Ruining the view
- A weed harvester can solve the problem of water hyacinth invasion in Fewa Lake
Sep 17, 2014-
In the last decade, Jalakumbhi (water hyacinth) invasion has become a chronic problem in Fewa Lake. Jalakumbhi is a fast growing aquatic plant that has earned the notoriety of being an invasive species. Under optimal conditions—which include relatively high nitrogen and phosphorous levels and temperatures in the range of 28-30 degrees Celsius—its mass doubles in as few as 12 days. If uncontrolled, it eventually blankets the water surface killing and displacing other aquatic plants and animals and creating a visually unappealing landscape.
It is not clear how and why water hyacinth was introduced into Fewa Lake. It was first noticed in the early 1990s. Evidently, its presence now threatens the very existence of Fewa Lake as well as the tourism industry in Pokhara.
In 2013 alone, about 798,000 tourists visited Pokhara. Fewa Lake serves as one of the main attractions for tourists for its beauty and enthralling reflections of snow-clad mountains on its water. The health of Fewa Lake is, therefore, directly linked to the earning potential of the tourism industry in Pokhara.
Each year there is a rapid expansion of Jalakumbhi mostly in the western part of the lake where the Harpan river flows in. The plant reproduces both through seeds and via vegetative propagation of roots. The seeds can survive for a long period of time; hence once a lake is infested with Jalakumbhi, it is very difficult to remove it completely.
So far, the response to Jalakumbhi invasion has been to manually remove the plants when they start to expand. This may be a good start. However manual removal is labour intensive, inefficient and unreliable.
There is no single solution for an effective removal of Jalakumbhi once and for all, but what we can do is to control its growth so that it does not get out of hand. There are two approaches to do so. The first is to reduce water pollution by curtailing the illegal dumping of sewage and promoting organic farming in the Fewa watershed. The second is to remove Jalakumbhi through biological or chemical control and mechanical harvesting.
Biological control has not proven effective whereas chemical control might pose a risk of water contamination and could have unintended impacts on fish and other aquatic species. Hence these two options are not popular.
An efficient means
The most commonly employed method is mechanical harvesting of Jalakumbhi by using a weed harvester. Through this, a large swath of Jalakumbhi can be
removed in no time and the process is less labour intensive than manual removal. It is efficient and highly reliable. With a weed harvester, almost all of Jalakumbhi from the banks, the water passage leading to the lake and the main body of the lake can be removed. In the long term, all we have to do is to deploy it from time to time in places where Jalakumbhi makes a comeback.
The cost of a weed harvester varies by its size and function. A medium size, which is appropriate for Fewa Lake, will cost about Rs 10 million, not including import duty, if it is purchased from India. Import duty can be waived by requesting the Nepali government as the weed harvester is going to be used for the restoration of Fewa Lake, a task of public utility.
Once the initial investment is made, the subsequent operation and maintenance costs are not that high.
Moreover, Jalakumbhi can be utilised for various economically beneficial purposes. It can be fed to ducks, goats and pigs. It can be mixed with dung and converted into compost that can be used for organic farming—a rapidly growing and popular agricultural enterprise in Nepal these days. In countries like Bangladesh and the Philippines, dried water hyacinth has already been used to produce beautiful and artistic handicrafts such as bags, mats, baskets, brooms and decorative pieces—we could do the same in Pokhara. This would even give a slight boost to the local economy by employing people in the handicraft sector.
A sure winner
Considering the dual benefits of a weed harvester—controlling Jalakumbhi to revitalise Fewa Lake and generating incomes from the plant’s various uses—the deployment of a mechanical harvester is a sure winner.
Raising the necessary money to purchase a weed harvester and covering its subsequent operation and maintenance costs is not a difficult undertaking. All we need is an initial fund of about Rs 20 million. Already several million rupees have been raised and spent by several NGOs in an effort to raise awareness and solve the environmental problems of Fewa Lake, but the problems persist. Considering the huge economic stake linked to the preservation of Fewa Lake and its beauty, we should easily be able to raise Rs 20-30 million from hoteliers and concerned residents, especially in the Lakeside area.
Let’s not waste time and join this noble endeavour. To do so, first a Fewa Lake Preservation Committee with responsibilities of raising funds and overseeing the operation and maintenance of a mechanical weed harvester has to be formed. Secondly, Rs 20-30 million must be raised quickly in order to purchase the harvester and the government should be requested to waive the import duty.
Baral is an environmental scientist with expertise on climate change mitigation, alternative fuels, life cycle analysis, environmental management and policy
Published: 18-09-2014 09:26