| Abstract | High rate of groundwater withdrawal, in different parts of Tha Phra district, Khon Kaen, Northeast Thailand, has affected the local hydrogeological balance. The steady declination of groundwater levels has also led to other environmental impacts such as saltwater intrusion. One of mitigation measures is artificial recharge to restore groundwater levels back to their original. A relatively new and rapidly-spreading practice in artificial recharge is the ASTR technique using a combination of recharge and recovery wells. This technique can be used for recharge when surplus water is available and for pumping when the water is needed. Previous researches and relevant studies on artificial recharge in Thailand were reviewed, especially the researches on artificial recharge through wells which were conducted in the last two decades, to show the technical applications and developments of artificial recharge technique in Thailand. This study deals with application of ASTR for a fractured sandstone aquifer in Khon Kaen, Thailand, whose groundwater level has declined due to groundwater pumping by a nearby beverage factory. An ASTR program development was proposed to investigate specific features of well recharge into the Upper Phu Tok aquifer of the study area and to bring out possibilities of further application to other similar sites. The ASTR program development comprises of four major components, i.e., pre-design information analysis, ASTR well design, specific recharge design and design of pilot test program. The data were collected to construct the hydrogeological model to implement the ASTR program development. The target of recharge operation is the Upper Phu Tok fractured rock aquifer, which is quite different from a sedimentary unconsolidated aquifer and its flow behavior is much more difficult to model. The double-porosity concept was used to analyze the flow response of this fractured aquifer. A comprehensive well testing program was designed and performed. The pumping test was conducted continuously for 4 days. The pumping test results had been analyzed by different methods such as Bourdet and Gringarten (1980), Warren and Root (1969) and Kazemi et al. (1963) for a fractured aquifer model. The results were then compared to those analyzed by Jacob (1946)'s and Theis (1935)'s methods for an unconsolidated aquifer model. It was found that the fractured aquifer behaves similarly as an unconsolidated aquifer when the pumping time has reached the late-time period. The Bourdet and Gringarten (1980)'s method seem to be the most suitable in determining the hydraulic properties of fractured aquifer for the early pumping time. Moreover, two parameters, i.e., w, the storativity ratio and A,, the interporosity flow coefficient, were determined to characterize better deviation in behavior of a double-porosity medium from a single-porosity medium. FEM groundwater and artificial recharge modeling of the Upper Phu Tok aquifer was carried out. Clogging of the ASTR well was paid a special attention to. Two parameters, i.e., Recharge Clogging Factor (RCF) and Clogging Development Radius (CDR), were discussed and analyzed. A large number of artificial recharge models were performed and the results showed that the change in head rise is quite significant when the two-well ASTR system is operated with or without the additional industrial well. Once clogging is developed in the gravel pack of recharge well, 0.15 m thick, with the 50% of reduction in permeability, the piezometric head in the recharge well is increased by 10%. Furthermore, the clogged zone is extended up to 1.0 m the piezometric head in the recharge well is increased by 25%. An amount of recharge water can be accumulated in the aquifer and the groundwater level can be restored |