地下水浅埋干旱灌区水转化多过程模拟与调控研究

Quantitative simulation of hydrology and crop growth processes is very important and significant for the reasonable management of agricultural activities and water resources in arid irrigation districts. In this study, the Yonglian Irrigation System of Hetao Irrigtion District is selected as a typical study area with shallow water table conditions. The observation experiment related to hydrologic process and crop growth is applied, the purpose of which is to explore and clarify the temporal and spatial dynamics of soil water and groundwater and their impact factors. Then a full-coupled model for simulating the processes of soil water and salt transport, groundwater flow and crop growth is to be developed for arid irrigation districts with shallow water tables. We first focus on establishing the coupling mode in time and space between soil water and groundwater systems as well as solving their interface interaction. Then the coupled model, named MODSGC, is to be developed on the basis of coupling vertically one-dimensional soil water and solute transport model, three-dimensional groundwater flow model and crop growth model. At first, the typical lab experiments, which is related to variably saturated water flow in previous studies, is chosen to test MODSGC model. After that, several numerical experiments of variably saturated flow is constructed both using MODSGC model and some other maturity variably saturated flow models, which is used for further verifying the applicability of MODSGC. Meanwhile, the parameter sensitivity analysis is also required to be done for assisting in model calibration. Then we applied the MODSGC model to simulate the regional hydrology and crop growth processes in typical study area of Hetao Irrigation District, based on the data from our observation experiment and previous surveys. This could further validate the applicability of the developed MODSGC model in practical regional modeling. Finally, the response of soil water and groundwater dynamics as well as crop growth to different water-saving practices is evaluated in time and space, using the calibrated and validated MODSGC model. In summary, this research could promote the researches on simulation method of water cycle in irrigation districts. Meanwhile, it can also provide an efficient tool for assisting in development of agricultural water management strategies for arid irrigation districts with shallow water tables.

合理定量描述灌区水资源转化及作物生长过程，对于干旱灌区农业节水与水资源高效利用具有重要意义。本研究拟选取典型地下水浅埋干旱灌区-内蒙河套灌区作为研究对象，开展典型区（永联试验区）水文与作物生长的定位观测试验与资料收集，分析典型区土壤水盐与地下水时空动态规律及影响因子；发展灌区尺度土壤水-地下水耦合模拟中边界耦合与时空尺度耦合处理方法，以建立基于动力学机制的、适用于地下水浅埋干旱灌区的土壤水-地下水-作物生长耦合模型-MODSGC；基于变饱和流经典试验、数值试验及参数敏感性分析，验证耦合模型算法的正确性、稳定性及模型效率；建立典型区MODSGC模型，开展耦合模型在实际灌区模拟中的适用性研究，并基于率定后模型进行典型区水转化过程对农业节水响应的情景模拟与分析。研究成果将是对灌区水转化机制与定量模拟研究的重要补充，同时可为地下水浅埋干旱灌区制定合理的农业节水措施提供有效的决策支持工具。

合理定量描述灌区水转化及作物生长多过程，对于干旱灌区农业节水与水资源高效利用具有重要意义。本研究以我国西北典型干旱灌区为研究对象，围绕水转化关键环节及农业用水中存在的现实问题，开展了基于野外试验观测与动力学模型的农业水文过程模拟方法与应用研究。主要的研究内容和取得的成果如下：（1）发展了适用于农田及灌区尺度的农业水文模型SWAP-EPIC，结合观测试验数据在宁蒙河套灌区和黑河中游灌区进行了模型测试与应用，量化了复杂农田水文过程及其对农业节水的响应；（2）通过SWAP-EPIC的节水情景分析，提出了河套灌区春小麦生育期适宜埋深控制范围1.0-1.5m，通过改善渠系配水合理性可有效提高黑河中游灌区农业用水效率，并估算了灌区可能的最大节水比例约15%；（3）建立了基于LH-OAT和MGA的农业水文模型参数全局敏感性分析与参数优化方法，应用春小麦试验数据进行了模拟测试，表明该方法可有效的提高模型率定效率；（4）构建了灌区尺度土壤水—地下水耦合模拟中边界耦合与时空尺度耦合的处理方法，进一步建立了基于动力学机制的、适用于地下水浅埋干旱灌区的土壤水-地下水-作物生长耦合模型—MODSWAP，通过室内试验及实际灌区的应用测试检验了模型的适用性。上述研究成果将是对灌区水转化机制与定量模拟研究的重要补充，同时可为地下水浅埋干旱灌区制定合理的农业节水措施提供有效的辅助工具。