Q: What is the spatial extent of the ATLSS hydrology data?

Figure 2.1 : The boundary of the area of South Florida covered by the ATLSS hydrology data is shown is red. The black lines show the outline of South Florida as well as boundaries between major water control structures and management units.

      The extent of the ATLSS hydrology data is very similar to the extent of the SFWMM data. The ATLSS hydrology cover much of South Florida from southern tip of the state, north to the southern end of Lake Okeechobee and extending from the east cost westward covering much of Big Cypress National Preserve. The area covered includes the Everglades National Park, several water conservation areas and urban and agricultural areas of South Florida. Figure 2.1 shows the outline of the area covered by ATLSS hydrology relative to natural and managerial boundaries of South Florida. The area covered by the ATLSS models is slightly smaller than the area covered by the SFWMM (Compare with Figure 1.1). The area currently covered by ATLSS is identical to the area covered by earlier versions of the SFWMM. Since hydrology is important to the dynamics of biotic processes of South Florida the ATLSS models reflect this significance. As a result it was not meaningful for the ATLSS models to provide results in regions for which there was no hydrology data. Even when the SFWMM was expanded to cover new areas there was little need or ability to expand ATLSS into these areas. Many of the other data sets, such as the vegetation map, did not cover the new regions. Additionally the areas added to the SFWMM primarily consist of urban and agricultural area and Lake Okeechobee. There is insufficient data describing biotic response in these areas for ATLSS to make meaningful and useful predictions for these areas. This many seem contradictory since the ATLSS hydrology as shown in figure 2.1 includes both agricultural and urban areas. The early version of the SFWMM hydrology covered these areas. We simply kept these regions in our data, instead of trying to mess around choosing which cells to remove and which to keep. The ATLSS models do not run over these areas. While the added areas represent some waste of disk space and memory, these issues are not considered critical at this time. As time becomes available, work will be invested to cleaning up these details.

      A few of the ATLSS models, such as the Breeding Potential Index Models used ATLSS data which is identical to the SFWMD hydrology modulo a unit change. Most of the ATLSS models use hydrology data created by the High Resolution Hydrology Model which uses the High Resolution Topography Model. A description of the High Resolution Hydrology and Topography can be found in Sections ??? and ??? respectively.

      The Universal Transverse Mercator (UTM) values for the area covered by the ATLSS hydrology data are given in table 2.2. These UTM are in UTM Zone 17, NAD27.

Q: What is the spatial resolution of the ATLSS hydrology data?

      ATLSS models use hydrology at a number of different resolutions. This reflects both what is considered biologically reasonable and what is computationally feasible. Table 2.3 lists some of the ATLSS models along with the spatial resolutions used by each model. Some of the hydrology data sets used by the ATLSS models are identical in resolution to the resolution provided by the SFWMM. For these data sets one value is provided for each 2 x 2 mile block on the landscape. Other models need hydrology data at a much finer resolution. For example the Fish model requires hydrology data at a 500 x 500 meter resolution. For these models hydrology data is created with the ATLSS High Resolution Hydrology (HRH) Model. The HRH is capable of providing hydrology at any resolution down to 28.5 x 28.5 meters. See the section of the HRH and HRT for an explanation of how this is done.

Q: What is the temporal extent/resolution of the ATLSS hydrology data?

      The ATLSS hydrology data generally has the same time extent and resolution as the SFWMM data. For most data sets this means the data provides daily water depths across the landscape for the 31 year time period beginning January 1 1965 (1/1/1965) and ending December 31 1995 (12/31/1995). This results in 11322 days worth of data.

      For the Calibration/Validation runs the data is daily water depths across the landscape from January 1 1979 (1/1/1995) to December 31 1995 (12/31/1995). For these data set there are 6209 days worth of data.

      The hydrology data used by the fish model is currently the only exception. This model operates on a 5 day time step. For this reason the hydrology data for this model is also has a five day time step. Each data set for the hydrology data set is a five day average of water depths. For each time step ( each fifth day) the average is taken from the current date to the current date less four days. Figure 2.2 shows pictorially which days are included in the average for the i^th time step.

Q: In what units is the data provided?

      Each cell provides stage heights in millimeters relative to local ground surface elevation.

Q: What is the difference between the high resolution hydrology data and other forms of hydrology data?

      The short answer to this question is the ATLSS High Resolution Hydrology (HRH) data is available at much finer resolutions. Currently the ATLSS HRH is available at any resolution down to 28.5x28.5 meters. Other hydrology data sets, namely the SFWMM, provide hydrology data only for 2x2 mile pixels. Each pixel in the ATLSS HRH has its own water depths, based on ground surface elevation provided by the High Resolution Topography (HRT) model. This hydrology data is available for any of the hydrology alternative produced by the SFWMM, including all alternative used in the restudy program, and all ModWater alternatives. These data sets represent a redistribution, within each cell, of the volumes of water produced by the SFWMM. In all cases, the redistribution process preserves the volume of water in each cell of the landscape, for every day of the simulated time period.

      There are some forms of ATLSS hydrology which are different in ways other than spatial resolution. The hydrology data for the ATLSS fish model uses hydrology data which has both a finer resolution that the SFWMM hydrology, and has a different temporal resolution. Spatially the fish model uses hydrology in which each cell represents a 500x500 meter plot of land. This data is created with the ATLSS HRH model, and provides a different water depth for each 500x500 meter cell. Temporally the fish model runs on a five day time step and so require hydrology data on a similar time step. Each data set represents an average of five days worth of data, taken on a per cell basis. The five days in the average are the four days between the previous time step and the current time step plus the current time step.

Q: What is the format of the ATLSS hydrology?

      ATLSS hydrology data is stored in two files. One file contains the actual stages heights for each point across the landscape, the other file contains metadata about the data set.

      The file containing the stage heights is stored in binary format, using big endian byte ordering. Each value is stored using a 2 byte signed integer. For each day's worth of data, the first element stored in the file is the element from the north west corner. Element within the file precede from left to right, top to bottom. There are no intervening characters between elements of a row, and not intervening characters between rows. The data sets, each representing a single days worth of stage heights, are stored sequentially within the file. The first day's worth of data appears first in the file with each subsequent day following in order. Unlike the SFWMM hydrology data all grid cells are saved. Even if a cell is outside the study area, it is saved.

      The metadata file is usually stored in the same directory as the binary data file. This file is a plain text file and can be viewed and edited with any text editor. This file contains a number of fields which provide important information about the data set. Each field must fit onto a single line, and is broken into three parts. Each part is delimited by a single colon ( : ). The first part is the name of the field. This can be any alpha-numeric string but can not contain a colon or a space. The second part of the line is a comment. This like the name can be any string, but may included spaces. The third part is the value to be associated with the name. There are also a number of special lines with appear in the metadata file. These lines contain only a single string, such as BEGIN_META_DATA_ZZZ. These lines have special meaning when reading metadata and help structure the metadata within the software. A list of these special tags along with there meaning is given in table 2.4.

      Many of the field provides spatial information about the data set. Included are the UTMs of the upper left and lower right hand corners of the box which contains the data set, the size of a cell in meters, the number of rows and columns. The file also contains information about the type and size of a variable used to hold a single stage height values in memory. Figure 2.2 gives an example of a metadata file for ATLSS hydrology.

Q: How do I create ATLSS hydrology?

Q: How do I create the programs needed to create ATLSS hydrology?

Q: Where do I get the programs needed to create ATLSS hydrology?