Wastewater irrigation along polluted Sabarmati river in the downstream adversely affects crop quality: IWMI study

Sabarmati near Vautha

By Rajiv Shah 

Latest study carried out by five experts -- P Amerasinghe, RM Bhardwaj, C Scott, K Jella and F Marshall -- “Urban Wastewater and Agricultural Reuse Challenges in India”, for the International Water Management Institute (IWMI), Colombo, has identified Gujarat as one of the three states which has “some of the most polluted rivers”, adding crops irrigated with wastewaters discharged into Sabarmati in the downstream have adversely affected crop quality along the river.
The other two states are Punjab and Andhra Pradesh. Put out this year, the study is based on household surveys at selected sites in several river basins, including in two kilometres periphery of downstream of the Sabarmati river, which passes through Gujarat’s commercial capital, Ahmedabad. The villages involved in the study are Gyaspur, Asamli, Bakrol, Chitrasar, Fatehpura, Navapura, Rinza, Saorda and Vautha.
The authors says, “Secondary and primary data together with livelihood analyses of farmers from Ahmedabad, Delhi, Hyderabad, Kanpur and Kolkata formed the basis for the analysis. These cities were considered as a representative cross section of the country”. They add, though “wastewater treatment” may have improved in Ahmedabad, and the city’s four sewage treatment plants (STPs) with a capacity to treat 633 million litres per day (MLD), are sufficient to cater to all wastewater, ”infrastructural development lags behind and the plants run below capacity.”
The study says, an overview of water supply and wastewater generation in the case study suggests another major factor, that farming quality by irrigating through wastewater has actually deteriorated in the downstream area of Sabarmati. While respondents that “wastewater provides a reliable water supply”, there was a serious concern on the water of quality. In Ahmedabad, as in Delhi, “the soil fertility had declined and impacted agricultural productivity”. This was attributed to “poor water quality affecting the soils.
In the past, the study said, in villages near Ahmedabad clean river water was available in 90 per cent of the land area. Presently, there is year-round wastewater for irrigation. The quality of farmers cultivating along the cultivating paddy and wheat, fruits and horticultural crops has deteriorated. Agricultural cropping pattern has changed. The study underlines, “Wastewater carries many biological and chemical agents that pose hazards and can impact environmental and human health. Wastewater-related health impacts could be direct or indirect, manifesting as short- or long-term illness episodes.”
It adds, “Most studies tend to look at potential health risks by identifying contaminants in water rather than actual crop contamination and human exposure during farm work or consumption of contaminated food. The state-level Pollution Control Boards in India have the capacity to test a range of these parameters in their routine water-quality monitoring, including physical, chemical and biological parameters such as heavy metals and a variety of pesticides and polynuclear aromatic hydrocarbons.” Yet, it laments, “The soil and agricultural products are not monitored routinely although they could be tested on request.”
The study says, wastewater used for agriculture in the cities under study, including Ahmedabad, is “contaminated with sewage, and hospital and industrial wastes at different degrees, and the possible health impacts will depend on the pollution load, irrigation history and level of exposure on the respective sites. The water and soil-quality studies in all four study sites clearly showed the presence of elements that can have potential health impacts.” It underlines, “Impacts were evident in the water-quality parameters. There is plenty of evidence in the literature that particular chemical hazards have to be expected. Water, soil and grain analysis in sites close to Sabarmati river (Ahmedabad) showed elevated levels of some metals (Cd, Cr, Cu) in the river water and chromium and copper in the well water. High levels of lead were found in wheat irrigated with groundwater which was also contaminated.”
As for Delhi, “heavy metals (Cd, Pb and Zn) were a serious concern in and around Delhi, as several studies showed elevated levels (above the Indian standards under the Prevention of Food Adulteration Act) in commonly eaten vegetables like spinach, okra, and cauliflower. In Kanpur and Delhi, the surface water and soils were contaminated with a variety of metals (Cu, Cd, Cr, Fe, Mn, Ni, Pb and Zn), discharged by small-scale industries which are not monitored stringently.”
It adds, “Responses to the questionnaire revealed that in Delhi, Kolkata and Hyderabad farmers complained of skin irritations, apart from the smell that caused breathing problems, but they did not consider it a major problem. Kolkata farmers were aware of the deteriorating water quality, and were taking precautionary measures to safeguard their skins when engaging in wastewater-related activities, using natural herbs and oils.”
Things were found to be not very different for Ahmedabad and Kanpur, where there is heavy concentration of industry. Here, the “complaints were more pronounced, with visible ulceration, callous tissue formation, heavy skin irritations and dark finger nails. Public health concerns were raised over the high prevalence of helminth ova in commonly consumed vegetables like mint, lettuce, spinach, celery and parsley.”
The study points out, “Although the communities did not complain, the health officials in the hospitals stated that dysentery/diarrhea, worm infections and skin problems were common among the communities, and a good majority did not seek treatment at government hospitals. Therefore, private practitioners and local quacks play an important role in treating these communities. As a result, these episodes never get into the overall health statistics. Epidemiological and microbiological investigations along with health economics studies are required to assess the health risks and economic costs associated with wastewater farming in the communities.”
Another study, which was made last year, “Wastewater Irrigation in Gujarat: An Exploratory Study”, sponsored jointly by IWMI and Ratan Tata Trust, Mumbai, says that the key factors driving increasing use of wastewater are three fold. “First set of driving factors is based on limited availability of freshwater. There is no access to canal water; groundwater is saline; water table has gone very deep and/or diesel costs are too high. The second, and more recent driver of wastewater irrigation expansion is rapid urbanization which has resulted in competition between irrigation needs and municipal demand with priority being given to the later. There is ever-growing sewage generation and its use for irrigation turns out to be a convenient way for cities to dispose off this otherwise unmanageable sewage. The third set of driving factors for expansion in wastewater irrigation is related to farmers' convictions.”
Carried out by Alka Palrecha, Dheeraj Kapoor and Teja Malladi, it says, “Many farmers irrigate with wastewater despite having the option of freshwater irrigation because they are convinced that wastewater is more reliable and accessible throughout the year, cheaper to lift, and more profitable because of its nutrient value leading to higher yields and savings in fertilizer input costs.”
It further says, “A critical factor in wastewater irrigation is that untreated and partially treated water is being applied to land. Its impact needs to be studied especially, on soil quality and groundwater aquifers, where it gets leached. The small holders of land did not have any aversion towards using sewage water for irrigation. They claimed that it does not cause any harm to soil quality as the flow in river naturally cleanses the water and in addition, it is rich in nutrients. On the other hand, large landowners felt that the use of this water may harden the soils due to detergent and other chemicals present in it.”
The authors insist that, given this factor, the “amount and quality of the nutrients present in the wastewater have to be ascertained by technical experts and farmers in order to guarantee proper application. It needs to be discussed by experts, farmers and extension support may be required for making this knowledge available. Currently, conventional irrigation techniques of either flood or furrow irrigation are used to irrigate with wastewater. Micro irrigation technology is not suitable for using wastewater. Hence, suitable irrigation technique needs to be explored.”