascaris spp. The overall prevalence of these intestinal parasites was approximately 97% with a relatively high frequency of protozoa over helminths and more specifically E. histolytica/dispar/moshkovskii. This incidence could be correlated to the lack of hygiene practices, sanitation and education. This situation requires the need for frequent monitoring of the water quality and management in these areas.