天津市地下水资源与可持续利用

Groundwater resources and its sustainable development in Tianjin

天津市是我国主要缺水城市之一。1990～2000年地表水年平均用水量16 33×108m3,地下水年平均用水量7 11×108m3,地下水的供水比例约占30%左右。1990～2002年,按全国统一部署,对天津市地下水资源进行了新一轮评价,评价结果是天津市地下水天然资源为18 13×108m3 a,矿化度小于5g L的天然资源为15 75×108m3 a,可开采资源为8 27×108m3 a,其中浅层水2 58×108m3 a,深层水3 56×108m3 a,隐伏岩溶水1 24×108m3 a,山区1 10×108m3 a。天津市地下水开采程度已达90 45%,除蓟县、宝坻、宁河、静海略有盈余,其余各区、县已超采。要解决天津市规划需水量(2010年)56 76×108m3 a的要求,必须采取外调水源、工农业节水和污水回收利用、海水淡化利用、利用坑、塘、洼、淀尽可能拦蓄汛期弃水等措施。天津市每年7×108～8×108m3的地下水资源为多年稳定补给的地下水资源,属可持续利用的水资源,但必须调整开采布局,压缩深层水的开采量,以遏制地面沉降继续发展。在连续干旱年份,为解决城镇生产及生活用水的燃眉之急,保证城市供水安全,建立一种非常规的并有一定开采周期的应急供水水源地,可缓解一部分供水压力。经初步论证,蓟县平原区和宝坻中北部第四系全淡水区及邻近的咸水分布区,有望建成大型集中供水水源地。经勘查,蓟?

Tianjin Municipality is one of the regions suffering from the most water-shortage in China. From 1990 to 2000, the annual average surface-water supply is 1.633 billion m^3, the annual average groundwater supply is 0.711 billion m^3, the proportion of the groundwater supply is about 30%. The latest evaluation on groundwater resource in Tianjin Municipality reveals the supply capacity of the natural groundwater is 1.813 billion m^3/a, and that of groundwater with mineralization degree less than 5g/L is 1.575 billion m^3/a; it also indicates the exploitable capacity is totally 0.827 billion m^3/a, and that of the shallow groundwater, the deep groundwater, the covered karst groundwater and the mountainous groundwater are respectively 0.258, 0.356, 0.124 and 0.110 billion m^3/a. The exploitation degree of groundwater in Tianjin reaches 90.45 percent, groundwater overdraft is founded in most districts/cities in Tianjin Municipality except Jixian, Baodi and Ninghe districts. Surface water importation, economization in agricultural and industrial water utility, sewerage reutilization, seawater desalination and flood water impound might be effective methods to meet the expected water demand of 5.676 billion m^3 for Tianjin in 2010.For Tianjin Municipality, although annual groundwater supply of 0.7～0.8 billion m^3 is extracted from the perennial steady recharge which can be served as continuous utility, measures such as exploitation regulation and deep groundwater pumping reduction still should be taken to alleviate the expand of the land subsidence.Aiming to meet the emergency of the industrial and domestic water shortage especially in perennial dry years and insure the urban water-supply security, it is very necessary to construct a kind of unconventional water supply source with certain pumping period for emergency uses. According to some preliminary argumentation, the Quaternary Fresh water zone in Jixian plain and middle-north Baodi area could be a prospective water supply source. In this water supply source, total calculated produced quantity of the four kastic water-storage structures in Jixian City, Dagang County, Xilonghuyu and Baodishihua is about 1,005,700m^3/d, and (645,000m^3/d) of which could be directly supplied for water utility in urban area of Tianjin. Water supply source construction for large cities like Tianjin is of great meaning strategically.