The government has made some progress in promoting water management. However, in response to the challenges of urban rapid development and climate change, the Water Resources Agency of the Ministry of Economic Affairs (WRA) has proposed runoff allocation and outflow control. The relevant water law amendments have been implemented in June 20th, 2007. The amendments were introduced to adjust the rainfall runoff originally absorbed by the channels to the sharing of waterways and lands. Thus lands and buildings are going to share the surface runoff to increase the overall flood tolerance of the city.
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Runoff Allocation in Keelong River
The project of runoff allocation in Keelong River is numerically analyzed by using the SOBEK model based on the flood inundation map. The sketch of SOBEK model in Keelung River is demonstrated in Figure. 1. First we analyze the allowable discharge and the amount of runoff allocation in Keelung River. Then the potential lands for runoff allocation should be checked thoroughly, especially the public lands. As a result, the potential areas where can provide spaces for the flood detention during the rain storm event or typhoon periods are demonstrated in Figure. 2.
Figure.1 The Sketch of SOBEK model in Keelung River
Figure.2 The Potential Spaces for Flood Detention in the Catchment of Keelung River
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The Evaluation of the Work of Runoff Allocation in the Rivers Administrated by Central Government.
In this work, we check whether the rivers administrated by central government are allowable for expanding the river width, dredging the river channel or increasing the height of levee. If the methods as mentioned previously could not be utilized, the runoff allocation should be considered. Then we suggest the order of priority of promoting runoff allocation in those rivers. By checking the flood control facilities and analyzing potential inundation areas, we could determine the areas where the runoff allocation method is required.