| Shijiazhuang City is one of the major cities in China which take groundwater as main water supply resource, over 80% urban water supply use groundwater. Industrial and mining enterprises are too concentrated in the urban areas, coupled with indiscriminate and unplanned abuse of groundwater, the cone of groundwater level depression formed as a result, the area of the cone is 436.5 km2 in 2006, and the depth of the groundwater level at the center of cone is 52.40m, resulting part of the aquifer dewatering, reducing single well water supply, and some shallow wells dry up or out of use, deteriorating the groundwater quality, and these issues are making important restricting factors in socio-economic development in Shijiazhuang City. The distributive water of Shijiazhuang City from the South-to-North Water Transfer Project have some residual water under the condition of meeting urban water supply. in order to give full play to the South-North Water Diversion economic and social benefits, taking into account the existing urban water facilities are main supported the exploitation of groundwater, the remainder of water can be infiltrated into the groundwater aquifer by the way of artificial recharge, the regional cone of depression will be the storage space for groundwater reservoirs, making the bed of Hutuo River as infiltration sites, Hutuo River Groundwater Reservoir will be constructed.Based on the research of regional geological and hydrogeological conditions, this study has determined the scope of groundwater reservoir, the feasibility analysis of Hutuo River groundwater reservoir has been done from the angles of recharge water resources, storage space and infiltration site. The groundwater numerical simulation model of study area has been constructed. Combined with the local water resource of study area and South-North Water diversion, the artificial recharge programs of Hutuo River Groundwater Reservoir has been drawn, forecasting the recover effect of groundwater level under a variety of conditions, making a scientific basis for the construction of Hutuo River Groundwater Reservoir.The main achievements in this study including:(1) Boundary conditions of Hutuo River Groundwater ReservoirAccording to the general principles of the location of groundwater reservoir, analysis the appropriate conditions to construct Hutuo River Groundwater Reservoir from the spatial distribution characteristics of water storage conditions, water transmit conditions, boundary conditions and recharge conditions. the scopes of Hutuo River Groundwater Reservoir have been determined as: the mountain-plain line as the western boundary, the main dam and auxiliary dam of Huangbizhuang reservoir as the northwestern boundary, the area between the Hutuo River flood fan and Ci River flood fan as the northern and northeastern boundary, the eastern boundary is the groundwater watershed, the southern boundary is the edge of Hutuo River flood fan.(2) Calculation and analysis of storage capacity in Groundwater Reservoir The storage capacity decides the regulation and storage of groundwater reservoir and the level of protection to regional water supply safety. The varieties of storage capacity have a good guide to make decisions of the artificial recharge programs. The main achievements as:①Considering the issues of urban construction history and anti-floating design of ground and underground structures, making the water table of June 30, 1980 as the upper limit water level of Hutuo River Groundwater Reservoir;②the water table of study area have been lower than the limit-low water level which will not make environmental geological problems, the total storage capacity and empty storage capacity will be considered only in this study;③the GIS-based calculation methods have been given for the storage capacity of groundwater reservoir, the calculating results show that, the total storage capacity of Hutuo River Groundwater reservoir is 106.30×108m3, the real-time empty storage capacity is 33.5×108m3 in 2006, and increasing with the velocity of 2.46×108m3 / a.(3) Groundwater numerical simulation Groundwater numerical simulation can reproduce the groundwater flow variety characteristics of study area better, providing a scientific means for the analysis of artificial recharge effects in groundwater reservoir, the main achievements as:①the hydrogeological conceptual model has been constructed, the water table of phreatic water as the upper boundary, the bed of Mid-Pleistocene as the bottom boundary, the mountain-plain line as the western specific flow boundary, the specific head boundary decided by the locations of groundwater observation wells as the northern, eastern and southern boundary;②groundwater numerical simulation model of phreatic aquifer in study area was constructed, making use of the MODflow module of GMS soft package to solve the model, and made June 30, 2004 to June 30, 2005 as the identification period, June 30, 2005 to June 30, 2006 as the validation period, achieving the hydrogeological parameters zoning through the parameter-adjust method, and the observe wells and groundwater have a well fit results at the end of identification period and validation period, the results show that, the numerical model that established can reproduce the groundwater flow characteristics in study area.(4) Plentiful or scanty Encountering analysis between Han River basin and Shijiazhuang CityThe plentiful or scanty precipitation in Han River Basin decided the available water quantity for the South-to-North Water Transfer Project, The plentiful or scanty precipitation in Shijiazhuang City decided the regional water shortage and the acceptance capacity to the South-to-North Water Transfer Project water diversion, the encountering research have an important guide to make the decision of artificial recharge programs, the main achievements as:①introduced the conception"membership degree"of fuzzy mathematics into Plentiful or scanty Encountering analysis, can avoid the mutation in the vicinity of the boundaries well, making the analysis results closer to reality;②Plentiful or scanty Encountering characteristics research results showing that, over 90% of years are conducive to South-to-North Water Transfer Project;③on the assumption that there are no additional surface water supply facilities and no change of urban water supply system, analysis the water quantity could be used as the infiltrate water of Hutuo River Groundwater Reservoir, the maximal water quantity is 8.72×108m3, the minimal water quantity is 4.64×108m3.(5) Analysis of groundwater level recovery According to the water resources characteristics of Shijiazhuang City and South-North Water Diversion, analysis the infiltrate site and infiltrate capacity of Hutuo River Groundwater Reservoir, combined with the precipitation variation encountered characteristics between Han River Basin and Shijiazhuang City, 10 forecast programs have been made, the forecast results showing:①before the South-to-North Water Transfer Project water diversion to Shijiazhuang City, the groundwater levels of study area persistently decline, the lowest level is 11.82m in 2013, 6.13m in 2020;②when the South-to-North Water Transfer Project water diversion is decided, the precipitation variation can change the effects of groundwater recovery through the abandoned water from Huangbizhuang Reservoir and infiltration from precipitation, the velocity of groundwater level recovery have a maximal variation as 1.16m/a;③when the precipitation variation of Shijiazhuang City is decided, the South-to-North Water Transfer Project water diversion can affect the groundwater level recovery by infiltrated through infiltrate sites, the velocity of groundwater level recovery have a maximal variation as 0.93m/a, but there are little changes between the normal years and wet years, the maximal change is 0.06m/a;④Artificial recharge to groundwater reservoir rise the groundwater level, groundwater lateral discharge outside the study area will occur, when Han River Basin and Shijiazhuang City have a plentiful-plentiful encounter, the largest amount of lateral flow is 1.70×108m3/a, the effective storage rate of artificial recharge water is 80.54%; when Han River Basin and Shijiazhuang City have a scanty-scanty encounter, the smallest amount of lateral flow is 0.42×108m3/a, the effective storage rate of artificial recharge water is 90.99%, as the amount of artificial recharge increasing, the effective storage rates present a decline trend.
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