Author
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Logsdon, Sally |
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Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/22/2015 Publication Date: 4/1/2015 Citation: Logsdon, S.D. 2015. Relation of depressional flooding to soil water and upslope accumulated area. Transactions of the ASABE. 58(2):343-352. Interpretive Summary: Low areas in the field pond with water even though tiles and inlets are present. Ponding within fields slows the rate of downstream flooding. This study showed that the ponded depressions gained and lost up to three times more water in 2010 than a similar depression reported for 2008. The depressions also remained for weeks rather than days because tile outflow was backed-up. Presence of slotted risers and partially-plugged tiles resulted in incorrect water balance calculations. This study is of interest primarily to scientists; however, the bigger picture of flood reduction downstream would be of interest to landscape managers, state and local agencies, and the general public. Technical Abstract: Depressions may pond with water even when tiles, inlets, and ditches are present. The purpose of this study was to use the Roth and Capel water balance approach for calculating distribution of water to and from the depression. Two depressions were monitored using a "surface" well. The north depression was larger and had two slotted risers for the two inlets, so the calculation procedure had to be modified to allow for risers. The south depression had only one inlet with no riser. For each rain event, the maximum inflow was calculated for the flow accumulation. Smaller rain events resulted in lateral additions with only a fraction of maximum inflow because water infiltrated before reaching the depression. When the maximum inflow exceeded the calculated surface and subsurface lateral addition, the lateral addition was decreased to the maximum inflow, and by water balance, the tile outflow was also reduced. These adjustments improved the calculations; however, calculated lateral inflow and tile outflow were still too high for some events. The Roth and Capel study showed maximum inflows and outflows of 7490 and -6790 m3, compared with the current study showing 22110 and -36530 m3 for the north depression. The Roth and Capel water balance approach is a simple and useful procedure for determining inflow and outflow water pathways from depressions that have tile inlets. Overall the approach was useful to understand water storage and loss from depressions within a field. |
