Archive for the ‘Technology’ Category

Village tank project provides lessons for restoration

February 26, 2017

Sri Lanka is famous for its irrigation heritage, but only the marvels of large tanks built for irrigation draw attention, while small village tanks are ignored. In many cases village tanks function as a ‘cascade system’ – so using wrong methods to restore them ignoring specific functions of associated components can do more harm, according to experts who discussed the issue recently in Colombo.

People engaged in building an irrigation canal. Pic by Kumudu Herath@IUCN

The International Union of Conservation of Nature and Department of Agrarian Development together with Bandaranaike Centre for International Studies, shared their experiences under the theme “ecological restoration and sustainable management of small tank cascade systems,” on February 14.

The experts say that in Sri Lanka’s dry zone there are 14,000 small ancient village tanks and many are in good shape, supporting 246,000 hectares, about 39 percent of the total irrigable area. In most cases these tanks are designed to function as interconnected clusters often referred to as ‘cascade systems’ called as ‘ellangawa’ in Sinhala.

These tank cascade systems are identified as very efficient water management systems in the world with water being recycled in each tank without letting it go to waste. The entire tank system functions as a single unit, so restoring only a single tank is not useful, said IUCN’s Program Coordinator Shamen Vidanage.

Each tank in a given cascade system adopts geographical and functional features to harmonise with nature. The functional components of a tank perform specific purpose and roles of these components can even be explained in modern science although they were designed centuries ago, he added.

The first set of components of the cascade system is designed to improve the quality of water entering the tank from the catchment.
‘Kulu wewa’ also known as the ‘Forest Tank’ and water holes known as ‘harak wala’ and ‘goda wala’ are all located in the catchment of the tank, retaining dead leaves, mud and other debris, or sediment, experts explain. Next, before the tank is grass cover known as ‘perahana’ located between catchment and high flood levels for purifying the water by holding granules of earth, and sediment functioning similar to a preliminary treatment step of a modern waste water treatment system, the experts explain.

The water stored in the tank is protected from evaporation by tree belt naturally growing on either side of the uppermost areas of each tank. These are called ‘gasgommana’ acting as windshields minimising dry wind contacting the water surface minimizing evaporation, the experts note. “Kattakaduwa’ or interceptor, is a thick strip of vegetation located between tank bund and paddy fields. It also has a water hole called ‘yathuru wala’ to retain saline water seeping from the tank. Various plants of salt absorbing features are found on ‘kattakaduwawa’ which reduce the salinity of the water seeping through the bund before it reaches the paddy fields, the experts say.

“Sadly the cascade systems are poorly understood. For example, there are instances that forest tanks have been used for irrigation,” Vidanage points out.

“Every village had a patch of forests called as ‘gam kele’ and that has disappeared as they are being encroached for agriculture. As a result of these wrong land use patterns, these small tanks now get more sedimentation, increasing tank siltation,” says Professor C M Madduma Bandara of the University of Peradeniya.

Tank sedimentation due to soil erosion is the main factor in the deterioration of the cascade system. Silted tanks retain less water and over the years, these tanks dry out and paddy fields are lost experts say. In addition, pesticides and fertilizers applied in upper areas pollutes the tank water without getting proper natural filtering mechanisms. So experts fear that in future, many of these tank cascade systems will deteriorate and will be abandoned owing to mismanagement.

Meanwhile, as a pilot project, IUCN partnered with Department of Agrarian Development to ecologically restore the Kapiriggama small tank cascade system in the Anuradhapura District. This three-year project was initiated in 2013 with financial assistance from the HSBC Water Programme.

Kapiriggama cascade is in the basin of Malwathuoya and consist of 21 tanks. During the project over 38,000 of cubic metres of silt was removed from five tanks in the Kapiriggama and the removed silt was deposited upstream IUCN says. The project also setup soil conservation mechanisms building soil conservation bunds. Over 7,500 plants on kattakaduwa on 13 tanks were also planted according to IUCN.
“We have also got community participation for all these tasks, so even when the project finishes the villagers who will benefit will be engaged making sure of the sustainability of the Kappirigama tank cascade system,” Dr Ananda Mallawatantri the Country Representative of IUCN said. The north central canal project can also use cascade systems in its design taking additional water into cascades before providing to paddy fields, Dr Mallawatantri said.

Published on SundayTimes on 26.02.2017 http://www.sundaytimes.lk/170226/news/village-tank-project-provides-lessons-for-restoration-230491.html

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Tank cascade system in Kappirigama – photo courtesy IUCN Sri Lanka 

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‘Kattakaduwa’ or Tree Belt between the tank and paddy fields

Drones – a handy tool in trained, trusted hands

January 29, 2017

A drone being prepared for a habitat mapping operation.

When police seized a drone that recorded the Hambantota port protests last week, it renewed the debate on whether to welcome this ‘new kid on the block’ or to ‘rope him tightly’.

While few view drones as a menace, their applications in different fields can open up new opportunities that had not been previously thought of. Professionals in different fields welcome this new kid on the block while recognizing the need to ‘discipline’ it.

Dr Eric Wickremanayake, a conservation scientist of the World Wildlife Fund, points out that drones can be used in protected areas to map habitat, monitor traffic, and track illegal activities.

A drone is an unmanned aerial vehicle (UAV) that can be remotely operated and transmits video and images. Infrared sensors can be used for different applications.Drones have been used over decades specially for military applications, but now they are used for commercial, scientific, recreational, agricultural, and other purposes.

Dr Wickremanayake said mapping habitat is essential for wildlife park management and previously it was done using satellite imagery. But satellite imagery is expensive, difficult to process and can’t be obtained immediately. “But now we can send a drone on a pre-programmed grid, photograph the terrain and using specific software, prepare the map.”

Dr Wickremanayake is the chairperson of Environmental Foundation Limited and also conservation scientist of WWF. He is assisting conservation work in Nepal.

“We got down drones also with the aim of tracking poachers, but found that habitat mapping is a better application,” he said.

Drones can be used to track Sri Lanka’s illegal cultivations of ganja for example.

In Africa, drones have been used in anti-poaching operations, but this is a difficult proposition in Sri Lanka, he said, especially because of closed canopy forests.

“However, opportunities to use drones in conservation are enormous. For example, we may use drones to control traffic in parks. Take Yala, for example, where adrone can easily detect areas that has problematic congestion and take action,” Dr Wickremanayake suggests.

Drones can be used to address the conflict between humans and elephants.

The Sri Lanka Wildlife Conservation Society under guidance of Ravi Corea in Wasgamuwa has begun research on how drones can be used in the conflict. WCSG research scientist Chandima Fernando said he noted elephants can be deterred by drones, but that the drawback is elephants raid farms at night, when operating a drone is a challenge.

Dr Wickremanayake suggests that a network of pre-programmed drones be set up on the perimeter of villages. These can then be automatically activated in response to infra-sounds made by elephants. The drones can then help scare the elephants. “It is, of course, a futuristic project, but technology is available and it is a matter for an engineer to piece them together to present a practical solution” Dr Wickremanayake said.

Fernando also worked closely with a research team in New Zealand’s Auckland University using drones for conservation and even locate injured elephants.

In 2014, there was an attempt to introduce drones to wildlife applications. This was done by Tropical Ecosystem Research Network together with the University of Singapore. They mapped sections of protected areas such as the Horton Plains, Udawalawe, and Lunugamwehera.

These experts say the Wildlife Department should explore the use of drones in their work. They also accept drones need to be operated based on rules and regulations. Fernando said that in New Zealand, permission is needed to operate drones.

Drone- ' new kid on block' - can also be used for conservation and many other applications

Drone- ‘ new kid on block’ that can be used for many different applications

Drone can be used effectively in responding to natural disasters, as well. “During the floods, we used drones to find out paths of the floodwater. Dronescould be used in rescue missions. They can be particularly used for precision agriculture, or what is called smart farming,” points out Manju Gunawardana, a research scientist who studies use of drones in agriculture.

Gunawardana and the team last year introduced a way to spray weedkillers in farmlands by first identifying where it is needed.

“What is happening now is spraying agrochemicals evenly across a field irrespective of need. The use of drones can cut down agrochemical use,” Gunawardana said.

The International Water Management Institute, too, has been experimenting with drones for a number of applications in Sri Lanka. The data management unit’s Salman Siddiqui told the Sunday Times that the institute studied how drones can be used to give farmers early warning of problems. “Using infrared sensors we can identify stress in a plant 10 days before the effects are visible to the eye. It could be water shortage, lack of fertilizer, or due to a pest attack,” he said.

The institute also assisted the survey department to map Badulla town, which is prone to landslides. Drones have been used to map location of wells suspected to be linked to chronic kidney disease.

Sri Lanka should be ready to use drones for various purposes with proper regulation, experts agree.

Published on SundayTimes on 22.01.2017 http://www.sundaytimes.lk/170122/news/drones-a-handy-tool-in-trained-trusted-hands-225710.html