Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. T...Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (about 2.5 m) in 2030, but the saltwater intrusion has advanced diagonally to reach 4.7 km under the freshwater of groundwater of this aquifer.展开更多
针对EPR核电厂ARE主给水调节阀由同一个FUM280卡件控制有跳堆风险的问题,本文研究了一种FUM280卡件冗余配置的方式,单一FUM280故障后切换至备用卡,提升ARE流量调节阀门的稳定性,防止单一卡件故障导致的ARE阀门意外关闭,进而导致的机组...针对EPR核电厂ARE主给水调节阀由同一个FUM280卡件控制有跳堆风险的问题,本文研究了一种FUM280卡件冗余配置的方式,单一FUM280故障后切换至备用卡,提升ARE流量调节阀门的稳定性,防止单一卡件故障导致的ARE阀门意外关闭,进而导致的机组跳堆。后续可根据现场使用经验大范围推广,从而保证核电厂给水流量调节系统的安全稳定运行,有效减少由于设备尤其是重大关键设备故障导致的停机或停堆次数及相关损失,降低机组运行和维修工作量及成本。In this paper, in order to solve the problem of main feed water supply regulating valve of ARE in EPR nuclear power plant controlled by same FUM280 card with the risk of reactor jump-off, a redundant configuration of FUM280 card is studied. After a single FUM280 failure, the standby card is switched to improve the stability of the ARE flow regulating valve and prevent the accidental closure of ARE valve caused by the failure of a single card unit jump-off. The follow-up can be widely promoted according to the field use experience, so as to ensure the safe and stable operation of the regulating system in water supply of the nuclear power plant and effectively reduce the shutdown times and related losses caused by the failure of equipment, especially major key equipment, and reduce the workload and cost of unit operation and maintenance.展开更多
The coastal plain aquifer down gradient of Wad Essaquia Elhamra(WEE),is the main source of groundwater in the arid region of Laayoune Essaquia El Hamra located in south of Morocco.The over-exploitation of this aquifer...The coastal plain aquifer down gradient of Wad Essaquia Elhamra(WEE),is the main source of groundwater in the arid region of Laayoune Essaquia El Hamra located in south of Morocco.The over-exploitation of this aquifer over the last decade for water supply,agriculture and industry led to deterioration of groundwater quality,including seawater intrusion.The objective of this study is to investigate the spatial variation of groundwater quality,and to assess the influence of sea water intrusion on the groundwater quality using hydro-chemical tools.Several measurement campaigns of physico-chemical parameters of the groundwater were performed,which shows a very high mineralization ratios versus chloride,confirming the double influence of mixing mechanisms of fresh and saline waters and the water-rock interactions.Computed seawater fraction for sampled water shows that the average mixing rate of seawater intrusion reached 10.5%,confirming the marine intrusion in the aquifer.The highest values were registered in coastal wells.In the upstream around Laayoune and the spreading area,nitrate concentrations exceed 50 mg/L which is the threshold set by the World Health Organization,revealing a high level of contamination by domestic sewage.The combination of ionic ratios and seawater fraction is a useful tool to assess marine intrusion.This study reveals that the phenomenon of marine intrusion is not the only process that dominates hydrochemistry of ground water.The high groundwater mineralization is also due to rockwater interaction associated with reverse ion exchange with clay material and anthropogenic pollutants.展开更多
目的观察中药熏眼结合内服治疗准分子激光原位角膜磨镶术(1aser in situ keratomileusis,LASIK)术后干眼症的临床疗效。方法选择LASIK术1个月后确诊为干眼症且经中西药物常规治疗临床疗效不满意的患者49例98眼,随机分为观察组和对照组,...目的观察中药熏眼结合内服治疗准分子激光原位角膜磨镶术(1aser in situ keratomileusis,LASIK)术后干眼症的临床疗效。方法选择LASIK术1个月后确诊为干眼症且经中西药物常规治疗临床疗效不满意的患者49例98眼,随机分为观察组和对照组,观察组27例54眼采用中药熏眼结合内服方法 ,对照组22例44眼采用人工泪液滴眼。观察患者治疗前和治疗20 d后的干眼自觉症状,裂隙灯下观察泪膜破裂时间(BUT)、泪液分泌试验(SIt)、荧光素染色(FL)情况。结果观察组总有效率为64.8%,对照组为38.6%,两组比较,差异有统计学意义(P<0.O5);观察组治疗后干眼症状、BUT、SIt、FL与对照组比较,差异均有统计学意义(P<0.05)。结论中药熏眼结合内服治疗LASIK术后顽固性干眼症疗效优于人工泪液滴眼液滴眼。展开更多
文摘Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (about 2.5 m) in 2030, but the saltwater intrusion has advanced diagonally to reach 4.7 km under the freshwater of groundwater of this aquifer.
文摘针对EPR核电厂ARE主给水调节阀由同一个FUM280卡件控制有跳堆风险的问题,本文研究了一种FUM280卡件冗余配置的方式,单一FUM280故障后切换至备用卡,提升ARE流量调节阀门的稳定性,防止单一卡件故障导致的ARE阀门意外关闭,进而导致的机组跳堆。后续可根据现场使用经验大范围推广,从而保证核电厂给水流量调节系统的安全稳定运行,有效减少由于设备尤其是重大关键设备故障导致的停机或停堆次数及相关损失,降低机组运行和维修工作量及成本。In this paper, in order to solve the problem of main feed water supply regulating valve of ARE in EPR nuclear power plant controlled by same FUM280 card with the risk of reactor jump-off, a redundant configuration of FUM280 card is studied. After a single FUM280 failure, the standby card is switched to improve the stability of the ARE flow regulating valve and prevent the accidental closure of ARE valve caused by the failure of a single card unit jump-off. The follow-up can be widely promoted according to the field use experience, so as to ensure the safe and stable operation of the regulating system in water supply of the nuclear power plant and effectively reduce the shutdown times and related losses caused by the failure of equipment, especially major key equipment, and reduce the workload and cost of unit operation and maintenance.
文摘The coastal plain aquifer down gradient of Wad Essaquia Elhamra(WEE),is the main source of groundwater in the arid region of Laayoune Essaquia El Hamra located in south of Morocco.The over-exploitation of this aquifer over the last decade for water supply,agriculture and industry led to deterioration of groundwater quality,including seawater intrusion.The objective of this study is to investigate the spatial variation of groundwater quality,and to assess the influence of sea water intrusion on the groundwater quality using hydro-chemical tools.Several measurement campaigns of physico-chemical parameters of the groundwater were performed,which shows a very high mineralization ratios versus chloride,confirming the double influence of mixing mechanisms of fresh and saline waters and the water-rock interactions.Computed seawater fraction for sampled water shows that the average mixing rate of seawater intrusion reached 10.5%,confirming the marine intrusion in the aquifer.The highest values were registered in coastal wells.In the upstream around Laayoune and the spreading area,nitrate concentrations exceed 50 mg/L which is the threshold set by the World Health Organization,revealing a high level of contamination by domestic sewage.The combination of ionic ratios and seawater fraction is a useful tool to assess marine intrusion.This study reveals that the phenomenon of marine intrusion is not the only process that dominates hydrochemistry of ground water.The high groundwater mineralization is also due to rockwater interaction associated with reverse ion exchange with clay material and anthropogenic pollutants.
