A sensor apparatus may include a channel structure configured to couple with an external element and a fluid conduit, such that the channel structure may receive a fluid, at least partially drawn through the external element from an ambient environment, and direct the fluid through the fluid conduit. A sensor may generate sensor data indicating a flow rate of the fluid through the fluid conduit based on monitoring a variation in a pressure at a location in hydrodynamic contact with the fluid conduit and in relation to an ambient pressure of the ambient environment. The sensor apparatus may enable generation of improved topography information associated with flows of fluid drawn from the external element based on measuring a local pressure at the location in hydrodynamic contact with the fluid conduit and determining the ambient pressure based on monitoring the local pressure over time.