| Groundwater pollution usually is complex and concealed, remediation of which is difficult, high cost, time-consuming, and ineffective. Therefore, the feasible method to control groundwater pollution is preventing, that is providing an early warning ahead of groundwater quality deteriorated, and preventing and remedying timely, which makes groundwater system under good recycling condition. Therefore, it is significant that studying groundwater pollution early-warning theories and establishing computer warning system.The early warning system of groundwater pollution can be used to evaluate current water quality, to forecast water quality changing trend, and to analyze space-time influencing range of groundwater quality by natural process and human activities. Therefore, groundwater pollution early-warning could reflect potential and hazard extent of groundwater contamination qualitatively and quantitatively. Providing effective and timely warning ahead of pollution could help decision-maker and manager to establish groundwater management strategies and protection guidelines. Groundwater evolvement direction could be controlled using corresponding countermeasures and measures. Researching on groundwater pollution warning could make groundwater resources protection forecasted and contraposed, reduce disasters and great losses because of groundwater quality deterioration, realize sustainable utilization of groundwater resources.Purpose of this work presented as follows, which aimed at problems of establishing groundwater early warning system:Variation of groundwater quality with time and space is a complex system. Understanding current situation and time-space changes of groundwater quality is the premise of groundwater pollution early warning. Therefore, first of all, methods of current groundwater quality situation assessment and time-space vary analysis should be studied. Single index evaluation, comprehensive index evaluation (national standards GB/T14848-93) Fuzzy comprehensive evaluation and BP neural network evaluation which were widely used to assess groundwater quality; precise results have achieved. In order to get special changing rules of whole study area, regional groundwater quality assessment methods based on spatial interpolation were studied. Water quality state in sometime of the future could be forecasted using gray model and time-sequenced analyzing methods; water quality varying trend in a period was analyzed by Spearman's rank correlative coefficient.Conceptions and significances of groundwater pollution risk assessment were interpreted. Risk assessment system of regional groundwater pollution which comprises inherent vulnerability, load risk of pollution source and contamination hazard was established depending on groundwater pollution risk analysis. Detailed researches on evaluating indexes and evaluating methods of inherent vulnerability, load risk of pollution source and contamination hazard assessment were performed. Mature DRASTIC method used to assess inherent vulnerability of aquifer. Load risk of pollution source analyzed based on the potential of contamination and pollution degree. Assessment index of load risk of pollution source which involves the variety of pollution source (including toxicity), quantity of contaminants, releasing potential of pollutants (have liners or not), and distance were determined. The load risks of all sources considered comprehensively by GIS overlay technology. Groundwater assessment methods which include three factors, that is inherent vulnerability, load risk of pollution source and contamination hazard were determined, which makes groundwater pollution risk assessment more practically and easy to apply. According to the principles of early wraning, the groundwater pollution early warning theoretical system was established and the frames and modes were determined based on the analysis of groundwater pollution paths and mechanisms; the current groundwater quality, groundwater quality varying trend, and groundwater pollution risk were considered comprehensively; single and comprehensive groundwater pollution early warning were performed. Comprehensive index system of groundwater pollution early warning were constructed, warning degree partition and warning line setting were studied, and calculation mode of groundwater early warning was determined.On the basis of early warning system's composition of groundwater pollution, Analysis and design of regional groundwater pollution early warning system were performed using early warning theory and software engineering thoughts. System's whole configuration and mainly functions determined. The system mainly includes: system administration, water quality assessment, water quality forecast, aquifer inherent vulnerability appraisal, source of pollution load risk assessment, pollution risk assessment, and groundwater pollution early warning function module etc.Detailed studies performed on arithmetic of groundwater quality assessment, forecast, and tendency analysis, methods of groundwater pollution risk assessment, and groundwater pollution early warning models. The professional models and early warning models was combined with GIS technology organically based on GIS module development technology; the early warning model and the computer software establishment and the development were completed; the regional groundwater pollution early warning information system which could operate independent of GIS platform was developed. The system has the stronger data analysis function including fuzzy synthesis appraisal, nerve network, grey model, time series analysis mathematical models, etc. At the same time, the system has pretty strong spatial analysis function, possesses buffer analysis, overlay analysis, and spatial interpolation functions, etc. Moreover it can draw contour and isosurface using spatial data. This system is easy to use and administrate, and also convenient to update data; it has optimized system structure, perfect database system, and friendly user interface; operating results could describe user needed information by outline, intuitionistic maps, forms and graphs, and complex maps combined mutually, etc.Finally, Qiqiha'r was taken as a case. Confined and unconfined water quality data from 1998 to 2002 were collected and hydrogeological conditions, pollution source, land utilization and groundwater utilizing conditions in research area were investigated. The maps of Qiqiha'r, the lothological distribution map, the early warning parameter partition map, the land utilization condition map, the pollution source and the water source distribution maps formed using ArcGis, and the groundwater quality and its environmental information space-database established. Groundwater pollution early warning system used to warn the pollution of Qiqiha'r area. The results indicated that the inorganic nitrogen pollution was searious; arsenic, total hardness, chloride, sulphate were exceed standard in some of area; content of iron and manganese higher because of the background of this area. The main pollution sources are effuse disposal in hong-xing, li-ming, xiang-yang, nan-shan and solid waste dumping site in gongrentun, oxidation pond and wastewater discharging ditch. The early-warning results showed that the water quality in the northeast of research area was better, that is low alarm and middle alarm; northwest was the high alarm and the highest alarm, especially, near oxidation pond and the wastewater discharging ditch in the south urban belongs to the highest alarm. Finally the main pollution reasons in Qiqiha'r area have been analyzed, and the contamination control and remediation measures were presented.The innovations of this work are:(1) domestic and abroad studies on groundwater pollution risk assessment mainly focused on the health risk assessment or evaluation of vulnerability currently. The studies considered three aspects, that is inherent aquifer vulnerability, risk coming from pollution, and the harmful of the pollution were rare. According to the relative research, regional groundwater pollution risk assessment system was set up, which include inherent aquifer vulnerability, risk of pollution load, and pollution hazard. Regional groundwater pollution risk assessment models and methods were studied.(2) The domestic and aboard studies on groundwater pollution early warning are still at the initial stages. Most of the evaluation and analysis of early warning was base on the analysis of groundwater monitoring data, without considering of the pollution sources, hydrogeology conditions, and other factors. Early warning theoretical system of the regional groundwater pollution was brought forward based on the pollution risk assessment and establish, and groundwater pollution index early warning system was established in this paper. Groundwater pollution early warning system comprehensively considered the present state and trends of the groundwater quality, and the risks of groundwater pollution from both the time series and spatial distribution, and achieved the integration of the state and the process.(3) Software engineering thoughts and GIS module development technology were adopted, and ArcGis Engine and Visual Basic.NET were used as development platform. Professional model, early warning model combined with GIS technology organically, and the regional groundwater pollution early-warning information system which can operate independently were developed, and applied it into Qiqiha'er groundwater early warning.Groundwater pollution early warning system makes groundwater early warning theory into computer models. Establishment of computer system could provide a new and convenient managing platform for groundwater management and research department and provide warning and relative water quality information at any moment, which makes manager making corresponding decisions in time.
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