Jiaozhou Bay Seawater Intrusion Hazard Assessment And Prediction

The Kiaochow Bay region is the population high degree of concentration and the economical fast development area. In the 1970s, with the developmentof industry and agrieulture, more and more groundwater is pumped at coastal areas.Continued significant decline in ground water level, resulting in salt and freshwater interface change, seawater intrusion to freshwater aquifers, groundwater salinity increases and water salinization; also a result of changing farming practices, or coastal tidal waters caused by improper development of the invasion. According to the study of the seawater intrusion in Kiaochow Bay region, there will be practical significance in the coming implementation of Kiaochow Bay's development strategy, economy and social sustainable development in Qingdao city, it also provides geological evidences for the urban planning, construction, management and hazard prevention and mitigation, profiting and avoiding loss and so on, it also conducive to the rational development and protection of regional water resources, geological resources. The achievements, which include geological survey data, mechanism of seawater intrusion and evolution rules and so on, have academic reference meaning for this region and other ralated areas.Since early March 2008 to the end of December 2008, according to the study of the status of seawater intrusion in Kiaochow Bay region in the scale 1:25000, we get the newest seawater intrusion data which corresponds to a hydrological year's. With the content of Cl- 200mg/L,250mg/L,300mg/L in groundwater as main index we divide Kiaochow Bay region into four parts:non-seawater intrusion region, the slight one, the more serious one and the severe one. And we can conclude that the most serious seawater intrusion region is the river estuary of Dagu river, Baisha river and Yang river and Xin'an region of Huang island, it will be gradually less serious in backland and two banks of rivers.On the basis of this, according to the Kiaochow Bay region groundwater quality monitoring data, we select t four evaluation factors are Cl-, sodium adsorption ratio(SAR), SO42+ and Mg2+ as a secondary indicator of seawater intrusion identification. On the basis of fuzzy mathematics comprehensive evaluation method, we make comprehensive evaluation to the current status in the Kiaochow Bay region of seawater intrusion. Combined with expert clustering and fuzzy mathematics comprehensive evaluation method, we make comprehensive evaluation to the risk of the seawater intrusion which happens in the Kiaochow Bay coastal region.Based on this, we make use of GM (1,1) grey model theory to predict the risk of seawater intrusion with average rate is 8.7m/a for many years, which conclude that the seawater intrusion area in 2015 in every region will be increased by 9.4km2,5.4km2, 3.2km2,2.1km2, separately compared to 2008, the seawater intrusion boundaries continue to be the trend of moving to freshwater area. According to the characteristic of Qingdao geological and hydrogeological conditions and the development and utilization of groundwater, put forward to prevent seawater intrusion of groundwater system, realize benign operation strategy.