Shao-Yang Huang

Identifying hydrograph parameters and their relationships to urbanization variables

Abstract This study examines relationships between model parameters and urbanization variables for evaluating urbanization effects in a watershed. Rainfall–runoff simulation using the Nash model is the main basis of the study. Mean rainfall and excesses resulting from time-variant losses were completed using the kriging and nonlinear programming methods, respectively. Calibrated parameters of 47 events were related to urbanized variables, change of shape parameter responds more sensitively than that of scale parameter based on comparisons between annual average and optimal interval methods. Regression equations were used to obtain four continuous correlations for linking shape parameter with urbanization variables. Verification of 10 events demonstrates that shape parameter responds more strongly to imperviousness than to population, and a power relationship is suitable. Therefore, an imperviousness variable is a major reference for analysing urbanization changes to a watershed. This study found that time to peak of IUH was reduced from 11.76 to 3.97 h, whereas peak discharge increased from 44.79 to 74.92 m3/s. Editor D. Koutsoyiannis; Associate editor S. Grimaldi Citation Huang, S.-Y., Cheng, S.-J., Wen, J.-C. and Lee, J.-H., 2012. Identifying hydrograph parameters and their relationships to urbanization variables. Hydrological Sciences Journal, 57 (1), 144–161.

Typhoon Morakot and Institutional Changes in Taiwan

Typhoon Morakot hit Taiwan in 2009 with numerous rainfalls and caused nearly 700 deaths from mudslides and huge agricultural losses that have been estimated to be reaching NT

Identifying disaster risk: How science and technology shield populations against natural disasters in Taiwan

14.59 billion. For reconstructing the damaged buildings, traffic and houses and avoiding the same problems happen again, some institutional changes were made in post-Morakot period. The major changes include amending law and establishing new organizations to reduce problems like unclear responsibilities because of the overlapping affairs. Briefly speaking, the major changes are replacing “National Fire Agency” (NFA) by “National Disaster Prevention and Protection Agency” (NDPPA) as a professional institution in dealing with future disasters and gives emphasize on the role of local governments, establishing “Special Reconstruction Regulation for typhoon Morakot” to supply more finical support for houses or industries reconstruction, amending “Disaster Prevention and Protection Act” to make the whole disaster managing system more consistently, combining the “Central Disaster Prevention and Response Council” and “National Disaster Prevention and Response Committee” to reduce the problem of affairs overlapping, and establishing “Office of Disaster Management” to supervise central and local governments to execute disaster prevention and response plans.

An adaptive sampling approach to reduce uncertainty in slope stability analysis

Abstract Effective disaster management is essential for all the levels of disaster response in Taiwan, including topic, regional, and national. In order to increase the potential of the response phases for sensitive groups, new techniques and technologies have been applied over the last decades. For that reason, innovative strategies and systems have been developed by both central and local governments that include disaster warning mechanisms, earthquake real-time report systems, resource applications, disaster information and intelligence networks, disaster educational and training programs, etc. In central-west Taiwan, the local governments of Chiayi City and the counties of Changhua and Yunlin have established programs in which their populations are informed about the possible impacts of disasters and adopt effective practice concepts for disaster management. These programs focus on areas with high disaster risk potential and vulnerable populations, aiming at providing necessary supplies to local populations for disaster awareness and response.

Post-Morakot Land Use Implications for Taiwan

An adaptive sampling approach is proposed, which can sample spatially varying shear strength parameters efficiently to reduce uncertainty in the slope stability analysis. This approach employs a limit equilibrium model and stochastic conditional methodology to determine the likely sampling locations. Karhunen-Loève expansion is used to conduct the conditional Monte Carlo simulation. A first-order analysis is also proposed to ease the computational burden associated with Monte Carlo simulation. These approaches are then tested using borehole data from a field site. Results indicate that the proposed adaptive sampling approach is an effective and efficient sampling scheme for reducing uncertainty in slope stability analysis.

Chapter 16 The experiences of DRR through CCA in Taiwan

Because of its geographic position and special topography and geological conditions, many disasters have been caused by earthquakes and extreme rainfall in Taiwan in recent years. Especially, climate change brings about extreme rainfall intensity, and typhoons bring extreme torrential rain, which usually causes landslide, debris flow, and flooding in mountain areas and low-lying areas in Taiwan, such as the disaster Morakot that resulted in the greatest casualties to Taiwan in 2009. Based on the results of field surveys, the lack of an integrated plan of land use and extreme rainfall are the causes bringing about these catastrophic disasters. The Government has applicable policies in response on rule-making and policy implementation for avoiding similar problems happening again. For example, in the Typhoon Morakot Reconstruction Special Act, development is prohibited in specific areas and insecure areas to avoid repeated threats to living safety in environmentally sensitive areas and vulnerable areas. In addition, after Morakot many counties reviewed the articles of the regional planning law to enhance the measures of disaster adaptation and disaster mitigation, including the norm of land use on hillside land and governing in coastal flooding areas, intending to reduce casualties and property losses from disasters through applicable land use strategy.

Chapter 13 The water community case of Chou-Shui River in Taiwan

Taiwan is located between the worlds largest landmass, the continent of Asia, and its largest ocean, the Pacific Ocean. The Tropic of Cancer passes through the island of Taiwan, giving it a subtropical and tropical oceanic climate. High temperatures and rainfall and strong winds characterize the climate. Because of Taiwans position in the Asian monsoon region, its climate is greatly influenced by monsoons as well as by its own complicated topography. The annual mean temperatures in the lowlands are 22–25°C, and the monthly mean temperature exceeds 20°C for eight months starting with April each year. The period from June to August is the hottest season with mean temperatures of 27–29°C. Temperatures are cooler between November and March; in most places, the coldest monthly mean temperature is above 15°C. The climate is mild rather than cold and temperatures only fall dramatically when a cold front affects the region. Average annual rainfall in the lowlands of Taiwan is in the range of 1,600–2,500mm. Due to the influences of topography and the monsoon climate, the rainfall differs greatly with different areas and seasons. In mountainous areas, average rainfall may exceed 4,000mm/yr. Rainfall is generally higher in mountainous areas than in lowland areas, higher in the east than in the west, and higher on windward slopes than on the leeward side. The northeast monsoon prevails during the winter; this is the rainy season in the north though rainfall is not intense. But the same winter period is the dry season in the south. During the summer, the southwest monsoon prevails, often giving rise to convective thunderstorms and bringing intense and copious rainfall. With added downpours brought by typhoons, this season often accounts for over 50% of annual rainfall in the south so that central and southern regions often suffer greatly. Relative humidity on the island of Taiwan, surrounded by ocean, is high, usually measuring in the range of 78–85%. In the north, relative humidity is higher during winter than during summer. The situation in the south is the opposite. Over the past 100 years, the rainfall in the north has increased, while the rainfall in the south has decreased. The trend is not as consistent as that of the temperature change (Environmental Protection Administration, Executive Yuan, R.O.C. (Taiwan), 2002).

Identifying peak-imperviousness-recurrence relationships on a growing-impervious watershed, Taiwan

Rivers flowing through the land are a source of life. They have different importance and functions such as for drinking, sailing, irrigating crops, generating electricity, sightseeing, fishing, and so on. In addition, animals like amphibians, birds, and mammals also live and propagate near the river environment. Therefore, rivers are ecosystems for some animals and plants that are special, rare, or on the brink of extinction (Water Resources Agency, Ministry of Economic Affairs, 2006).