By Sarojini Devi Boominathan
Since 1997, World Wetlands Day has been celebrated every year on February 2 to raise awareness about the importance of wetlands for the planet. It is significant that over 1 billion people globally depend on wetlands for their livelihoods. Wetlands have crucial linkages in watershed management as they play a role in protecting water quality and moderating water quantity. In this blog, we are going to take a detailed look at the importance of wetlands in general and the current situation of wetlands in the Purna river basin, Maharashtra.
The importance of wetlands
Wetlands are one of the most important gifts of nature. They are defined as an area of land that is saturated with water either permanently or seasonally. Wetlands can be freshwater, brackish, or saline. The major functions of wetlands include the storage of water, transformation of nutrients, growth of living matter, and diversity of plants species and they have value for surrounding ecosystems and for humans. The wetlands are credited with several benefits to the local environment such as influencing the local hydrological cycle, climatic regime, water purification, flood control, and giving stability to the shoreline. Besides this, they support rich and diverse food chains for hundreds of species of animals including birds, both local and migratory, from within and outside India.
A photo of a wetland in Sewri, Mumbai. Photo: IWP Flickr
Wetlands also play a major role in adapting and mitigating the impact of climate change. It is therefore appropriate in these times of rapid climate change that the theme for World Wetlands Day 2019 is “Wetlands and climate change”. Wetlands act as sinks for carbon and respond to rising atmospheric carbon-dioxide (CO2) and climate change in various ways. Wetlands have high amounts of carbon sequestration as wetland plants like mangrove forests, sea grass and salt marshes are highly productive ecosystems which store large amount of carbon.
For example, coastal marshes and mangroves capture an average of six to eight tons of carbon equivalent per hectare per year which is about two to four times greater than global rates observed in mature tropical forests. According to the 2011 National Wetland Atlas, Maharashtra alone has 23,046 wetlands that covers a geographical area of 10,14,522 hectares, which is around 3.3% of the total geographic area of Maharashtra (NWIA Maharashtra 2011). 
However, in the recent times, wetlands have come under stress due to rapid population growth, urbanization, technological and economic development. Additional pressures on wetlands from natural causes like land subsidence, drought, hurricanes, erosion etc, and increasing extreme events that have led to shallow wetlands being flooded and which affects the wetland ecosystem.
The human threats coming from over exploitation, encroachment, reclamation of vast wetland areas for agriculture, commercial and residential development, and silviculture have altered the rate and nature of wetland functions particularly in the last few decades. Moreover dam constructions are important threats to wetlands. Dams alter the natural flow of water and impact on existing ecosystems. Although there is much debate about the need for dams to be built, World Wide Fund for Nature argues that development should be as sustainable as possible to minimise negative impact on biodiversity. While we are celebrating World Wetland Day, it is also sobering to realize that between 2012 and 2017, 523 wetlands were destroyed in Maharashtra alone. 
In this overall context, it is instructive to examine the loss of wetlands in the Purna river basin in Maharashtra, between 1991 and 2015. The Purna river basin covers parts of six districts in Maharashtra, which include Aurangabad, Jalna, Buldhana, Hingoli, Washim and Parbhani, and has a large catchment area measuring approximately 8,197 km.
In 2008, the Khadakpurna Dam was constructed in in the path of the Purna river. It is located in Buldhana district. Due to the dam construction, the wetland area in the basin downstream has been reduced. The river flow modifications, lessening of flood magnitude, and encroachment of agricultural land are the leading factors for reduction in wetlands area in this area.
The satellite imagery of the Land Use/ Land Cover (LULC) changes in the past 25 years in the Purna river basin help us to understand wetland transformation. According to the LULC results the major area under wetlands have reduced and been converted into agricultural land. The satellite imagery between 1991 and 2015 show the reduction of wetlands in Purna river basin (Figure 1). The red color in the imagery indicates the agriculture land and water bodies are in black color. The larger portion of water spread area has been occupied by agricultural development in last 25 years. The following image brings this out clearly.
Figure 1-Wetland losses in Purna river basin between 1991 and 2015. Source: Sarojini Devi Boominathan
In India, at a national level, 24% of wetland area have been lost due to reclamation through agriculture (Vass, 2006).  Saha and Pal have documented that over 70% wetlands in the Barind tract of Bengal basin has been converted to agriculture land . However, it is important to note that wetlands have much greater economic turnover than agriculture land, according to the Millennium Ecosystem Assessment 2005 conducted by the World Resources Institute, Washington D.C. .
The international convention on wetlands, called the Ramsar Convention, is an intergovernmental treaty that provides the framework for the conservation and wise use of wetlands and their resources.The Convention was developed as a means to call international attention to the rate at which wetland habitats were disappearing, in part due to a lack of understanding of their important functions, values, goods and services. Governments that join the Convention are expressing their willingness to make a commitment to helping to reverse the history of wetland loss and degradation.
Within the Indian context, the M. S. Swaminathan Research Foundation has done research on the different types of the wetlands and emphasized the need to conserve them. the Ministry of Environment, Forest and Climate Change (MoEFCC) sponsors multidisciplinary research projects by different institutions on various aspects of wetland conservation to better implement the Convention.
Recognising that the health of wetlands influences human life directly and indirectly, it is important that governments and non-governmental organizations work for wetland conservation. So on the occasion of World Wetlands Day, we must all strive to do what we can to preserve wetlands for the future generations. After all, it is only through individual actions that we can have change at the level of a society.
References and further reading
- Vass, K. K. (2006). Sustainable fisheries and environmental concerns of floodplain wetlands in India. International Journal of Ecology and Environmental Sciences, 32(1), 49-62.
- Emerging conflict between agriculture extension and physical existence of wetland in post-dam period in Atreyee River basin of Indo-Bangladesh. Environment, Development and Sustainability, 1-21.
- Assessment, M. E. (2005). Millennium ecosystem assessment. Ecosystems and Human Well-Being: Biodiversity Synthesis, Published by World Resources Institute, Washington, DC.