Bamboo drip irrigation
For more than 200 years tribal farmers of the north-eastern part of India, in the state of Megalaya, have been using an indigenous technique of bamboo drip irrigation to irrigate their plantation crops. These farmers of the Jaintia and Khasi hill areas have developed this system of tapping springs and stream water to grow betal leaves, black pepper and arecanut (3).
Terrain and water availability
The topology of the region is hilly with steep slopes and rock boulders. The soil depth on these hills is low and has poor water retention capacity (1). Though the region gets plenty of rain during the monsoon season, irrigation becomes a necessity during the dry season. The terrain imposes a challenge in bringing the water from distant water sources to the plantations. Diverting water through ground channels is not possible. Faced with this need for water, and the challenges imposed by the terrain, the tribal farmers came up with this unique irrigation system.
Bamboo Irrigation in Meghalaya (Duration 0:25:35)
The bamboo drip irrigation system is based on gravity and the steep slopes facilitate in implementing it (1). Water from an uphill source is tapped and brought to the plantation by a main bamboo channel. Usually these water sources are far off from the plantations and the main bamboo channel runs hundreds of meters — in some cases even few kilometers. The water is then regulated through a complex bamboo network of secondary and tertiary channels to all the parts and corners of a plantation, right up to the bottom of the hill.
Fig. 1: Construction sketch of bamboo drip irrigation system. Image courtesy (1)
These bamboo networks usually have 4-5 diversion stages [Figure 1] before water is delivered at base of the plant (1, 2). 18-20 liters per minute of water from the main channel gets reduced to 10-80 drops per minute at end of the network [Figure 2], (1, 2, 6). After this long journey, the water trickles or drips drop by drop at the base of the plant. Sometimes water is diverted to distant houses for domestic use.
Fig. 2: Principle of water distribution in bamboo drip irrigation system. Image courtesy (2)
Bamboos of varying diameters are used to build the channels, support structures, diversion pipes and strips [Figure 2]. Channels are held above the ground by bamboo or wooden Y shaped sticks. One stretch of channel is lashed to another by thin bamboo strips. Indigenous tools like a dao, a type of local axe, and chisels of various shapes and design are used to build the bamboo network. Two laborers can construct a network covering 1 hectare of land in 15 days [4, 8]. They are built with such skill that water wastage by leakage is minimal. The construction is based on a simple rule of thumb — the ratio of diameter of primary channel to tertiary channel determines the quantity of water which will reach the trees . It is a subtle skill which comes with years of observation and experience.
Cost and maintenance
The cost involved in building the system is minimal. Bamboo is available freely in this region. Usually the farmer himself sets up the system in his plantation with some help from 1 or 2 labourers. The region gets heavy rain, so as a result each installation lasts for about 2-3 years . After the rainy season the undergrowth is cleared and reinforcements are provided. Old bamboo is left to rot, which over time returns to the soil as humus.
Cooperatives are formed and each farmer provides his skill and labour to build and maintain the system. The distribution of water from one plantation to another is done by diverting water at fixed timings. This avoids the occurrence of conflicts between various farmers. By this method the whole community works harmoniously — sharing the limited resources judiciously.
Fig. 3: Cistern and main channel. Image source (9)
Fig. 4: Channels feeding the plants. Image source (9)
In Blake Garden, located in Kensington California, there is another example of this bamboo drip irrigation system . Water is collected from the rooftop and is stored in a 200 gallon cistern [Figure. 3]. Water from the cistern flows through bamboo channels and irrigates the plants in a green house [Figure. 4]. Though the scale and magnitude of implementation is small compared to the one in Megalaya, it is a good example for an urban setup. Watch this beautiful video showing the bamboo aqueduct system in action.
Blake Garden Bamboo Aqueduct (Duration 0:03:25)
The good thing about this system is it doesn’t need any fuel or power. One can consider implementing it in regions where bamboo is available for free or at a low cost. One notable drawback is that bamboo starts to rot in rain, so the whole network needs to be rebuilt after 2-3 years. Overall it looks to be an economical and sustainable irrigation system which can be set up for farm needs or for an urban permaculture garden.
- "Traditional land and water management systems of North-East hill region", R A Singh & R C Gupta, Indian Journal of Traditional Knowledge, Vol.1(1), July 2002, pp. 32-39
- "Indigenous Techniques of Soil and Water Conservationin North Eastern Region of India", P. P. Dabral, 12th ISCO Conference, Beijing 2002
- "Traditional agricultural practices in Meghalaya, North East India", Solomon Retna Dhas Nadar Jeeva, Roytre Christopher Laloo & Bhanu Prakash Mishra, Indian Journal of Traditional Knowledge, Vol. 5(1), January 2006, pp. 7-18