M.Arch Thesis

M.Arch Thesis Urban Flooding Typology

Ao Chin Wen Prof. Alstan Jakubiec 2016 June

M.Arch Thesis Urban Flooding Typology

Ao Chin Wen Prof. Alstan Jakubiec 2016 June

Content

1 2 3 4 5 6 7 8

Introduction Geography of Taipei Urban Development Cause of Flood Current Flood Prevention Case Study Design Criteria & Opportunity Site Proposal

1 Introduction Typhoon Time Distribution Graph

DEC

JAN

FAB

NOV

OCT

MAR

SEP

APR

MAY

AUG

JUL

JUN

Rainfall Distribution Graph Source: Central Weather Bureau

This thesis aims to tackle the issue of flooding in the urban region of Taipei, through thorough investigation of the causes of flood, current strategies employed by the Taipei government and the future urban development of Taipei city. From there, it will be used to guide the development of an integrative solution that is aimed to improve the living quality of Taipei city in the event of a typhoon.

Due to typhoon, Taiwan has an extremely uneven distribution of rain fall across the year.

During summer, rain fall depth can reach up to 400mm(Typhoon Herbe, 1996), with 4 to 5 typhoon visiting Taiwan per year, accounting for 63% of annual rainfall, while during winter, there can be little to no rain fall at all.

Despite that, typhoon still plays an important role in Taiwan as it contributes to the local water supply.

As Taiwan lacks huge reservoirs, she is reliant on the typhoon to replenish the water supply in the local dams. This means that in the absence of typhoon, there is a risk that there will be a drought that persist till the following summer, as the existing dams are unable to cope with the locals’ demands.

Source: Taiwan Climate Change Projection and Information Platform

Introduction

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Exploring on the opportunities that allow us to provide an alternative perspective on the relationship between people and typhoon through architecture.

Being a highly urbanized city, Taipei has suffered huge losses due to typhoon. According to a report by March Insurance Agency for Taiwan Water Resource Agency, the potential loss for a flood occurrence with a 200 year return period could amount to 7.5 billion NTD of insurance compensation, with more than 60,000 units being affected.(2005 Marsh) 9

2 Geography of Taipei

Outline of Taipei City

Located at the northern part of Taiwan,Taipei is a highly urbanized and global city. Since Japan occupation, by placing administration HQ here in Taipei,the city has become the capital of Taiwan. Over the years, the city continues to gain importance as a major ďŹ nancial center in Asia, and currently has the highest population density (2.7 million in 271.7997 sqkm, 9,950people/ sqkm, 2016) among Taiwan cities.

Surrounded by 3 main mountain ranges-Datun Volcano group-altitude 1120m,Linkou Plateaualtitude 400m,Xueshan Range-altitude 3492m, Taipei is located within the Taipei Basin, which compromises of Taipei City and New Taipei City, in which 243 sqkm of at land to be 20m below sea level. These mountain ranges could produce a phenomenon called rain shadow, where the warm air is lifted upwards due to orographic lifting, the decreased pressure and expanded air is cooled to a point of adiabatic dew point, causing rainfall on the windward side of the mountain.(Whiteman, 2000)Although Taipei is on the leeward side, most typhoon has alot more moisture content then a typical warm moist air, thus, rainfall would instead land on the leeward side of the mountain as well, and collected at Taipei Basin.

Tamsui River and Branches

Geography of Taipei

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There is one main water outlet in Taipei, TamSui River, which then splits into 3 sub river-Xindian Creek, Dahan Creek, and Keelung River.

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Geography of Taipei

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3 Urban Development

1921

Photo of Early Da Dao Cheng Source: http://www.dili360.com/ch/article/p54128e64a576737.htm

As Taipei become the capital of Taiwan, during the Japanese occupation, rapid urban development was carried out to respond to the population growth and intensification of Taipei City.

1956

Source: http://tmap.geospatial.org.tw/

Urban Development

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1993

However, this development has also destroyed the original landscape of Taipei Basin. During Qing Dynasty, Taipei’s economic rely heavily on DanSui River and is one of the 3 major port cities in Taiwan (一府二鹿三艋舺) where the residences used to fight over control over the port region at Meng Jia and Da Dao Cheng.

From the historical maps, we can see how Taipei City starts to expand inland. Due to ill maintenance of the upstream river, sediments accumulated at the port region, rendered it dysfunctional as a river for transportation, and reduced the water capacity of

the river. （温、戴 ，1999）The rise of onland transportation such as railway and cars also causes the reduced need of water transport.

Even though Taipei city manages to transform itself from a port for goods export to a service orientated industry, the rapid development comes at a cost.

The rapid urbanization and influx of population into the city causes a great demand for housing, that are cheap and reliable. In respond, concrete cast building filled the earlier housing development of Taipei city, reducing public green space to 5.6%(Taipei Parks and Street Lights Office,2016), narrow alley allows a super compact and high dense residential development.

Wetlands or forests are converted into roads and buildings, greatly affecting the water retention value of flat lands in Taipei city.

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Xue shan Mountain Range

Taipei City

DamSui River

4 Causes of Flood 4000 BC

?? ~ 1683

SOURCE: http://pansci.asia/archives/55515

1683

1895 Accumulation of sediments causes water capacity for the river to reduce, causes overflow

Causes of Flood

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Current Dense urban development increases impervious surface on flat land and mountain.

The 3 main causes of flooding in Taipei city are 1) low altitude terrain, surrounded by mountain ranges 2) high percentage of impervious surfaces in the developed region 3) low water retention potential for shallow river streams, causing river overflow.

The cause of flood relate closely to the development of the city. From the diagram on the right, it indicates the shift in industry and the center of the city, while the development alters the environment of Taipei city, making it susceptible to flooding.

government agencies and public amenities, the average percentage of impervious surface is 82%, while the most abundant residential typology having 88% impervious surfaces.(林,2002) The impact of flooding goes beyond disruption of traffic, city functions and damages to property. The flood could transmit diseases, causes mosquitoes outbreak, contamination of water supply, hygiene issues in the city, land slide, power outage.

According to a study on Taipei’s impervious surfaces, buildings such as residential, business, industrial,school, 17

Within Taipei urban zone, the amount of impervious surface can be estimated by multiplying the percentage of impervious surface for each building typology (residential,commercial, industrial,public amenities and parks) and multiply by the area dedicated to each typology.

Using a study done on Taipei’s impervious surfaces (林,2002) ,more than 64.7% of the area are impervious surfaces. For 600mm of rainfall, impervious surface would result in 594mm/ m2 of runoff volume. Multiply by the total urban area,129.96km2, the runoff volume would be nearly 50 million liter.

Residential: 3800 Ha Commercial: 880 Ha Industrial: 411.5 Ha Public Buildings: 7341.85 Ha Park: 140 Ha (Ministry of Interior Taiwan,2014)

Causes of Flood

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Current Taipei City Development

Corrugated metal rooďŹ ng

Ceramic tile facade

No presence of plants along roads

Asphalt Typical Taiwan Apartment Buildings

Causes of Flood

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Typical Taipei Residential Alleyways

Source:http://www.worldcitiescultureforum.com/data

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Major Public Green Space in Taipei

Taipei city’s terrain causes rain water to accumulate, while collecting rain runoff from the mountain ranges. With more mountain surface area facing the city (187.4 sqkm, outlined in red) than the flat area of the city(129.96 sqkm), there is a significant amount of rain water that enters the city. The development on the mountain does not help with water retention on the mountain as well. Residential buildings ,car parks and roads increases the percentage of impervious surfaces that were once forests.

Causes of Flood

With an average slope of around 30%, the mountain of Taipei mountain consist of mainly woods cover with hydrology group C soil (CN=73), we can estimate the rain runoff volume using the equation: Q=(P-I)2/(P-I+S) Q=precipitation(inch) P=rainfall(inch) S=potential maximum soil moisture(inch) I=initial amount of water (inch) Under 600mm/m2 rain fall, the runoff volume would be 518mm/m2, with a total volume of 97 million liter.

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With the influence of both urban and mountain rain run off, this graph shows the flooding simulation of a 200 year return period, rain fall amount of 600mm. Most of the urban region are flooded, where only regions beside the mountain are excluded.

Source Sou rce ce e: Taiw a an Climat a e Chan at ange an ge Pro Projec jec ectio t n and tio and Inf Inform ormati orm at on Pla ati atfo tform rm

Taipei 27 Flood Prediction-200 Year Return Period 650mm Precipitation

5 Current Strategy

River Side

Dadaocheng Flood Gate Source:

Two main strategies that Taipei government employed are 1)flood wall 2) 90% coverage drainage system, which include rain water drains and pump stations.

City Side

One of the most common strategies against flooding, would be to include a larger flood zone besides the river. However, due to rapid development of the city, the river bank is already saturated with buildings, hence the flood zone is unable to be broadened, resulting in a variation of river width from 400m to 150m.

The narrow part of the river is susceptible to flooding when a sudden increase of water volume occur on the upstream.

To counter this, flood walls

Current Strategy

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been erected around Taipei city in 1960s. Flood wall and flood gates up to 9.2m are installed along Dan Sui River and its branch, to prevent water overflow from the river into the city.

Flood walls are an effective and cost effective measure to stops river from flowing into the city. However, it takes huge amount of maintenance fee each year to repair the wall, while it also disconnects the river scene with the urban living environment.

The tall flood wall blocks the visual connection and impedes citizens from accessing the river that were once so important to the aboriginals and early immigrants in Taipei.

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The red dashed lines indicates the extent of the ood wall for Taipei city. It has basically surrounded the entire city, disconnecting the urban area with river.

Besides blocking the river from owing into the city, it also means that water within the city has to rely completely on pumps and drainage system since the water is basically trapped within the wall.

Current Strategies

The water from the pump stations are then drained out to the river and various dams. However, during high tide or when the river itself is taking lots of rain water, and dams themselves will also be full due to the heavy rain fall, such system will not be suďŹƒcient when the total rain volume exceeds the capacity of water retention storage.

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Thesis Statement Due to the low-laying terrain of Taipei basin,frequent occurrences of typhoon and rapid urban development, Taipei city is susceptible to floods, causing significant loss to the city and disruption to citizen’s daily life.

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The current strategies such as ood wall along the river, and continual upgrade of drainage system could mitigate the ood issue temporarily, but it also detaches the society from the water resources.

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Through investigating the cause of ooding in Taipei city, this thesis propose a new residential typology that could mitigate ooding in Taipei while re-kindle the relationship that Taipei City once had with water, with a secondary function as public space when the primary function of water retention is not needed.

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6 Case Studies

Benthemplein Water Square

Benthemplein Water Square Source:

Solutions to tackle flooding can be ranges from retaining, delaying, re-directing to rejecting water.

In order to combat the flooding issue in Taipei, all 4 strategies should be deployed as the there is a wide range of scenarios, such as mountain side, urban run off, river over flow etc. These case studies would offer insights to strategies that can be deployed at various scale and scenarios.

Situated at Rotterdam, Netherlands, Benthemplein water square is a unique public space that had the intention of flooding in mind. By combining water retention device with a recreational space, the outdoor sport facility will be used as per normal during non rainy days, during rain, it became a water retention device and a pool.

Case Studies

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Such infrastructure is useful in places where there is a clear distinction between rainy seasons and dry seasons. Incorporating a secondary function to the retention facility could prevent under utilization during dry seasons.

Most of the public spaces in Taipei are made of flat concrete floors, where the impervious surface does not help with the infiltration of water, and the public space contributes to the impact of urban rain run off.

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6 Case Studies The BIG U

DOUBLE-BENCH

SHOP

GARDEN

SEATING-SHELTER

SLIDE

SINGLE-BENCH

BIKE-POINT

MEDIA

SKATE Various functions that can e attached to the wall

The BIG U Source: Rebuild By Design

This proposal by BIG for Rebuild by Design proposes a infrastructure installation along the shore of Manhattan island to prevent the water from flooding into the city.

This design combined various functions to be incorporated with the flood wall. Recreational space, shops, sport facility or sitting area etc. This combination allow the flood wall to be utilized out of the rainy season or high tide scenario, and also provides the citizen an opportunity to connect with the water scape.

of Taipei city. However, I believe that the design should instead incorporate this periodic surge of water. Systems that hide away the presence of water will only further enhance the negative attitude towards typhoon.

Comparing with the current design strategies in Taipei City, the system that BIG proposed does not disconnect the water resource with the city itself. Both flood wall and drainage systems in Taipei focuses on making water disappear from the everyday life The Big U

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Sou So S ource o r e: e: Rebu uild ild ld By

By Desig Desig De sig si ign

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Design Criteria & Opportunity

Dual Functions-Due to the uneven distribution of typhoon occurrences throughout the year, the design has to have multiple functions that can be activated during dry and rainy seasons.

Integration-To fully utilize the impact of typhoon, there is a need for a thorough integration between living space and flood prevention strategies. To increase the amount of surfaces and volumes in which can retain water and reduces run off, design at multiple scales, individual apartments, buildings, blocks and urban planning, should be considered. This would also help in changing the role of typhoon in the daily life of Taipei city.

Environmental Sensitivity-However, there is a need to also take into consideration on the issue of mosquito infestation that might result from the water retention design.

----------------------------------------------------------------------------------------------------------------------------------Reduction in population-As Taipei City development starts to mature, we are expecting a declination in the population. The need for cheap and dense housing is no longer a priority for Taipei citizens, but should place more priorities on improving the living quality such as public space, green spaces etc.

Old and ill maintained housing-Although the old housing development has cultivated a culture that many Taipei citizens could identify with, narrow alley ways, family shops and restaurants at each corner of the blocks.

Zhong Shan District is also saturated with residential housings that are in need of new development.

More than 57% of the buildings are over 30 years old (Department of Urban Development, Taipei Government, April 2016), ill maintained building elements, with the lack of amenities such as lift or public spaces.

Shift in housing needs-As the family structure evolves over time, the need for the size of a housing unit changes as well. Compared to the early 90’s, the major demand shifted from 3 to 4 room unit to 1 to 2 room unit. This could also be related to the shift in the age of house owners in general.

Lack of green space-Compared to Singapore’s 66sqm/capita, Zhong Shan District is only 7.4sqm/ capita. The green spaces are sparsely located, some units are not near any green spaces. There is a strong need for the improvement of living quality and to improve urban rain run off.

Access to river scape-Besides the flood wall that isolates the city with the river, there is also major highway that run along the river, worsen the connection between the two. The traffic network is placed along the river as the urban region is unable to accommodate such major infrastructure due to the high dense development in the earlier era. The proposal should address the connectivity issue of the residents with the river.

Zhong Shan District600mm rain fall flood zone (0.5m, 1m, 3m and above)

Flooding Simulation

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Site Proposal

From the research done on causes of flood, urban rain run off and mountain runoff are equally important factors that contributes to flooding, with a volume of 50 million liter and 90 million liter respectively. Hence this proposal would focus on how architecturally mitigate flooding issue on both types of terrain, while ensuring the connectivity between the river and urban built environment is not lost by nullifying the need for flood wall.

The proposed intervention will be focusing on the Zhong Shan District.

This district is expected to have the worst flooding occurrences in the event of a 600mm rain fall. With the amount of flooding occured, we can expect it to be contributed from neighbouring district’s rain runoff.

Being one of the early district that undergoes urban development when Taiwan government just started, the site is occupied by many old houses made up of either bricks or concrete with plenty of impervious surfaces. Zhong Shan District also span across various hydrology condition, urban, river side and mountain slope. With such a diverse landscape, a new residential typology that can responds to various conditions can be explored within this district.

Site Proposal

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Source: National Development p Council

Population (thousands)

Residential Housing Distribution

Compact Housing Development

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Taiwan Population Trend Prediction

Source: National Development p Council

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Zhong Shan District 7.4 sqm/capita

Singapore

66 sqm/capita

Source: Top: Department of Budge, Accounting & Statistics, Taipei Government,2016 Bottom:Siemens and economist intelligence unit, 2011

Green Space Distribution

Lack of Green Space

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Limited Access to River Scape

Disconnected River & City

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Flood wall between city and river 51

Since the mountain region would experience a greater flow of water per area, the main function of housing typology would be to delay and cleanse run off water.

Mountain

With the removal of the wall, the original Dan Sui River can serve as a bridge between the mountain rain run off towards the multiple water containment area in the urban region.

River

With the highest density of buildings, a new typology that can responds to storm water management will be most effective. This region of the city would serve as the main water containment area.

Urban

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Amsterdam

Tokyo

In the city of Amsterdam, an evolution of the pre-existing dykes forms the canal that interwinds with the built environment. The city has a strong affinity with the water element of the city, where boats is one of the transportation method within the city.

City Study

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Tokyo’s G-Can project created a giant cistern underground that could prevent flooding of a 200 year return period rainfall. Excess water from each smaller river in Tokyo city are collected in 5 cisterns before pumping out to Edo river that connects to the sea.

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Singapore

Taiwan

In the city of Amsterdam, an evolution of the pre-existing dykes forms the canal that interwinds with the built environment. The city has a strong affinity with the water element of the city, where boats is one of the transportation method within the city.

City Study

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Tokyo’s G-Can project created a giant cistern underground that could prevent flooding of a 200 year return period rainfall. Excess water from each smaller river in Tokyo city are collected in 5 cisterns before pumping out to Edo river that connects to the sea.

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26L/hr,625mm/day (evaporation rate with 40sqm)

STORM SEWER BIOSWALE

PUBLIC SPACE

PURIFICATION

PHYTOREMEDIATION RAIN GARDEN

300MM

5L/hr (evaporation with 13sqm)

Concept

GRAVEL

POTABLE WATER 9.6L/day x sqm

600MM FINE SAND FILTRATION

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51%

49% Waterfall by Olafur Eliasson Source:

AFTER

In this art installation, Olafur Eliasson created a series of waterfall by stacking basins one on top of another, both the sound and visual of the natural environment is being expressed through the simple use of gravity and height.

BEFORE

The high urban density of Taipei is part of what makes up the character of the city. Urbanisation also provides a huge amount of untapped volume that could be used to be part of strategy for stormwater management.

Conventional water retention strategy focuses on ground surface storage. The advantage of such strategy lies in its ease of implementation and potential to increase inďŹ ltration rate into the soil as well. However, In this thesis, I would like to explore a new living environment that could bring various qualities of rain that is pleasant into the living space.

STREET

100% 58

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BUILDINGS

10 Existing Typology 4

BD 2 Toilet

BD 3 Kitchen

BD 1

Dining Room Living Room

Yard

3

2

1

Residential buildings, such as low rise apartments, shophouse, mixed use apartments, of zhong shan district account for more than 52% of the land area .

Therefore, by redefining the function of residential typology is a crucial factor in designing and impactful urban flooding strategy.

Responding to the demand of a unit with less room and more green space in the city. The extra space could be converted into a semi outdoor space that each resident could enjoy, in which it also serves as a intermediate space between nature and living space.

often under developed back alley space between apartments.

These back alley though not as vibrant as the alley itself, due to the lack of commercial activity, it has a tranquil quality that is unique in a bustling modern city like Taipei. However, many of the back alley only has a shallow sunken concrete ground for runoff water to be collected by city’s sewage.

Due to rapid development, there’s Site Analysis

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On the left is a series of sectional study in which water could interact with human through dierent scale, height, active and passive, transient or permanent.

As there will be many dierent needs and condition in which a building could exist in a city, the proposal will serve as a potential development of a certain combination of the relationship between water and human could be, as illustrated on the left through architecture.

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Extended balcony that provides space for potted plants and a barrier for privacy from the street.

the house, serves as a filtration system that purifies rainwater through slow sand filtration, and a private space for contemplation. The filtrated water is then stored within the staircase which is directly besides the kitchen for potable use.

As water is gathered in the low laying urban region, the houses in this region is designed to store and purify water that comes from the mountain ranges and direct rain fall.

The living area is designed to be surrounded by semi-outdoor spaces that could capture water in it’s motion before it goes to a halt. The focus of the living space is always towards the 2 semioutdoor space at the front and at the back of the house. The garden at the front is made up of large gravel which allow water to be stored between the substance while still allowing human usage of the space, and is also the main focus in which living room is facing towards.

The close proximity of apartment buildings creates an intimate atmosphere in each alley space.

The bedrooms comes with a terraced garden in which a gentle flow of water will flow through each steps of the planters, which then seperate into a pond directly besides the toilet, for non potable water usage, or overflow drainage. The step terraced also provides an opportunity to let more rain and light into the sand garden space of the below unit due to its chamfered geometry.

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With a simulated rainfall of 600mm/day, the total rainfall volume on the area of one unit area would be 52,200 litre. while one unit could store 25400 litre (gravel garden:~2000 litre, sand garden:23200 litre, terrace planters: 3m3 of soil) of water storage. Each unit is stacked upon one another, with an overflow portal at the front and back of the house.

A secondary suspended circulation that utilises the once neglected back lane of Taipei apartment, providing access to various amenities of its zones. The space below the bridge becomes a vibrant bioswale that would take in nutrient from the polluted run off water before infiltration or entering the city’s sewage system.

Above the living room, a sand garden which could be accessed from within

Urban Typology Proposal

The living space is made of timber wood as to contrast with the concrete which made up the region that are in contact with water.

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Urban Typology Proposal

Street level commercial provides the services and groceries that the neighbourhood needs and draws people. It also distinguish each alley from each other.

1

2

Offset floor levels to create catchment area

3

4

The ground floor commercial is an important element in the Taipei alley.

However, being the first level, they’re usually hit the hardest as well when typhoon strikes. The flooding will bring dirt and other pollutants into the restaurant, more than loss of income for a few days, the damage to the goods and equipments could be devastating to all these small business.

By elevating half of the shop to a higher ground, it provides a path for run off water to enter the bioswale without affecting the existing shop space.

Staggering each unit doesn’t just provides more spatial hiearchy to the original flat floor slab, it also introduces opportunity for water catchment to exist between units and directly above the living space of each unit.

Opening ground level commercial to let runoff through the building. Sloped inward to allow rain to flow into the building.

Urban Typology Proposal

Verticle punctures for water overflow and daylighting

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Sand Garden 15,000litre

Gravel Garden 2000 litre

恔 ࢮ 掭

Terraced Planter 3m3 of soil

Zhongyuan St

Minquan East Rd

Lane 3 Xinsheng North Rd

Lane 11 Xinsheng North Rd

Bioswale 38mm/hr (912mm/day)

Pervi Pe rv vious ious road io 12.7 12 2.7 .7mm m /hr mm (304 (3 0 mm 04 m /day)

Axometric diagram of water distribution within an apartment building and water flow vertically through each unit and various condition.

Site plan

Urban Typology Proposal

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Sectional drawing

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The living space is directly connected to the garden in which rain from the fecade perforation and above units could enter. The elements of trees and gravel brought back the phenomenom in which used to only exist in nature, into the urban environment.

71 Unit plan

concept diagram

On the ground floor, water becomes a dynamic element in the space that has the potential to divide each spaces into individual islands, while the moving water creates the atmosphere of living on top of a river.

While the rainwater that flows through the surface brings in nutrients that could be beneficial to the otherwise difficult-to-raise indoor plants.

The above units are designed to increase the duration of water before it reaches the ground by having multiple falls, and obstaces, they also incorporated the idea of filtering pollutants out of the water in its course.

Typical slow sand filtration consist of fine sand, course sand and gravel layer, with a respective depth of 600mm, 200mm and 200mm each, each layer is distributed among each unit, so while the water is being circulated through each floor, the water is also being filtered passively before entering the next layer. Overflow water that are not being filtered will go through several green zone in which plants and soil could contribute to the water uptake, before falling to the unit below for the next path.

The meandering path increases the time taken for water to reach the ground and also provides opportunity to have a living space surrounded by water feature

Mountain Typology Proposal

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Mountain Typology Proposal

In the mountain region, this typology focuses on how to delay and reduce the amount of pollutant before it goes to the urban region. As mountain region would experience more rain fall and much more water passing through per unit area, the house is designed to increase the path in which water is needed to travel its original course and to reduce its velocity by introducing materials such as gravel, sand or rocks instead of concrete.

By slowing down the velocity of the water, it would also mean a higher volume of water infiltrating into the soil instead of becoming surface runoff.

Lane 57, Dazhi St

Dazhi St

Alley 1, Lane 94, Dazhi St

94, Alley 3, Lane

Dazhi St

Lane 127 , Da zhi S t

Lane 101, Dazhi St

Axometric diagram of water distribution and path, and location green spaces

Site plan

Mountain Typlogy Proposal

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75

600

5

150

4

6 150x300x800 dark granite slab w/ flame finish

5 drainage layer

4 reinforced concrete w/resin coating on the top side, bottom with archtecturally exposed raw concrete

3 drainage pipe beyond dashed for clarification

6

2 reinforced concrete w/boifilter and resin coating

1 300mm depth soil substrate

aluminum louvre with white finishes

laminated glass

300

1000

1200

1000 300

4900

laminated glass window

150

1

2

3

Unite plan

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2500 250

References A study on urban water cycle- the investigation on the percentage of imperviousness and the experimental analysis of surface runoff -2002, 林子平 Whiteman, C. David (2000). Mountain Meteorology: Fundamentals and Applications. Oxford University Press. 颱風洪水風險評估,美商达信保险,2005 温振華、戴寶村，《淡水河流域變遷史》，1999