Tapestry of Life

PROJECT NARRATIVE

In the 2019 Fall Design Studio, we mainly focused on solving the urban flood mitigation issues by two study areas, Houston and Venice. Both of them are threatened by flooding in different season of the year due to flat topography, adjacency to ocean and highly density population. However, they have developed different strategies to cope with it throughout the history. And most importantly, Venice is a great example for Houston to learn from in urban flooding aspect due to its early and thoughtful development, such as multi-scale defensive system. It entrenches from the coastline to inland by sea walls, tankers and lagoons. They have maximized their natural effects by exploiting their characteristics in location and sizes. And Houston could do a better job as long as it has applied more scientific and systematic criteria when planning those elements, which is a crucial part I have worked on during the beginning of the semester. The proposal explores the possibilities in Houston to build multiple flood defensing system at different scales and types, from community park to regional park and from linear park to nodal park, which does not only aim to handle with massive flooding events but also to provide Houstonians with outdoor recreational space to interact with nature. And in the following three paragraphs, the report will discuss the pre-design analysis, design strategies and post design evaluation. Firstly, it is about the pre-design analysis, which mainly focus on flooding intervention scoring system development. The scoring system is consisted of two categories: flood mitigation suitability and flood vulnerability. Both of them represent two major concerns when dealing with flooding mitigations. The former indicates planning and designing concern only, and the latter implies human needs from different perspective. All of related factors will be scored by watershed, including upper watershed, middle watershed and lower watershed. For instance, in the flood mitigation suitability, I took floodplain, job density, population density and slope into consideration. If they locate in the upper watershed, they would be given higher score, indicating more suitable to develop with flood mitigations. And as the flood vulnerabilities, it flows the reverse logics. If those factors locate in lower watershed, indicating they are vulnerable to flooding. In order to organize them as a whole system working for design, I circled area based on two major criteria, finding the most suitable areas in various scales to cope with flooding vulnerabilities through watershed strategies. Secondly, it will discuss the flooding defensive strategies I planned for Houston from 2020 to 2100. All of the design elements will serve as a green necklace for Houston- Galveston Area, which is a loop circling the diverted channel, bayou green-ways and IKE Dike to handle with inland flooding and storm surge. And there are three major types of strategies to be developed through three phases, linear park, bayou green-ways and nodal parks. Specifically, the linear parks are majorly located in the western and eastern diverted channel and elevated highway in the Houston – Galveston Area; the bayou green-ways will integrate with the Houston Government proposed project Greenway 2020; and the nodal parks are transformed from regional scale detention ponds combining with outdoor recreational activities. And all of these design elements will be intrigued by different rainfall intensity by 2100. In 2020, the estimated rainfall intensity will be 30 inch / hour, and Houston can only use elevated highway with container beneath ground to store storm water; In 2060, the estimated rainfall intensity will be doubled, and Houston can react with elevated highway and linear park; In 2100, the estimated rainfall intensity will be four times, and Houston can response with three schemes, including elevated highway, linear park and nodal park, and all of them will serve to hold and to divert storm-water. Moreover, those three scheme will evolve in each two decades. The elevated highway will grow from constructed container to rain garden to intercept rainfall; the linear park will extend from Harris County boundary connecting with bayous in the Houston; and the nodal park will merge two existing reservoirs into a regional park. The highlight of the project is the eastern diverted channel part, which will be named as Blue Greenway Park. It will transform the existing highway over San Jacinto River into Dam with greenway for bicyclists and pedestrians. Northward looking the highway, we will see barrier island in the middle of widened water path, which will not only create more habitats for local wildlife, but also buffers to slow down runoff. Southward looking the Galveston Bay, we will see linear wetland park serving to divert the runoff from San Jacinto River to ocean directly, which will bypass the Galveston Bay to reduce potential sea level rising. Also both them will be wonderful spots for people to boat, to fly kites and to fish adjacent while enjoy the coastline scenery. Lastly, the report will elaborate the post-design performance evaluated by the water volume diverted from Harris County. Overall speaking, mine proposed solution will add 322.2 miles of bayou greenway, 42.16 Square Miles of linear park and 100.4 Square Miles of nodal park to Harris County. And all of them will used to mitigate with flooding by different rainfall intensities. Under the most extreme scenario of flooding, Harris County currently will deal with 45 KM3 water if the most severe flood happens (estimated by the rainfall intensity of hurricane Harvey, 35 inch / hour), which is sixty times of the sum of Baker Reservoir and Addick Reservoir. However, after the intervention, the newly built flood mitigation facilities will divert one fourth of the water volume from Harris County to ocean directly, which will relieve its flooded stress. Therefore, mine proposed flood mitigation plan will work for human beings and wildlife together. And the goal of mitigating with massive flooding events will be achieved through multiple defensive system by their best performance location implement. It is not just planned for the current flooding situation, but more for the future worsen scenarios, continuing sea level rise, expanding population center and increasing rainfall intensity. Existing storm water management facilities will not be effective enough to handle it, thus, we need more aggressive strategy to reduce floodplain in the city.

Problem Statement
In the next three decades, population will increase 2.7 million more and job opportunity will do accordingly. However, their centers continue to expand within 100 year and 500 year floodplain, indicating great human and economical loss if flooded.

Scoring System Introduction
The data set will be divided into two categories: Flood mitigation potential and flood vulnerability. The former suggests appropriate locations to manipulate with flooding; and the latter suggests potential loss if flood happens.

PROPOSED DIAGRAM – Best Flood Mitigations
Based on flood mitigation suitability map and surrounding land cover, it would be the best option to build a channel diverting water of reservoirs into ocean directly to decrease Houston upper watershed flooded risk.

PROPOSED DIAGRAM – Most Flood Vulnerability
Add flood vulnerability map into consideration, it would be better to construct an eastern channel to protect bay surrounded chemical plants and to reduce Galveston Bay runoff volume.

MASTER PLAN – Regional Strategies
Two types of regional strategies would be implemented for Houston-Galveston Area, Bayou green-ways and detention pond for inner Houston; Linear park for diverted channel outreaching from Houston to Galveston coastline.

STRATEGY EVALUATION – Watershed Performance
The runoff volume under the worst hurricane Harvey scenario is 60 times more than two Houston current reservoirs. And proposed diverted channel would reduce one-fourth of the runoff from seven watershed.

ADAPTIVE PATHWAY -Design Strategies Evolvement
There are three major design strategies for flood mitigation: Elevated highway, urban detention pond and diverted channels. Three of them will evolve within each two decades based on rainfall intensity. And different rainfall intensity will intrigue different models to cope with flooding.

STRATEGY EVALUATION – Section Comparison
Before the implementation, only highway bridge is over San Jacinto river. And after our design, two out of six highway lanes will be converted into linear park for pedestrian and bicyclists. Also the highway itself will be served as dam to prevent runoff running into bay to reduce the rising sea level.

AESTHETIC EXPERIENCE – Bird’s Eye View of Blue
In the North of Highway, we will transform it into dam with linear parks. Also, we will construct barrier island in the middle of water to reduce flow speed and to create more habitat for local wildlife.

AESTHETIC EXPERIENCE – Eye Level Perspective
In order to reduce the runoff into Galveston Bay, we will transform previous surface parking lot into widened river channel, build barrier island in the middle of river to slow down the water speed, and divert original San Jacinto River by creating wetland to provide ecological habitats for local species.