Surjeet Singh

Identification and Planning of Water Quality Monitoring Network in Context of Integrated Water Resource Management (IWRM)

Hydrological system is a quite complex and dynamic in nature because of the heterogeneity of the earth crust and surrounding atmosphere. Water exists on the earth in all three forms of liquid, solid and gas. The scarcity of its liquid freshwater has resulted because of increasing demand in response to growing population, contamination and pollution of freshwater bodies due to urbanization and industrialization. Precise measurement of water quality, in present time, has become the necessity because of increasing scarcity of this precious resource. In a global perspective, organizations dealing with water supply and monitoring are ever concerned about precise assessment of water quality. Researchers are focusing on the assessment of surface and ground water quality on spatial scale rather than point scale, which needs strengthening of monitoring networks time-to-time. The design of a hydrometric network starts ideally with a minimum number of stations, and increases gradually until an optimum network is attained when the amount and quality of data collected and information processed is economically justifiable and it meets the user’s needs to make specific decisions. In hydrology, monitoring of data is mostly site-specific and proper representation of this data on spatial scale requires proper network planning. Since the drivers of water quality vary in space and time, the quality of water also varies in space and time. It is therefore imperative to monitor the quality of water under heterogeneous space-dependent conditions for which a specialized water quality monitoring network is essential. The present paper is in the context of identifying and planning of water quality monitoring network for data acquisition for Integrated Water Resources Management (IWRM).

Index-based assessment of suitability of water quality for irrigation purpose under Indian conditions

Agriculture is a major sector in India which contributes around 14% of country’s gross domestic product (GDP). Being an agriculture-based country, good quality of water for irrigation has been a prime requisite. Highly growing population and accelerated industrial development are causing anthropogenic pollution to both surface and groundwater on one side and geogenic contamination like arsenic, fluoride, high dissolved solids, sodicity, and iron in groundwater on other side. As a result, ensuring safe water quality for the irrigation has become a major challenge to both the central and state governments. The present irrigation water quality standards being followed in India have been set by the Central Pollution Control Board (CPCB) and Central Ground Water Board (CGWB) in the year 2000. These standards are solely based on four parameters, namely electrical conductivity, sodium percentage, sodium absorption ratio, and residual sodium carbonate, which are quite subjective and many times are not capable to exactly decide the quality of irrigation water particularly when there are large variations in the source water quality. Therefore, in the present paper, an indices-based approach is presented for categorization of irrigation water quality. These indices are mathematical equations that transform water quality data into a numeric value, which describes the quality of irrigation water. The proposed irrigation water quality index (IWQI), which is based on 12 parameters, classifies the water into five categories, viz. excellent, good, medium, bad, and very bad in the same manner as given by the CPCB and CGWB. In order to give proper rating to various parameters of the index, weights are computed using Saaty’s analytic hierarchy process (AHP)-based multiple criteria decision analysis (MCDA) approach. This approach minimizes the subjectivity in assessment of weights and improves understanding of water quality issues by generating an overall index to describe the status of water quality. The proposed index will be beneficial for the water management authorities in ensuring safe water to the stakeholders.

Process Based Integrated Models for Managed Aquifer Recharge and Aquifer Storage Treatment and Recovery

Process based semi-analytical models for surface and ground water management of a recharge basin, based on the concept of managed aquifer recharge (MAR) and aquifer storage treatment and recovery (ASTR), are presented. The model for simulation of aquifer responses due to recharge and extraction of recharged water is developed by integrating the hydrologic components into basic water balance equation; and the models for simulation of contaminants’ fate in the recharge basin and through the soil column beneath are developed by considering: (i) in-basin mass balance with decay of contaminant and, (ii) 1-dimensional advection-dispersion-decay equation coupled with linearized sorption isotherm equation, respectively. The estimate of hydrologic components included: inflow to the recharge basin from its catchment by SCS-CN model, water surface evaporation by combination of Priestley-Taylor and Penman method, recharge by Hantush’s analytical equation for water table rise due to recharge from a rectangular spreading basin in absence of pumping well, and drawdown due to pumping by Theis’s well function equation. The contaminant’s fate estimate included: time varying changes in concentration due to assimilation and detention of contaminant in the recharge basin and transport of assimilated materials through saturated soil column until they reached the groundwater table. The performances of recharge-pumping and contaminants’ transport models are illustrated by examples. These models can successfully be used and upscale as potential tools for MAR and ASTR.

Spatio-Temporal Variation and Trend Analysis of Groundwater Level in Raipur City, Chhattisgarh

Assessment of spatio-temporal variation provides a principal source of information regarding groundwater recharge, storage and discharge. Spatio-temporal variation of groundwater level (GWL) in Raipur city has been studied using statistical and graphical methods. Monthly trend of GWL has been investigated using Mann–Kendall test and Sen’s slope estimator. The monthly GWL data of thirty observation wells (dug well) of Raipur city for the period 2010–2014 have been used for the study. The minimum and maximum GWL has been found out to be 0.84 m below ground level (bgl) which is 267.98 m above mean sea level (amsl) and 16.61 m bgl (271.53 m amsl). Contour map shows that average GWL varies between 1.74 and 13.80 m bgl (i.e. 280.34 m to 287.12 amsl) during pre-monsoon and 1.64 m to 6.75 m bgl (i.e. 279.92 m to 282.54 m amsl) during post-monsoon. GWL is shallower in central part of the city, whereas deeper GWL has been observed in western and northern part of the city. The groundwater contour maps depict that the groundwater flow direction is towards north and west. The results of trend analysis reveal that no significant trend is detected at 5% significance level except few locations.

Impact of Canal Recharge on Groundwater Quality of Kolayat Area, District Bikaner, India

Rajasthan is one of the water scarce states of India where the annual average rainfall varies from less than 100 to 1000 mm. Kolayat area of district Bikaner located in western part of the state, receives average annual rainfall of 275 mm. Owing to the less rainfall of this low magnitude, the water availability problem in the Kolayat area is critical in comparison to many other parts of the state. The water requirement, of the area, is mainly met by Indira Gandhi Nahar Project (IGNP) canal. The groundwater quality of the area through which IGNP canal passes has been studied to understand the effect of canal recharge on groundwater and subsurface movement of recharge pathways. The canal trends in NE-SW direction and flows towards SW. The study has been carried out across the canal 40 km in the eastern and 20 km in the western direction. The depth to water varies between 10 and 55 m bgl. The water levels are shallow in western direction and upto Bajju in eastern direction from the canal. The water levels become deeper as one moves towards eastern direction. This suggests that the groundwater regime receives recharge from the canal towards western direction and upto Bajju in eastern direction. The groundwater flow directions obtained from water table contours also reveal the presence of groundwater mound in the vicinity of the canal. The EC of the canal water is 302 μS/cm where as the EC of groundwater varies from 563 μS/cm to 23600 μS/cm. The EC of groundwater along the canal varies from 563 μS/cm (Bajju) to 1916 μS/cm except Modayat where as EC is high away from the canal. Water quality analysis confirms the same result as interpreted from groundwater contours. The groundwater of the area has high calcium, magnesium, sodium, potassium, chloride, sulphate, they range upto 634, 787, 5890, 1015, 7908, 2650 mg/L respectively. Further, fluoride in the areas around Chak 4 GMR (3.8 mg/L), Bajju (1.93 mg/L), Godu Krishi farm (4.12 mg/L), Godu village (1.93 mg/L) exceeds the permissible limit for drinking purpose. The study also reveals that recharge from IGNP canal has a long term influence in the study area where groundwater is withdrawn for various activities.

Forecasting Groundwater Level Using Hybrid Modelling Technique

In India, groundwater serves about 70 % of rural population, 50 % of urban population and about 60 % of agricultural area. There are more than 20 million groundwater extraction structures in place which are being used to meet requirement for domestic, industrial and agricultural activities. There is intensive development of groundwater in certain pockets of India, which has resulted in over-exploitation of groundwater resources and led to steep declining trend in levels of groundwater. As per the assessment of groundwater resources (CGWB 2007), out of 5,723 assessment units (blocks/mandals/taluks) in the country, 839 units in various states have been categorized as “over-exploited” meaning that annual groundwater extraction exceeds the annual replenishable resource. In addition, 226 units are critical with stage of groundwater development hovering between 90 % and 100 % of annual replenishable resource.