Debris flow hazard had been one of the major slope hazards in Taiwan, through proper risk management and risk governance could effectively reduce the possible losses. This study reviews the spatial distribution of the risk treatments conducted by government agencies in the past 15 years in Taiwan to identify if the villages with high debris flow risk torrents were properly covered. Soil and Water Conservation Bureau (SWCB) is in charge of the mitigation and management of debris flow hazards in Taiwan. As of 2015, there are 1,673 potential debris flow torrents which distributed in 684 villages around Taiwan and each torrent has been identified with different risk levels (high, medium, low). SWCB has the responsibility to assist the local governments to prevent debris flow hazards by conducting the risk treatments in advance.

Risk is the probability of harmful consequences or expected losses resulting from a given hazard to a given element at danger or peril over a specified time period. In Taiwan, the risk level of enlisted potential debris flow torrents is based on the product of potential degree and protected object degree. The analysis procedure was modified by SWCB and published in 2013. When SWCB went public the information of potential debris flow torrents, the risk classification of each torrent (high, medium, low) were also provided. Of the 1,673 torrents, 485 were classified as high risk, 474 are medium risk, and 714 are low or no risk. 278 villages held at least one high risk torrent, and 406 held only none-high risk (medium or low) torrents.

In this paper we focus on the debris flow risk governance during the preparedness stage, which reflects the degree of risk awareness before the onset of the hazard. The four risk treatments include:

(1) Debris flow prevention and evacuation drill (2,160 counts between 2004 and 2014);

(2) Debris flow education and publicity (675 counts between 2000 and 2014);

(3) Debris flow disaster resistant community (445 counts between 2007 and 2014);

(4) Debris flow volunteer specialists (1,004 qualified specialists as of 2014).

It could be assume that the more items or more frequent the treatments were conducted within the village, usually represented the higher degree of risk awareness to the inhabitants, and would reduce hazard losses.

Of the 278 villages holding high risk torrent, 14 did not hold any education and publicity, 83 had never held any evacuation drill, 53 were not yet becoming disaster resistant community, 49 had no qualified volunteer specialists. In total, 2 villages did not hold any of the 4 types of risk treatments.

Agencies could easily understand and monitor the completeness of debris flow risk treatments within each village, thus could screened out those required more attention and adjust the resources to speed them up. For those villages occupy too much resources, some should be release to those urgently needed, thus could better distribute the most needed mitigation efforts to those in need, and to reach the most cost-benefit value.