Monitoring stations (Nitrates Directive) deep filters (WMS)

The Landelijk Measuringnet Groundwater Quality (LMG) was built between 1979 and 1984 and consists of approximately 350 measuring locations spread throughout the Netherlands. Sampling shall be carried out in permanent wells specially constructed for monitoring purposes. These observation pits were constructed just outside the fields in order to be easy to sample and not to interfere with work in the field. The sites have been selected on the basis of land type, land use and hydrological condition. Groundwater samples shall be taken at each site at depths of 5-15 m (shallow filters) and 15-30 m below the ground (deep filters). On sandy soil samples are taken from shallow observation pits each year, while samples are taken from shallow wells on the other soils (clay and peat) every two years. From deep wells a sample is taken every four years, as well as from shallow filters at measuring points with marine influences. The wells that are not sampled every year shall be interpolated for the years absent.荷兰全国地下水质量监测网（Landelijk Measuringnet Groundwater Quality，简称LMG）于1979年至1984年间建成，共设约350个监测点位，遍布荷兰全境。监测工作需依托专为监测目的修建的永久性井位开展，此类观测井场选址于农田外侧，既便于采样作业，又不会干扰田间农事活动。监测点位的选取依据土地类型、土地利用方式及水文条件确定。每个监测点位需分别采集地下5-15米（浅层滤层监测井，shallow filters）与地下15-30米（深层滤层监测井，deep filters）的地下水样品。针对砂质土壤，每年采集浅部观测井场的样品；针对黏土、泥炭等其他类型土壤，则每两年采集浅井样品。深层滤层监测井与受海洋影响的监测点位的浅层滤层监测井，每四年采集一次样品。未按年度采样的井位，其缺失年份的监测数据需通过插值法补全。