eChapters

ABSTRACT

The over extraction of water from the coastal environment, results in reduction of groundwater resources which has reflected in lowering of water level. In general, the depletion of water level enhances the landward migration of saltwater wedge. Pondicherry is one such region with recent alluvium as the major litho unit. A study has been attempted to calculate the extraction of water and to estimate the amount of recharge into this alluvial aquifer. The monthly water level fluctuation was observed for the study period in eighteen locations (20002002). The highest water level observed during 2000 was taken as the initial water level for the study and the subsequent decline in water level up to 2001 was monitored monthly until the rising trend was noted. This was taken as the fall in water level due to extraction. Keeping this as the initial value increasing trend was studied until there was a notice of decline in water level. This was taken as the rise in water level due to recharge. The spatial representation of these data in the above said eighteen locations were carried out by using GIS and the area occupied by different water level contours were calculated and the amount of water withdrawn was estimated. The maximum recharge was noted in the central and the northern part of the study area when compared to the other regions. Similarly, the maximum discharge was noted in the northern and the southern part of the study area.

Keywords: Rainfall, Recharge, Groundwater Budget, GIS.

ABSTRACT

Groundwater geochemistry is largely a function of mineral composition of aquifer through which water flows thus, differences in aquifer composition are reflected as differences in groundwater chemistry. To understand water quality and flow pattern multivariate statistical analysis are used due to its relative importance in combining chemical variables and organize voluminous data and group into variables of similar characters. R-mode factor analysis is used in the field of hydrogeochemistry to interpret complex hydrogeological process. A total of 216 samples representing complete lithology like peninsular gneiss, Charnockite and calc gneiss for four different seasons was collected and analyzed for major ions like Ca, Mg, Na, K, HCO₃, Cl, SO₄, NO₃, PO₄, F and H₄SiO₄. Correlation analysis reveals Mg, Cl and Na are spinal and others seasonal. Factor analysis indicates ascendancy of anthropogenic basis followed by lithological weight. Factor score superimpose indicate governing hydrogeochemical regimes spread in western and eastern part. In southern part the same has superior influence than northern part.

ABSTRACT

The study was aimed to identify and delineate the groundwater potable zone in and around Madurai region. The study area is composed of Charnockites and Khondalites of Archaean age. The information of lithology, geomorphology and land use/land cover was generated using the Resourcesat (IRS P6 LISS IV data) and Survey of India (SoI) toposheets of scale 1:50,000 and integrated them with GIS to identify the groundwater potable zones of the study area. On the basis of hydrogeomorphology, groundwater potential zones was identified and delineated. From the overlay analyses landuse and EC, it is inferred that, poor category groundwater is found in the scrub forest, current fallow, canal and scrub with land areas.

ABSTRACT

Topsoil erosion, loss of fertile soil and subsequent deposition in the reservoir as well as in the low-lying region are one of the major problems in the tropical mountainous region. Knowledge of sediment yield from the river basin is a prerequisite to address such issues. Rivers from the Western Ghat region of Uttara Kannada district bring lot of sediments causing siltation in their mouth. In the present study, sediment yield from a Venkatapur river basin in Bhatkal Taluk of Uttara Kannada district is estimated by Universal Soil Loss equation (USLE). Morphometric characteristics of the river basins that reflect sediment yield potential of the river basin are used to constrain the data obtained. Various parameters for USLE is derived from the IRS 1D LISS III image and data are handled in GIS environment. Sediment yields in the basin 101 tons/yr. Morphometric characters of the basin such as drainage density, bifurcation ratio, basin circularity (0.6) and form factor (0.43) suggest its low potential of sediment yield.

ABSTRACT

The present study reports shoreline changes at Gopalpur along east coast of India for 30 years during 1973-2003. In order to understand the trend of sediment transport, shoreline changes at the vicinity areas viz. Rushikulya and Bahuda estuaries are also discussed. Geomorphological investigation is also carried out to understand the processes acting on this system. One Landsat image (1973) and two IRS 1C/1D images (1993 and 2003) were used for the study. The data were subjected to digital analysis using ERDAS Imagine and management of information layers using ARC/INFO GIS software. The results of the study show that the changes occurred differently in three distinct spatial features namely, i) sand spit ii) beach and, (iii) channel zone. Changes documented in these imageries reveal that the lengths of NE spit and SW spit are increased and decreased respectively in thirty years. Areas of NE and SW spits are also showing the similar pattern. Beach is almost stabilised and a slight decrease of 0.28 km in length is observed. However, area has been increased in the southern beach. Towards north, the beach area is also increased over a period of thirty years. The change of width of the beach is not found to be significant. The mouth near channel zone is reduced to 70 meter from 135 meter during the period of study.