Applications of remote sensing, GIS, and groundwater flow modeling in evaluating groundwater resources: Two case studies; East Nile Delta, Egypt and Gold Valley, California, USA
Quaternary aquifer, East Nile Delta, Egypt. Due to the progressive increase in the development of desert land in Egypt, the demand for efficient water resources management and accurate land cover change information is increasing. In this study, we introduce a methodology to map and monitor land cover change patterns related to agricultural development and urban expansion in the desert fringes of the Eastern Nile Delta region. Using a hybrid classification approach, we employ multitemporal Landsat TM/ETM+ images from 1984, 1990, and 2003 to produce three land cover/land use maps. Post-classification comparison of these maps was used to obtain “from-to” statistics and change detection maps. The change detection results show that agricultural development increased 14% through the study period. Land reclamation during 1990-2003 exceeded that during 1984-1990 by a factor of two, reflecting a systematic national plan for desert reclamation that went into effect. We find that the increase in urbanization (by ∼21,300 hectares) during 1990-2003 was predominantly due to encroachment into traditionally cultivated land at the fringes of urban centers. Our results accurately quantify the land cover changes and delineate their spatial patterns, demonstrating the utility of Landsat data in analyzing landscape dynamics over time. Such information is critical for making efficient and sustainable policies for resource management.
A three dimensional GIS-based groundwater flow model was developed to delineate a safe future framework for groundwater development in the Quaternary aquifer north Ismaelia Canal, East Nile Delta where a progressive rise in head associated with agricultural development is reported. The calibrated transient model was used to predict the future head distribution after 20 years assuming the same landuse. Results of this run showed that the groundwater head continued to increase with maximum increase up to 2.0 m in the unconfined part of the aquifer which jeopardizes a considerable area of the agricultural land with soil salinity and water logging. Therefore, three strategies, each with three scenarios, extending between 2004 and 2024 were designed to involve different pumping stress and infiltration rates from irrigation return to control the rising water level and estimate the production potential of the aquifer during drought.
Gold Valley, Death Valley, California, USA. This study evaluates the hydrogeology of Gold Valley as a typical example of intermountain basins of Death Valley area and develops a GIS-based model that reasonably estimates the precipitation infiltration rates from altitude and slope data of the catchment area. Water balance calculations of the hydrological parameters in Gold Valley, provided by Inyo County, California, indicated that the majority of recharge takes place at high altitude (>1100 m) during winter with a negligible effect of evaporation on the stable isotopic composition of groundwater. Furthermore, water balance calculations in Gold Valley were utilized in identifying the coefficients of a GIS-based model that subsequently was refined to the best fit with the calculations of the water budget. A resistivity survey conducted in Gold Valley showed that groundwater is collected in upstream compartmentalized reservoirs and suggests that groundwater flow mostly takes place through the fracture zone of the bedrock. This pattern explains the relationship between precipitational infiltration in the Gold Valley catchment area and the attachment spring flow in Willow Creek.
The estimated water budget in Gold Valley and the geoelectric profiles provided from this study can be investigated into the Death Valley Regional Groundwater Flow model (DVRGWF). In addition, the GIS-based model can be efficiently applied in other intermountain basins in Death Valley or other areas of arid environment of the Western U.S. to estimate the local precipitational infiltration. Accurate estimates of flux, well defined flow systems, and locations of recharge/discharge in mountain ranges provide essential parameters that can enhance the performance of the DVRGWF model and consequently its prediction capability. (Abstract shortened by UMI.)
0799: Remote sensing