Other structures include fixed charges per hectare for nonmetered agricultural abstraction or a price per megawatt-hour for energy production. In Belgium (Flanders region), the level of the tax varies with the quantity of water abstracted. For groundwater abstraction, water abstracted is sometimes paid through increasing block tariff (IBT): the volumetric price is higher for larger volumes. In contrast, the volumetric price sometimes decreases for larger volumes in the case of surface water, the so-called decreasing block tariff (DBT). One issue with decreasing or increasing block tariffs is that the market signal sent to consumers on the value of the resource might become misleading.