Sustainable Groundwater Development
Overview
The program has generated new knowledge to support sustainable groundwater development in the EGP, using a food-energy-water (FEW) nexus lens. Individual projects have looked at patterns of availability and access to groundwater, local level water management solutions (i.e. CASI, managed aquifer recharge), and the impacts of commonly used policies that aim to influence groundwater development and sustainability.
Results indicate that FEW links are not always as expected. For example, increased access to electricity has not resulted in a strong change in groundwater use or productivity in West Bengal; and water savings at the farm scale do not always result in reduced groundwater use overall. In the EGP, impacts of climate change will result in delayed monsoons and increased incidence of flooding, which makes summer crops more vulnerable to water stress (both too much and too little). Groundwater resources, which in many places are annually recharged – as at least four ACIAR SDIP studies have confirmed – are more resilient to climate change and offer assured irrigation in the dry winter months.
Several key messages have emerged around supporting sustainable groundwater development.
The importance of understanding the links between local and regional hydrology
Groundwater resources are in general underexploited in the EGP, meaning there is room for further development in many locations. However, there is variation in district level groundwater use – even though at a state/regional level the system is in balance. Some locations have seasonal (pre monsoon) decline in groundwater levels, which is important to monitor because we need to know whether this seasonal decline is compensated by recharge in the wet season.
To cater for this variability at district levels, we need a suite of management options and policies that can be applied.
The bottom line is that hydrology matters. While it is true that in many locations groundwater is abundant and extractions can increase, it does not take long for this to change, and coordinated monitoring efforts are required.
Identifying reasons for groundwater decline
There is a misconception that when groundwater is used for irrigation, that everything pumped from the system is lost. This is not true in places where groundwater is of good quality, as is the case in the EGP – water that is not used by plants contributes to recharge and is used by others .
The true loss from the system is actual evapotranspiration (ETa = water taken up by plants + evaporation). Reducing farm level water use does not reduce ETa and hence water use overall. To really save water, you need to reduce ETa by changing cropping patterns or reducing crop duration.
Groundwater decline is a concern in the northwest of Bangladesh, and there are policies that encourage farm level water savings to halt this pattern. However, there are multiple causes of groundwater decline, both on and off-farm – including changes in climate, river flows and land use change. We need to know what causes groundwater decline in specific locations, because if groundwater decline is driven by off-farm factors, on-farm solutions will have very limited value.
Improving access to pumps
Informal, private rental markets play a major role in ensuring irrigation access for almost all farmers in the EGP. In a survey conducted by IFPRI in 2015, only 25% of farmers owned pump sets, with 75% renting pumps to access irrigation. Water buyers are often smaller and poorer farmers.
There is considerable heterogeneity across water users and one policy won’t work the same for everyone. A subsidy on pump ownership for example, will likely benefit those who traditionally own pumps (men, larger farmers) but does not guarantee any welfare gain for others (e.g. women, tenant farmers).
Better targeting of support could produce multiple, integrated benefits. For example, subsidizing access to pumping technologies for those more likely to sell water into groundwater markets is a better option than a universal subsidy if the aim is to lower the cost of water access.
The changing energy-water nexus
When groundwater is used, energy and irrigation are closely tied together, and energy costs and access can influence the amount of water pumped. The energy – irrigation nexus is changing in the EGP, with rates of rural electrification increasing rapidly. However, large scale electrification in West Bengal has not led to the majority of farmers greatly increasing the amount of crops they produce (especially boro rice), or changing the kinds of crops they grow. However, at the district level (e.g. in northern West Bengal) there were impacts in locations that previously did not have access to electricity. Because of this, groundwater levels have remained stable.
We know that grid electrification is happening rapidly in the EGP. What tariffs and power supply arrangements will improve agricultural development? And if we get that right, what impact will it have on local and regional hydrology? These questions remain key to sustainable groundwater development in the future.
Water alone is not enough
Improving access to water alone is not enough to increase development; farmers also need access to inputs, stable output prices and better market infrastructure to improve productivity and profitability.
Agricultural development in the EGP is tied to groundwater. In Bangladesh, agricultural growth that targeted national food security began once groundwater restrictions were removed. In West Bengal, the target of groundwater preservation has resulted in a focus on diversification. This has resulted in lower levels of development in West Bengal in the past decade.
Within India, given the serious levels of overexploitation of groundwater in the western IGP, there is the potential for rice production to be shifted to the EGP. This makes sense from a hydrological perspective, but what would it take for that to happen sustainably? There are limits to the traditional ways of promoting groundwater development. Water and energy policies need to be made in collaboration with agriculture and food policy if they will be successful in sustainably increasing food production among farmers.
Groundwater access and the constraints around that access are heavily contingent on the other resources available to water users. Addressing development challenges must go beyond ‘just adding water’.
At the ACIAR SDIP Final Review, program team members Dr Mainuddin, Dr Aditi Mukherji, Dr Don Gaydon and Professor Somnath Bandyophadyay joined Robyn Johnston for a discussion about sustainable groundwater development in the EGP. Watch a recording of the discussion here.