Water Level Regulation Research Articles

Model predictive control and moving horizon estimation for water level regulation in inland waterways

This work regards the design of optimization techniques for the purposes of state estimation and control in the framework of inland waterways, often characterized by negligible bottom slopes and large time delays. The derived control-oriented model allows these issues to be handled in a suitable manner. Then, the analogous moving horizon estimation and model predictive control techniques are applied in a centralized manner to estimate the unmeasurable states and fulfill the operational goals, respectively. Finally, the performance of the methodology is tested in simulation by means of a realistic case study based on part of the inland waterways in the north of France. The results show that the proposed methodology is able to guarantee the navigability condition, as well as the other operational goals.

苔草草丘恢复湿地的景观格局变化——以哈尔滨太阳岛为例

PDF HTML阅读 XML下载 导出引用 引用提醒 苔草草丘恢复湿地的景观格局变化——以哈尔滨太阳岛为例 DOI: 10.5846/stxb201809071921 作者: 作者单位: 中国科学院东北地理与农业生态研究所;中国科学院大学,东北师范大学,中国科学院东北地理与农业生态研究所,中国科学院东北地理与农业生态研究所,中国科学院东北地理与农业生态研究所,中国科学院东北地理与农业生态研究所,中国科学院东北地理与农业生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41871101）；吉林省科技发展计划项目（20190201115JC） Analysis of landscape pattern changes of restored tussock wetland in Sun Island, Harbin, China Author: Affiliation: Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences;University of Chinese Academy of Sciences;,Northeast Normal University, China,Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences,Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences,Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences,Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences,Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences Fund Project: National Natural Science Foundation of China (No. 41871101); Science and Technology Development Project of Jilin Province (No. 20190201115JC) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:湿地景观变化是湿地生态学领域研究的重要内容。湿地景观要素在不同时间和空间的变化过程研究是揭示湿地演变规律，开展生态恢复实践的重要科学基础。以哈尔滨太阳岛苔草草丘恢复湿地为例，采用野外调查与3S技术相结合的方法，选取草丘面积、斑块形状特征、草丘数量及形态特征等指标，探究草丘湿地恢复过程中的景观变化，为开展湿地恢复提供了重要的科学依据。结果表明：经过8年的恢复，苔草草丘景观变化明显。草丘数量增多，丘墩高度、直径、植株高度、冠幅显著增加（P < 0.05）；湿地恢复后，苔草群落向外扩展722 m2，苔草草丘总面积达2222 m2，扩展率为48.13%；在湿地微地貌和水文条件等因素的综合作用下，草丘群落扩展方向具有一定规律性，斑块边界和质心分别向西南方向扩展了29.91 m和迁移了5.9 m，扩展度和曲线边界比重不断增加，斑块形状和边界趋于复杂，景观空间异质性增强；利用根茎克隆繁殖结合水位调控可实现苔草草丘的快速恢复。 Abstract:Changes of wetland landscape is an essential component of wetland ecology. Study of the temporal and spatial changes of landscape elements provides the scientific foundation for revealing the rule of wetland evolution and carrying out ecological restoration practices. We selected the restored Carex appendiculata tussock wetland in Sun Island as the study area and used 3S technology and filed survey to clarify the characteristics of the spatial and temporal variations in landscape patterns during restoration succession. The area of tussock wetland, expansion rate, shape, number, and morphological characteristics of tussock were determined for analysing the landscape pattern changes of tussock wetland across restoration processes. The results showed that the landscape pattern changed significantly after 8-year restoration:1) The number, height and diameter of tussocks, as well as the plant height and crown width greatly increased (P < 0.05). 2) The area of tussock wetland was increased by about 722 m2 with an expansion rate of 48.13%, and the total area of restored tussock wetland reached 2222 m2. 3) The combined effect of microtopography and hydrology led to regular expansion in the Carex tussock community. The patch boundary and centroid expanded 29.91 m and migrated 5.9 m to the low-lying southwest, respectively. Additionally, the increasing development (D) and weight of curve boundary (W) indicated that the shape and boundary of a patch tended to be complex, and thus enhancing landscape heterogeneity. 4) Rapid recovery of Carex tussock can be achieved by rhizome reproduction accompanied with water-level regulation. 参考文献 相似文献 引证文献

Water level characteristics of Lake Caizi, lower reaches of the Yangtze River during wintering period based on long-term hydrological alteration

湖泊生态水位过程对维持湖泊生态系统结构、过程和功能的完整性具有重要意义，也是当今湖泊科学领域面临的重要科学问题.基于菜子湖湖区水位站（车富岭水位站）1956-2018年日水位资料，采用pettitt突变检验法分析水位的突变性特征.结合年保证率法得到菜子湖车富岭水位站低水位值，并在此基础上分析了低水位发生时间及历时、候鸟越冬期水位变化速率及其生态水位的区间阈值.主要结论有：菜子湖车富岭水位站1956-2018年年均水位无显著突变.菜子湖车富岭水位站低水位发生时间均值为年内的344 d，年际标准差为27 d，低水位的年均历时为69 d，标准差为49 d，有6年（1978、1997、2015-2018年）未发生低水位事件.菜子湖候鸟越冬期水位变化速率的均值为-0.009 m/d，年均值为-0.034~0.009 m/d，日均值为-0.051~0.016 m/d.菜子湖低水位发生时间的区间阈值为332~351 d，历时的区间阈值为33~98 d，变化速率的区间阈值为-0.070~0.020 m/d.加强菜子湖候鸟越冬期湿地生境保护适应性调度试验研究及生态环境监测，为菜子湖输水水位优化控制和菜子湖湿地生态保护提供科学依据.;The ecological water level process of lakes is of great significance for maintaining the integrity of the lake ecosystem structures, processes and functions, and is also an important scientific issue of lake science field nowadays. Based on the daily water level data, pettitt test was used to analyze the abrupt change characteristics of water level of Lake Caizi at Chefuling Station from 1956-2018. The low water level of Lake Caizi at Chefuling Station was obtained using the annual guaranteed frequency method. The starting time and duration of low water level, the water level change rate during the overwintering period of migratory birds and the interval threshold of ecological water level were analyzed accordingly. The main conclusions are as follows:there is no significant abrupt change point in the average annual water level of Lake Caizi at Chefuling Station from 1956 to 2018. The average occurrence time of low water level of Lake Caizi at Chefuling Stations is day 344, with the inter-annual standard deviation 27 days. The average duration time of annual low water level is 69 days with the standard deviation 49 days. Among the calculated 63 years, there are 6 years (1978, 1997, 2015-2018) without low water level event. The average rate of water level change during the overwintering period of migratory birds is -0.009 m/d, the annual average rate is -0.034-0.009 m/d, and the daily average rate is -0.051-0.016 m/d. The interval threshold of the occurrence of low water level of Lake Caizi is 332-351 d, the interval threshold of the duration time is 33-98 d, and the interval threshold of water level change rate is -0.070-0.020 m/d. Strengthening experimental study on habitat adaptation and ecological environment monitoring during the overwintering period of migratory birds to provide scientific basis for water level regulation and wetland protection of the Lake Caizi.

Water Environment Variation in the Three Gorges Tributary and Its Influencing Factors on Different Scales

Long River is a small tributary typical of the Three Gorges Reservoir. In order to clarify the influence of hydro-meteorological factors and human regulation of the reservoir water level on the water environment, we monitored water environment parameters at six sites along Long River for three years, and were able to assess the degree to which variation in the water environment was affected from the micro-scale to macro-scale processes. We found that the water environment parameters have obvious seasonal variation and spatial distribution patterns. From upstream to the estuary, the influence of the backwater was gradually enhanced, whereas the influence of inflow gradually weakened. The distance coefficient between the samples in the backwater area and control sites in the upstream and the Yangtze River had a significant longitudinal gradient pattern (ANOVA, p &lt; 0.05). Through redundancy analysis (RDA) forward selection, we found that cumulative precipitation, water level, cumulative net radiation, daily average temperature, daily net radiation, and daily precipitation all had significant influences on the water environment of the Long River (global permutation test, p &lt; 0.05). The perennial backwater area was mostly affected by water level fluctuations (explaining 39.9% of data variation), whereas the fluctuation backwater area and the upstream inflow area were most affected by cumulative precipitation (explaining 42.9% and 44.0% of data variation, respectively). On the macroscale, the contribution rate of monthly change to the variation of water environment variables reached 54.9%, and the contribution rate of geographical change to the variation of water environment variables was only 7.2%, indicating that the water environment of Long River was mainly affected by exogenous input factors driven by the monsoon climate. Furthermore, we showed that the spatial interpolation method combined with the distance coefficient can easily and efficiently describe the complicated dynamic influences of the upstream inflow and the Yangtze River backwater on the water environment in the Long River bay. The conclusions are helpful in explaining the driving mechanisms of the water environment in the tributaries of the Three Gorges Reservoir, which can provide reference for water environmental protection and management in the Three Gorges Reservoir.

Fractional order PID control of steam generator water level for nuclear steam supply systems

Abstract The main part of nuclear powered system is the nuclear steam supply system (NSSS) to produce the steam needed for electricity or cogeneration. The NSSS mainly contains the fission reactor, based on pressurized water reactors or small modular reactors, and the steam generator. One of the most important control strategies in the NSSS is water level regulation to keep the water level of the steam generator around programmed setpoint because violation of the level jeopardizes the plant availability in making the electricity and supplying the heat for industrial applications. The appearance of fractional calculus made it possible to realize the control design requirements in optimum and efficient ways. In this paper, we proposed a gain scheduled Fractional order PID (FOPID) control system for steam generator level control system in entire operating range. Nelder-Mead tuning strategy which takes into account the desired gain- and phase- margin with integral time absolute error (ITAE) performance index has been devoted to adjust the FOPID parameters. Simulation results indicate that the new control system can enhance the transient response in contrast to the conventional PID. The performance comparison of the FOPID regulator with the classical PID shows that the fractional controller has huge superiority which is comparable with the advanced quantitative feedback theory (QFT) controller. The Nyquist stability analysis is also provided to demonstrate the favorable robust stability of the gain scheduled FOPID controller over the wide range of operating conditions.

Response of Physiological Indicators to Environmental Factors under Water Level Regulation of Paddy Fields in Southern China

Agricultural water level control is the key to the combined control of water-saving irrigation and controlled drainage. It is easy to observe and master in farmland practice, and has important theoretical and practical significance. In this paper, a systematic study on stomatal regulation and photosynthetic-evapotranspiration coupling mechanism, as well as the effect of meteorological environmental factors on photosynthetic-evapotranspiration coupling mechanism of paddy rice in drought and flooding conditions was conducted by taking paddy field’s water level as a regulation indicator of paddy rice’s irrigation and drainage. Results showed that net photosynthetic rate (Pn) and evapotranspiration rate (Tr) had quadratic and linear relationship with stomatal conductance (Gs), respectively. The responding range of Gs in drought condition was lower than that in flooding condition. Drought stress aggravated the photosynthetic stomatal limitation of rice leaves at noon, and partial closure of stomata was the main reason resulting in the reduction of Pn suffering from drought at noon. Change curve of paddy rice’s leaf temperature difference (ΔT) showed a W or V type daily change curve and its change rule was rightly contrary to that of Tr. Pn had quadratic curve relationships with photosynthetically active radiation (PAR) and surrounding CO2 concentration (Cs) both in the morning and in the afternoon, Pn had quadratic curve relationships in the morning and linear relationships in the afternoon with air temperature (Ta), respectively. Tr showed linear relationships with PAR, Ta, relative air humidity (RH) and barometric pressure saturation deficit (VPD).

Impact of regulated water levels on willows (Salix subfragilis) at a flood-control dam, and the use of hydrogen peroxide as an indicator of environmental stress

Plants are subjected to various environmental stressors, both natural and artificial. Environmental stressors that lead to an excessive generation of reactive oxygen species (ROS) may adversely affect physiology and well-being of organisms. The amount of ROS, therefore, could potentially be used to quantify environmental stresses in plants. In this study, the effect of changes in the water levels and elevation at which plants are located was examined in the drawdown zone of a flood control dam (Miharu dam), located in Fukushima in northern Japan. The Salix subfragilis willows are an important plant species in the reservoir as these plants are resistant to prolonged submerged conditions and provide the most suitable habitat for the growth and reproduction of many aquatic organisms. S. subfragilis growing in the drawdown zone exhibited high mortality rates from 2008 to 2016. Leaf samples of S. subfragilis were collected in the drawdown zone at different elevations shortly after drawdown (June), and several months after drawdown (August and October). The samples were taken under light exposure; additionally, dark-adapted (30 min) samples were collected in order to evaluate photosystem-induced ROS generation. The mortality rate of S. subfragilis trees was abnormally high over the previous years, particularly at higher elevated sites. Foliar H2O2 concentrations were significantly increased in samples collected at August and October samples, compared to June samples. Catalase, ascorbate peroxidase, and guaiacol peroxidase activities were also increased, corresponding with the H2O2 content. No significant difference in H2O2 concentrations was found between samples from the lower edge of the drawdown zone and those collected at constantly inundated sites. The H2O2 concentration of light- and dark-treated samples indicated that there was no additional ROS accumulation due to photosynthesis. The results indicated that the high mortality of the trees was associated with long-term exposure to drought conditions due to the drawdown, although this was not confirmed by conventional monitoring. These findings support the use of H2O2 as an environmental stress indicator in vegetation management.

Extended Water-Level Drawdowns in Dammed Rivers Enhance Fish Habitat: Environmental Pool Management in the Upper Mississippi River.

Environmental Pool Management (EPM) can improve ecosystem function in rivers by restoring aspects of the natural flow regime lost to dam construction. EPM recreates summer baseflow conditions and promotes the growth of terrestrial vegetation which is inundated in the fall, thereby improving habitat heterogeneity for many aquatic taxa. A three-year experiment was conducted wherein terrestrial floodplain areas were dewatered through EPM water-level reductions and the resulting terrestrial vegetation was (1) allowed to remain or (2) removed in paired plots in Mississippi River pool 25. Fish assemblage and abundance were quantified in paired plots after inundation. Abundances of many fish species were greater in vegetated plots, especially for species that utilize vegetation during portions of their life history. Fish assemblages varied more between plot types when the magnitude of EPM water-level drawdowns was greater, which produced greater vegetation growth. Young-of-year individuals, especially from small, early maturing species and/or species reliant on vegetation for refuge, feeding, or life history, utilized vegetated plots more than devegetated plots. Vegetation growth produced under EPM was heavily used by river fishes, including young-of-year individuals, which may ultimately positively influence recruitment. Increased habitat heterogeneity may mitigate some of the negative impacts of dam construction and water-level regulation on river fishes. Annual variability in vegetation responses that occurs under EPM enhances natural environmental variability which could ultimately contribute to increased fish diversity. Low-cost programs like EPM can be implemented as a part of adaptive management plans to help maintain biodiversity and ecosystem health in anthropogenically altered rivers.

Interactions between environmental factors and vertical extension of helophyte zones in lakes in Finland

Sheltered shores in boreal lakes are typically dominated by emergent helophytes in which the perennating organ lies in soil below the water level, but the aerial shoots protrude above the water. Changes in natural water-level regimes due to hydropower development may significantly affect the longitudinal extent of the helophyte zone. We explored the vertical distribution of helophyte zones under water-level regulation to develop tools for estimating hydropower impacts. We recorded the vertical extension of the three most common helophyte species (Carex L. spp., Equisetum fluviatile L., and Phragmites australis (Cav.) Trin. ex Steud.) along 238 macrophyte transects in four regulated lakes and one nonregulated lake in Finland. We used random forest (RF) models to quantify the degree to which water-level fluctuation and site-specific environmental variables uniquely explained the variation in helophyte zonation. The vertical extension of Carex spp. was most strongly associated with the water-level fluctuation of the open-water period (OWP), followed by Phragmites and Equisetum. Overall, the RF models explained 4–41% of the variation observed in the helophyte zones. The models indicated that OWP fluctuation, slope, openness, and cover of other macrophyte groups were key factors explaining the extent of the helophyte zones. OWP fluctuation was the most important variable for zonation of Carex spp. and the upper limit of Phragmites. Slope was the most significant variable for the lower limit of Equisetum and Phragmites. Our study demonstrates the importance of taking into account natural habitat-level variability to increase confidence in quantifying the environmental impacts of hydropower production. This approach could be used in future impact assessments of new water-level regulation practices.

Plan 2014: The historical evolution of Lake Ontario–St. Lawrence River regulation

In the 1950s Ontario and New York built hydroelectric structures in the St. Lawrence River, while the federal governments of Canada and the United States constructed the St. Lawrence Seaway to work in conjunction with these power works. The engineering works that enabled this megaproject, approved by the International Joint Commission (IJC), were also designed to regulate water levels and flows on the upper St. Lawrence and Lake Ontario, and a method of regulation was established to set outflows, named Plan 1958-D. This paper covers the initial establishment of this regulation plan, identifying its weaknesses. Though the new water regime provided benefits for certain interests (primarily power, navigation and property owners), it could not always adequately cope with high and low water supplies into the system outside those originally anticipated. Moreover, as is shown, the creation of the St. Lawrence dual project and the connected method of regulation had a range of negative ecological impacts and harmed other interests – including the Mohawk groups in the territory that straddles the project area. By the late twentieth century, serious consideration was being given to replacing Plan 1958-D. This paper explores the technical study, negotiations and political intrigue that involved hundreds if not thousands of professionals, public servants, riparians and commercial interests in both countries that eventually led to a new method of regulation. On 6 December 2016 the governments of Canada and the United States formally gave concurrence to a revised Order of Approval from the IJC that replaced Plan 1958-D with Plan 2014. The rationale for these changes is explored, as well as the challenges faced by the IJC and its technical advisory groups, and the lessons that can be learned are identified.

Quantifying the effects of hydrological changes on long-term water quality trends in temperate reservoirs: insights from a multi-scale, paleolimnological study

Declining water quality in reservoirs is of growing concern in many regions, yet there is still little understanding of long-term water quality trends in these systems. Across the landscape, reservoirs have diverse origins, functions, and operational strategies. In temperate environments, winter water-level drawdown is a common operational practice in reservoirs but the long-term impacts of this hydrological modification has not been extensively studied. We paired a comparative, pre-dam-to-contemporary study (i.e. a top–bottom design) of 12 reservoirs with a detailed paleolimnological study of a focal lake to generate quantitative insights into the relative effect of hydrological changes vs. landscape and climatic drivers on water quality. The focal reservoir, Grand Lac Saint-Francois, is of relatively similar morphometry, geography, and limnology to our other sites, and has experienced annual winter water-level drawdown of ~ 5 m since it was dammed approximately 100 years ago. Based on our top–bottom analysis, we did not find strong correlations between long-term changes in water quality (i.e. diatom-inferred TP estimates) and winter water-level drawdown amplitudes. Instead, reservoir morphometry and watershed characteristics (i.e. geography, maximum depth, and cropland areas) appeared to be stronger drivers of trends across the region. From the detailed paleolimnological analysis, we found that sedimentary pigments and DI-TP concentrations significantly increased over the last century based on Mann–Kendall trend analyses. Breakpoint analyses showed that changes in biological-proxy trends, as well as the sedimentology (i.e. lithology and accumulations rates), coincided with dam construction and the onset of water level regulation. However, given the high variability in metrics and the extent of water level monitoring records, we were unable to quantitatively associate the impacts of drawdown with water quality trends at Grand Lac Saint-Francois. Conversely, we did find that watershed nutrient surpluses from livestock farming, and warming temperatures were significant explanatory variables of water quality metrics.

Schistosomiasis in the Senegal River basin

Schistosomiasis in the Senegal River basin

Enhancing water levels of degraded, bare, tropical peatland in West Kalimantan, Indonesia: Impacts on CO2 emission from soil respiration

Astiani D, Burhanuddin, Gusmayanti E, Widiastuti T, Taherzadeh MJ. 2018. Enhancing water levels of degraded, bare, tropical peatland in West Kalimantan, Indonesia: Impacts on CO2 emission from soil respiration. Biodiversitas 19: 522-527. The major drivers of deforestation in West Kalimantan have been the development for large or small-scale expansion of agricultural activities; the establishment of oil palm and other plantations; fire; and degradation of forests particularly from industrial logging. Our previous research findings have shown that such activities in affected peatland areas have lowered the water table levels (down to 0.5-1.0 m depths), and have significantly increased CO2 emissions from the peat soils. It has been demonstrated that unmanaged, lowered water tables in peatlands act as one of the main factors inflating soil carbon emissions - an issue that has assumed global significance in recent decades. Regulating peatland water tables has the potential to mitigate degraded peatland carbon emissions as well as improve the hydrological functions for communities who farm the peatlands. However, we are still uncertain exactly how much impact controlled raising of the peatlands water tables will have on reducing soil CO2 emissions. The research described here aimed to mitigate CO2 emissions by raising and regulating water levels on drained peatland to restore and enhance its hydrological functions. The results confirmed that raising the water table significantly decreases CO2 emissions and improves water availability and management for crop production in the coastal peatland of Kubu Raya district, West Kalimantan. Water levels previously at 60cm below the soil surface were regulated to raise the watertable up to just 30 cm below the surface and this reduced peatland carbon emissions by about 49%. However, longer-term monitoring is required to ensure that the hydrological benefits and CO2 mitigation can be sustained.

INTEGRATION OF DELPHI TECHNIQUE AND ANALYTICAL HIERARCHY PROCESS IN SELECTING THE TYPE OF DAM: A CASE STUDY OF BUNGOH CATCHMENT IN SARAWAK, MALAYSIA

Dams are built ancient structures, which serve to retain, collect, and store water. Over the years, the function of dams has been diversified to flood prevention, water level regulation, and even recreational purposes. However, selecting a suitable type of dam based on the characteristics of a potential dam site is consistently a concern in the preliminary construction stage. Therefore, this study attempts to integrate the Delphi technique and Analytical Hierarchy Process (D-AHP) to develop a set of influential attributes, which assists in the selection of a suitable type of dam for the potential dam site. These influential attributes are determined based on comprehensive literature reviews and corroborated by twelve experts from relevant fields through three rounds of interviews. Using the Delphi technique, 9 important criteria and 25 sub-criteria are finalized. Expert’s judgments are measured through pairwise comparisons to derive eigenvectors. Based on prioritisation of AHP, the gravity dam scores the highest total weight, and is selected as the optimal type of dam for Bungoh catchment. The selection of the gravity dam is quantified based on the developed influential attributes, which include environmental criteria, social criteria, and engineering criteria. Essentially, the selection takes the characteristics of the potential dam site into account during the pairwise comparison process. In this context, the developed set of influential attributes could objectively assist related organizations in their decision making process. These attributes are also applicable in the preliminary stage of any dam development project.[1] &#x0D; This work is supported by Exploratory Research Grant Scheme (ERGS/1/11/STWN/UPM/02/8-5527027)&#x0D;

Quantifying the failure probability of a canal levee

ABSTRACTPolders in the Netherlands are protected from flooding by flood defence systems along main water bodies such as rivers, lakes or the sea. Inside polders, canal levees provide protection from smaller water bodies. Canal levees are mainly earthen levees along drainage canals that drain excess water from polders to the main water bodies. The water levels in these canals are regulated. During the last decades, probabilistic approaches have been developed to quantify the probability of failure of flood defences along the main water bodies. This paper proposes several extensions to this method to quantify the probability of failure of canal levees. These extensions include a method to account for (i) water-level regulation in canals, (ii) the effect of maintenance dredging on the geohydrological response of the canal levee and (iii) survival of loads in the past. The results of a case study demonstrate that the proposed approach is capable of quantifying the probability of failure of canal levees and is useful for exploring the relative benefit of risk mitigating measures for canal levees.

Improving Water Reuse in Paddy Field Districts with Cascaded On-farm Ponds using Hydrologic Model Simulations

On-Farm Ponds (OFPs) are an important irrigation facility in rice-based irrigation systems. An OFP water reuse system in paddy field districts is composed of upstream commanded paddy fields, irrigation and drainage ditches, cascaded OFPs and downstream irrigated paddy fields. This study assesses the performance of an OFP water reuse system and explores potential water management strategies to enhance return flow reuse for rice production. A cascaded model including a modified two-tank module and a pond water balance module is developed to describe hydrologic characteristics of the water reuse system. Model calibration and validation show that the measured and simulated data are in a good agreement and the proposed model can be used to hydrologic analyses of OFP water reuse systems. The water reuse system has high water reuse efficiency as the return flow regulated by OFPs was reused several times from the upstream to downstream of the paddy fields. Return flow and actual reuse water increase with the maximum ponded depth of paddy fields. As the water level in a drainage ditch decreases, the available return flow increases and local water shortage can be alleviated. The supply-and-demand gap between seasons becomes more harmonized when the regulated water level in pond increases, resulting in a decrease in water shortage. The reuse of return flow is a quick-response water supply solution to meet the rice water demand during peak demand periods.

On the morphological evolution of restored banks: Case study of the Meuse river

In recent years, many riverbanks in Europe had their protections removed to reactivate natural erosion processes and improve riparian habitats. Yet, other river functions may be affected, such as navigation and flood conveyance. The quantification and prediction of erosion rates and volumes is then relevant to manage and control the integrity of all river functions. This work studies the morphological evolution of riverbanks along two restored reaches of the Meuse River in the Netherlands, which are taken as case studies. This river is an important navigation route and for this its water level is strongly regulated with weirs. Through aerial photographs and two airborne LIDAR surveys, we analysed the evolution over nine years of restoration and reconstructed the topography along 2.2 km. of banks. An extraordinary low-water level after a ship accident provided the opportunity to observe and measure the bank toe. The banks show a terrace of erosion close to the normally regulated water level, highly irregular erosion rates up to 7 m/year, embayments evolving with upstream and downstream shifts, and sub-reaches with uniform erosion. Probable causes of erosion include ship-waves, high water flows and water level fluctuations. Distinct patterns might be explained by the presence of riparian trees and soil strata of different compositions. These intriguing case studies will continue to be studied to disentangle the role of different erosion drivers, predict erosion magnitudes and establish whether bank erosion will stop or continue in the future.

Loon Nest Viability Model: A Performance Indicator for Improving Water-Level Regulation of Large Water Bodies

Rule curves dictating target water levels for management have been implemented in several water bodies in North America over the last 70 years or more. Anthropogenic alterations of water levels are known to affect several components of wetland ecosystems. Evaluating the influence of rule curves on biological components with simple performance indicators could help harmonize water level management with wetland integrity. We assessed the potential of using the probability of common loon nest viability as a performance indicator of long-term impacts of rule curves on nesting wetland birds. We analyzed the outcome of rule curves on the probability of loon nest viability in Rainy Lake and Namakan Reservoir, 2 regulated water bodies located along the Ontario-Minnesota border. The analysis was focused on 4 hydrological time series between 1950 and 2013: 2 sets of time series simulating rule curves used to manage the water bodies in the past decades (referred to as the 1970RC and 2000RC), one of the historical measured water levels, and one of computed natural water levels. The probability of loon nest viability under the 1970RC was 2× higher than under natural conditions in both water bodies. The probability was also 2× higher under the 2000RC than under the 1970RC in the Namakan Reservoir but not in Rainy Lake. The rule curves generally improved conditions for nesting loons in both water bodies. The presented performance indicator can be used to evaluate future rule curves before they are implemented in the Rainy-Namakan or other similar systems.

Effect of Different Water Levels on Growth Performance of Sesame(Sesamum indicum L.) in Paddy Field Soil

The present study aimed to investigate the change in the morphological and physiological characteristics within sesame plant when subjected by regulating water levels. The experiment was conducted at ground water level(GWL) 0, 20, and 40 cm in a paddy field soil. The results showed that sesame growth characteristics, such as shoot length, stem thickness, leaf length, and leaf width were significantly higher in sesame at GWL 0 cm at 10 days after treatment(DAT) and 20 DAT than in those grown at a GWL of 40 cm. The shoot length and stem thickness of sesame grown at a GWL of 20 cm was significantly higher than those grown at a GWL of 40 at 10 DAT. The chlorophyll content was significantly lower in plants grown at a GWL 40 cm at 10 and 20 DAT over sesame grown in GWL of 0 and 20 cm. The stomatal conductance remained consistent in all the GWL at overall time period. Moreover, the Ca content of sesame was reduced in both GWL 40 cm and 20 cm at 10 DAT and 20 DAT as compared to GWL 0 cm. The K content was increased at 10 DAT but was reduced at 20 DAT at both GWL 20 cm and GWL 40 cm over plant grown at GWL 0 cm. Likewise, the P content was decreased at 10 DAT in both GWL 20 and GWL 40 cm but was significantly increased at 20 DAT in GWL 20 cm as compared to plant at GWL 0 cm. Since the experimental soil is paddy field soil these results helps to understand the efficiency of sesame to tolerate the different stress levels of soil moisture. Therefore, these research may help to predict the appropriate level of irrigation to be provided at different time period for the sesame if it is grown in rice field as a commercial crops.

Controlling Cattail Invasion in Sedge / Grass Meadows

As a result of water-level regulation, cattails have invaded sedge/grass meadow in all wetlands on Lake Ontario. Even with a change in water-level-regulation to a more natural hydrologic regime, restoration requires methods for active cattail management without the ability to manipulate water depths and without imperiling other vegetation. We conducted replicated studies at a wetland site with an active invasion front in zones of nearly mono-dominant cattail and transitional invasion. We tested various combinations of cutting cattail ramets when carbohydrate reserves were minimized, spraying cut stems with herbicide, slicing rhizomes to mimic tilling, and hand-wicking resprouted ramets with herbicide. We also collected companion environmental data. The most effective treatment in both zones was cutting during the period with reduced rhizome carbohydrates followed by hand-wicking resprouted ramets with herbicide in late summer, which allows the herbicide to be absorbed by the rhizomes. Two years of treatment provide the best results, reducing cattail stem counts and cover by more than 50%, but follow-up applications in ensuing years may be warranted to treat surviving cattails. Given the widespread problem of cattail invasion, these treatments may have broad application in wetlands where water levels cannot be manipulated.