Look-up Tables are an important features of a good data base design. Typically they are small tables, which contain parameter codes and general values.
Altogether, the Irrigation module uses the following Look-up Tables (sorted alphabetically):
| Table name | Notes | Database location | Online /offline |
|---|---|---|---|
| AGENCIES | Agencies operating monitoring networks | internal | - |
| AGRO_CLIMATIC_ZONES | internal | - | |
| APPLICATION_EFFICIENCY | internal | - | |
| Hyyear | Relation of calendar months to months of the hydrological year | internal | - |
| IRRIGATION_METHOD | 3 different irrigation technologies | internal | - |
| MAIN_CROP_GROUP | 10 Main crop groups | internal | - |
| Perennials | Property for main crop groups | internal | - |
| Projections | projection years 2005 ... 2040 | internal | - |
| Ref_year | Reference years for agricultural statistics, 1994 - 2000 | internal | - |
| Salinity Class | internal | - | |
| Scenarios | 3 alternative planning scenarios | internal | - |
| Y_Type | dry, median, wet year types | internal | - |
N.B. Internal means, that the table is not linked from an external database but that it is built-in the irrigation module.
For example, the LUT for salinities looks as follows:
Table Salinity_Class TDS (total dissolved solids) in mg/l
| S_CLASS | DESCRIPTION | TDS_MIN | TDS_MAX | COMMENTS |
|---|---|---|---|---|
| 1 | Salinity Class 1 | 0 | 1000 | Good for Drinking & generally no restriction in irrgtn |
| 2 | Salinity Class 2 | 1000 | 2000 | Slight to moderate restriction on irrgtn use |
| 3 | Salinity Class 3 | 2000 | 2800 | Severe restriction on irrgtn use, only for special crops |
| 4 | Salinity Class 4 | 2800 | 50000 | Usable only after desalination |
| 0 | no Leaching | 0 | 0 | No consideration of salinity |
In the corresponding tables (particularly the STP tables), only the entry of the salinity class field [S_CLASS] is used. If salinity classes are to be redefined, it would be sufficient just to modify the Look-up table.