Gowdy Output, conceived in spreadsheet form by Mark Gowdy of the California Central Valley Regional Water Quality Control Board, is used to allocate load between various sources. It includes three components:
The Longitudinal Concentration Plot shows the concentration overlayed with flow along a length of river
The Cumulative Loading Plot shows the cumulative load (flow * concentration) inputs, load diverted, and net load along the same length of river
The Source Allocation Bar Chart shows the sources of the loading at the downstream end of the length of river. The sources include individual tributary rivers, tributary land areas, point sources, and controlled flows such as reservoir releases and agricultural return flows. Diversions are counted as negative sources.
Gowdy Output is created by post-processing model inputs and outputs to determine individual loading sources contributing to the load at a particular location on a particular day. It is designed so that it can be applied to any watershed simulated by WARMF for any simulation date and any constituent simulated by the model.
The Gowdy Output is activated by selecting one or two river segments and then accessing the postprocessor by selecting Longitudinal / Gowdy Output under Mode in the menu as shown below (Gowdy Output is also available through the Manager Module). If two river segments are selected along a flow path, the reach defined is between them. If only one segment is chosen, then the reach defined is from the chosen reach to the downstream terminus of the watershed.
Once activated, the Gowdy Output dialog is displayed as shown in the next figure. Flow is shown by default when the dialog appears. The date in the dialog is the beginning simulation date. In the upper right is a longitudinal output plot showing flow (blue) and travel time (black) for the selected date along the length of selected river. In the lower right is a cumulative plot showing cumulative inputs (green), diversions (red), and net flow (black) going down the river. The bar chart on the left shows the individual inputs and outputs of flow. The date has up and down arrows to animate the date. As the date is changed, the graphs automatically animate as they update to the changed date.
The last figure (below) shows the Gowdy Output for total phytoplankton. The longitudinal plot of total phytoplankton shows its concentration in black with flow overlayed in blue. The cumulative loading graph in the lower right shows the cumulative inputs (green), diversions (red), and net load (black) of phytoplankton with the option chosen to ignore in-stream processes. The same inputs and outputs are identified individually in the bar chart on the left. Note that in-stream processes can either be accounted for or ignored. When ignoring in-stream processes, the net phytoplankton at the downstream end is much higher than the inputs due to algae growth within the defined river reach. The three Export buttons at the bottom of the dialog are used to put the values in each of the three charts in a comma delimited or column format text file.
