Utilización de MAXMAGN en la búsqueda de materiales multiferroicos tipo II

Sewer network data for the city of Palermo has undergone some changes and some simplifications in order to be used in the chosen hydraulic model.

The first modification work consisted of .inp file conversion (version 4.0 for PCSWMM software), into an .inp file for next software version (version 5.0 for PCSWMM software). This was achieved by using a conversion program provided by EPA (Environmental Protection Agency).

Then a second conversion from .inp file to .mbd file for 3Dnet interface program was done. This conversion was performed through software owned by the research team that developed the hydraulic model.

It was realized that data during conversions had some inconsistency. For example, some variables are renamed. Then all variables were controlled to exclude some variables with same name or nonexistent variables.

Due to several changes in the past, other inconsistencies, such as sewer collectors with same upstream and downstream nodes, or different elevation for the same node, etc ... have been also identified. In this case the network was compared to the original information present in other studies.

Another correction was made on the direction of water flow in sewer collectors. In GIS sewer collectors are plotted with a different flow direction in some cases. SWMM software directly converts downstream node with upstream node when slope is negative. Instead SIPSON returns an error. The same correction was made for those sewers that have zero slope. SWMM automatically assigns a minimum slope equal to 0.0001 while SIPSON reports an error. No slope was corrected outside the program.

At this point, after having corrected transcription and conversion errors, some simplification was operated. Sewer network is too extensive and problematic. A simplification of the network was needed, consisting of unifying very short sewers (less than 10 m) or suppressing secondary sewers with not big size (mostly ovoidal size 200 x 300 mm). SIPSON has been shown to have some problems with such sewers not perfectly coupled with subsequent larger.

The main problem using this program also concerns the inability to solve parts of the network with very steep slopes, typically greater than 20%. In the original sewer network there were about 10 sewers with slopes greater than 20%. These sewers, according to the same practice to solve the problem above, were combined with afterwards sewers in order to make the slope less pronounced or they have been suppressed if they are not critical to study Palermo sewer system. In only one case, it was not possible to apply any of the previous techniques. Sewers that connect Piazza Indipendenza to Danisinni hollow has a slope of about 40%. However, to analyze storm water system, connections with this sewer with others

sewers have changed, taking care not to suppress any draining area and respecting connections between sewer network and flooding surface. In fact this area is very important because it is subject to flooding on the side of Piazza Indipendenza and in further downstream areas. Also this part of sewer network belongs to the main area of the network that collects all the sewage from the upper basins and to the old town of the city.

To facilitate fast calibration and to control previous correction operations, a first calibration of 1D-1D model was performed, setting the parameters as in the Table 5.3.

Sewer network files have been used for 1D-2D model. SIPSON-UIM runs in DOS commands. Also this program, as SIPSON, was written in FORTRAN computing language. Figure 5.12 shows the starting simulation file in which the list of other necessary data can be red.

This file contains surface parameters in the first line, represented in this case by a .txt file containing the DEM of concerned area.

The available DEM was derived from LIDAR data, aggregated at a resolution of 2 m. In order to use it, the DEM was later aggregated through a local average, up to a resolution of 60 m per pixel, that is equal to the pixel resolution of rainfall data, provided by the radar. Spatial window size is 1081 x 3090 pixels.

Second line contains simulation parameters, such as start and end of simulation and step simulation for runoff on the surface.

Finally, the last section concerns surface variables and commands for printing obtained results. In particular connections between sewer network and surface drainage, definition of areas with homogeneous precipitation, precipitation series for each area, nodes of sewer network to observe, definition of boundary condition, information about possible interactions with other waterways and some output commands such as printing of variables in float or ascii format for viewing and processing post-analytical can be specified.

In detail, case_roughness and dem file contains information about surface roughness and terrain elevation.

Table 5.3: Simulation parameters.

Check-points file, as mentioned above, is used only to specify which parts of

sewer network must be printed. In particular, this file contains node identifier and its coordinates.

Description Value Units

Surface parameters

Retention capacity of pervious surfaces 2.5 mm

Retention capacity of impervious surfaces 0.5 mm

Darcy infiltration coefficient 1 1.e-6 m/s)

Porosity 0.3 -

constant-value of capillary rise 0.002 m3/2s-1/2

Basin shape factor 0.1 -

Manning coefficient for pervious surfaces 0.03 m-1/3s Manning coefficient for impervious surfaces 0.03 m-1/3s

Percentage of water that flow from roof

directly into sewage 1 -

Percentage of water that flow from roof in

impervious area 1 -

Percentage of water that flow from

impervious area into sewage 1 -

General parameters

Initial condition definition 4

Steady flow, plus base flow added

in dry conduits

Base flow system method 0 L/s/ha

Base flow hydrograph 0 L/s/km

Total dry flow 200 L/day/PE

Time starting rainfall and runoff 0 h

Time ending runoff 600 min

Time step for runoff 600 sec

Time starting simulation 0 h

Time ending simulation 600 min

Time step for simulation 3 sec

Advanced parameters

Preissman method convergence criterion 0.003 %

Time weighting coefficient 1 -

Courant number 7 -

Max. number of iterations of node level

simulation 0.01 -

Convergence criterion in conjugate gradient

method 0.01 -

Relative width of open slot 1 %

Velocity distribution coefficient 1 Equal to 1

Treatment of computational instabilities 1 No automatic action Treatment of supercritical flow regime 1 Reducing channel

Link -points file contains information on nodes for which the equations are

solved which provide runoff input water flow in sewer network. These points have been chosen so as not to overload the simulation. They have been chosen first during the simulation of linear cascade model, developed in 2008.

Weir.txt file contains boundary conditions to be attributed to outlet nodes.

Sewer network ante 2007 had 4 outlet nodes. Two were located on Cala harbor, which represent the discharge of storm water. They were eliminated by this simulation, because full closure of these discharges, in correspondence of such flood event, has been verified.

Another outlet node is located near the harbor and it was maintained for simulation. Another one allows the discharge along Foro Umberto I. According to the restructuring of the final stretch sewer network of Palermo, another outlet node in Foro Umberto was added. It discharges exceeding storm water to protect the downstream pump station.

Consequently, Palermo sewer network has been simulated with this new architecture, inserting three outlet nodes and not imposing any boundary condition because there is no interest in understanding the effects of discharges but only surface runoff in the city.