Document(s) 13 of 19

Abstract

Wastewater is gaining popularity as a source of irrigation water in different countries around the world. This is especially true in India, where it has been in use for a long time. Its economic benefits and its importance as a coping strategy for the poor have had little recognition. The rural areas downstream of Vadodara in Gujarat, India, present an interesting case where wastewater supports annual agricultural production worth Rs. 266 million (US$5.5 million). Both food crops and cash crops are irrigated by domestic wastewater and industrial effluent. In this area one of the most lucrative income-generating activities for the lower social strata is the sale of wastewater (and renting pumps to lift it). The lack of alternative sources of water has generated viable markets for wastewater. Increased disposable incomes have resulted from the catalytic use of wastewater that was formerly not socially acceptable, i.e. the farmers considered it unhealthy and unclean. The use of wastewater to grow food crops poses uncertain risks to the health of both consumers and those who actually handle the wastewater. Livestock, land and groundwater resources are also at risk. City planners and administrators view wastewater as a disposal problem. They are not concerned with the impact on the livelihoods it presently generates or with the health of the stakeholders. Politics and corruption play an important role in the decision to construct expensive treatment plants that often fail to function properly, if at all, once they are commissioned. The dynamics of agricultural wastewater use and a potential roadmap for optimal productivity are presented in this chapter.

Background

Worldwide the role of wastewater in agriculture has become increasingly important. Its agricultural use is not limited to arid areas. Humid regions like Vietnam (Raschid-Sally et al., Chapter 7, this volume) also make efficient use of wastewater. As both industry and populations continue to increase and freshwater availability decreases, wastewater becomes an important regional planning variable.

In India, wastewater irrigation is increasingly used for such crops as vegetables, fruits, cereals, flowers and fodder. Kolkata (formerly Calcutta) has a long history of using wastewater stabilisation tanks for aquaculture. An estimated 2.4 t/ha (Gopal et al., 1991) of fish is produced annually in Kolkata from about 3200 ha of ponds with inflow of about 3 m³/sec Throughout India industries recycle wastewater to reduce the requirements for freshwater. This trend is led by industries in Saurashtra, Gujarat and Chennai, Tamil Nadu. Vadodara is the third largest city in Gujarat and growing rapidly. At present, water there is used by three major sectors. Industrial use began in the 1950s and 1960s with oil, chemical and pharmaceutical plants. It is concentrated in such peri-urban areas as Nandesari, Bajuva, Ranoli and Makarpura, where a separate effluent channel handles much of the industrial effluent. Domestic water supply serves a population estimated at about 1.5 million in 2001. A large agricultural area extends well beyond the peri-urban limits into the rural areas to the southwest of the city. Municipal sewage is used to grow vegetables, wheat, paddy rice, and flowers along an 80-km stretch of the rivers Jambuva, Vishwamitri and Dhadar [termed the municipal sewage use area (MSU area), in this chapter]. Effluent is also used for irrigation along a 56.3-km stretch of the Effluent Channel Project (termed the ECP area).

Annual rainfall in the region averages approximately 800 mm, but, there was a 3-year drought in 1999–2002. Flat land that slopes gently towards the sea characterises the topography. Due to proximity to the sea, saline water ingress is a problem that limits the availability, discharge, and duration of operation of wells for exploiting groundwater. The region is classified as a ‘No-Source Zone’ by the State Ground Water Board, signifying that there are no new freshwater sources that could be tapped. The very high degree of urbanisation assures farmers of stable and lucrative markets.

Fig 11.1. Map and sketch showing the wastewater irrigated area (Effluent Channel Project and municipal sewage use areas) around Vadodara, Gujarat, India.

The ECP is a concrete-lined covered channel 56.3-km long. It disposes 18 million gallons/ day (MGD) of treated effluent into the Cambay Channel leading to the Gulf of Cambay. The ECP follows guidelines and procedures developed by the National Environmental and Engineering Research Institute (NEERI) at Nagpur. Nine industries joined together to plan, promote and execute the project that was commissioned in 1983 at a cost of Rs.130 million (approximately US$14 million in 1983). Wheat, tobacco and pearl millet production characterise the agriculture in the region. Untreated effluents are illegally and flagrantly released by erring industries into the last few kilometres of the channel, and cause widespread land degradation and crop loss.

In 1962, the city was divided into three drainage zones, each equipped with a collection system and a sewage treatment plant (STP). The effluent from the treatment plants discharges into the Ruparel Kaans, then into the natural seasonal river system of the Vishwamitri to the southwest of the city, and finally joins the Dhadar River and runs into the sea.

At present none of the three STPs is fully functional. The oldest, Gajrawadi STP, is now beyond repair. It receives close to 85 million litres per day (MLD) of sewage. At the Atladra STP, only the primary settling tank is in working condition, and only partially treats 27 MLD. The Tarsali STP utilises obsolete oxidation ditch technology. Although it receives 40 MLD of sewage, according to a report submitted to Vadodara Municipal Corporation for the future planning of a sewage collection system (AIC Watson Consultants Ltd, 1999), it only has a capacity of 9 MLD. In the village of Kapurai, farmers buy municipal sewage from the municipality to use for irrigation.

Methodology

The methodology for the study comprised a combination of the following:

• Exploratory visits to the area that were necessary to comprehend the region and the issues involved.
• Preliminary group discussions that were helpful in sample design and planning, for the selection of study tools and for qualitative analysis.
• The sample design which involved selecting five villages along the ECP area and 10 along the MSU area. Villages were chosen from along each bank, maintaining a uniform spread over the whole area. For the MSU area this sample comprised eight villages along the river Dhadar, and one village each along the rivers Vishwamitri and Jambuva (where the flow length is short). In the ECP area, the area was divided into six sample sites depending on the intensity and cropping pattern of agriculture. A village was chosen from the centre of each of five sites. The sixth site was excluded, as the Effluent Channel Project Limited (ECPL) authorities permit little or no use of effluent for irrigation there. Through group discussions the extent, type and interlinkages involved in the use of wastewater for irrigation were estimated.

Three questionnaire surveys were carried out at the farmer and household levels. One questionnaire dealt with agriculture-related information and included a minimum of eight farmers from each group using wastewater, groundwater and rainfed agriculture, totalling 25 in each village. The second questionnaire pertained to the health impacts of water use and covered 25 households from each village including a significant number of households that use wastewater. The third questionnaire captured the dynamics of water markets for irrigation and was administered to three wastewater and two freshwater sellers in each village. The questionnaires consisted of structured closed-ended and open-ended questions supported by informal discussions with respondents and non-respondents alike.

Data on crop economics were collected at the village level and aggregated by crop for the study area. This was done to reduce the error due to direct extrapolation from field to study area level. The statistical package for social sciences (SPSS) and Excel were used to determine the averages, variations and correlations. The results were confirmed through the focus group discussions with the farmers and interviews with the farmers in the villages.

Results and Discussions

Municipal sewage use (MSU) area

About 200 years ago the Dhadar was a perennial river but over time became seasonal, carrying water only during the monsoon. Municipal sewage started flowing in 1962 when the three STPs were commissioned. Since then the perennial flow in the Dhadar has been restored, albeit with municipal sewage. Only twice in its 41 years of wastewater conveyance has the river dried up (70 km downstream of Vadodara city beyond Amod) (Bhamoriya, 2002). The characteristics of water use including wastewater, groundwater and rainfed farming in the MSU area are presented in Table 11.1.

Group discussions elicited the fact that rainfed farmers marginalised by failing rains were an important group that had converted to wastewater irrigation. Wastewater farmers have been using municipal sewage for about 7–8 years on average. Because wastewater is available, farmers have been able to bring a significant area of land under cultivation and irrigation. Wastewater agriculture has thus become an attractive livelihood option in the area.

Three cropping seasons are possible. The most common crops grown with wastewater irrigation are:

• Rainy season (kharif): Pearl millet, tobacco, rice and elephant grass
• Postrainy season (rabi): Wheat, tobacco, banana and elephant grass
• Summer: Pearl millet and elephant grass.

ECP area

The effluent channel conveys treated industrial effluent for 56 km before discharging into the sea. The extent of the wastewater-irrigated area along the channel is less than that of the MSU area. There is intensive agricultural use of effluent close to the channel itself, but there is systematic under-reporting on its prevalence, because it is illegal to lift effluent to irrigate fields.

Prior to using wastewater, farmers had no source of irrigation water. About 8–9 years ago they discovered the benefits of wastewater irrigation (although some farmers claim to have been using it since 1983). They would prefer to use freshwater but this is not an option here. The recent drought years have seen an increase in the use of effluent for a variety of other purposes, like drinking water for cattle, and for washing utensils and clothes, thus exposing the population to undocumented health hazards.

The farmers reported pH variations in the effluent ranging from 2 to 11, which can be very detrimental to crops, so they steal pH-measuring strips from nearby factories to check the pH of the effluent, and only use it when the pH is between 6.5 and 8.5.

Downstream of Uber untreated wastes brought in by trucks from as far away as Jagadhia and Bharuch are discharged into the ECP channel. From this point downstream, the effluent flow is totally unfit for agriculture. Even upstream along the ECP channel, many farmers who took up wastewater irrigation now find that their land has become infertile or they have incurred heavy crop losses, and as a result have been forced to leave agriculture.

Table 11.1. Comparison of wastewater and groundwater (tubewell-irrigated) and rainfed agriculture in the MSU area.

Table 11.2. Comparison of wastewater and tubewell-irrigated and rainfed agriculture along the Effluent Channel Project (ECP).

^a Some critical protective irrigation can be given by a few to their kharif crop when the rains fail, hence this value appears.

Coping with Poverty: Creating A New Social Order

From information collected mainly through the focus group discussions supported by survey data it became clear that the region has suffered from unemployment as a direct result of water shortage in an area with a large population dependent on agriculture. The following social order existed before wastewater was used for irrigation, in order of incomes and economic opportunities:

Tubewell owners

Tubewell water buyers

Well owners

Employees of a factory or other unit

Shopkeeper/Trader in village Rainfed farmer

Agricultural labourer

The top three groups represented irrigating farmers but well owners had limited available water and were dependent on rainfall to recharge their wells. As education and skill levels were low, employment was not very remunerative. Shopkeepers had limited markets within the villages. Rainfed farmers and agricultural labourers lived with the high risks and vulnerability of uncertainties linked to water availability for agriculture. A combination of accelerated pumping and erratic rainfall resulted in wells drying up and increasing groundwater salinity. The rural economy was unable to keep up with the larger processes of economic growth fuelled by industry and urbanisation.

In this crisis, some rainfed farmers rented pumps and applied wastewater to their fields to save their parched crops. This proved a revolutionary step. The stigma attached to wastewater use proved a barrier for the so– called ‘well-to-do’ to take up sewage as an irrigation option. This resulted in sewage use being self-selecting towards the poorer and marginalised sections of the society who had no options but to use it or face drought and poverty.

Sewage and industrial effluent flows have hardly any seasonality in quantity, and therefore are reliable and assured sources of irrigation. Farmers clearly indicate that wastewater is an excellent resource for poverty alleviation.

Besides the direct benefits to farmers who irrigate with wastewater, an indirect benefit has been the sale of wastewater. The data for water selling in Table 11.3 shows higher incomes (despite under reporting) for wastewater sellers (diesel pump owners) than for tubewell owners. This is partly based on the fact that the average pumping time for wastewater (11.25 hours/day) is twice that for groundwater tubewells (6.6 hours/day).

The increased income for wastewater sellers is because there are more customers and larger areas irrigated per diesel pump lifting wastewater than those using groundwater from deep tubewells. This is despite the fact that diesel pumps cost more to run than electric pumps.

Table 11.3. Gross and net monthly incomes [Rs.(US$)] of different groups of water sellers.

Note: Rs.48 = US$1.

Wastewater has catapulted wastewater irrigators into the higher economic strata of irrigating farmers and pump owners (water sellers), which are the most remunerative agricultural occupations in the region. This process has benefited the poor and has helped to reduce social inequality.

In the ECP area there have been some interesting cropping shifts. Sugarcane that was not grown prior to the availability of effluent has been introduced. All the sugarcane farmers interviewed were irrigating their crops with effluent. The tubewell owners (groundwater irrigators) do not plant sugarcane because they do not have enough water. A similar trend is cultivation of banana, another remunerative cash crop. Amla (Phyllanthus emblica) (fruit) and drumstick (Moringa oleifera) trees whose edible seed pods are used as a vegetable are gaining popularity among wastewater irrigators as they provide a good source of revenue with less irrigation than sugarcane, thereby saving the cost of diesel needed to pump wastewater.

Agricultural Value and Impacts

Table 11.4 presents the cropped area derived from the field studies and calculates the value of agricultural production sustained by wastewater (both municipal and effluent).

Note that ECP and the MSU areas were estimated by extrapolating from irrigated area data collected at the village level (through focus group discussions) based on the total number and area of villages along the channel reaches known to receive wastewater. The average irrigation depth applied was calculated by dividing the total estimated wastewater irrigation volume by the gross cropped area.

Despite using only one-third of the municipal area and higher cropping intensity the value of produce from the ECP area is lower than that from MSU area, because farmers under report fearing legal action against them for using effluent. The above calculations show that from 100 villages in the area the value of annual agricultural production is Rs.266 million (US$5.5 million).

Table 11.4. Estimated value of wastewater irrigation, Vadodara, Gujarat.

In the MSU area there is no correlation between the horsepower of the pumps used and the area they irrigate, indicating that the irrigation depth applied is variable. However, there is a correlation between the horsepower of a given pump and the number of customers served, suggesting that higher discharge pumps are used in areas with small landholdings. On the wastewater-irrigated farms fertiliser use has gone down, but pesticide use and labour inputs have increased in the past few years. The farmers recognise the fertiliser-saving benefit of wastewater and also the need for more pesticides because municipal sewage also contains plant pathogens.

Observations and Recommmendations

Agricultural production of net annual value Rs.266 million (US$5.5 million) is generated by wastewater irrigation in and around Vadodara. This substantial sum accrues to 100 villages – an annual average of Rs.2.66 million per village. Wastewater is now being used in an unregulated and sub-optimal manner. The health risks to humans and livestock exposed to sewage and industrial effluent are poorly understood, but undoubtedly have significant economic implications. There is a trade-off between sustaining the economic agricultural activity of 100 villages that have few other options than to irrigate with wastewater and the risks related to its use.

Wastewater is not viewed as a resource by civic authorities. City planners and administrators see it as a disposal problem, with no concern for the livelihoods it presently generates and little recognition of the health risks of stakeholders who use it. Planners and administrators need to identify wastewater as a critical input for agriculture and integrate this into wastewater management and disposal planning. Based on the very real threats to the consumers of wastewater-irrigated food products and to farmers directly and indirectly exposed to it, a research and management agenda must be developed in order to optimise wastewater use and balance its social costs and benefits.

The uncertainty associated with water availability for agriculture, particularly for marginalised farmers without access to groundwater, could be overcome to some extent with planned use of wastewater. Whilst wastewater irrigation represents the only agricultural production option for many farmers, there is increasing awareness of the benefits it brings if optimally used, particularly the opportunities it provides for marginalised groups. In order to achieve greater social gains, there is a need to improve users’ knowledge of trade-offs and risk-mitigation strategies.

The present quantity of wastewater flows applied to agricultural land in Vadodara is sufficient to give 81 cm irrigation to each crop in the MSU areas, and 106 cm to each crop in the ECP areas. This signifies grossly inefficient use of wastewater for irrigation given that wheat, a prevalent winter crop in the region, needs only 49 cm of irrigation.

A planned initiative is needed to maximise the benefits that could be derived from wastewater resources. It will be necessary to develop knowledge-based agriculture, focusing on farming and irrigation practices suited to wastewater use systems to generate the maximum benefits.

A number of farmers are increasingly using wastewater conjunctively with other sources of water as a coping mechanism against water quality and scarcity problems. This group of farmers represents a potential ‘regular user’ group in that many of the current regular users started off using mixed water sources. The increasing number of users requires that the agricultural and planning authorities address the issue of wastewater agriculture on an urgent basis.

The ECPL faces the problem of not having enough funds to carry out even routine monitoring functions properly, as evidenced by the alarming pH variations of 2 to 11. They have to manage with composite samples rather than point samples which can help single out defaulters in treatment standards. The Pollution Control Board needs to develop ways to support the ECPL.

Sale of wastewater by pump owners who rent out their equipment is an indirect benefit of wastewater agriculture in the region. Particularly because of the low lift and associated energy costs, renting out pumps to lift wastewater is more remunerative than selling ground-water. The further development of wastewater markets could have far-reaching impacts on the use and development of this resource as a vehicle for economic prosperity. It might be feasible for the municipality to levy a fee on pump owners and a sewage discharge fee (sewerage cess) that could be used for pollution abatement and management, particularly through wastewater treatment and improved irrigation practices.

References

AIC Watson Consultants Limited. (1999) Report on Master Planning of Sewerage System, December, 1999. (Submitted to Vadodara Municipal Corporation).

Bhamoriya, V. (2002) Wastewater and Welfare: Pump Irrigation Economy of Peri-urban Vadodara. Annual Partners’ Meet 2002, IWMI–Tata Water Policy Program, Anand, Gujarat, India.

Gopal, B., Bandhopadhyay, S., Sah, M., and Chatterjee, K. (1991) Land Application of Municipal Sewage for Resource Recovery: the Indian Experience. National Institute of Ecology, New Delhi, India.

Document(s) 13 of 19