Hong Kong Water Supply – Irrigation Reservoirs
Tymon Mellor: Farming in Hong Kong has always been a challenging vocation; small field sizes, labour intensive, often rugged terrain and unpredictable weather. In good times two crops of rice could be grown a year but with erratic rainfall and the expansion of the reservoir catchwaters system, the agricultural community were under pressure. They wanted infrastructure investment to support farming and mitigation for the loss of water to the new reservoirs. It was time for the Government to build irrigation reservoirs to maintain the peace.
Before the Pacific War about one-tenth of the Colony’s population lived off the land. The farmers of the New Territories were primarily rice producers with other crops being grown as subsidiary produce. The rice from the Sha Tin area was highly desired and was much too valuable for local consumption; in the time of the Manchus it was supplied to the Emperor but in later years it was supplied to overseas markets such as New York. For local consumption, cheaper rice of poorer quality was imported from Vietnam, Burma and Thailand.
Rice planting was undertaken on family run small holdings, with an average size of around 2 acres. There were very few tenant farmers who cultivated land in excess of 3 acres and the few owner operated farms rarely exceeded 5 acres. The great majority of farmers were sub-tenants and in many cases sub-tenancies were held through two or three hands. Land was usually rented for a period of one year and rent was charged at the rate of 40%-60% of the rice yield. An arrangement whereby the tenant and the landlord farmed in partnership was successfully operated for many years in the New Territories.
Farming utilised ploughs, harrows and hand tools locally made and a plentiful supply of human labour for the digging, harrowing, seeding, transplanting, spraying, watering and weeding. During the dry weather, water was lifted by tread wheels and distributed by watering cans from wells or centrally placed concrete storage pits. The latter was also used as receptacles for diluting nightsoil with water before feeding it to the vegetable plots, and these can still be seen in the small holdings of the New Territories.
It was not practical to undertake crop rotation or prolong a long fallow period to maintain the soil fertility. To maintain the soil quality fertilizers were extensively used, but there was limited access to modern chemicals so the farmers relied on traditional fertilizers such as nightsoil, bone meal, ashes, duck feathers, meal cakes and dried pulverized animal manure. The farmers were naturally adept in the cultivation of rice, and they had evolved varieties and farming techniques to conform to the local environment. The cultivation of rice usually took around 100 days from planting to harvest . The total annual yield of rice was around 600kg per acre from two crops on average land and 1,000kg on the best soils.
Where the fields were watered only by rainfall or swamp areas irrigated with brackish water, only one crop of rice could be produced a year. Where irrigation was provided, the fields could yield two crops of rice so doubling the annual production. Typically, around 25,000 tons of rice were produced a year, enough to satisfy the needs of the whole population of Hong Kong for about one month, with imported rice making up the balance.
With the construction of Tai Lam Chung Reservoir and the extension of the catchwater system encroaching into the agricultural water supplies, it became apparent that the Government would need to address the farmers’ needs with the provision of irrigation reservoirs. As noted by the Governor at the opening of Tai Lam Chung Reservoir, “Let me reassure them [the farmers] that the building of the catchwaters will no rob them of the water that they have hitherto enjoyed for their paddyfields”. He also announced the proposal to build irrigation dams to ensure the farmers would have a constant water supply throughout the year, removing the risk of drought. Thus, construction of the irrigation schemes started in earnest in 1957 and continued through to the late 1960s to address the impacts of Plover Cover Reservoir.
In addition to the irrigation reservoir, local dams and concrete channels were constructed along with river protection and improved access roads. By the early 1960s there was an increasing demand for vegetables, fruit, eggs and poultry meat requiring a marked change in farming practices. The move towards market gardening along with pig and poultry production was undertaken at the expense of rice framing. By 1962 more than 35% of the two-crop paddy fields were being used for winter season cash crops of vegetables . However, with new employment opportunities within the growing urban areas, workers left the rural areas and migrated to the towns abandoning the agricultural work and rice production.
Rice production reached its peak in 1959, but by the end of the 1970s it had diminished to almost nothing, along with much of the local farming activity, leaving all the water irrigation infrastructure unused.
Throughout the New Territories, small dams and channel features can be found on all the rivers and streams. These were constructed by authorities, local communities and famers to support their agricultural activities. Most are now abandoned other than where active farming practices persist, such as in Kam Tin and Long Valley. Most of the major irrigation dams have been maintained and now form part of the rural landscape. Below is a brief description of the main reservoirs, structures and their GPS locations.
1954 Shap Long Reservoir (22.2338, 113.9995)
This reservoir is located on the Chai Ma Wan Peninsula on Lantau Island in a northeast facing valley. Construction of the dam commenced in September 1954 to impound 30 million gallons of water for a new fresh water supply to Cheung Chau Island . On the Island, filters, pump house and a service reservoir were constructed. Water was supplied to the island through a 150mm steel submarine pipeline 1.3km long and 3.6km of 150mm cement asbestos pipe.
In 1963 a new 300mm water main was installed , providing water from the new Silver Mine Bay Water Treatment Works, rendering the reservoir obsolete. It was then utilised to supporting local farming and their irrigation needs.
1956 Sha Tong Dam (22.5103, 114.1329)
The Sha Tong dam was constructed on the River Indus and was opened by the Director of Public Works, T L Bowring on the 2 June 1956, replacing an old rubble masonry structure. The dam was 1.8m high and 40m long retaining sufficient water to support 400 acres of fertile rice paddy and improving the lives of 6,000 people. The cost of the works was $55,000. The new concrete dam included a 1.5m deep foundation to avoid the river undermining the structure. The dam was located on the site of an earlier structure that was referenced in the Gazetteer of San On District in 1820 but fell into disrepair due to scour from the river. The dam remained in place until the 1990s when as a result of river training, it was bypassed to improve the water flow and avoid flooding.
1957 Sham Tseng Settlement Basin (22.3711, 114.0532)
The Sham Tseng Settlement Basin was constructed as part of the Tai Lam Chung Reservoir scheme, providing a holding reservoir for water supplied by two catchwaters. The water would then pass through a tunnel to the main reservoir, with a controlled amount being discharged into the stream to support farming activities downstream. Work on the basin commenced in 1956 and was completed in 1957 .
1957 Hung Shui Heung Reservoir (22.4134, 113.9986)
The reservoir is located in a steep valley to the east of the Lam Tei quarry; construction commenced in 1956 and was completed and formally opened on the 28th March 1957. The reservoir addressed water shortages to the farmers of the Ping Shan valley and was commissioned in time for the first rice crop of the season. The dam is 18m high and 77m long impounding 26 million gallons of water .
The dam along with the adjacent Lam Tei structure was commissioned by the Governor, Sir Alexander Grantham, together providing irrigation water for 2,000 acres of arable land increasing the yield from one to two crops a year and bringing into production a further 250 acres that was unproductive. The total cost of the two new reservoirs was $1.3 million and was the largest public works project to assist the agricultural community.
1957 Lam Tei Reservoir (22.4115, 113.9902)
The reservoir is located in a steep sided valley to the west of the Lam Tei quarry, and the dam is 23m high and impounds 24 million gallons of water. The dam was constructed concurrently with the Hong Sui Hang dam in the adjacent valley. Construction started in 1956 and the reservoir was completed in March 1957 ready for planting the first rice crop . This reservoir is also referred to as Lo Fu Hang in some Government documents.
At the opening ceremony on the 28th March 1957 the Governor unveiled a plaque commemorating the occasion. He also noted, “In many Chinese slang expressions ‘water’ mean money. I hope that these two irrigation reservoirs, the biggest public works so far done in this Colony for agriculture, will bring wealth and contentment to the farmers of Tuen Mun, Ping Shan and Ha Tsuen” .
1961 Wong Nai Tun Reservoir (22.4010, 114.0172)
The dam was first mentioned in the Governor’s opening speech of the Tai Lam Chung Reservoir in December 1957. The Governor announced the construction of two new reservoirs, Tsing Tam and Wong Nai Tun , which would ensure that farmers had water throughout the year. Construction work on the Wong Nai Tun Reservoir commenced in 1959, with the construction of a 23m high and 73m long granite faced concrete dam. A 3.6m wide road was constructed along the top of the dam, providing vehicular access to the associated Tai Lam Chung catchwaters and tunnels. Construction was forecast to take 18 months.
1961 Kwu Tung Reservoir (22.4977, 114.0968)
Construction of the reservoir was first announced in September 1960 with the construction of a new access road, and works on the dam commenced shortly after. The structure impounds 14 million gallons of water to support the local farming community.
1962 Ho Pui Reservoir (22.4072, 114.0745)
Site investigation for the Ho Pui Reservoir started in 1959 with the aim of establishing a 120 million gallon irrigation reservoir. Work commenced in 1961 on the 15m high and 152m long dam and was completed in late 1961. A joint opening ceremony with the Tsing Tam dams was performed by the Director of Public Works, Mr A Inglis on the 29th January 1962, where he unveiled a plaque to the new reservoirs. The combined cost of the three dams was $6 million with a total storage capacity of 145 million gallons.
The dam was provided to secure the water supply for the Pat Heung farmers and to contribute to the new Tai Lam Chung Reservoir. The Ho Pui Reservoir had a catchment of 580 acres and all the over flow water from the reservoir was diverted into the new Tai Lam Chung catchwater that contoured the hillside.
1962 Tsing Tam Upper and Lower Reservoir (22.4162, 114.0867)
The provision of the dams was first mentioned in the Governor’s opening speech of the Tai Lam Chung Reservoir as a way to ensure a secure water supply to the famers in the event of late summer rain and impacts from the Tai Lam Chung Reservoir catchwaters.
Work on the two dams commenced in 1959 to store 30 million gallons . Initial progress was slow due to difficult foundation conditions at the upper dam site but the dams were formally opened by the Director of Public Works on the 29th January 1962 and a plaque was erected on the site.
The two dams were constructed across the same valley with a catchment area of 392 acres. The dams were designed to impound water from the valley and from the Shek Kong catchwater through a tunnel driven through the hillside. Any excess water was then transferred to another tunnel through the hillside and connecting to the Tai Lam Chung catchwater.
1966 Hok Tau Reservoir (22.4923, 114.1811)
Construction work on the Hok Tau Reservoir started in 1966 providing a 14m high concrete dam across the Hok Tau gorge. The dam formed part of the Plover Cove project, impounding water for the local farmers while excess was transferred to the new Plover Cove Reservoir.
A tunnel connects to the adjacent Lau Shui Heung Reservoir providing a combined storage capacity of 50m gallons .
1966 Lau Shui Heung Reservoir (22.4972, 114.1671)
The reservoir was formed at the head of a valley with the construction of a 12m concrete gravity dam and a 10m earth filled dam. The dam is connected to the Hok Tau Reservoir with a tunnel to provide water transfer. Construction started in 1966.
By 1961, the Public Works Department had constructed 14 dams in the New Territories for the supply of water, and more were to follow. Not all of these were for irrigation, as some were for water supply to remote communities or to supply flushing water such as those at Jordan Valley and Ma Lau Tong. These will be covered in a separate article along with private supplies.
Between 1954 and 1960, the land under rice cultivation reduced from 20,191 acres to 16,796 acres, a reduction of 17%, but the harvest increased by 19%. Part of this was a result of improved farming practices but much is probably due to the provision of a continuous irrigation water supply. The provision of the irrigation reservoirs not only boosted agricultural production but supported the local community and also ensures that Hong Kong still has farming activities to this day.
- Hong Kong Annual Reports
- Hong Kong In Its Geographical Setting, Dr S G Davis, 1949
- Director of Public Works, Annual Departmental Reports
- An Investigation into Improving the Fresh Water Supply to Cheung Chau
- South China Morning Post
- Public Records Office 156-1-3375
- Hong Kong Public Libraries
- HKU Image Database
- Hong Kong Annual Digest of Statistics, Census and Statistics Department
This article was first posted on 2nd August 2020.
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