Hot, Thirsty, Sweaty & Wet: HK’s Future Down The Drain?

By Woody Chan, Debra Tan 19 August, 2019

CWR's Chan & Tan look beyond current tensions & see very real threats to HK's future from climate change

Hong Kong is certainly in the hot seat these days, but we want to talk about a different type of heat – temperature. It has been baking like an oven this summer:

• June: 5 “Very Hot Days” (daily max temperature >33°C as defined by the HK Observatory), way above the historical normal of 1.11 “Very Hot Days”
• July: “much hotter than usual” as per the HKO with the highest recorded monthly mean minimum temperature ever (27.7°C) plus 8 “Very Hot Days”
• August: so far we have already had 9 “Very Hot Days” and it reached a sweltering 37.1°C in Kowloon City.

Even at +2°C, impacts to our water resources are already baked in…

 

… it’s how we adapt to these impacts that matters

Climate change does not just bring more heat but also affects water availability and brings extreme rains… in short, it make us hotter, thirstier, sweatier and wetter. As can be seen from “8 Water Risks Here Today, Here To Stay In Asia”, climate and water risks are here to stay and even at the targeted +2°C (which we are not reaching, since we are heading to +3°C or more), impacts to our water resources are already baked in. It is how we adapt to these impacts that matters.

It’s not just water we need to focus on. Climate change is increasing the frequency and intensity of typhoons and storm surges; already this year we have had our first T8 typhoon. We faced Typhoons Hato and Mangkhut in the past two years, which brought disruptions to transport and logistics. Due to Hong Kong’s proximity to Guangdong and the fact that Guangdong accounts for a significant amount of trade between Hong Kong and China, resilience in the Greater Bay Area (GBA) also matters. Therefore, any disruption in the other GBA cities will affect Hong Kong’s logistics and trade sector.

HK’s food supply will be severely disrupted if key roads, airports & ports are impacted

Food will also be affected – 90% of the total food supply in Hong Kong is imported. Mainland China is Hong Kong’s most important food source, especially for fresh food. Back in 2011, 94% of fresh pork, 100% of fresh beef, 100% of live chicken, 97% of live freshwater fish, 92% of vegetables and 66% of eggs in Hong Kong come from Mainland China. Although these numbers have likely fallen since, Hong Kong’s food supply will still be severely disrupted if key roads, airports and ports are impacted.

According to experts, Hong Kong’s food storage only allows 3 days of resilience if logistics systems go down. Note that even if Greater Bay Area ports and airports are all safe, if ports where goods originate from are not safe, then neither is Hong Kong. Therefore the more roads to the Mainland the better? Just how resilient are the GBA’s airports and ports? What’s Hong Kong doing to ensure food and water security in a changing climate?

Don’t forget to submit your views on HK’s Decarbonisation Strategy by 20 Sept!

At the moment, climate change is clearly the last thing on anybody’s mind in Hong Kong and the public engagement for Hong Kong’s Long-term Decarbonisation Strategy has fallen by the wayside (don’t forget to submit your views by 20 September). However it is not going away and we have to start thinking about how to address these risks now. As such, we set out below five pressing challenges we worry about the most and which we have to start thinking about today:

1.  There are hotter and more humid days ahead!

According to the HKO, both “Very Hot Days” and “Extremely Warm & Humid Days” (maximum wet bulb temperature is at 28.2°C or above) are on the rise.

By 2030, under the IPCC’s RCP8.5 climate scenario (which we are heading towards given current inaction), the number of “Very Hot Days” will increase to 17-40 days whereas “Extremely Warm & Humid Days” will increase to 9-24 days. By 2050, these increase to 23-58 days and 19-59 days respectively. By 2100, on average, around 3 months of the year will be either “Very Hot” and/or “Extremely Warm & Humid”.

Unfortunately, the 2030 projections are already happening now – Hong Kong had 33 “Very Hot Days” in 2014, 38 in 2016 (highest on record) and 36 in 2018. Compare this with an annual mean of just 8.6 Very Hot Days from 1884-2014. Are we still underestimating just how hot it can get?

2.  There’ll be more rain, but more rain doesn’t mean more water + could lead to slope failures

We are not just getting hotter, we are also getting wetter. Although the average projected annual rainfall anomaly falls between 2010-2030 under RCP8.5, the projected likely range is shifting upwards as shown in the chart below.

It is important to note that water needs to be managed at the extremes and not at the averages. Hong Kong will have to deal with 317mm more rain by 2030 or 806mm more rain by 2100. According to the HKO, Hong Kong’s current annual rainfall ranges from 1,400mm to 3,000mm depending on location, with a mean rainfall of 2,241mm. However, the highest recorded rainfall was 3,343mm in 1997, +343mm above the max range; while the lowest recorded rainfall was 901mm in 1963, -499 below the min range. It is at these extreme levels that we need to be prepared for, especially given that between 2021 and 2030 we could be seeing rainfall anomalies of +317mm under RCP8.5. By 2061 we could even be facing +607mm of rain annually.

Is the government prepared if the frequency of extreme rainfall keeps rising?

What’s more, the HKO has warned that the frequency of an extreme 3-hour rainfall event of >200mm used to be once in 41 years back in 1900; but has now increased to once in 21 years in 2000. Is the government prepared if this frequency keeps rising? It remains to be seen which scenario the government is planning for and if it is using old projections to expand drainage systems and for overall adaptation plans for floods. Can Hong Kong’s drainage systems handle revised estimates?

Higher temperatures will likely accelerate evaporation and while more rain could provide more water for use, Hong Kong may have limited space for water storage. Clearly drainage systems will have to be expanded to ensure resilience going forward. Cascading risks like landslides should also be considered.

“Extreme weather affects everyone. Bad weather affects tourism for one.”

Former Secretary for Commerce & Economic Development for Hong Kong

Impacts and resilience go beyond infrastructure; hot, sweaty and wet days ahead could have social and cultural implications and could even deter tourists from coming to Hong Kong. Elsewhere, the 2018 heat wave in Europe led to 1.2 million fewer tourists in the Canary Islands. The former Secretary for Commerce and Economic Development for Hong Kong has warned that “Extreme weather affects everyone. Bad weather affects tourism for one.”

3.  Dependent on water from the Dongjiang River, which is “very close to exploitation limit”

Hong Kong’s local water supply is inadequate for its needs. Local rainwater only provides 20-30% of Hong Kong’s water plus it fluctuates significantly and is unreliable. Seawater is provided for flushing purposes but this does not fulfill Hong Kong’s freshwater needs. Therefore, Hong Kong has been relying on imported water from the Dongjiang river from Guangdong since 1965. Currently, 70-80% of Hong Kong’s water is from the Dongjiang river basin, which is water scarce but supplies freshwater to more than 40 million people including Guangzhou and Shenzhen. Water from the Mainland brings the water use-to-availability (WTA) ratio for Hong Kong down from 333% to 102%.

Hong Kong’s Water Supplies Department itself states, “the water resource utilisation rate of the DJ has already reached a level very close to its exploitation limit, indicating a fairly tight supply of water resources”. Given its high reliance on Dongjiang water and the tightness of this supply, Hong Kong’s wastefulness is shocking.

4.  Very wasteful (up to 25% of water wasted) + using more and more water

According to a 2019 report “Modernising Hong Kong’s Water Management Policy Part I: Conservation and Consumption: Towards a Water-Smart Hong Kong” by Hong Kong-based think tank Civic Exchange, 25% of Hong Kong’s total water supply is lost due to leakage and unauthorised consumption. Granted, Hong Kong has reduced its government water mains leakage rate as shown in the Hong Kong Climate Action Plan 2030+ but private mains leakages are still difficult to access and rectify. Moreover, water tariffs remain low and heavily subsidized, giving no incentive to reduce water use. All this points to Hong Kong being very wasteful with its water.

25% of HK’s total water supply is lost due to leakage & unauthorised consumption

For the time being, Hong Kong’s water supply is currently guaranteed as it signs a 3 year contract on a rolling basis with the Guangdong Provincial Government that ensures round-the-clock water supply even under extreme drought conditions. The latest agreement is in place until the end of 2020 on an agreed price totalling HK$4.8bn per year.

In 2011-2018, HK’s freshwater use rose ~10% yet Guangdong lowered its water use despite growth

Since Hong Kong is downstream of rapidly growing cities in the Pearl River Delta which are also just as dry as Hong Kong, surely we should be stepping up our water savings? But we are not – Hong Kong’s freshwater use has risen by almost 10% between 2011 and 2018. Yet in same period Guangdong has managed to lower its water use despite unprecedented growth. Can we continue to be so laissez-faire with the planet’s most vulnerable resource to climate change?

5.  HK builds desal plant while Guangdong diverts water from the Xijiang River

With unpredictable rain and increasing scarcity exacerbated by climate change, surely we should also look to diversify the risk by seeking more water sources?

Hong Kong has plans to “add an additional tap” by building a desalination plant. However, this will only provide 5% of Hong Kong’s freshwater supply. Meanwhile, the Guangdong government is taking action through large-scale water diversion projects.

Water diversion projects in Guangdong province are not new. Water has been diverted from Foshan to Guangzhou, with a daily water extraction capacity of 3.5 million m³. Water from Xijiang River is transferred to Guangzhou in a fully enclosed pipeline with the guaranteed water quality. The total budget for the project completed in 2010 was close to RMB9bn (USD1.2bn).

In May 2019, the largest water conservancy project in Guangdong province was launched. Water from the Xijiang river will be diverted from Foshan to Guangzhou, Dongguan and Shenzhen. Hong Kong will also benefit from the project since it will provide an emergency backup water source for Hong Kong. According to the Ministry of Water Resources (MWR), the project is expected to cost around RMB35.4bn (USD5.14bn) and take 60 months to complete. It is designed to supply an average of 1.71bn m³ annually.

Further Reading

• 8 Asia Water Risks: Here Today & Here To Stay In Asia – Damaging typhoons, life & business disrupting water outages and threatening sea level rise… China Water Risk review’s 8 water threats too great to miss in Asia from just the past 3 years
• Climate Change, Groundwater & Agriculture In India – The hidden risks of groundwater are clear in India as it is key for the country’s food security and already is largely over extracted. What can India do? Dr Aditi Mukherji from the ICIMOD, shares ways forward
• 3 Takeaways From CEWP’s 2019 Groundwater Policy Dialogue – With China and Europe joining forces to tackle groundwater over-exploitation, China Water Risk’s Yuanchao Xu was on hand to bring us the latest policy and tech ideas from the Jinan forum
• Going Dutch! Smart Drinking Water Networks – Gondwana, an optimisation tool equipped with evolutionary algorithms, adds a nervous system to make drinking water networks ‘smart’. See how from Ina Vertommen, Dr Karen van Laarhoven, Dr Mirjam Blokker & Dr Peter van Thienen from KWR
• Environmental Watering In The Murray-Darling Basin – Megan McLeod from the Alliance for Water Stewardship explores how the Renmark Irrigation Trust benefits the Murray-Darling Basin by providing environmental watering, enhancing biodiversity and promoting tourism
• Hong Kong’s Pricey Water Deal With China – Much is made of the DongShen Agreement’s price tag but discussions need to move onto more complex issues such as the city’s rampant overuse & leakage. Hear from Civic Exchange on HK’s ‘illusion of plenty’
• Securing Water For Hong Kong’s Future – The Jockey Club Water Initiative on Sustainability & Engagement (JC-WISE) aims to secure long-term water sustainability for Hong Kong. CWR sat down with Dr Frederick Lee of the University of Hong Kong
• Inside The World’s First Museum Of Climate Change In HK – It is the world’s first museum of climate change but what does it really do? Take a brief tour with its director Cecilia Lam and explore its four key initiatives from education activities to an action monitor
• Confronting Storms & Climate Risk In HK – Typhoons Hato and Mangkhut have wreaked havoc in the Greater Bay Area but Dr. Faith Chan from the University of Nottingham Ningbo believes these climate risks can be confronted, with Hong Kong leading the way
• Hong Kong: A Climate Resilient Sponge City – Hong Kong is prone to tropical cyclones, which will be exacerbated by climate change. Can the city become climate & flood resilient? Hear from Richard Leung from the Drainage Services Department on actions taken so far