Complex hydrology model

[EricButler]

I'm dealing with a hydrological landscape that is extensively diked, culverted, and otherwise modified/managed (for irrigation), and which has multiple parallel river channels in many places. Consequently, my attempts to create, for instance, a watershed for the system (the existing HUC for the area shows significant error) gives me very disappointing results (think "watersheds" ~30m long). I'd also like to be able to model flow accumulation and impoundment effects behind dikes given the capacities of the outlet culverts/control structures. Is there a way to reflect these factors in a hydrology DEM?

Basically, we're using the same irrigation system as the Mesopotamians (i.e., controlled seasonal field inundation), and I'd like to be able to model how well it functions. The data I have includes a 10m DEM for the whole watershed, points for the various water management structures, dike polylines, and a pretty detailed and accurate NWI polyline set. Ideally, I'd be able to simulate a few different irrigation scenarios and have a baseline model for comparison.

Any help is appreciated!

[neilo_brien]

The first step in any of the hydrologic modeling tools in ArcGIS is to fill the elevation grid. You must start with a surface that has no sinks. Sinks are areas of internal drainage, that is, areas that do not drain out anywhere. The reason that sinks need to be filled in is because a drainage network is built that finds the flow path of every cell, eventually off the edge of the grid. If cells do not drain off the edge of the grid, they may attempt to drain into each other, which will lead to an endless processing loop.

[bredonadam]

i do agree with h2o building services that there should be some sort of procedure applied. Drainage system should be perfect as it leads to water supply. Improper drainage system can lead to many problems.