土壤学报2019，Vol.56Issue(1)：101-113,13.DOI:10.11766/trxb201802120016
大沽河流域土壤水-地下水流耦合模拟及补给量估算
Numerical Simulation Coupling Soil Water/Groundwater and Estimation of Groundwater Recharge in Dagu River Basin
摘要
Abstract
[Objective]The water-bearing layers in the Dagu River Basin are distributed mainly in a long and narrow strip of area alongside the middle and lower reaches of the Dagu River, forming a huge underground reservoir, which is one of the major water sources supplying water to Qingdao. Currently, the groundwater resource in the Dagu River Basin has been over-exploited causing a series of environmental problems, like seawater intrusion, surface subsidence, etc. With rapid development of the economy and population in the region, the problem of water resource shortage significantly constrain sustainable development of Qingdao. To enhance comprehensive management of the water resources in the region, it is essential to accurately assess groundwater recharge. Although much work has been done on groundwater recharge, few of the relevant researches have taken into account the transformational relationship between soil water and groundwater, which has resulted in big gaps between the calculation of groundwater recharge and the reality. This study aimed to establish a soil water and groundwater coupled model, with which to analyze movements of soil water and groundwater in the studied region, and further to calculate accurately groundwater recharge in the Dagu River Basin under the current precipitation and irrigation conditions.[Method]Based on the principle of the software of HYDRUS package for MODFLOW coupled with the GIS technology, a basin-scaled (4 781 km2) soil water and groundwater coupled model (SWGCM) was developed. The model was used to simulate moisture movement between vadose and saturated zone, flux at the bottom of a profile was worked out through multi iteration of the Richards-1 D equation, using the HYDRUS sub-model within each time step of the MODFLOW model, and through calculation of the acquired flux, the MODFLOW model yielded a new groundwater table, which was used as water head value at the bottom boundary for the next step of calculation. With all the relevant data put under comprehensive consideration, including precipitation, evaporation, plant water absorption, soil texture, aquifer distribution, and soil water and groundwater related parameters, such as groundwater exploitation capacity, soil moisture content, and groundwater table, the SWGCM model was used to simulate movement of soil water and groundwater in the Dagu River Basin, and accuracy of the model was varied through fitting of soil water content and groundwater in the soil profiles.[Result]Results show that the simulated soil profile moisture content and groundwater table well agree with the measured data. In the calibration phase, the determination coefficient of the soil profile moisture content in the soil profile varies in the range of 0.65～0.91, and the RMSE in the range of 0.005～0.01; and that of the groundwater table does in the range of 0.52～0.68, and of 0.12～0.38, respectively, while in the validation phase the determination coefficient of the soil profile moisture content does in the range of 0.53～0.86, and the RMSE in the range of 0.006～0.011 and that of the groundwater table in the range of 0.56～0.81 and of 0.17～0.19, respectively. The fitting of soil profile moisture content and groundwater table indicates that the SWGCM model is good enough to simulate water movement in variably-saturated porous media and groundwater recharge. In the calibration phase, the groundwater recharge is 315 million m3, and in the validation phase, 477 million m3.[Conclusion]To accurately assess groundwater recharge, it is necessary to take into account the relationship between soil water and groundwater in movement. The SWGCM model can be used to accurately simulate spatiotemporal variation of the soil water and groundwater in the Dagu River Basin, and hence to calculate vertical infiltration supplementary capacity of groundwater in the region with quite high reliability and accuracy. Therefore, the SWGCM model may provide certain scientific basis for development of a rational allocation of water resources of the basin and an effective approach, too, to accurate assessment of groundwater recharge.关键词
土壤水/地下水/耦合模型/大沽河流域/地下水补给量Key words
Soil water/Groundwater/Coupled model/Dagu River Basin/Groundwater recharge分类
天文与地球科学引用本文复制引用
张旭洋,林青,黄修东,徐绍辉..大沽河流域土壤水-地下水流耦合模拟及补给量估算[J].土壤学报,2019,56(1):101-113,13.基金项目
国家重点研发计划项目(2016YFC0402807)、国家自然科学基金项目(41571214)共同资助 （2016YFC0402807）
Supported by the Nationa1 Key Research and Development Program of China (No. 2106YFC0402807) and the Nationa1 Natural Science Foundation of China(No. 41571214 ) （No. 2106YFC0402807）
