Systems approach to an unsaturated-saturated groundwater quality model,including adsorption,decomposition and bypass

In this paper an unsaturated-saturated model for groundwater pollution from diffuse sources is developed. As a linear systems approach has been applied, a time-dependent input concentration can easily be incorporated. Processes as first-order decomposition and linear adsorption can be accounted for as well as the phenomenon of bypass flow. An example is given of a bimodal breakthrough curve as a reaction on a pulse-type input concentration. A program written for an HP41CV pocket calculator is presented in the appendix.     

Simulation of water flow in the soil under sub-surface trickle irrigation with water uptake by roots

Water uptake by roots is presented as a continuous sink function and introduced into the flow equation in the unsaturated zone. The steady-state non-linear equation is linearized and then solved numerically. The results show the influence of water demand, and of the intensity of the water source, on uptake by roots, on leakage under the root zone, and on the progress of the wetting front. The unique feature of this procedure is that it leads to a relatively simple differential equation which is essentially a corrected form of the solutions that disregard the uptake effect and the pressure head at the outlet of the sub-surface emitter. Although further confirmation is needed before the results can be applied for engineering purposes, the general behaviour and flow characteristics in the soil are satisfactorily simulated, and are also validated by the field experiments.     

Combining an ecological model with remote sensing and GIS techniques to monitor soil water content of croplands with a monsoon climate

Soil water is an important factor affecting photosynthesis, transpiration, growth, and yield of crops. Accurate information on soil water content (SWC) is crucial for practical agricultural water management at various scales. In this study, remotely sensed parameters (leaf area index, land cover type, and albedo) and spatial data manipulated using the geographic information system (GIS) technique were assimilated into the boreal ecosystem productivity simulator (BEPS) model to monitor SWC dynamics of croplands in Jiangsu Province, China. The monsoon climate here is characterized by large interannual and seasonal variability of rainfall causing periods of high and low SWC. Model validation was conducted by comparing simulated SWC with measurements by a gravimetric method in the years 2005 and 2006 at nine agro-meteorological stations. The model-to-measurement R² values ranged from 0.40 to 0.82. Nash-Sutcliffe efficiency values were in the range from 0.10 to 0.80. Root mean square error (RMSE) values ranged from 0.028 to 0.056 m³ m⁻³. Simulated evapotranspiration (ET) was consistent with ET estimated from pan evaporation measurements. The BEPS model successfully tracked the dynamics and extent of the serious soil water deficit that occurred during September-November 2006. These results demonstrate the applicability of combining process-based models with remote sensing and GIS techniques in monitoring SWC of croplands and improving agricultural water management at regional scales in a monsoon climate.     

水泥粉体喷射搅拌桩在南湖排涝站工程地基处理中的应用

泵站基础处理是泵站工程的关键,对于含水量大、压缩性高、透水性差、灵敏度高、承载力低的软基面处理,水泥粉体喷射搅拌桩在技术经济方面有着明显优势,本文结合南湖排涝站工程地基处理施工实际,探讨水泥粉体喷射搅拌桩(简称水泥粉喷桩)施工工艺及质量控制.     

水泥粉体喷射搅拌桩在南湖排涝站工程地基处理中的应用

泵站基础处理是泵站工程的关键，对于含水量大、压缩性高、透水性差、灵敏度高、承载力低的软基面处理，水泥粉体喷射搅拌桩在技术经济方面有着明显优势，本文结合南湖排涝站工程地基处理施工实际，探讨水泥粉体喷射搅拌桩（简称水泥粉喷桩）施工工艺及质量控制。     

Optimal allocation of water from a single purpose reservoir to an irrigation project with pre-determined multiple cropping patterns

A model for optimal allocation of water from a single-purpose reservoir to an irrigation project with pre-determined multiple cropping patterns was developed. The model consisted of two modules: (I) the intra-seasonal allocation model (non-linear programming) which is used for allocation of water among different crops for a definite combination of state variables (inflow class, rainfall class, reservoir storage classes at the beginning and at the end of the season) for the non-dormant season to maximize total farm income; and (II) the seasonal allocation model (stochastic-dynamic programming) which is used for the convergent operating policy over seasons for optimal expected farm income over a year. The model was applied to Ardak reservoir dam (I.R. Iran) in an arid region. Low river inflow in the dormant season at the study area could not admit the reservoir class changes for specific combinations of state variables, and therefore resulted in a non-usable result. Imposing a fictitious positive relative net benefit for all possible combinations of reservoir class changes eliminated this problem. It was also shown that rainfall did not play a marked role in the study area, which is an arid region, and its stochastic nature can be removed from the model.     

生态视角下半干旱区水资源优化配置研究 ——以辽宁省建平县为例

文章以辽宁省建平县为例,将生态环境需水纳入用水部门,基于多目标优化理论,构建出综合效益最大化为目标的生态半干旱地区水资源合理配置模型,并以设定水平年在不同保证率下的水资源供需状况为依据拟定相关参数进行函数求解,获得相应的优化方案.