Ali Fares

Hydraulic Fracturing and Its Potential Impact on Shallow Groundwater

Unconventional natural gas extraction from impermeable geologic formations is getting momentum in recent years due to advances in horizontal drilling and hydraulic fracturing. By 2040, shale resources are projected to account for 53 % of all natural gas production in the U.S. However, the development of unconventional oil/gas production from hydraulic fracturing has raised serious concerns about its potential impact on the quantity and quality of water resources and the environment due to the large volume of water needed and the use of toxic substances in hydraulic fracturing fluids. This paper gives an overview of the hydraulic fracturing used to extract shale gas, its potential impact on water resources, provides an overview of modeling studies and tools used to assess its potential impacts, and regulation issues related to it. The most significant risks resulting from hydraulic fracturing and shale gas development are (1) the excessive withdrawal of water, (2) gas migration and groundwater contamination due to faulty well construction, blowouts, (3) contamination by wastewater disposal, and (4) accidental leaks and spill of wastewater and chemicals used during drilling and hydraulic fracturing process.

Remote Sensing Applications for Monitoring Water Resources in the UAE Using Lake Zakher as a Water Storage Gauge

The potential of remote sensing has been fully demonstrated in large scale and regional hydrological studies where in situ observations are limited. However, the use of satellite imagery to monitor water resources in small watersheds remains challenging, mainly due to coarse resolution satellite data. In this study, we assessed the efficacy of remotely sensed data to investigate changes in water storage in Al Ain watershed, in the United Arab Emirates (UAE). Lake Zakher, in the watershed, was used in this study as a gauge indicating changes in water storage. The area of the lake was monitored using Landsat 7 and 8 images, which were then used with a 15 m-Digital Elevation Model (DEM) to calculate time-series lake volumes. In addition, water storage anomalies over the watershed were estimated using Gravity Recovery and Climate Experiment (GRACE) images. Changes in water storage estimated from Landsat and GRACE were in agreement with water consumption and wastewater treatment reported by local agencies in the Emirate of Abu Dhabi. Discharged water from the wastewater treatment plant and volume of water in Lake Zakher showed similar patterns. The results from this study confirmed the reliability of remotely sensed data in monitoring water resources in arid and remote watersheds where ground-based observations are scarce.

Groundwater and Surface Water Interactions in Relation to Natural and Anthropogenic Environmental Changes

Groundwater and surface water interaction is an essential component of the hydrological cycle. The hydraulic connectivity and exchange of water between surface water (e.g. rivers, lakes, wetlands) and underlying aquifers provide many ecosystem services that sustain human and ecological well-being. Climate change, increased population, and industrial growth have resulted in substantial environmental (e.g. land use and land cover, climate, groundwater) changes across the globe. As a result, decline in groundwater levels, drying of streams, shrinking lakes, wetlands, and estuaries have been observed across the world. This generates concerns about the effects of such environmental changes on groundwater and surface water interactions, and on the quality and quantity of water resources. This chapter presents an overview of groundwater and surface water interactions, pressing environmental change issues centered on natural and anthropogenic environmental changes, and available management tools that quantify the integrated groundwater and surface water flow processes. This chapter also briefly discusses exciting research opportunities enabled by satellite remote sensing. We close in with a discussion of future management challenges and strategies for sustainable use of groundwater and surface water resources. One outcome of this chapter is to provide resource managers, researchers, consultant groups, and government agencies basic understanding of the types, mechanism, and effects of natural and anthropogenic landuse changes on groundwater and surface water interactions, and available management tools for studying groundwater and surface water interactions.

Effects Of Land-use Changes And GroundwaterPumping On Saltwater Intrusion In CoastalWatersheds

This chapter describes the occurrence of saltwater/freshwater interface in coastal aquifers. It has a brief description of the physics, hydraulics, and mathematics behind the theory of saltwater intrusion and the saltwater/freshwater interface. It also includes a section on numerical modeling techniques and the available computer models for saltwater-intrusion problems in coastal aquifers. Anthropogenic effects on saltwater intrusion such as changes in land use and landscape vegetation cover, groundwater pumping patterns, and the amount of pumping are also discussed. Finally, remedies, control and management of saltwater intrusion such as implementation of recharge wells, creation of artifi cial recharge basins, and construction of barriers are discussed. This chapter is expected to be useful to agricultural communities of coastal plains whose irrigation water is solely dependent on groundwater resources. It may also be of interest to individuals working in coastal-watershed and land-management businesses and governmental or local decision makers by addressing the problem of saltwater intrusion into coastal aquifers and its possible remediation and control techniques.

Carbon dioxide emission in relation with irrigation and organic amendments from a sweet corn field

ABSTRACT Soil moisture and organic matter level affects soil respiration and microbial activities, which in turn impact greenhouse gas (GHG) emissions. This study was conducted to evaluate the effect of irrigation levels (75% [deficit], 100% [full], and 125% [excess] of reference crop evapotranspiration requirements), and organic amendments (OA) type (chicken manure [CM] and bone meal [BM]) and OA application rates (0,168, 336 and 672 kg total N ha−1) on (i) soil physical properties (bulk density, organic matter content and soil moisture content) and (ii) soil carbon dioxide (CO2) emissions from a highly weathered tropical Hawaiian soil. Carbon dioxide readings were consistently taken once or twice a week for the duration of the cropping season. A drip irrigation system was used to apply the appropriate amount of irrigation water to the treatment plots. Treatments were randomly selected and corresponding organic amendments were manually incorporated into the soil. Plots were cultivated with sweet corn (Zea mays ‘SS-16’). Soil moisture content within and below the rootzone was monitored using a TDR 300 soil moisture sensor (Spectrum Technologies, Inc., Plainfield, IL, USA) connected with 12 cm long prongs. Soil bulk density and organic matter content were determined at the end of the cropping season. Analysis of variance results revealed that OA type, rate, and their interaction had significant effect on soil CO2 flux (P < 0.05). Among the OA rates, all CM mostly resulted in significantly higher soil CO2 fluxes compared to BM and control treatment (p < 0.05). The two highest rates of BM treatment were not significantly different from the control with regard to soil CO2 flux. In addition, organic amendments affected soil moisture dynamics during the crop growing season and organic matter content measured after the crop harvest. While additional studies are needed to further investigate the effect of irrigation levels on soil CO2 flux, it is recommended that in order to minimize soil CO2 emissions, BM soil amendments could be a potential option to reduce soil CO2 fluxes from agricultural fields similar to the one used in this study.