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Journal of Hydrology
Elsevier
Journal of Hydrology

Elsevier

0022-1694

Journal of Hydrology/Journal Journal of HydrologySCIISTPEIAHCI
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    Analysis of environmental dispersion in wetland flows with floating vegetation islands

    Wang, HuilinCong, PeitongZhu, ZhengtaoZhang, Wei...
    11页
    查看更多>>摘要：The fate of the contaminant transport process within wetland flows considering contaminant depletion via a floating vegetation island (FVI) is the focus of this work. To identify the feature of contaminant cloud expansion under an FVI, multiscale theory is extended to obtain a two-dimensional spatial concentration distribution analytical solution. The characteristics of two-dimensional concentration distributions under upper FVI absorption and damping factor within wetland flows are illustrated. The performance of the contaminant depletion process via an FVI is also examined in this work, with discussions on removal efficiency, the absorption ratio, and the nonuniformity of contaminant mass. As FVI removal intensity changes along the stream direction, the analytical solution of removal efficiency is obtained to illustrate the longitudinal variation in the FVI removal intensity. Furthermore, the effects of removal intensity and damping factor on FVI removal efficiency are expressed separately. In addition, the removal intensity variance in the vertical direction is discussed using the defined absorption ratio. Moreover, as residual mass is a fatal issue in the contaminant removal process, temporal residual mass is discussed, and the residual mass proportion within different layers is depicted. Finally, the difference of the mass proportion between layers is employed to explain the transformation of the contaminant cloud.
      原文链接:
    • NSTL
    • Elsevier

    Soft-cooperation via data sharing eases transboundary conflicts in the Lancang-Mekong River Basin

    Gao, JinyuCastelletti, AndreaBurlado, PaoloWang, Hao...
    12页
    查看更多>>摘要：Water resources management in the Lancang-Mekong River Basin (LMRB) is challenging in face of the complex trans-national geopolitical context, the acceleration of hydropower dam expansion, and the growing demands for energy, food, and riverine ecosystem preservation across the basin. Centralised management through coordinated operation of all the basin water infrastructures ("hard cooperation") across the river basin is ideal but hard to achieve given the existing geopolitical context of the region. To overcome these barriers and facilitate a more adaptive and reliable operation of the LMRB's water system, this paper focuses on the concept of "soft -cooperation", i.e. the idea of indirectly fostering cooperation by sharing data across countries to inform the noncooperative (or independent) operation of their systems. Here, we first quantify existing riparian conflicts and synergies for the non-cooperative scenario, where upstream and downstream act independently without any form of cooperation, and for the "hard cooperation" configuration, where an ideal centralised operator jointly operates all the infrastructures. Then a "soft cooperation" scheme assuming data sharing across riparian countries is evaluated. The most effective and informative data is selected via machine learning and used to inform the design of the river reservoir system operation via evolutionary multiobjective direct policy search. Results show that the riparian conflicts around water mainly exist between the sectors, i.e. hydropower production vs ecosystem conservation, rather than among countries. For reservoirs with various capacities and locations, the value of information varies. Generally, sharing data about the water currently available in the different river storages results in a large improvement in hydropower production. This study highlights the value of appropriate data sharing and selection in water system operation as an indirect way of promoting cooperation in trans boundary river management.
      原文链接:
    • NSTL
    • Elsevier

    Real-time methods for short and medium-term evapotranspiration forecasting using dynamic crop coefficient and historical threshold

    Han, XinZhou, QingyunZhang, BaozhongChe, Zheng...
    11页
    查看更多>>摘要：Crop evapotranspiration (ETc) plays a fundamental role in agronomic and water resource management. Accurate forecasting of ETc is a major challenge for agricultural researchers and experts. Based on the measured ETc of the Eddy Covariance system and weather forecast data (1-15 d: short and medium-term) in North China, the realtime short (1-7 d) and medium (8-15 d) term ETc forecast models were developed by coupling with the dynamic crop coefficient and modifying the historical threshold. The results demonstrated that compared with the single crop coefficient model recommended by the Food and Agricultural Organization (FAO-56, M1), the M2 model (a modification of the M1 model developed using the dynamic crop coefficient) accurately forecasted the winter wheat and summer maize ETc, with an increased accuracy of 11%. Moreover, the ETc forecasting accuracy using the M2 model for short and medium-term was over 77%, of which the short-term accuracy was higher (greater than84%). The ETc forecasting accuracy increased with the decrease in the forecast period at different growth stages. Further, the short and medium-term accuracies of M3 model (a modification of the M2 model developed by incorporating the historical threshold) were over 81%, of which the accuracy of the 1 d forecast period was approximately 95%, which was 6% higher than that of the M2 model; the root mean square error and the mean absolute error were reduced by 0.1 mm d(-1) and 0.11 mm d(-1), respectively. Thus, these results indicated that the M3 model, which was developed by integrating the dynamic crop coefficient and the historical empirical threshold, can predict short and medium-term ETc more accurately.
      原文链接:
    • NSTL
    • Elsevier

    Quantifying the spatio-temporal variability of total water content in seasonally frozen soil using actively heated fiber Bragg grating sensing

    Sun, MengyaShi, BinZhang, ChengchengLiu, Jie...
    14页
    查看更多>>摘要：Actively heated fiber-optic (AHFO) method has become a research focus for soil water content measurement in recent years due to its advantages such as small size, distributed measurement and good durability. However, the AHFO method is presently coupled to distributed temperature sensing (AHFO-DTS) which is inevitably limited by low temperature measurement accuracy and spatial resolution. Furthermore, the existing studies about AHFO method do not consider the existence of frozen soil caused by temperature changes, which further limits its application in the field. Here a new method for total water content measurement in frozen soil using actively heated fiber Bragg grating (AHFO-FBG) sensing is proposed for the first time, which directly determines the calibration formulas of frozen soil under different soil temperatures from the calibration formula of unfrozen soil. Moreover, the feasibility and reliability of AHFO-FBG technology are proved through laboratory calibration tests and in-situ monitoring data of Chinese loess, and the temporal and spatial distribution of total water content in shallow seasonally frozen loess is also revealed. It is suggested that the AHFO-FBG technology can complement with the traditional techniques to achieve quasi-distributed and in-situ total water content monitoring in seasonally frozen soil.
      原文链接:
    • NSTL
    • Elsevier

    A global synthesis of transpiration rate and evapotranspiration partitioning in the shrub ecosystems

    Gao, GuangyaoWang, DiZha, TianshanWang, Lixin...
    13页
    查看更多>>摘要：Transpiration (T) is a fundamental process in understanding the ecophysiology of plants, and it is the dominant component of evapotranspiration (ET) in the terrestrial water cycle. Although previous studies have examined T characteristics of shrub ecosystems in some regions, global-scale synthesis that integrates the spatial variations of T, ET and ratio of T to ET (T/ET) and the associated influences of bio-/abiotic factors in the shrub ecosystems is currently lacking. In this study, we synthesized and analyzed T rate, ET rate and T/ET of the shrub ecosystems from the peer-reviewed articles using field observations around the world. These studies were mainly distributed in drylands with aridity index (ratio of precipitation to potential ET) < 0.65, which accounted for 86.4% of the study locations. Globally, the mean daily T and ET rates of shrubs were 1.5 +/- 1.0 mm d(-1) and 2.4 +/- 0.8 mm d(-1), with coefficient of variation of 63.2% and 36.2% among the study locations, respectively. Mean T/ET of the shrubs over the growing season was 0.54 +/- 0.14, which was generally lower compared with forest, grassland and cropland ecosystems. The T rate of shrubs was positively related to shrub age, shrub height, leaf area index, and vegetation coverage (p < 0.05), and the effects of biotic factors on T rate were stronger compared with abiotic factors. The ET rate of shrubs was positively related to aridity index, long-term annual mean precipitation, mean soil water content, as well as shrub height and vegetation coverage (p < 0.05). By contrast, the effects of biotic factors on variations of shrub T/ET were weaker than those of abiotic factors, and the T/ET of shrubs was negatively related to aridity index, long-term annual mean precipitation and mean soil water content, but positively related to latitude (p < 0.05). This study is an important supplement of our knowledge gap in terrestrial water cycle, and the findings suggest that T accounted for about half of the water into atmosphere from shrub ecosystems, and the variations of T rate of shrubs were mainly controlled by biotic factors, whereas ET rate and T/ET was mainly affected by abiotic factors.
      原文链接:
    • NSTL
    • Elsevier

    Two-dimensional semi-analytical solution of land-derived solute transport under tidal fluctuations considering variable boundary conditions on the seaward boundary

    Suk, HeejunChen, Jui-ShengPark, EungyuHan, Weon Shik...
    23页
    查看更多>>摘要：Transport of contaminants in coastal aquifers subject to tidal fluctuations is an important topic and a growing problem due to increasing populations and development in coastal areas. Many studies have used variable boundary conditions to simulate transport behavior at the interface between seawater and groundwater. However, to the best of our knowledge, no analytical solution accounting for variable-concentration boundary conditions exists for plume migration of land-derived contaminants passing through the inland zone of aquifers under tidally induced periodic flow. Here, a two-dimensional (2D) semi-analytical solution for land-derived solute transport was developed with variable boundary conditions at the seaward boundary under tidal fluctuations. The proposed 2D semi-analytical solution was verified through comparison with an existing one-dimensional semi-analytical solution and a 2D numerical solution developed using the finite-element method. Sensitivity analysis was performed to explore factors including hydraulic properties, tidal amplitude, and the location and distribution of initial contaminants, which affect the characteristics of land-derived pollutant transport in coastal aquifers. Through comparison of the calculated masses remaining over time in the aquifer using the proposed semi-analytical solution under two types of variable boundary conditions (Dirichlet-Neumann and Cauchy-Neumann variable boundary conditions), we found that the Cauchy-Neumann variable boundary conditions reflected reality better than did the Dirichlet-Neumann variable boundary conditions. The proposed analytical solution will be useful for obtaining insights into the mechanisms that drive the plume behavior of contaminants such as radionuclides or toxic chemicals released into coastal aquifers of tidally affected systems.
      原文链接:
    • NSTL
    • Elsevier

    Transboundary water treaty design for poverty reduction and climate adaptation

    Baah-Kumi, BernardWard, Frank A.
    16页
    查看更多>>摘要：When transboundary basins are developed in poor regions where freshwater resources are fully committed, it becomes important to design economically sustainable action plans to address existing poverty, especially in responding to mounting evidence of climate change and population growth. Increasing competition over shared water resources as well as climate water stress has attracted research efforts internationally addressing the benefits and costs of establishing water-sharing treaties. Despite this ongoing interest, few peer-reviewed works have investigated water development and use patterns that could produce economic gains for all parties from establishing transboundary water sharing agreements. This work develops an approach to address the gap by formulating and applying a basin-scale hydro-economic optimization model of West Africa's Volta River Basin. The work analyzes the effects of a prospective multilateral water allocation and hydropower trade agreement on the size, sign, and distribution of basin-wide economic benefits. The model includes two new large storage reservoirs, five water use purposes, and two climate water supply scenarios with and without a water sharing treaty. From that, it assesses the net economic benefit-maximizing patterns of water use with and without the treaty. Results show a Pareto Improving outcome is achievable for all riparian countries from new storage capacity in the basin for which at least one country is better and none is worse off. This improvement is achievable with a multilateral water sharing treaty implemented with power trading among the six basin countries. Results indicate that all basin countries have the potential to secure significant economic gains from additional hydropower production with the treaty. Under its implementation, upstream countries would reduce agricultural water use in exchange for higher valued hydropower benefits under the climate-stressed low flow scenario. Despite potential benefits that are shareable from negotiation, practical implementation of such a treaty will require considerable diplomatic skill, patience and effort.
      原文链接:
    • NSTL
    • Elsevier

    Dual-domain model of advective-diffusion transport with variable mass transfer rate for long-term contaminant transport simulation at radwaste injection site

    Pozdniakov, S. P.Lekhov, V. A.Bakshevskaia, V. A.
    9页
    查看更多>>摘要：Since 1963, liquid radioactive waste has been injected into deep artesian aquifer waste disposal sites at the Siberian Chemical Combine. The injection and overlaying zones are sandy clay formations with complex internal architectures. Therefore, obtaining relevant forecasts of long-term waste migration largely depends on accounting for the heterogeneity of water-bearing sediments. At present, it is impossible to create regional models that consider detailed hydraulic heterogeneity (due to the insufficient provision parameters and limitations of computing capacities). Therefore, for long-term forecasts of the migration of contaminants in groundwater, the solution is to use a dual-domain model. To use a dual-domain model, one must set the mass transfer parameter. To estimate this parameter, the article proposes an approach using an auxiliary three-dimensional (3D) high-resolution model of hydraulic heterogeneity. This model was constructed using the transition probability/Markov chain geostatistical approach (TP/MC method) and detailed lithological analysis data of the sections of 295 boreholes in the Siberian Chemical Combine region, which were obtained by core studies and using geophysical methods for studying boreholes. An important feature of this model was that the thicknesses of the low-permeability hydrofacies have an exponential-like distribution with an average thickness of about 6 m. This thickness heterogeneity, as it appeared from the simulation results, essentially affects the overall subsurface contaminant spreading during long time. The effective mass transfer rate coefficient was obtained by processing the breakthrough curves of the flux concentrations by modeling horizontal migration on the auxiliary model, providing setting the highest weight coefficients in the "tail" part of the breakthrough curve. As a result of the selection, the effective mass transfer rate coefficient for the assessment of long-term subsurface waste migration for the conditions of the Siberian Chemical Combine was 6.4 x 10-8 day-1.
      原文链接:
    • NSTL
    • Elsevier

    An improved numerical model for groundwater flow simulation with MPFA method on arbitrary polygon grids

    Gao, YulongDu, ErhuYi, ShupingHan, Yu...
    15页
    查看更多>>摘要：Groundwater models are critical for simulating subsurface hydrological processes and guiding informed policymaking for groundwater management. However, the widely applied groundwater models typically use regularshaped grids to discretize aquifer systems and require that the directions of the grid edges are aligned with the hydraulic conductivity tensor. Such rigorous requirements for spatial discretization have constrained the models' application in aquifer systems with anisotropic hydrogeological characteristics. To address such limitations, we develop an improved groundwater flow model based on the multipoint flux approximation (MPFA) method in this study. The new model allows us to use arbitrary-shaped polygon grids to discretize aquifer systems and relaxes the rigorous requirement of the alliance between polygon edges and hydraulic conductivity tensor. The functionality and performance of the new model are demonstrated by comparing the output between our model, MODFLOW, and analytical solution in four case studies with various hydrogeological conditions. In a real-world watershed with complex-shaped boundaries, our model outperforms the conventional groundwater model in boundaries. The modeling results show that our model can yield accurate simulation of subsurface hydrological processes in aquifer systems with complex-shaped boundaries. Furthermore, our model can provide a more flexible discretization solution to couple surface water and groundwater model in integrated hydrological model development.
      原文链接:
    • NSTL
    • Elsevier

    Comparative analysis of long short-term memory and storage function model for flood water level forecasting of Bokha stream in NamHan River, Korea

    Kim, DonghyunLee, JoonseokKim, JongsungLee, Myungjin...
    13页
    查看更多>>摘要：In this study, the applicability of machine learning models was investigated for real-time flood forecasting of a small river basin with a short time of concentration and the modes were compared with the storage function model (SFM), a rainfall-runoff model. Bokha stream basin located in the NamHan river, Korea was selected as the study area. Flood water level forecasting was performed for Heungcheon bridge station which is located in the downstream of Bokha stream using hydrological data observed at Bokha bridge station located in the upstream of the stream. For each of the upstream and downstream basins, Rainfall, water level, and discharge data from 2005 to 2020 were collected at two stations and especially the collected rainfall data were classified into 53 rainfall events using Interevent Time Definition (IETD) analysis of rainfall data. In addition, flood water level forecasting at downstream point was performed using machine learning models such as GB (Gradient Boosting), SVM (Support Vector Model), and LSTM (Long Short-Term Memory). Also the SFM which is a rainfall-runoff model was used for the forecasting. For the application of machine learning models, 33 rainfall events were used for learning and 23 rainfall events were used for evaluation. With the SFM, the flood discharge was forecasted first and then the flood water level was forecasted through the rating curve. The flood water level forecasted by each model was compared with the observed flood water level and predictive power for each model was evaluated by calculating NRMSE (Normalized Root Mean Squared Error). The NRMSEs for the models were ranged from 0.18 to 0.27, and the predictive power was good in the order of the LSTM model at 0.18 followed by the SFM at 0.21. Therefore, the LSTM model showed the best predictive power and was selected as the optimal model for real-time flood water level forecasting in this study. However, the SFM is currently employed in Korea for flood forecasting and warning, and the model well incorporates the basin characteristics, showing relatively good predictive power. Based on the models presented in this study, an optimal model suitable for real-time flood water level forecasting can be selected for flood forecasting and warning points of a small river basin, and it is expected that the forecasting results can be used as base data for decision making.
      原文链接:
    • NSTL
    • Elsevier