INTEGRATED GEOPHYSICAL MAPPING OF GROUNDWATER AQUIFER FOR SPATIAL DISTRIBUTION OF GROUNDWATER DEVELOPMENT IN IPERINDO AND ITS ENVIRONS, SOUTHWESTERN NIGERIA

Assessment of groundwater potential of Iperindo area, Southwestern Nigeria was conducted by mapping spatial distribution of groundwater availability within the area and consequently locating areas of groundwater reserve to serve the community and its environs. This was achieved by integrating geophysical techniques involving landsat ETM-7 satellite data, aeromagnetic data, VLF-EM and electrical resistivity methods to delineate subsurface structures, understand the direction of groundwater flow, and detect the depth to groundwater aquifer. The result of landsat and aeromagnetic revealed some lineament intersection approximately NE-SW direction and interpreted to be potential sites for groundwater development. VLF-EM revealed geologic structures of significant hydrogeological importance at depths of 40 m to 200 m. Vertical electrical sounding (VES) confirmed high groundwater prospect in the areas with estimated depth to water table between 30 m and 100 m. The integrated results of the study revealed adequate groundwater spatial distribution for effective groundwater development in the area.

Determination of Priority Areas for Groundwater Development by Using the Analytic Hierarchy Process Method in Rote Island

This study aims to determine other exploration targets related to priority areas for groundwater utilization development on Rote Island. In arranging priority areas for groundwater development, remote sensing data and Geographical Information Systems (GIS) are integrated with the Analytic Hierarchy Process (AHP) method. The parameters used are lineament (F), lithology (L), slope (T), drainage density (D), and rainfall (R). F, T, and D were obtained from DEM map analysis. L was obtained from regional geological maps. Moreover, R was obtained from annual rainfall data from the rain station of the study area. All parameters were overlaid using GIS and assign weights using the AHP method. The results will be compared to the locations of springs and wells scattered in the study area. There are five classifications of potential groundwater areas on Rote Island, namely very high is 34 km2 in the East part; high is 383.25 km2 in the South, East, and Northeast part; moderate is 549.50 km2 in the North and South part; low is 246.50 km2 and very low is 2.198 km2 in the West part of the research area. Considering the existing observation springs in Rote Island using average yields in each classification area confirms the correctness of the potential groundwater areas.

Cooperation in hydrogeophysics: Enhancing practitioners and institutions′ groundwater assessment capacity, Vientiane Plain, Lao PDR

The lowland floodplains of the Lao PDR experience prolonged dry seasons characterized by pronounced and common water scarcity, with water supplies increasingly offset with groundwater. Groundwater assessment is still at a very rudimentary stage in Laos, making it difficult to ensure that new water supplies are developed successfully and managed sustainably. The goal of this study was to apply a variety of field hydrogeophysical techniques to this problem, and in the process, help build and strengthen human and institutional capacity with various stakeholder groups from government, university and the community. The study area focused on a cross-section of the Vientiane Plain in the Lower Mekong Basin in central Lao PDR to identify and characterize the hydrogeology and groundwater quality. The research collaboration built and strengthened stakeholder capacity by developing and progressing the hydrogeological field mapping of the Vientiane Plain. It provided local undergraduate and postgraduate training opportunities using several different near-surface geophysical and hydrogeological techniques; some previously untested in Lao PDR. At one of the survey sites, the geophysics showed the spatial extent of the shallow aquifer, and in the process identified an extensive conductive zone, interpreted as more saline groundwater. Any groundwater development within this or similar zones is likely to be unsuitable as sources for drinking and irrigation water. Engagement with the local village authorities supported local community members and government to expand groundwater development for rural water supplies. Access to groundwater as a reliable, safe and secure resource provides an opportunity to strengthen the resilience of farmers to changing climatic conditions. Participatory research collaboration of this kind can positively enhance data and build capacity, which is a required precursor for improving knowledge and management of poorly understood groundwater resources.

Groundwater development, use, and its quality in Korea: tasks for sustainable use

In this study, the current state of groundwater development and use and groundwater quality has been examined based on official groundwater data collected from the Republic of Korea. The groundwater data indicate a steady increase in the number of groundwater wells and an increase in groundwater pumping. The well diameters also increase with increasing well depth, owing to the development of drilling technology. Although groundwater is predominantly used for agricultural and living purposes, the former has recently outnumbered the latter. According to the groundwater quality monitoring stations covering the entire country, the groundwater levels, dissolved oxygen, and oxidation–reduction potential decrease with a steady increase in the water temperature, pH, and electrical conductivity, indicating an aggravating groundwater environment in this region. The most concerning contaminants found are nitrate, ammonia, arsenic, zinc, toluene, xylene, chloroform, and fluoride. Thus, based on these observations, we propose three essential tasks for sustainable groundwater use: a paradigm shift in groundwater management, conjunctive use and integrated management of groundwater and stream water, and groundwater governance and data quality control.