Keyword: Urban Growth, Map Certainty, Integration, Remote Sensing Data, Geographic
Information System
Abstract In planning for rapid urban growth process in Ha Noi City, local planners have to
use the existing land use maps, which are often out-of-date, incomplete and inconsistent. In
order to exact information for planning they should need to know how reliable these maps are.
This paper selects the data integration method as a supportive tool such a purpose. The argument
is that reliable land use mapping can be assessed from the convergence between changes
recorded in the local mapping system and changes detected by remote sensing (RS) data. The
integration method provides different solutions, from verifying map certainty to improving map
quality and building spatial database. The case application shows the similarity as well as
variations between the local maps and the comparative RS data on mapping the conversion of
water surfaces into construction sites in Ha Noi.
1. Introduction
Since the launch of the reform policy, urban areas in Viet Nam have been developing rapidly. In
Ha Noi city during the 1989-1998 period the population increased by a half and the area twice
(see Table 1). The urban growth mainly consists of incorporation of urbanized settlements in the
city fringe, and redevelopment of the old city areas.
Table 1. Urban Growth in Ha Noi City
| Urban components |
1989* |
1994** |
1998*** |
| Population (person) |
906,149 |
1,082,000 |
1,344,300 |
| Land (km2) |
43.00 |
47.57 |
82.78 |
Sources: * NIURP, 1992; ** VUTAP, 1995;*** HSO, 1998.
To plan and manage the rapid urban growth, local planners need reliable data on
locations and features of urban activities. However such a need is rarely met because the
existing spatial data, particularly the land use maps in Ha Noi City are often out-of-date,
incomplete and standard varying (Nghi et al. 1999). Under the planned system, there was no
land constraint to planning so these spatial data were not attended and adequately built. After
reform the land has value and use constraint while planning and construction are booming.
Various maps and plans produced by separate sectors have improved the spatial data but the
map quality and quantity are still lacking. Thus the local planners have to secure all existing
maps possible. They need effective method to assess the map certainty in order to get right
information for use in planning work.
Mapping certainty refers to the accepted closeness of the mapped contents (position,
attribute, representation model and lineage) to the real world phenomena. Assessment of the
map certainty involves selection of relevant method and comparative data sources. Conventional
field check is cost-intensive and time-consuming whereas the map overlay and data integration
using secondary sources is relative fast and low-cost (Aggarwala et al., 1997). The integration
method does not only transform different maps into common system for assessing overlap and
gap but also solve their inconsistency for data integration (Nghi, 1999). The integration between
RS and geographic information system (GIS) for spatial applications is gaining momentum
recently. RS images offer complementary sources which are often classified and compared with
the ground check and/or local maps for mapping “what is there and how much” (Stein et al.,
1998) and for detecting changes of urban land-use features (Paulsson et al., 1995).
This paper assumes the integration approach to assessing the map certainty on urban
growth. The argument is that reliability of urban growth mapping can be assessed through the
convergence between the changes recorded by the local mapping system and the changes
detected by RS data. After discussing the method the paper presents an application over a an
area in the City of Ha Noi, Viet Nam where the comparative data are available.
2. The Method
The procedure and supportive tools of the integration method could be seen in Figure 1.
It does not only enable the assessment of data reliability in the first stage but also the data
improvement in the subsequent stage. In the first step planner identifies the local maps, RS and
supportive tools that would bring possible information needed and be relevant for the integration.
In the second step the selected data are registered and transformed into a common system. This
enables the third step to verify the map contents (theme, location and attributes) and to analyze
map variations and solutions for improvement. After the third step new and accurate land use
information could be extracted for update and use in planning. The method application needs a
standard desktop GIS for data input and overlay, spreadsheet and geo-statistic programs for
comparing the data aggregates.
Figure 1: Integration Method for Assessing Map Certainty
