scholarly journals Research on the Comprehensive Optimization of the Hydraulic Performance and Frost-Heaving Resistance of a Parabolic Channel

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2574
Author(s):  
Zhuo Yang ◽  
Wuquan He ◽  
Yubao Wang ◽  
Zongke Lou ◽  
Pinzhang Duan
Keyword(s):  
Land Use ◽  
Hydraulic Performance ◽  
Frozen Soil ◽  
Irrigation District ◽  
Concrete Lining ◽  
Original Design ◽  
Frost Heaving ◽  
Channel Section ◽  
Depth Ratio ◽  
Optimal Section

Hydraulic performance and frost-heaving resistance should be considered simultaneously in the channel design of seasonally frozen soil areas. Quadratic parabolic channels have good water and sand transport capacities and high frost-heaving resistances. The width–depth ratio of a parabola determines its section structural form, which in turn determines the hydraulic performance and frost-heaving resistance. In this research, based on the current lack of a comprehensive optimization method that accounts for the hydraulic performance and frost-heaving resistance of the cross-section structures of parabolic channels, a multi-objective optimization model was established with the goal of achieving a minimum cross-sectional flow area and a uniform channel section force. Taking the flow velocity, the width–depth ratio and the crack resistance of concrete lining plate as constraints, the α method of the linear weighted sum method was used to optimize the calculation, and the comprehensive optimal quadratic parabolic channel section was obtained. The comprehensive optimal section of an actual parabolic channel in the Shijin Irrigation District was determined using this method, and the comprehensive optimal section was analyzed and compared to the original design section and two typical parabolic channel sections. The comprehensive optimal section was compared with the original design section in the Shijin Irrigation District. The force uniformity of the optimal section was 23.2% better, the hydraulic performance was 1.96% better, and the land use was 12.35% less. Compared with the values for the hydraulic optimal section, the maximum positive and negative bending moments of the comprehensive optimal section decreased by 5.6% and 11.89%, respectively, and the force uniformity increased by 7.62%. Additionally, compared with the values for the practical economic section, the force uniformity and the hydraulic performance of the comprehensive optimal section increased by 1.79% and 0.2%, respectively, and the land use decreased by 4.49%. Thus, the comprehensive optimal section met the engineering requirements and it could provide a reference for the design and selection of parabolic channels in seasonally frozen soil areas.

scholarly journals RAPELD: a modification of the Gentry method for biodiversity surveys in long-term ecological research sites

2005 ◽  
Vol 5 (2) ◽  
pp. 19-24 ◽  
Author(s):  
William E. Magnusson ◽  
Albertina P. Lima ◽  
Regina Luizão ◽  
Flávio Luizão ◽  
Flávia R. C. Costa ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Planning ◽  
Amazon Basin ◽  
Local People ◽  
Ecological Research ◽  
Original Design ◽  
Biological Surveys ◽  
Incomplete Coverage ◽  
Long Term Ecological Research

Our objectives were to develop a method that would be appropriate for long-term ecological studies, but that would permit rapid surveys to evaluate biotic complementarity and land-use planning in Amazonia. The Amazon basin covers about 7 million km². Therefore, even a sparse coverage, with one sample site per 10.000 km², would require about 700 sampling sites. Financial considerations limit the number of sites and investment at each site, but incomplete coverage makes evaluation of biotic complementarity difficult or impossible (Reddy & Dávalos 2003). Our next challenge is to install similar systems throughout Amazonia. The cost, based on modification of Al Gentry's original design is moderate (less than US$ 50.000 per site if it is not necessary to immediately identify all vascular plants in plots) and we can obtain RAP results for most taxa in the short term at much lower cost. However, biological surveys will only be relevant if the local people participate and the surveys serve as much to teach the local communities about the value of their natural resources as they serve to teach the international community about biodiversity. Therefore, we want to see each site run as a long-term ecological research project by local people and institutions. Biological surveys are an important tool in land-use planning, but only the local people can implement those plans.

Heave and Heaving Pressures in Frozen Soils

1971 ◽  
Vol 8 (2) ◽  
pp. 272-282 ◽  
Author(s):  
R. N. Yong ◽  
J. C. Osler
Keyword(s):  
Frozen Soil ◽  
Soil Freezing ◽  
Critical Examination ◽  
Frost Heaving ◽  
Moisture Movement ◽  
Soil System ◽  
Capillary Model ◽  
Wide Range ◽  
Generative Mechanism ◽  
Major Factors

Most previous studies of frost heave and associated frost heaving pressures have been concerned with the process of ice lensing and ice segregation, and the primary mechanism used to explain the related phenomena of heave and pressure is seen to be consistent with the process of formation of ice lenses. Thus, while certain investigators may disagree on various details, there appears to be general agreement on the mechanisms which form the basis for the so-called capillary model for the prediction of frost heaving and associated pressures. In addition, various criteria used for the assessment of frost susceptibility rely implicitly on the admissibility of this model as their rationale.This study questions the advisability of using a singular capillary model, in view of the wide range of conditions and constraints prevailing at any one time. Since soil freezing involves moisture movement and associated resultant volumetric expansion at both the macroscopic and microscopic scale arising from temperature and osmotic gradients, it is clear that a comprehensive theory to rationally explain heave and (or) heaving pressures is needed to account for all major factors which influence the total response of the frozen soil system. In this respect, the results of a critical examination of recent field and laboratory tests performed at McGill University and elsewhere are used to show that the available theories may be too restricted in scope to explain all facets of the observed behavior of frozen natural soils. To overcome the shortcomings noted above, an extended generative mechanism is developed and procedures for the examination of actual results are presented.

scholarly journals Designing a suite of measurements to understand the critical zone

2016 ◽  
Vol 4 (1) ◽  
pp. 211-235 ◽  
Author(s):  
Susan L. Brantley ◽  
Roman A. DiBiase ◽  
Tess A. Russo ◽  
Yuning Shi ◽  
Henry Lin ◽  
...  
Keyword(s):  
Land Use ◽  
Critical Zone ◽  
Basic Unit ◽  
Spatial Density ◽  
Earth Surface ◽  
Original Design ◽  
Creek Watershed ◽  
The Individual ◽  
Landscape Morphology ◽  
Shale Hills

Abstract. Many scientists have begun to refer to the earth surface environment from the upper canopy to the depths of bedrock as the critical zone (CZ). Identification of the CZ as an integral object worthy of study implicitly posits that the study of the whole earth surface will provide benefits that do not arise when studying the individual parts. To study the CZ, however, requires prioritizing among the measurements that can be made – and we do not generally agree on the priorities. Currently, the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) is expanding from a small original focus area (0.08 km2, Shale Hills catchment), to a larger watershed (164 km2, Shavers Creek watershed) and is grappling with the prioritization. This effort is an expansion from a monolithologic first-order forested catchment to a watershed that encompasses several lithologies (shale, sandstone, limestone) and land use types (forest, agriculture). The goal of the project remains the same: to understand water, energy, gas, solute, and sediment (WEGSS) fluxes that are occurring today in the context of the record of those fluxes over geologic time as recorded in soil profiles, the sedimentary record, and landscape morphology. Given the small size of the Shale Hills catchment, the original design incorporated measurement of as many parameters as possible at high temporal and spatial density. In the larger Shavers Creek watershed, however, we must focus the measurements. We describe a strategy of data collection and modeling based on a geomorphological and land use framework that builds on the hillslope as the basic unit. Interpolation and extrapolation beyond specific sites relies on geophysical surveying, remote sensing, geomorphic analysis, the study of natural integrators such as streams, groundwaters or air, and application of a suite of CZ models. We hypothesize that measurements of a few important variables at strategic locations within a geomorphological framework will allow development of predictive models of CZ behavior. In turn, the measurements and models will reveal how the larger watershed will respond to perturbations both now and into the future.

scholarly journals Research on the Temperature Field and Frost Heaving Law of Massive Freezing Engineering in Coastal Strata

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Chaochao Zhang ◽  
Dongwei Li ◽  
Junhao Chen ◽  
Guanren Chen ◽  
Chang Yuan ◽  
...  
Keyword(s):  
Temperature Field ◽  
Three Dimensional ◽  
Element Model ◽  
Freezing Temperature ◽  
Frozen Soil ◽  
Physical Parameters ◽  
Frost Heaving ◽  
Soil Frost ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this study, based on the background of massive freezing engineering in coastal strata, the thermal physical parameters and some freezing laws of soil were obtained through soil thermal physical tests and frozen soil frost heaving tests. When the freezing temperatures were −5°C, −10°C, −15°C, and −20°C, the frost heaving rates of the soil were 0.53%, 0.95%, 1.28%, and 1.41%, and the frost heaving forces of the soil were 0.37 MPa, 0.46 MPa, 0.59 MPa, and 0.74 MPa, respectively. In the range of test conditions, the frost heaving rate and the frost heaving force of the soil increased with the decrease of the freezing temperature, and the relationship was roughly linear with the temperature. The entire cooling process could be roughly divided into three stages: active freezing stage, attenuation cooling stage, and stability stage. The range of the frozen soil expansion did not increase linearly with the decrease of the freezing temperature, and there was a limit radius for the frozen soil expansion. A three-dimensional finite element model was established to simulate the temperature field and frost heaving of the soil under the on-site working conditions. The entire frost heaving process could be roughly divided into two stages. The calculated temperature values and the frost heaving force values were compared with the on-site measured values, and the results verified that the numerical calculation could accurately reflect the temperature field and frost heaving law of the formation.

scholarly journals Application of SWAT model with CMADS data for hydrological simulation in western China

2020 ◽  
Author(s):  
Yuejian Wang ◽  
Guang Yang ◽  
Xinchen Gu ◽  
Xinlin He ◽  
Yongli Gao ◽  
...  
Keyword(s):  
Land Use ◽  
Assessment Tool ◽  
Swat Model ◽  
River Basins ◽  
Frozen Soil ◽  
Western China ◽  
Runoff Simulation ◽  
Land Use Patterns ◽  
Hydrological Simulation ◽  
Flood Season

Abstract Precise simulations of hydrological processes under the influence of climate change and human activities have special significance in arid basins. During the past 60 years, the annual average temperature and precipitation at the northern foothills of the Tianshan Mountains have increased at the rates of 0.035 °C/year and 0.881 mm/year, respectively. Rising temperatures will change the temporal and spatial distributions and forms of precipitation, accelerate glacier retreat, melt snow on high mountains, cause the degeneration of frozen soil, and change the runoff composition in the Tianshan area. In this work, the CMADS (China Meteorological Assimilation Driving Dataset for the SWAT model) was combined with the SWAT (Soil and Water Assessment Tool) model to simulate runoff in the upper reaches of the Jing River and Bo River Basins in the Tianshan area. The results were as follows. (1) On the monthly scale, the average Nash–Sutcliffe efficiency (NSE) coefficients of the calibration period in the Wenquan and Jinghe–Shankou hydrological stations were 0.79 and 0.87, respectively, and the NSE coefficients of validation period were 0.71 and 0.82, respectively. On the daily scale, the NSE coefficients of the two hydrological stations were between 0.69 and 0.77. The simulation results were considered to be ideal on the monthly and daily scales. (2) Under different climate scenarios and land-use patterns, the cultivated land in the basin leads to the reduction of runoff, and the grassland and woodland stabilise the river flood season. Lakes and wetlands, which can reduce the flow in the flood season and provide water for rivers in the dry season, are very important for runoff regulation. Compared with the traditional meteorological stations, CMADS demonstrates good representativeness and reliability in the Jinghe River and Bohe River Basins under different climate and land-use scenarios, greatly improving the runoff simulation ability.

Simulation supported scenario analysis for water resources planning: a case study in Northern Italy

2005 ◽  
Vol 51 (3-4) ◽  
pp. 11-18 ◽  
Author(s):  
A. Facchi ◽  
C. Gandolfi ◽  
B. Ortuani ◽  
D. Maggi
Keyword(s):  
Land Use ◽  
Water Availability ◽  
Irrigation Water ◽  
Irrigation System ◽  
Groundwater Resources ◽  
Northern Italy ◽  
Irrigation District ◽  
Zone Model ◽  
Crop Water ◽  
The Impact

The work presents the results of a comprehensive modelling study of surface and groundwater resources in the Muzza–Bassa Lodigiana irrigation district, in Northern Italy. It assesses the impact of changes in land use and irrigation water availability on the distribution of crop water consumption in space and time, as well as on the groundwater resources. A distributed, integrated surface water-groundwater simulation system was implemented and applied to the study area. The system is based on the coupling of a conceptual vadose zone model with the groundwater model MODFLOW. To assess the impact of land use and irrigation water availability on water deficit for crops as well as on groundwater system in the area, a number of management scenarios were identified and compared with a base scenario, reflecting the present conditions. Changes in land use may alter significantly both total crop water requirement and aquifer recharge. Water supply is sufficient to meet demand under present conditions and, from the crop water use viewpoint, a reduction of water availability has a positive effect on the overall irrigation system efficiency; however, evapotranspiration deficit increases, concentrated in July and August, when it may be critical for maize crops.

Research on Frost Heaving of Subgrade Filling in Seasonal Frozen Soil Area

2014 ◽  
Vol 1065-1069 ◽  
pp. 783-787
Author(s):  
Jin Fang Hou ◽  
Rui Qi Zhang ◽  
Jian Yu
Keyword(s):  
Water Content ◽  
High Speed ◽  
Freezing Temperature ◽  
Frozen Soil ◽  
Coarse Grained ◽  
Freezing And Thawing ◽  
Frost Heaving ◽  
Factors Affecting ◽  
Seasonal Frozen Soil ◽  
Soil Area

Research on frost heaving of high speed railway subgrade filling in seasonal frozen soil area is developed indoor. Through freezing and thawing strength and frost heaving amount test, the research analyzes factors affecting frost heaving of subgrade filling, points out that water content, fine stuff admixing amount and plasticity of fine-grained soil have relatively large influence on frost heaving, while freezing temperature and freezing and thawing cycle index have relatively small influence. Water content is main factor to have effect on frost heaving of subgrade filling. When the water content reaches to some certain value, even coarse-grained soil can produce considerable frost heaving amount. Therefore, taking effective waterproof and drainage measures is of great importance in subgrade frost heaving prevention and treatment.

Detailed observations on the nature of frost heaving at a field scale

1989 ◽  
Vol 26 (2) ◽  
pp. 306-312 ◽  
Author(s):  
M. W. Smith ◽  
D. E. Patterson
Keyword(s):  
Frozen Soil ◽  
Frost Heave ◽  
Field Scale ◽  
Frost Heaving ◽  
Moisture Movement ◽  
Ice Accumulation ◽  
Thermodynamic Conditions ◽  
Soil Strain ◽  
Detailed Picture ◽  
Complex Manner

Observations made using a system of ring magnets have provided a detailed picture of differential soil strain associated with frost heaving at a field scale. The results reveal the evolution of heave as freezing advances through the soil and the variation of soil strain with depth and time, and with soil temperature conditions. The results indicate that soil strain characteristically continues within frozen soil, sustained, it is proposed, by continuing water migration into the frozen soil. Consequently a considerable thickness of frozen soil appears to be actively involved with moisture movement and ice accumulation during frost heaving. The observations support the view that frost heave generally depends in a complex manner on the thermodynamic conditions of temperature and water and ice pressures as they are modified by the rheological properties of the soil. Key words: frost heave, differential soil strain, frost heave measurement.

scholarly journals Cropping pattern simulation-optimization model for water use efficiency and economic return

2021 ◽  
Vol 52 (4) ◽  
Author(s):  
Cesar Augusto Terán-Chaves ◽  
Sonia Mercedes Polo-Murcia
Keyword(s):  
Land Use ◽  
Optimization Model ◽  
Agricultural Development ◽  
Water Productivity ◽  
Temporal Distribution ◽  
Irrigation District ◽  
Economic Losses ◽  
Cropping Pattern ◽  
Forage Production ◽  
Sustainable Resources

Sustainable agricultural development is one of the most important tools for the economic growth of a country. Therefore, water and land use management is considered a priority. This research aimed to develop a framework to optimize crops’ spatial and temporal distribution in an irrigation district. The AquaCrop- OS (FAO) water productivity model was integrated with a nonlinear optimization model to maximize the annual net profitability and minimize the water consumption of three crops (rice, corn, and forage). It was applied at a regional level to 905 simulation sub-units in the Zulia irrigation district (Colombia), in three typical climatic years’ scenarios, and at a multi-period level (monthly). The results indicated that: i) crop simulation for the study area was applicable and feasible; ii) rice can be combined with forage and corn; iii) corn is a viable option under dry year conditions; iv) under a wet year, forage production is the best option. On average, in the dry year, profitability decreased by 14.5% compared to the normal year in half of the study area, and in some areas, economic losses of up to 53% were obtained. In the wet year, profitability remained at the same level as the normal year in 43.8% of the area. However, there were significant decreases in profitability in 23.1% of the district. In the normal year, the water demand of the crops in each simulated period allows savings of up to 50% of water compared to the current concession amount, which is 1000 mm. This study is useful for making decisions on sustainable resources management and optimal irrigation water and land use under different biophysical and economic conditions.

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