Komamura,
Masahara, Prof.Dr.
Tokyo University of
Agriculture
Abstract
In Songkla Lake
Basin, the average annual soil loss was calculated using the Universal
Soil Loss Equation (USLE) and GIS technique. It is estimated that, in
1996, 5,340,192 ton of soil was lost from the basin. A comparison with
the soil loss value estimated in 1982 indicated that the amount of soil
eroded increased by 46.85%
In terms of water
quality, the measured values of electrical conductivity of the water
samples suggested that, during the dry season, sea water intruded into
the lake as well as into the water ways particularly Klong U-Thaphao.
The results obtained also showed that dissolved oxygen values in most of
the waterways were well above the standard values. Studies of nutrient
losses revealed that potassium concentration in the water samples were
higher than of nitrogen and phosphorus.
In assessing
impacts of soil erosion on the environment and natural ecosystem of the
basin, it was observed that the lake's ecosystem is at present in
warming stage. All types of land use in the basin could have an effect
on the lake's water quality.
In order to
mitigate the problem of soil erosion and its consequences, a land use
plan was formulated. The plan devides the basin into three major zones
including preservation, conservation and development zones. An attempt
has been made to outline management practices which are seen as
necessary in each zone from the point of view of addressing soil erosion
problems in the basin.
