Abstract:In order to evaluate heavy metal contamination in Sidi River Basin mining area of Yangshuo County, Guangxi, the Watershed Hydrological Model by ArcSWAT and the solute transport model by MT3DMS in GMS (Groundwater Modeling System) were combined to quantitatively analyze the migration of zinc and cadmium. The results suggest that: (1) Utilizing ArcSWAT and GMS can more accurately determine the vertical infiltration amount and accurately groundwater numerical simulation. (2) Mine wastewater posed a significant contaminated threat to groundwater environment without control measures: It was found that the content of zinc and cadmium in water sample of tailing cave outlet was 18.62 and 0.096 milligrams per liter respectively, which was the source of heavy metal contamination in entire basin. Within simulated period of 20 years, the contaminated halo of zinc and cadmium reached the river after about 16 and 44 days respectively, and the farthest front end of halo was 2 303.75 and 1 887.04 meters away from the center. The longest part at both ends was 3 159.57 and 2 478.57 meters, and the widest part was 1 533.54 and 1 128.36 meters. The mass of zinc and cadmium entered basin was 3 512.44 and 18.15 grams, and flowed out was 1 640.49 and 8.47 grams, remaining proportion were 53.28% and 53.33% separately in basin. (3) There are existing research results show that Solanum nigrum L. is hyperaccumulator for cadmium that the highest accumulation in plant is 1 084.4 milligrams per kilogram and strong tolerance to zinc with enrichment exceeding 1 000 milligrams per kilogram. Therefore, a simulated circumstance was set up to evaluate the ecological restoration of tailings reservoir. The content of zinc was 0.284 milligrams per milliliter and cadmium was 0.002 milligrams per milliliter in tailings pond which was taken as alternative contaminated source. The migration speed of zinc along river valley reduced from 94.38 to 80.78 meters per year, and cadmium reduced from 86.09 to 69.13 meters per year during simulated period. The maximum halo of zinc reduced from 3.80×10^6 to 2.50×10^6 square meters and of cadmium from 1.67×10^6 to 1.29×10^6 square meters. It indicated that the ecological restoration had achieved better effects and proposed continue investing in construction. (4) According to simulation results, it is recommended to construct anti-seepage curtains and other prevention measures at the mine tunnel outlet. And prevention areas are classified to strengthen groundwater quality monitoring. Simultaneously, emergency plans for groundwater accidents can be formulated to avoid further deterioration of contamination.