ALBERT

Description: Population growth, urbanization and global climate change have increased urban and agricultural water demands, stressing aquifer systems where groundwater is a source of water supply. The availability and utility of groundwater may further be threatened by factors stressing the quality of groundwater, such as industrial and domestic wastes and agricultural intensification. Consequences include, for example, over-allocation of groundwater, groundwater overdraft, declining well yields and land subsidence; degraded groundwater quality due to mobilization of natural pollutants (arsenic), salt contamination caused by seawater intrusion; increased demand for conjunctively used surface water, and resulting conflicts with junior users; and streamflow capture and resulting damage to ecosystems. These consequences may occur incrementally and inequitably across an aquifer. Natural environmental problems can further complicate use of groundwater and increase strain on the aquifer system; for example, underground structures, geothermal heating (such as heat islands), and geochemical evolution (such as karst formation, excessive salinity, acidity, fluoride, radioactivity, hardness, or turbidity). To address this issue, a joint symposium on the Trends and Sustainability of Groundwater in Highly Stressed Aquifers was held during the 8th Scientific Assembly of the International Association of Hydrological Sciences, IAHS, and the 37th Congress of the International Association of Hydrogeology, IAH, in Hyderabad, India, September 2009. The symposium was organized by the IAHS International Commission on Groundwater (ICGW), supported IAH and by the IAHS International Commission on Water Quality (ICWQ). This symposium brought together scientists, including modellers, geochemists and hydro-geologists, with water supply managers and policy makers to discuss scientific and management ideas and approaches for improving the sustainability of highly stressed aquifers. The importance of this topic was reflected in the large number of contributions to the symposium. Selected papers from this symposium have been compiled in this volume. The editors gratefully acknowledge the assistance of the reviewers who made valuable contributions to this volume. We thank Penny Perrins and Cate Gardner from IAHS Press for their professional approach and help with the processing of the manuscripts.

Description: Published

Description: V

Description: open

Description: An increase in atmospheric CO〈sub〉2 〈/sub〉is one of the main drivers of climate change, which necessitates an understanding of the carbon cycle. Rivers play a critical role in the global carbon cycle, yet their contribution is less understood. Also, carbon pathways in non-perennial rivers are seldom studied and hence the present study was carried out with the objective to assess the carbon outgassing from a non-perennial tropical river, Cauvery situated in Southern India. Periodical sampling was carried out from 2013-2018, once in four months where about 506 river water samples were collected. The samples were measured for pH, temperature, and alkalinity which were used to estimate the partial pressure of CO〈sub〉2〈/sub〉 (pCO〈sub〉2〈/sub〉). The sentinel imageries were used to delineate the changes in the areal extent of the river surface area. The pCO〈sub〉2 〈/sub〉of river water in most of the locations was supersaturated in the order of magnitudes ranging from 2 to 51 with respect to CO〈sub〉2〈/sub〉 equilibrium with air. The pCO〈sub〉2〈/sub〉 of river water was higher at the upper and the middle regions and decreasing towards the lower part of the basin. The CO〈sub〉2〈/sub〉 outgassing to the atmosphere was maximum during the wet periods than the dry seasons because of the high flooded surface area and higher pCO〈sub〉2 〈/sub〉of water. It is evident that the hydrology along with climate, lithology, landuse-landcover, and biogeochemical process of the basin controls the carbon outgassing of the river. This study highlights the need for carbon outgassing assessments in non-perennial rivers to reduce the uncertainties in carbon budget estimates.

Description: Understanding of groundwater and surface water interactions is essential since it provides information on the changes in their ecosystems that affects quality and quantity of both. Hence, the present study was carried out with an objective to identify the river water and groundwater interactions in Cauvery, a major river basin of Southern India. The river water and groundwater samples were collected once in four months from 2013 to 2019. The samples were analysed for major ions, trace elements and stable isotopes (δ〈sup〉18〈/sup〉O and δ〈sup〉2〈/sup〉H). Inverse modelling was carried using PHREEQC to understand the hydrogeochemical reactions during surface water and groundwater interaction. It was found that both groundwater and the surface water falls under Ca-Mg-HCO〈sub〉3〈/sub〉 and Na-Cl water type. The temporal variation of major ions between groundwater and river water shows similar pattern, indicating their interrelationships. The isotope results shows that groundwater and river water falls between precipitation and the evaporation during wet seasons, whereas few samples have been isotopically enriched during the dry season as a result of evaporation, suggesting the groundwater contribution to the river water. The weathering of hornblende, plagioclase, biotite, K-feldspar occurs during groundwater-river water interaction which then transforms to stable clay minerals. It was evident that at the lower part of the basin, the river water discharges into groundwater during the wet periods and vice versa during dry seasons. Thus, this current study on river water- groundwater interactions act as a baseline knowledge in developing sustainable water management plan in the river basins.