Regulation of farm groundwater table to sustain grass production: a case study in the Netherlands

Drought periods in recent Dutch summers are becoming longer and more intense. There is a need for cost-effective drought adaptation by farmers to keep and sustain grass production. A case study was performed on a dairy farm on light sandy soil by building an adaptable weir in a ditch to control the local surface water level. Monitoring tubes were placed to monitor surface and groundwater level. Satellites measured remotely the grass temperature and NDVI on four 0.5 hectare plots to determine crop evapotranspiration and need for irrigation. The surface water level in the ditch before the weir remains higher compared to the level in the surrounding area (control) shortly after rainfall. The famer noticed that after a period of rainfall water infiltrates quickly into the soil but with no increased crop growth or decreased irrigation demand. Remote sensing with the SEBAL-model showed a lower irrigation demand on land adjacent to the ditch with the weir. Due to an insufficient rainfall in the summer season and fast water infiltration the function of the weir could be doubted.