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| 考虑地下水侧向流动与土壤水-地下水相互作用的陆面过程模式及其应用 | |
| 其他题名 | A Land Surface Model with Groundwater Lateral Flow and Soil water-Groundwater Interaction and Its Applications |
| 于燕 | |
| 出版年 | 2014 |
| 学位类型 | 博士 |
| 导师 | 谢正辉 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 作为水循环过程的重要组成部分，地下水运动受地形、土壤、植被、气候条件以及人类活动的综合影响。地下水在水平方向上的辐合辐散以及在垂直方向上与非饱和土壤水的相互作用改变土壤湿度的时空分布，影响陆面与大气之间的水分能量交换，进而影响气候。在陆面过程模式中合理表示地下水的侧向流动过程以及垂向与土壤水的相互作用，对于完善气候系统中陆地水循环过程的描述、深入理解人类活动引起的区域水文循环变化规律具有重要意义。本博士论文的研究目标是发展考虑地下水侧向流动与水资源开采利用的陆面过程模式，为研究陆面水文循环过程以及人类活动影响下的水资源变化规律提供模式平台，研究并揭示地下水侧向流动及土壤水-地下水相互作用对陆面过程的影响规律，增加对陆气相互作用的理解。围绕上述研究目标，本论文在地下水模型发展、与陆面过程模式耦合、模型评估与应用等方面开展研究。论文主要成果总结如下：(1) 建立了考虑地下水侧向流动的陆面过程模式。基于隐式差分格式建立了二维地下水侧向流数值模型，并针对黑河流域将其与陆面过程模式CLM3.5耦合，建立了考虑地下水侧向流动的陆面过程模式。对地下水侧向流模型数值算法及地下水排泄速度进行的敏感性分析表明了模型计算的稳定性与合理性。地下水侧向流模型模拟的黑河流域平衡态地下水埋深较CLM3.5气候态埋深空间变异性强，在中游的高台与金塔地区较CLM3.5更接近观测值。耦合模型模拟结果显示，中游自南向北(临泽、高台、金塔)递减的地下水埋深空间分布特征与观测吻合。中游山前地区地下水埋深变浅使得土壤湿度增加，三个农业气象站点(39.77°N, 99.48°E；38.93°N, 100.43°E；38.45°N, 100.82°E)土壤湿度平均增加0.04mm3/mm3，一定程度上改善了原模式对中游地区土壤湿度的低估。对于受水分限制的西北干旱区，蒸散发的变化主要由土壤蒸发决定，而对于以农作物为主要植被类型的部分中游平原区，蒸散发的变化主要由植被蒸腾控制。总径流深变化主要集中在地形复杂的上游地区，且主要由次地表径流变化所贡献。水分循环的改变影响到能量循环，从而影响到感热与潜热的分配。(2) 发展了综合考虑地下水侧向流动与开采利用的陆面过程模式，探讨地下水侧向流动与开采利用对陆面过程的影响。在建立的考虑地下水侧向流动的陆面过程模式基础上，进一步耦合了人类地下水开采利用方案，发展了综合考虑地下水侧向流动与开采利用的陆面过程模式。利用上述建立的综合模型针对黑河流域进行长期模拟试验，探讨综合考虑地下水侧向流动与开采利用对陆面过程的影响，以及地下水开采利用条件下侧向流对陆面水文能量要素的影响。结果表明，考虑了地下水开采利用过程后，能够较好的模拟出人类活动影响较大的张掖、酒泉盆地的地下水位降落漏斗。中游平原区高强度地下开采利用导致地下水位下降，而地下水侧向流的辐合作用补给能力明显有限，不超过20%；平原周边地区由于地下水开采和侧向流辐散作用的共同影响导致地下水位严重下降；而上游山区与下游河岸附近侧向补给作用较强且地下水开采程度较弱，使得水位上升，其中侧向流贡献率超过85%。地下水的开采利用使得中游平原区陆地表面降温增湿，而地下水侧向流过程进一步增强了降温增湿幅度，对土壤增湿的贡献率为53%。地下水开采利用过程减弱了大部分陆面水分要素的年际变率，而侧向流过程进一步减弱了包括土壤湿度在内的各陆面水分要素的年际变率，表明地下水侧向流使得陆面水文要素的年际波动趋于平缓。 (3) 改进的考虑土壤水-地下水相互作用的土壤水数值计算方案在陆面过程模式CLM3.5与区域气候模式RegCM4/CLM3.5中的应用与评估。为了消除基于质量守恒的土壤水方程数值解法的缺陷，改进的土壤水数值计算方案在Richards方程中去掉利用地下水埋深计算的平衡态土壤水势，从而使得土壤水与地下水直接耦合。将此改进的方案应用到陆面过程模式CLM3.5与区域气候模式RegCM4/CLM3.5中，探讨其对陆面过程(离线试验)与区域气候(耦合试验)模拟的影响。结果表明，修改后的RegCM4模拟夏季降水在东北、华北、华南区域系统偏差分别减小了29.7%、28.9%、55.9%。而对夏季气温的改进相对较小，系统偏差减幅均小于10%。耦合试验模拟的东北与华北区域土壤湿度变率与观测变率更加接近，相关系数明显提高。由于考虑了大气反馈作用，耦合试验模拟的多年平均夏季土壤湿度空间分布差异与离线试验差异存在明显的地理性差别。耦合试验中土壤湿度明显差异为偏干的青藏高原与偏湿的华北地区，而离线试验中明显差异是偏湿的西北地区与偏干的青藏高原北部地区。离线试验中偏湿的西北地区降水由于水汽辐散而减少，而降水的减少导致土壤湿度减小，蒸散发减小，从而进一步减少降水。 |
| 英文摘要 | As an important component of hydrologic cycle, groundwater is affected by topography, vegetation, climate condition, and anthropogenic activity. Groundwater horizontal convergence and divergence and vertical interaction with soil water result in variations of soil moisture, water and energy exchanges between the land surface and the atmosphere, which ultimately influences climate. Therefore, reasonable representation of groundwater lateral flow and vertical coupling with soil water is essential to understand land hydrologic cycle and the relationship between regional hydrologic cycle and human activities. This dissertation attempts to develop a coupled land surface model with groundwater lateral flow and its exploitation and utilization to detect changes in land hydrologic cycle caused by these processes. To achieve this goal, studies are devoted to groundwater model development and its coupling with land surface model, model assessment and application. The main conclusions of this study are presented as follows:(1) A coupled land surface model with groundwater lateral flow component is developed. Based on groundwater mass balance equation and fully implicit difference numerical scheme, a two-dimensional groundwater flow model is developed. Then the groundwater lateral flow model is coupled with land surface model CLM3.5 and is implemented in Heihe River Basin. Sensitivity tests on numerical solutions and the discharge rate demonstrate the computation stability and rationality of the groundwater lateral flow model. The spatial pattern of water table equilibrium simulated by the model over Heihe River Basin is more heterogeneous than annual mean values simulated by CLM3.5, and the equilibrium are much closer to observations averaged over Gaotai and Jinta region in the middle reaches area. The coupled model with groundwater lateral flow component agrees with observations in decreasing water table depth from south to north (Linze, Gaotai, Jinta) over middle reaches area. Shallower water table simulated by the coupled model increases soil moisture over piedmont areas in the middle area, which alleviates the underestimation of CLM3.5 over this region to some extent. Soil moisture averaged over three agriculture-meteorology sites (39.77°N, 99.48°E、38.93°N, 100.43°E、38.45°N, 100.82°E) increases 0.04mm3/mm3. Due to evapotranspiration is strongly dependant on soil water in arid areas, changes in evapotranspiration is mainly devoted by changes in soil evaporation over most areas. However, transpiration exerts a main control on total evapotranspiration over middle reaches area with a widely distribution of crop. Changes in total runoff primarily occur in upper reaches area with complex terrain and are mainly caused by changes in subsurface runoff. Energy distribution is affected by changes in hydrologic cycle, which results in redistribution of latent heat flux and sensible heat flux.(2) A coupled land surface model with groundwater lateral flow component and a sheme of human-induced groundwater exploitation and utilization is developed. Based on the coupled land surface model with groundwater lateral flow component, groundwater exploitation and utilization processes are further considered. Long-term simulation tests in Heihe River Basin are conducted to investigate the separate and comprehensive effects. The results reveal that the water table drawdown funnel over Zhangye and Jiuquan basin due to consideration of groundwater exploitation can be well simulated. Middle plains with high intensity of groundwater exploitation suffer decreased water table, because the compensation of groundwater lateral flow is obviously limited, no more than 20%; water table seriously declines over plain surrounding areas due to groundwater exploitation and lateral flow divergence; strong lateral groundwater flow convergence and weak groundwater exploitation result in rising water table over upper reaches mountain areas and lower reaches areas near river |
| 中文关键词 | 地下水侧向流 ; 地下水开采利用 ; 改进的土壤水数值计算方案 ; 陆面过程模拟 ; 区域气候模拟 |
| 英文关键词 | groundwater lateral flow groundwater exploitation and utilization modified Richards equation land surface modeling regional climate modeling |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 气象学 |
| 来源机构 | 中国科学院大气物理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287349 |
| 推荐引用方式 GB/T 7714 | 于燕. 考虑地下水侧向流动与土壤水-地下水相互作用的陆面过程模式及其应用[D]. 中国科学院大学,2014. |
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