极端干旱地区葡萄根系吸水数值模拟

Numerical simulation of root water uptake for grape in extremely arid region

研究成龄葡萄根系分布与吸水特征及耗水规律,能够为制定成龄葡萄灌溉制度、提出丰产与节水相协调的成龄葡萄田间水分管理模式和创建成龄葡萄水分高效利用技术体系提供技术支撑。该文在分析灌溉条件下葡萄吸水特征的基础上,建立了一维非饱和土壤水分运动的无网格数值模拟模型,并依据实测葡萄根系分布特征,获得了葡萄一维根系分布函数,将其与不同的经验根系分布函数应用于数值模型进行动态模拟。通过模拟值与土壤水分实测值的比较分析,结果表明,不同根系分布模型下土壤水分模拟差别不大,相对误差均在1%以下,但相对于其他根系分布,指数根系数分布模拟值与实测值的误差较大,因此,认为拟合的根系分布函数和无网格数值模型能很好的模拟极端干旱地区葡萄根系吸水和土壤水分运动,且在缺乏实际根长分布数据的条件下,线性根系分布和分段根系分布都可反映葡萄实际根系分布,为利用简单一维根系分布模型分析不同灌溉条件葡萄吸水特征提供参考。

According to the researches about the root distributions of mature grape, the characteristics of root water uptake and the laws of water consumption, it can be provided technical support for formulating the optimum irrigation system, proposing reasonable water management pattern and creating technical system of high-efficiency utilization of water. Based on analyzing the characteristic of water uptake and the measured data of the grape root distribution under condition of irrigation, a meshless numerical simulation model for one-dimensional water flow in unsaturated soils and one-dimensional root distribution function of grape were introduced in this paper. Further, the root distribution function and the other empirical root distribution functions were applied to numerical simulation model to demonstrate the appropriateness. According to the comparison between the results of dynamic simulation and data of field experiment, it shows that the simulated values of fitting root distribution, exponential root distribution, linear root distribution and piecewise root distribution are coincide well with measured values, and all of the relative errors are below 1%. However, compared with other root distribution functions, the error of exponential root distribution is larger. Therefore the fitting root distribution and the meshless numerical model can simulate the root water uptake of grape and the soil water movement in extremely arid region well. Moreover, under the condition of the shortage of the field root length distribution, linear root distribution and piecewise root distribution can be used to describe the practical root distribution of grape, and provide reference for using one-dimensional simple root distribution model to analyze the characteristic of grape water uptake under irrigation condition.