Technical Studies

This project aims to establish the geology data-base and layers in the geographic information system (GIS) of ten major river basins in Taiwan. The major purpose of the project is to provide a platform for common collection and acquisition of geologic information available for the planning and management in each river basin.

In this project, a large amount of available geology information collected from various sources was compiled to establish the geology layers in the river-basin GIS. The established GIS layers include: (1) layer for DEM, (2) layer for basic geology information, (3) layer for sensitive geology, (4) layer for river-bed, (5) layer for site-investigation data, and (6) layer for reference data, among other GIS layers. The GIS system in the Tou-Chien River basin contains eleven categories with 65 layers in total. The GIS systems in nine other river basins contain more than 30 layers in total.

In addition to the establishment of the geologic GIS system of major river basins, this project also discussed a few river-basin related geologic subjects as follows:

(1) The roles of geology of river basin on major river characteristics: The roles of geology of river basin on river morphology, the equilibrium of river system, river evolution, and river type were discussed. These characteristics may largely affect the planning and management works in a river basin. Real examples in Taiwan were used to demonstrate the relevant subjects.

(2) Usage of aero-photo for the interpretation of river conditions: Demonstrated by a serial of case studies on Tou-Chien River, it was demonstrated that aero-photo could help to interpret the river conditions.

(3) Site-investigation for river-bed materials: Appropriate approaches of site-investigation and interpretation for river-bed materials were reviewed and discussed.

Soil loss: The soil loss in a river basin usually depends heavily on climate geomorphologic, and geologic conditions in the river basin. Due to the severe climate and poor geology conditions often encountered in Taiwan, the soil loss in a river basin tends to be much greater than those occurred in other regions in the world. Approaches commonly used in other countries are not necessarily appropriate for directly adoption. Common approaches for the estimation of soil loss in a river basin were reviewed and discussed.