Study On The Planning And Design Of Pearl River Delta Based On The Thought Of Resilience

Pearl River Delta(abbreviated as the PRD)has become a pioneer region in China since the Reform and Open-door policy in 1978.After more than 40 years of rapid urbanization,the PRD has made remarkable improvements in its economic development.The PRD is one of three urban agglomerations,and it has the characteristics of largest population concentration,the strongest innovation and the strongest comprehensive strength in China.At the same time,we should also be aware that the rapid economic development makes the land resources in the PRD scarce,and the role of the natural base layer has often been ignored during the process of urbanization.Issues such as the extensive use of land resources,the fragmentation of the blue-green networks,the disorderly reclamation of sea areas,and the shrinkage of tidal flats alongside estuaries,etc.cause the natural base layer of the PRD vulnerable.In recent decades,natural disasters,such as flooding,land subsidence,typhoon,storm surge occurred in the PRD have become more varied,frequent and destructive than those in other regions.The future urban development of the the PRD is highly uncertain.Facing with the highly overlapping factors of the external disturbances--natural disasters caused by extreme climate change,and internal interactions--the contradiction between natural conditions and rapid urbanization,traditional urban design used to pursue mainly economic development could not be flexible enough to respond to the dynamic and uncertain future of the PRD.In the future,urban design should pay highly attention to the fragile natural base layer and unexpected external disturbances that will negatively impact the PRD caused by natural disasters,such as flooding and land subsidence situation.Therefore,it is of great theoretical and practical significance to research for a possible alternative approach to maintain the health of natural base layer and to better adapt to climate change by urban design for resilience.On the basis of an extensive study of literatures,this doctoral dissertation deeply analyzes the current urban system,previous planning and design practices of the PRD,as well as the case studies of the relevant urban design practices in deltas of America and the Netherlands.Based on the thought of resilience,the combination of "theoretical research and empirical validation" is applied as the streamline of this research.The main theoretical attributes of urban design for resilience are researched.The knowledge obtained from the theory and the method is applied to the further empirical research of urban design for resilient PRD.This doctoral dissertation carries out a systematic research from four parts: theory,method,application and conclusion.The main research contents of this doctoral dissertation are as followings.1.In order to understand the background of the PRD,literatures on exploring the physical context,the crucial stages of urban transformation,as well as planning and design practices of the PRD are reviewed.Urban design of typical deltas in America and the Netherlands are also studied from the perspective of both theory and practices,which can be applied as case reference.2.The theory of urban design for resilience is systematically researched.Based on the analysis of the development of the concept of resilience,as well as on the analysis of the difference among resilience and other synonyms,the meaning of resilience in this doctoral dissertation is explained.The core capacities pursued by urban design for resilience,the fundamental thinking characteristics of urban design for resilience,the main spatial characteristics of resilience presented by urban design,and the internal thinking logic of the approach of urban design for resilience are systematically researched.The reasons why these characteristics can help to improve the capacity of resilience of a urban system is explained in details.3.The methods of planning and design for the resilience of the delta are systematically studied.Guided by the theory of urban design for resilience,this doctoral dissertation focuses on the way to transform the theoretical characteristic of urban design for resilience into corresponding methods of planning and design for resilience of the delta,under the background of uncertain huge precipitation and sea level rise in the future.This doctoral dissertation explains the guiding ideology of planning and design for the resilience of the delta,and respectively studies on the corresponding guidelines and measurements of ecological space,agricultural space and urban space,as well as the waterfront space of the delta.Strategies with more targeted and operational for improving the capacity of resilience of the delta are put forward.4.Operational guideline for urban design for resilience is provided.This doctoral dissertation proposes the guiding ideology of urban design for resilience and explains the implementation principle,organization,technical route,the process of urban design for resilience.The contents and key points of each phases in the process,such as target determination,system interpretation,system projection,system planning and design,evaluation and feedback etc,are proposed for the implementation of the theory and method of urban design for resilience.5.The empirical research of the theory and method of planning and design for resilient PRD is conducted and possible new schemes are produced.This doctoral dissertation takes the situation of huge precipitation and sea level raise caused by extreme climate change as external disturbances,and systematically analyses spatial status,spatial evolution and existing main problems in the PRD.Based on the projection of the future scenario under the condition of extreme climate change,the corresponding principles and strategies of planning and design for the resilient PRD are researched in terms of land use,blue-green networks,coastline and community.6.The corresponding principles and strategies of resilient urban flood control and drainage on Hengli Island are proposed.Hengli Island is the most important core area of the Pearl Bay in the PRD.With the continuous urbanization on the island,the coordination between urbanization and water environment is very prominent.According to the theory and method of urban design for resilience,a new approach that can better lead the site to adapt to future climate change condition is proposed by widely applying the spatial characteristics of resilience that can be presented by urban design,such as regionality,connectivity,diversity,multifunctionality,redundancy and modularization.The strategies of resilient urban flood control and drainage on Hengli Island are proposed.The main innovations of this doctoral dissertation are as the followings.1.The Theoretical Features and Spatial Characteristics of Urban Design for Resilience Are Proposed,Namely,"Two Core Capacities,Four Fundemental Thinking Characteristics and Six Spatial Characteristics Presented by Urban Design for Resilience"This doctoral dissertation systematically puts forward that the "robustness and adaptability" are two core capacities pursued by urban design for resilience,the “systematic,collaborative,bottom-line and foresight thinking” are four fundamental thinking characteristics of urban design for resilience,the "regionality,connectivity,diversity,multifunctionality,redundancy and modularization" are six spatial characteristics presented by urban design for resilience.It points out that the approach of urban design for resilience need to pay more attention to profound the understanding of driving forces such as nature,ecology,society and economy,and to emphasize that urban design for resilience must be built on basis that enough land carrying capacity can be provided and harmonious human-nature relationships can be established,based on a comprehensive grasp of the natural base layer and socio-economic development trends.2.The Methods and the Operational Guidelines of Urban Design for Resilience Are ProposedConsidering the characteristics of the delta,this doctoral dissertation proposes the guiding ideology of planning and design for the resilience of the delta.The corresponding principles and technical measures of planning and design for the resilience of the delta for ecological space,agricultural space,urban space and waterfront area are respectively put forward.In addition,this doctoral dissertation proposes the implementation principle,organization work,technical route and the process of urban design for resilience.the key points of phases during the whole process,such as target determination,system interpretation,system projection,key control nodes,scene main line refining,system planning and design,evaluation and feedback,etc,are explained in details.Afterwords,the operational guidelines of“theoretical guidance,overall coordination,adaptation to local conditions and the environment,nature priority,moderate redundancy and gradual evolution" for urban design for resilience are put forward.3.The Strategies of Planning and Deisgn for Resilient PRD Are ProposedBased on the projection of the future scenario under the condition of extreme climate change,the corresponding principles and strategies of planning and design for the resilient PRD are researched in terms of land use,blue-green networks and coastline.From the perspective of land use,this doctoral dissertation proposes that future resilient land-uses distribution need to be based on the results of land-use suitability assessment.The possible new scheme of land use that consists of the spatial characteristics of “three-circle coordinated space,four categories of land use" is put forward.From the perspective of blue-green networks,the possible new scheme is suggested by integrating regional natural environmental resources and creating cross-regional hydrological-ecological corridors,based on the technical assistance of minimum cumulative resistance(MCR)model.From the perspective of the coastline,the possible new scheme of coastline is provided with the contents of arranging the coastline function and creating coastline buffering belt,based on the technical assistance of coastline development suitability assessment.4.The Strategies for the Resilient Urban flood Control and Drainage on Hengli Island Are ProposedBased on the characteristics of Hengli Island in Pearl Bay in the PRD,future development positioning and flood control and drainage problems under climate change,the current conditions of Hengli Island are analysed from the aspects of elevation and land use,hydrology,and current flood control and drainage systems.The capacity of current flood control and drainage system of Hengli Isalnd is projected and the main problems existing in the current flood control and drainage system are analysed.Main points for resilient flood drainage are proposed,such as modularized water collective units,improved water networks,classified inner-river functions,and multifunctional water storage spots.Main points for resilient flood control are proposed,such as appropriatedykes’ height,appropriate distance between dyke and shoreline,and multifunctional shorelines.Finally,multi-layer structure for resilient flood control and drainage are formed,as well as corresponding principles and strategies are proposed with key elements and measurements in each phase.Water level management measurements in different scenarios including regulation,self-drainage and artificial-extraction with the combination of nature-based work and civil engineering are proposed.The new scheme of resilient flood control and drainage can integrate the function of both flood control and drainage and landscape-viewing together.