GIS applicability to assess spatio-temporal variation of groundwater quality and sustainable use for irrigation

Sustainable and safe use of groundwater requires periodical monitoring of its quality. Because of the presence of multiple contaminants, spatial variation of overall groundwater quality is difficult to describe. The present study describes the overall groundwater quality for irrigation using a multi-criteria quality assessment system and sustainability of water use by incorporating the aspect of temporal variation of groundwater quality. The GIS-based multi-criteria system effectively amalgamated different quality parameters into an easily understandable format and assessed the spatial variation of groundwater quality for irrigation in west Delhi, India. The rate of spatial increment of poor quality groundwater within the study period was 3.7 km(2) per year. It has been observed that there is deterioration of groundwater quality from southwest to east, along the general groundwater flow direction, and improvement of groundwater quality from west to northeast, due to less urbanization and availability of groundwater recharge zones with good quality water. Temporal variation of groundwater quality is high (V>20 %) at northern part, moderate (V=10-20 %) at middle and southern parts, and less (V<10 %) at some pockets of southern part of the study area. The overall groundwater quality coupled with its variation reveals that while the groundwater use is mostly unsustainable in the southern part, groundwater sustainability is constrained by relatively poor and variable quality in western and northern fringes of the study area.