Fases y técnica de los lanzamientos de peso y martillo

The primary limitation comes from the missing sectors and detailed sub-sectorial information. Data limitations for the thermo-electricity sector make it very difficult to associate this sector with the SSP storylines in a consistent way. However, this maybe more important for water quality (i.e. temperature) considerations than for water quantity stress, since most of cooling water intake returns to the river again (Fthenakis and Kim 2010, Inhaber 2004).

Moreover, uncertainty lies in both estimation of manufacturing water use intensity and manufacturing products. Manufacturing water use intensity and economic gains heavily depend on the structural composition of this sector and the corresponding technology it adopts. However, no sub-sector water-use data is available. And it is unlikely that the industrial structure in the upstream basin will remain the same for the coming few decades given its fast industrialization process. Thus, the current projection of manufacturing water use and products may need to be updated when future long term plans become available.

Chapter 5

109 As the two-child policy has recently been issued, it is unclear how much the projected population growth may differ from the real development in the coming few decades. Although, the possible estimated domestic water use may have only limited impact on future water deficit in the PRB, because the total water use is dominated by agricultural and manufacturing uses for the whole PRB.

5.5 Conclusion

In this Chapter, the effect was evaluated of four water allocation strategies on water resources and economic development in the PRB under regional scenarios that are consistent with the global scenarios developed in the context of the fifth IPCC Assessment Report framework.

Results show that future demands for water are much higher than supply. Large scale increases in water demand are mainly from manufacture factor in the upstream Pearl River Basin. Furthermore, differences in water use and shortage are not substantial between the SSPs for the whole basin. Under SSP3, the basin has the highest water shortage. Results also show that almost all the regions in the PRB are likely to face water shortage under the four water allocation strategies due to combined effects of climate change and socio-economic development in the future. The delta region only has sufficient water resources under the delta-prioritized strategy. The economic losses differ greatly under the four strategies. Prioritizing the delta region or manufacturing production would result in lower economic losses than the other two strategies, whereas the economic loss is the highest when water for irrigation has the priority. All four water allocation strategies are insufficient to solve the water scarcity in the PRB. However, all of them are rather extreme strategies. Development of water resources management strategies requires a compromise between different water users. In addition, new technologies and increasing water use efficiency is important to deal with future water shortage in the PRB.

Chapter 6

113

Chapter 6

Synthesis

6.1 Introduction

Water use has rapidly increased over the last decades to meet the growing demand for food and industrial products, resulting from an ever growing world population and increasing living standards. Overuse of surface water has been reported for various regions all over the world, leading to doubts on the long-term sustainability of water supply (Wada et al. 2014). Climate change can exacerbate the situation by altering the natural hydrological cycle (Haddeland et al. 2014, Santos et al. 2014). Water is “second only to energy in serious problems that threaten humanity” in the future (Dong et al. 2013). Water shortage is not only one of the major challenges at present, but will also be more critical in the future in many regions in the world (Biemans et al. 2013, Mancosu et al. 2015, Martin-Carrasco et al. 2013, Milano et al. 2013, Ouda 2014, Shen et al. 2013)

The main theme of my thesis is water shortage under future climate change and socio-economic development, and possible adaptation strategies in a heavily urbanized delta area: the Pearl River Delta (PRD) in China. I focus on water use and its management.

The PRD, located in southeast China, is a water abundant monsoon region, receiving 1700mm average annual precipitation. Nevertheless, cities in the delta area suffer water shortage. Water shortage events are reported more and more frequent over the last decades, especially during the dry season (Chen and Chan 2007, Chen 2006a, Liu et al. 2010, Tu et al. 2012).

My study explored the potential water shortage and possible adaptation strategies by achieving two research objectives:

To quantify future sectorial water use developments and potential water deficits in the PRD

To explorer strategies to reduce and adapt to the projected water deficits.

These research objectives were addressed in line with the framing in Figure 1-3. In the synthesis below, different aspects of modelling and projecting the sectorial

Synthesis

114

water use under climate change and future socio-economic development in a heavily urbanized river basin are discussed, and illustrated by the results from this thesis.

In Chapter 2, I first developed a conceptualization of water use based on equations used in global water resource models. With this conceptual framework, I assessed the driving forces underlying water use changes in the domestic, industrial and agricultural sector for the whole PRD, as well as for each of the nine cities that constitute the PRD separately. This assessment obtained the first comprehensive overview of sectorial water use in relation to its socio-economic drivers in the PRD between 2000 and 2010 (Section 6.2).

The reported water shortage events in the PRD were caused by seasonal salt intrusion. Low discharge (Kong et al. 2011, Zhu et al. 2007) and continuous large scale dredging (Han et al. 2010, Luo et al. 2006) were reported as the main causes of severe salt intrusion. In Chapter 3, I further examined to what extent water use contributes to salt intrusion and freshwater shortages by first quantifying monthly sectorial water use and next comparing its effects on discharge with thresholds from the graded salt intrusion warning system. Additionally, I asked and answered whether management of water use, rather than water supply, can be part of mitigating salt intrusion (Section 6.3).

After obtaining insights on current water use status and its impact on reported water shortage events in the PRD, I started to investigate how much water the PRD will use in the future. In Chapter 4, I generated a set of regional water use projections for the PRD, consistent with the global water-use projections developed in the Water Futures and Solutions initiative (WFaS), which build on the Shared Socioeconomic Pathways (SSPs) of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR5; Section 6.4).

The research presented in this thesis is part of the thematic JSTP13 _{project “Working}

with Water: adaptive land use and water management in the Pearl River Delta under climate change and sea level rise”. Under this umbrella, in Chapter 5 I worked together with YAN Dan, whose research focussed more on hydrology and water availability in the PRB, to assess potential future water shortages and their impacts in the Pearl River Basin. The three water use scenarios I developed for the PRB were then confronted with water availability projections by YAN. Together,

Chapter 6

115 we evaluated four extreme water allocation strategies that prioritized different water users. (Section 6.5)

Finally, strengths and limitations of the used methodology are discussed in Section 6.6, followed by a discussion of possible implications of my research for defining a sustainable development strategy for the Pearl River Delta and the wider Pearl River Basin (Section 6.7). Contributions of this thesis to the science of sustainable water resource management and socio-economic scenario analysis are discussed in Section 6.8. This chapter closes with perspectives on further future research in Section 6.9.