Flow condition preference study using kriging and sequential indicator simulation: The case of Sicyopterus japonicus in Datuan stream
Date Issued
2010
Date
2010
Author(s)
Wang, Cheng-Long
Abstract
Fish communities play a important role in the freshwater ecosystem, and their life-cycles are obviously related to the environmental factors, especially flow conditions. Fish search for appropriate habitats for growing migrating, spawn, and refuge considering current velocity and depth. Therefore, it is necessary to delineate the correlation between the fish distributions and flow conditions. This main issue is to classify the flow conditions in the Datuan stream by the empirical rule and Froude number. However, various literatures showed that the two methods own the advantages but also drawbacks in the flow classifications. To determine whichever can describe better the flow conditions in the Datuan stream, we consider Sicyopterus japonicus as the indicator species for suiting flow conditions (Pool, Riffle, Run, and slack), and then compare the result to various of migration literatures. Meanwhile, using the Kriging to estimate the probability of occurrence of fish, velocity and depth value, and then qualify the preference of flow conditions of Sicyopterus japonicus. Lastly, display the variations in the flow conditions and the probability of fish in the spatial-temporal scale with geographic information system (GIS).
The result showed that the flow conditions react differently among reaches. Then, the preferences of Sicyopterus japonicus in flow conditions change in the spatial and temporal scale by overlapping the flow conditions map and the contour of fish probability. In particular, the preference of Sicyopteru sjaponicus in the flow conditions is pool and riffle at estuary, riffle in the downstream, run and riffle in the middle and upstream during the migration season (spring). In addition, the outcome are significantly different between the two classifications methods. The empirical rule for flow conditions classification comes out to be more appropriate in the Datuan stream. Nevertheless, owing to the great variation of water depth and current velocity, the consideration of uncertainty is essential. Thus, Sequential indicator simulation (SIS) is applied with 1000 iterations to simulate the overall current velocity and water depth value. Eventually, this research provides the basis of the classifications of flow conditions in the Datuan stream by comparing the result in SIS and Kriging.
Subjects
Flow condition
The empirical rule
Froude number method
Datuan stream
Sicyopterus japonicus
Kriging
Geographic information system
Sequential indicator simulation
SDGs
Type
thesis
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