Final answer:
When sediment removal exceeds sediment accumulation, the delta will not form as the necessary buildup of sediment deposits is not sustained.
Step-by-step explanation:
When sediment removal exceeds sediment accumulation, the delta will not form. This is because deltas require a consistent or growing deposit of sediments at the mouth of a river where it flows into a larger body of water, like an ocean or a lake. If the rate of sediment being washed away is greater than what is being deposited, the landform cannot build outward and maintain its structure as a delta. In such cases, existing deltas can even erode away.
A delta can build seaward if sediment accumulation outpaces erosion. Conversely, if sediment accumulation and removal are in balance, the delta will likely remain stationary. The formation of a barrier island is a separate process, often involving longshore drift and not directly linked to the conditions described in the question.