Skip to 0 minutes and 6 secondsWhen we come to change our development, one where there is an impact, it is a trade-off that when we do some development activity we will create some impact and we have to do the trade-off whether we accept the impact compared with what we can achieve. Example of rice intensification, for example. When we do that, one [impact] is that it creates a pollution from using pesticide, using fertiliser and chemicals, and that creates the pollution. Secondly, it changes-- in terms of water-- it changes the water regime, also. For example, when people irrigate more for the three crop during the rice season, there's less water in the river. So it's changing the habitat, it's changing the fauna, and the flora and the situation.
Skip to 1 minute and 14 secondsSo these are the impacts, that is, some impact immediately you can see, but some impact you can only observe because an ecosystem will adapt to the new condition. We cannot create or maintain the same situation like before, because of water regime change. Before, during the flood season, all flooded with water at these months and then drain out at this month. But now because of rice cultivation around, it's changed so it is now different. The other example, like when we do rice intensification, we create the-- we build the dike to protect in the flood season so that people can continue to grow. But when we build a dike, water levels at surrounding areas will increase.
Skip to 2 minutes and 10 secondsSo upstream of the dike, and downstream of the dike, water level is higher. And it's changing the environment-- the water regime and the environment of these areas. Aquaculture also creates similar [impacts], one is the pollution. One example is that in the acid sulphate soils in the Mekong Delta, when people want to raise shrimp because of acidity at the beginning of rainy season. So they apply a lot of lime to neutralise the acidity. So that is changing completely the water environment because before very acid during that month, now no more, so the habitat is changing there. But pollution from this also creates a problem.
Skip to 3 minutes and 4 secondsAnd one problem with pollution in streams is that the disease, the toxins and the disease, when it occurs in one stream the farmer drains it out and it may come and then expand in a larger area. So it requires a new system that can separate the drainage and the irrigation-- the intake water canal. But that will create a completely new system for agriculture, and we are not able to do that yet.
Environmental impacts of rice and aquaculture
As we heard already, agricultural intensification in Southeast Asia is increasing the pressure on natural resources, particularly land and water, and also having significant environmental impacts. In this Video, Dr. Chu Thai Hoanh, an emeritus scientist at the International Water Management Institute (IWMI) and an SEI Associate, explains these environmental impacts in more detail, focusing on rice production and aquaculture.
Dr. Hoanh talks us through the range of environmental impacts of intensification, from worsening air and water quality due to fertilizer use, to changing water regimes caused by the construction of dams and dikes.
Dr Hoanh ends his talk discussing the spread of disease from one aquaculture farm to another, because the water that drains out of one field becomes the irrigation water for the next field. While this is an efficient use of water, it matters very little if the product is ruined. But, he tells us, separating the drainage from the irrigation will require an entirely new agricultural system. It is these types of trade-offs that farmers and policy-makers are facing.
Image Source: “Leaves on riverbed” Copyrighted by May Thazin Aung
© Stockholm Environment Institute