Integrated Drainage Solutions for Waterlogged Saline Lands

Abstract

The anticipated increase in crop yields from irrigated lands has remained subdued due to widespread increase in waterlogging and soil salinity. Drainage, a technical intervention to manage waterlogging and soil salinity, has been generally known, and a number of techniques have been perfected and applied to solve the twin problems. However, drainage application has not kept pace with the increasing requirement. It is estimated that about 10–15 million ha area requires drainage improvements including 2–3 million ha area requiring subsurface pipe drains in the near future. This chapter reviews and collates the adverse impacts of waterlogging and soil salinity on land productivity, traces the history of land drainage and advocates shift from either this or that option approach to an integrated drainage approach so as to take advantage of the synergy of two or more drainage methods. It is brought out that any subsurface drainage technique in monsoon climatic conditions will not be effective unless integrated with surface drainage. It has been observed that at most places integrated drainage systems have been in operation, but the role of only one or the other is highlighted resulting in a skewed viewpoint on drainage technologies. For example, many horizontal pipe drainage schemes in India have been implemented in areas already having surface drainage and/or bio-interceptor drainage. In such cases, the role of only subsurface drainage is highlighted because it happens to be the new addition to the existing systems. In a similar way, the role of vertical drainage system is often underestimated at least in the initial years. A case has been made out for strong research inputs on integrated subsurface pipe, mole, vertical and biodrainage systems. The research outputs must help to translate hypothetical calculations of biodrainage potential and designs into thumb rules for easy applications as well as its integration potential with other techniques to take care of salt balance. Several options of integrated drainage systems have been presented. While either integrated or individual systems can be adopted at micro-scale, only an integrated plan would be a technically sound and cost-effective solution at macro-scale as illustrated by the drainage master plan of Haryana (India). Overall, the chapter challenges the conventional thinking that a drainage technique can replace another drainage technique in favour of complementary approach. It is suggested that an effective governance mechanism should be in place to manage land drainage as in the case of irrigation systems, since land drainage is a specialized activity requiring technical skills and equipment. However, the governing institution in this case needs to be multidisciplinary to ensure that every drop of water is used to fulfil the water requirement of the region before it is drained to the natural river system.