Problem Of Salinity In Delhi Region


Rajesh Bhagwat Jadhao


The hydrogeology of the southwest district of National Capital Territory (NCT) Delhi is challenging on the account of the fact that the quality of groundwater in the district shows horizontal and vertical variation with respect to salinity.  The present paper tries to study the variation in the depth to fresh (electrical conductivity equal to or below 1500-2000 micro siemens per cm)/saline (electrical conductivity above 1500-2000 micro siemens per cm) water interface of the district and locate the factors controlling  the variation in the depth to fresh/saline interface in the groundwater of the district. The map showing variation in the depth to fresh/saline interface in the groundwater of the district was studied vis-í -vis geology and cultural practices in the district, in order to identify the factors controlling the variation in the depth to fresh/saline water interface in the groundwater of the district.

In the irrigated areas of semi-arid regions, especially in northwest India, a considerable recharge to the groundwater leads to water logging and secondary salinization. In several sub-areas groundwater is mined, water tables fall, and salts are added to the root zone because a high proportion of irrigation water is derived from pumped groundwater of poor quality. Out of 1 million hectares of irrigation induced waterlogged saline area in northwest India, approximately half a million hectares are in the state of Haryana. Taking a homogenous physical environment as a starting point, the way and the extent to which farmers' activities will affect the salinity and sodicity situation depend on farming and irrigation practices. In the past, soil salinity was mainly associated with high groundwater tables, which bring salts into the root zone through capillary rise when water is pumped.

But nowadays, increasing exploitation of groundwater for irrigation purposes has led to declining groundwater tables and a threat of sodification and salinization due to use of poor quality groundwater. Farmers in northwest India are facing a situation in which they have to deal with salt volumes that are harmful for water uptake of crops. They are also facing the problem of sodicity, which has an adverse effect on the physical structure of the soil, causing problems of water intake, transfer and aeration. To mitigate the adverse effect of soil salinity on crop yield, the farmers irrigate frequently, either mixing canal water and groundwater, or alternately using canal water and groundwater. Due to differences in environmental parameters in the farming systems, such as groundwater quality, soil types and uneven distribution of irrigation water, income losses to the farming community are not uniform. This paper highlights the economic loss due to environmental degradation through the twin problems of water logging and soil salinity, which threaten the sustainability of agricultural production in Haryana state. Our analysis shows that the net present value of the damage due to water logging and salinity in Haryana is about Rs. 23,900/ha (in 1998–1999 constant prices). The estimated potential annual loss is about Rs. 1669 million (about US$ 37 million) from the waterlogged saline area. The major finding of the paper is that intensification per se is not the root cause of land degradation, but rather the policy environment that encouraged inappropriate land use and injudicious input use, especially excessive irrigation. Trade policies, output price policies and input subsidies all have contributed to the degradation of agricultural land.

Impacts of Urban Growth on Surface Water and Groundwater Quality (Proceedings of IUGG 99In recent years, water supply and groundwater resources in India have become threatened following uncontrolled disposal of urban waste into water bodies, open waste dumping and poorly designed landfills. Within the urban fringe zones of Delhi, the contamination of groundwater by industrial and domestic effluents now presents serious challenges. Subsoil waters in the area through which effluents from major industries infiltrate, are already polluted more or less permanently. Wells in many residential areas are contaminated with nitrate, detergents and high salinity levels with the high content of fluoride also posing severe health hazards in surrounding regions.