Lateral Withdrawals

I have a question about lateral withdrawals and downstream outflow structures. From the CE-QUAL-W2 manual, lateral withdrawals do not involve momentum computations. Does this mean that lateral withdrawals can only affect water balance and have no effects on flow velocity field (assuming the withdrawal intake and the outflow structure are in the same branch)? I have a reservoir which has very small releases from the downstream outflow structure and significant lateral withdrawals. Since cold water selective withdrawal is my study purpose, I need to accurately simulate flow velocity field and investigate whether cold spring flows can reach the withdrawal intake. Under this situation, should I configure the withdrawal intake as a downstream outflow structure of a branch? Also in the manual, downstream outflow structures have two types: Point or Line. There is no specification for the lateral withdrawals. Could you explain the difference? Looking forward to your response.