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[Online] Watershed Ecology

Guest Editors-in-Chief 
Yang, Zhifeng, Beijing Normal University, China
Crittenden, John, Georgia Institute of Technology, USA
Executive Editor-in-Chief
Yan, Denghua, China Institute of Water Resources and Hydropower Research, China
Brown, Mark T., University of Florida, USA
Chen, Qiuwen, Nanjing Hydraulic Research Institute, China
Daigger, Glen, University of Michigan, USA
Guan, Dabo, University of East Anglia, UK
Kondolf, G. Mathias, University of California, Berkeley, USA
Lega, Massimiliano, Parthenope University of Napoli, Italy
Petts, Geoffrey, University of Westminster, UK
Sudicky, Edward, University of Waterloo, Canada
Yu, Zhongbo, Hohai University, China
Yin, Xin-An, Beijing Normal University, China Liu, Gengyuan, Beijing Normal University, China
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Sustainable Resource Use in Enhancing Agricultural Development in China
Jianbo Shen, Fusuo Zhang, Kadambot H.M. Siddique
Engineering    2018, 4 (5): 588-589.
Abstract   PDF (288KB)
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A New Method of Assessing Environmental Flows in Channelized Urban Rivers
Xin-An Yin, Zhifeng Yang, Enze Zhang, Zhihao Xu, Yanpeng Cai, Wei Yang
Engineering    2018, 4 (5): 590-596.
Abstract   PDF (482KB)

Assessing environmental flows (e-flows) for urban rivers is important for water resources planning and river protection. Many e-flow assessment methods have been established based on species’ habitat provision requirements and pollutant dilution requirements. To avoid flood risk, however, many urban rivers have been transformed into straight, trapezoidal-profiled concrete channels, leading to the disappearanceof valuable species. With the construction of water pollution-control projects, pollutant inputs into rivers have been effectively controlled in some urban rivers. For these rivers, the e-flows determined by traditional methods will be very small, and will consequently lead to a low priority being given to river protection in future water resources allocation and management. To more effectively assess the e-flows of channelized urban rivers, we propose three e-flow degrees, according to longitudinal hydrological connectivity (high, medium, and low), in addition to the pollutant dilution water requirement determined by the mass-balance equation. In the high connectivity scenario, the intent is for the e-flows to maintain flow velocity, which can ensure the self-purification of rivers and reduce algal blooms; in the medium connectivity scenario, the intent is for the e-flows to permanently maintain the longitudinal hydrological connectivity of rivers that are isolated into several ponds by means of weirs, in order to ensure the exchange of material, energy, and information in rivers; and in the low connectivity scenario, the intent is for the e-flows to intermittently connect isolated ponds every few days (which is designed to further reduce e-flows). The proposed methods have been used in Shiwuli River, China, to demonstrate their effectiveness. The new methods can offer more precise and realistic e-flow results and can effectively direct the construction and management of e-flow supply projects.

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A Floating Island Treatment System for the Removal of Phosphorus from Surface Waters
Mark T. Brown, Treavor Boyer, R.J. Sindelar, Sam Arden, Amar Persaud, Sherry Brandt-Williams
Engineering    2018, 4 (5): 597-609.
Abstract   PDF (2950KB)

The goal of this project was to design, build, and test a pilot-scale floating modular treatment system for total phosphorus (TP) removal from nutrient-impaired lakes in central Florida, USA. The treatment system consisted of biological and physical–chemical treatment modules. First, investigations of prospective biological and physical–chemical treatment processes in mesocosms and in bench-scale experiments were conducted. Thirteen different mesocosms were constructed with a variety of substrates and combinations of macrophytes and tested for TP and orthophosphate (PO43) removal efficiencies and potential areal removal rates. Bench-scale jar tests and column tests of seven types of absorptive media in addition to three commercial resins were conducted in order to test absorptive capacity. Once isolated process testing was complete, a floating island treatment system (FITS) was designed and deployed for eight months in a lake in central Florida. Phosphorus removal efficiencies of the mesocosm systems averaged about 40%–50%, providing an average uptake of 5.0 g·m–2·a–1 across all mesocosms. The best-performing mesocosms were a submerged aquatic vegetation (SAV) mesocosm and an algae scrubber (AGS), which removed 20 and 50 mg·m–2·d–1, respectively, for an average removal of 5.5 and 12.0 g·m2·a1 for the SAV and AGS systems, Of the absorptive media, the best performance was alum residual (AR), which reduced PO43 concentrations by about 75% after 5 min of contact time. Of the commercial resins tested, the PhosX resin was superior to the others, removing about 40% of phosphorus after 30 min and 60% after 60 min. Under baseline operation conditions during deployment, the FITS exhibited mean PO43 removal efficiencies of 53%; using the 50th and 90th percentile of PO3 4 removal during deployment, and the footprint of the FITS system, yielded efficiencies for the combined FITS system of 56% and 86%, respectively, and areal phosphorus removal rates between 8.9 and 16.5 g·m–2·a–1.

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Application of Hydrogen Peroxide as an Environmental Stress Indicator for Vegetation Management
Takashi Asaeda, Senavirathna Mudalige Don Hiranya Jayasanka, Li-Ping Xia, Abner Barnuevo
Engineering    2018, 4 (5): 610-616.
Abstract   PDF (1515KB)

Adaptive vegetation management is time-consuming and requires long-term colony monitoring to obtain reliable results. Although vegetation management has been widely adopted, the only method existing at present for evaluating the habitat conditions under management involves observations over a long period of time. The presence of reactive oxygen species (ROS) has long been used as an indicator of environmental stress in plants, and has recently been intensely studied. Among such ROS, hydrogen peroxide (H2O2) is relatively stable, and can be conveniently and accurately quantified. Thus, the quantification of plant H2O2 could be applied as a stress indicator for riparian and aquatic vegetation management approaches while evaluating the conditions of a plant species within a habitat. This study presents an approach for elucidating the applicability of H2O2 as a quantitative indicator of environmental stresses on plants, particularly for vegetation management. Submerged macrophytes and riparian species were studied under laboratory and field conditions (Lake Shinji, Saba River, Eno River, and Hii River in Japan) for H2O2 formation under various stress conditions. The results suggest that H2O2 can be conveniently applied as a stress indicator in environmental management.

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Uncertainty Quantification for Multivariate Eco-Hydrological Risk in the Xiangxi River within the Three Gorges Reservoir Area in China
Yurui Fan, Guohe Huang, Yin Zhang, Yongping Li
Engineering    2018, 4 (5): 617-626.
Abstract   PDF (2810KB)

This study develops a multivariate eco-hydrological risk-assessment framework based on the multivariate copula method in order to evaluate the occurrence of extreme eco-hydrological events for the Xiangxi River within the Three Gorges Reservoir (TGR) area in China. Parameter uncertainties in marginal distributions and dependence structure are quantified by a Markov chain Monte Carlo (MCMC) algorithm. Uncertainties in the joint return periods are evaluated based on the posterior distributions. The probabilistic features of bivariate and multivariate hydrological risk are also characterized. The results show that the obtained predictive intervals bracketed the observations well, especially for flood duration. The uncertainty for the joint return period in “AND” case increases with an increase in the return period for univariate flood variables. Furthermore, a low design discharge and high service time may lead to high bivariate hydrological risk with great uncertainty.

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An Ecologically Oriented Operation Strategy for a Multi-Reservoir System: A Case Study of the Middle and Lower Han River Basin, China
Hao Wang, Xiaohui Lei, Denghua Yan, Xu Wang, Shuyue Wu, Zhengjie Yin, Wenhua Wan
Engineering    2018, 4 (5): 627-634.
Abstract   PDF (1197KB)

Constructing and operating a multi-reservoir system changes the natural flow regime of rivers, and thus imposes adverse impacts on riverine ecosystems. To balance human needs with ecosystem needs, this study proposes an ecologically oriented operation strategy for a multi-reservoir system that integrates environmental flow requirements into the joint operation of a multi-reservoir system in order to maintain different ecological functions throughout the river. This strategy is a combination of a regular optimal operation scheme and a series of real-time ecological operation schemes. During time periods when the incompatibilities between human water needs and ecosystem needs for environmental flows are relatively small, the regular optimal operation scheme is implemented in order to maximize multiple human water-use benefits under the constraints of a minimum water-release policy. During time periods when reservoir-induced hydrological alteration imposes significant negative impacts on the river’s key ecological functions, real-time ecological operation schemes are implemented in order to modify the outflow from reservoirs to meet the environmental flow requirements of these functions. The practical use of this strategy is demonstrated for the simulation operation of a large-scale multi-reservoir system which located in the middle and lower Han River Basin in China. The results indicate that the real-time ecological operation schemes ensure the environmental flow requirements of the river’s key ecological functions, and that adverse impacts on human water-use benefits can be compensated for by the regular optimal operation scheme. The ecologically oriented operation strategy for a multi-reservoir system that is proposed in this study enriches the theoretical application of the multi-reservoir system joint operation which considers environmental flow requirements.

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Environmental Data Acquisition, Elaboration and Integration: Preliminary Application to a Vulnerable Mountain Landscape and Village (Novalesa, NW Italy)
Massimiliano Lega, Marco Casazza, Laura Turconi, Fabio Luino, Domenico Tropeano, Gabriele Savio, Sergio Ulgiati, Theodore Endreny
Engineering    2018, 4 (5): 635-642.
Abstract   PDF (1269KB)

Climate conditions play a crucial role in the survival of mountain communities, whose survival already critically depends on socioeconomic factors. In the case of montane areas that are prone to natural hazards, such as alpine slope failure and debris flows, climatic factors exert a major influence that should be considered when creating appropriate sustainable scenarios. In fact, it has been shown that climate change alters the availability of ecosystem services (ES), thus increasing the risks of declining soil fertility and reduced water availability, as well as the loss of grassland, potential shifts in regulatory services (e.g., protection from natural hazards), and cultural services. This study offers a preliminary discussion on a case study of a region in the Italian Alps that is experiencing increased extreme precipitation and erosion, and where an isolated and historically resilient community directly depends on a natural resource economy. Preliminary results show that economic factors have influenced past population trends of the Novalesa community in the Piemonte Region in northwest Italy. However, the increasing number of rock fall and debris flow events, which are triggered by meteo-climatic factors, may further influence the livelihood and wellbeing of this community, and of other similar communities around the world. Therefore, environmental monitoring and data analysis will be important means of detecting trends in landscape and climate change and choosing appropriate planning options. Such analysis, in turn, would ensure the survival of about 10% of the global population, and would also represent a possibility for future economic development in critical areas prone to poverty conditions.

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A Comparison of SWAT Model Calibration Techniques for Hydrological Modeling in the Ganga River Watershed
Nikita Shivhare, Prabhat Kumar Singh Dikshit, Shyam Bihari Dwivedi
Engineering    2018, 4 (5): 643-652.
Abstract   PDF (2441KB)

The Ganga River, the longest river in India, is stressed by extreme anthropogenic activity and climate change, particularly in the Varanasi region. Anticipated climate changes and an expanding populace are expected to further impede the efficient use of water. In this study, hydrological modeling was applied to Soil and Water Assessment Tool (SWAT) modeling in the Ganga catchment, over a region of 15 621.612 km2 in the southern part of Uttar Pradesh. The primary goals of this study are: ① To test the execution and applicability of the SWAT model in anticipating runoff and sediment yield; and ②to compare and determine the best calibration algorithm among three popular algorithms—sequential uncertainty fitting version 2 (SUFI-2), the generalized likelihood uncertainty estimation (GLUE), and parallel solution (ParaSol). The input data used in the SWAT were the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM), Landsat-8 satellite imagery, soil data, and daily meteorological data. The watershed of the study area was delineated into 46 sub-watersheds, and a land use/land cover (LULC) map and soil map were used to create hydrological response units (HRUs). Models utilizing SUFI-2, GLUE, and ParaSol methods were constructed, and these algorithms were compared based on five categories: their objective functions, the concepts used, their performances, the values of P-factors, and the values of R-factors. As a result, it was observed that SUFI-2 is a better performer than the other two algorithms for use in calibrating Indian watersheds, as this method requires fewer runs for a computational model and yields the best results among the three algorithms. ParaSol is the worst performer among the three algorithms. After calibrating using SUFI-2, five parameters including the effective channel hydraulic conductivity (CH_K2), the universal soil-loss equation (USLE) support parameter (USLE_P), Manning’s n value for the main channel (CH_N2), the surface runoff lag time (SURLAG), and the available water capacity of the soil layer (SOL_AWC) were observed to be the most sensitive parameters for modeling the present watershed. It was also found that the maximum runoff occurred in sub-watershed number 40 (SW#40), while the maximum sediment yield was 50 t·a−1 for SW#36, which comprised barren land. The average evapotranspiration for the basin was 411.55 mm·a−1. The calibrated model can be utilized in future to facilitate investigation of the impacts of LULC, climate change, and soil erosion.

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