2.0 Methodology
Data used for this study are:
- The Administrative / Street Map
- The Electricity Distribution Network Map
- Attribute Data collected on the ground
- Data on the end-users
The administrative/street map was acquired from Anambra State Ministry of Lands, Survey and Urban Planning, Awka. The Electricity Distribution Network map and some of the attribute data were collected from National Electric Power Authority (NEPA), Onitsha District. Using on-spot observation and personal interview, some attribute data and data on the end-users were acquired.
A number of application software packages were used for data processing. Such packages include: photo-plus for scanning and AutoCAD map R2 for geo-referencing and on-screen digitizing. ArcView 3.2a was used for GIS overlay operation and analysis of spatial and spatial queries.
2.1 User-Requirement Survey
User-requirement survey was carried out to determine actually what the end-users would want the system to do for them. From the survey carried out, the types of analysis to carry out were known. It also guided in knowing the configuration of the hardware and software systems required of the work and in the choice of appropriate model and structure to use. Other possible benefits derived from good user-requirement survey have been given by Kufoniyi (1998).
2.2 Design of Database
In the design of database, four basic steps were taken. These include: articulation of reality, translation of reality to conceptual model, translation of conceptual model to logical design and physical design. Realities were articulated based on geographic data within the study area with respect to electricity distribution facilities. In this case, reality includes the following geographic features: Administrative Areas, Roads, Streets, NEPA Transmission, 11kv Lines, Power Transformer, Distribution Transformer.
In translation of reality to conceptual model, the articulated realities were represented in a simplified manner and at the same time satisfied the information required by the users. Hence, vector data modeling was adopted. The realities were represented and displayed as points, lines or area (polygon), with their attributes defined by pair of plane coordinates (X, Y). The objects together with the spatial relationships among them were carefully identified and analysed.
Translation of conceptual model to logical design involves representation of the designed data model to reflect the recording of the data in the computer. The data were structured to describe logically the organization of data in the database. Relational data structure was chosen to implement the model because of its flexibility capability and very wide deployment both within and outside GIS. During physical design, the designed data structure was represented in a form that is acceptable to the implementation hardware and software. The tables' names, the attributes, data type, and the width of the data were specified in Data Declaration as shown in Table 1.0
TABLE 1.0: DATA DECLARATION
| TABLE NAME |
ATTRIBUTES |
DESCRIPTION |
DATA TYPE |
WIDTH |
| ADMIN. AREA |
AD.A_id |
Administrative Area identifier |
Number |
5 |
| |
AD.A_Loc |
Place where the Administrative Area is located |
String |
20 |
| ROADS |
RD_id |
Road identifier |
Number |
5 |
| |
RD_name |
The name of the road |
String |
20 |
| |
N_Surface |
The nature of the road’s surface |
String |
15 |
| |
R_Class |
The class in which the road belongs |
String |
15 |
| STREETS |
St_id |
Street identifier |
Number |
5 |
| |
St_name |
The name of the street |
String |
20 |
| |
N_Surface |
The nature of the street’s surface |
String |
15 |
| NEPA TRANSMISSION |
NT_id |
NEPA transmission identifier |
Number |
5 |
| |
NT_Loc |
The place where the NEPA transmission is located. |
String |
20 |
| IIKV LINE |
IIKV_id |
IIKV Line identifier. |
Number |
5 |
| |
IIKV_Cap |
The capacity of IIKV Line. |
Number |
6 |
| |
A _ served |
The area or section of the town 11kv Line is serving. |
String |
20 |
| |
PT_Feed |
The power transformer feeding the I1kv line. |
Number |
10 |
| POWER TRANSFORMER |
PT_id |
Power transformer identifier. |
Number |
5 |
| |
NF_Serv |
The number of feeders that depend on it. |
Number |
5 |
| |
PT_Cap |
The Capacity of the power transformer. |
Number |
6 |
| |
PT_Loc |
The location of the power transformer. |
Number |
20 |
| DISTRIBUTION TRANSFORMER |
DT_id |
Distribution transformer identifier. |
Number |
5 |
| |
DT_ Loc |
The location of the distribution transformer. |
String |
20 |
| |
A _ Serv |
The area or section of town the distribution transformer is
serving. |
String |
20 |
| |
Yr_inst |
The year the distribution transformer was installed. |
Number |
6 |
| |
DT_Cap |
The capacity of the distribution transformer. |
Number |
6 |
| |
N_cons |
The number of consumers the d t is serving. |
Number |
6 |
| |
IIkv_serv |
The identifier of the IIKV line the distribution transformer is
serving. |
Number |
5 |
| |
Population |
The no. of people the distribution transformer is serving. |
Number |
6 |