Water and woes in the north-west

For obvious reasons, groundwater availability and thus access to irrigation in dry season have much to do with production of high-yielding variety (HYV) of rice in winter season. The HYV has bid a farewell to low-yielding traditional varieties. Irrigation, particularly groundwater irrigation, is considered as the lead input contributing to self-sufficiency in rice. But all that has been achieved so far through groundwater irrigation has not been a 'free lunch'. In fact, extraction of groundwater is alleged to have involved huge costs in terms of water table and withdrawal of excess water thus threatening sustainable water use. Ipso facto, concerns over unsustainable use of groundwater is mounting although not much empirics are available on that score. However, a recent research work by Nepal C Dey, Sujit K. Bala, AKM Saiful Islam, Ratnajit Saha and Abdur Rashid has shed some important light on the issue.
The findings reveal a declining trend of groundwater table over the last 30 years (1981-2011). This implies that groundwater use is not sustainable in the study areas such as Rajshahi,Pabna, Bogra, Dinajpur and Rangpur. The magnitude of the decline was found between  2.3 in 1981 and 11.5m in 2011. This can be adduced mainly to overexploitation of groundwater without having sufficient recharging aquifers. It needs to be mentioned here that shallow and deep tube wells are the major groundwater lifting devices in the study areas where the intensity of tube well use has increased, and the area per unit of tube well drastically declined from 14.5 to 2.8 hectare from 1984-85 to 2010-11. The number of tube wells has increased about nine times while the area of irrigated land increased by only about two times.
The analysis carried out by the researchers also reveals a declining trend of annual fluctuation of surrounding river water level and its discharge in the northwest region of Bangladesh over time. On an average, river water level and discharge decreased from 20m to 19m and 90.8 to 56.9m3/sec, respectively, from 1981 to 2010. The findings also show that the declining trend of average annual river water level is positively related to the decreasing trend of groundwater table.
More disconcertingly perhaps, a decreasing trend in the wetland area has been found in the study areas with around one-thirds of total wetlands lost during 1989-2010 period. Of course, the rate of decrease was much low during 2000-2010 period than that of 1989-2000. The decrease of wetland indicates a decrease of groundwater recharge resources. The findings also show a recurrence of below average rainfalls over the year.
Defects in the present irrigation water management system were identified by the research. The study revealed that about four-fifths of the lifted water went to Boro rice production and the rest one-fifth to other crops. The authors estimated that about one-fifths of the water used in Boro crop was excess water - the difference between the lifted water minus the irrigation water requirement of the crops. It is needless to mention that the excess water increased the cost of irrigation as well as crop production in a regime where 68 per cent of the groundwater is lifted by shallow tube wells and the rest by deep tube wells.
Due to non-availability of surface water, farmers were bound to lift groundwater which increased irrigation cost. Added to this is the price hike of agricultural inputs like fuel, electricity, agrochemicals, rent of land, labour, etc. These affected the ultimate production cost threatening the overall sustainability of agricultural production of the northwest region of the country.
The cost of excess water lifted by DTW was estimated to be Tk. 2,201-7,075.8 per hectare and that by STW was Tk 7,547.5-10,058.4 per hectare. This perhaps means that excess water raises cost of paddy by about Tk.2.0 per kg. The cost of irrigation by privately-owned tube wells was much higher than that of government tube wells and it was also higher in the case of diesel than electricity-driven pumps. The irrigation cost per hectare of private tube wells ranged from Tk. 15,000-Tk. 33,000, and that of public tube wells varied from Tk 7,500-Tk. 11,250.
The study also gives an impression on cost-benefit ratios of crops. The findings, by and large,  reveal positive net return for all the studied crops. The highest benefit to cost ratio was found for lentil followed by wheat and mustard. The domestic-to-border price ratio of the crops was less than unity and significantly negative except for mustard during the study period. The estimates of Domestic Resource Cost (DRC) showed that Bangladesh has a comparative advantage of production in all the crops under study. The study findings implied that production of potato and lentil would be highly efficient for import substitution. So, Bangladesh will need to enhance its supply-side capacity and pursue a broad-based diversified agricultural production and export strategy.
The survey and the focus group discussions (FGDs) with farmers reveal that three-fourths of them were well aware of lowering of groundwater level in their agricultural fields, while 53 per cent complained about inadequate water during the irrigation period. Further, about 90 per cent farmers were well aware of excessive pumping as well as of drying up of local water bodies and rivers. Groundwater was invisible and remained beneath the surface. Awareness of farmers and local people, including the educated ones, is still at a very preliminary stage. The water cycle and its interdependence of surface and groundwater, ecological balance and its services, quantity and quality, supply and demand, and, above all, the sustainability of the system as a whole, are poorly understood.
To achieve food security, the ecological approach with strong community participation is missing in the use of groundwater for irrigation. The use of groundwater should be ecology-friendly based on sound policy on recharge of groundwater through conservation and community participation. A focal-point organisation at national level should be identified for planning and execution of concerned activities. It is also imperative to follow the best irrigation management practices and climate change adaptation techniques for the sustainable use of groundwater.
Irrigation water was the life-line for north-west region in the past but now it threatens to become the woes of the region.

The writer is  Professor of Economics at Jahangirnagar University.
[email protected]