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.

Landscape controls of surface-water/groundwater interactions on shallow outwash lakes: how the long-term groundwater signal overrides interannual variability due to evaporative effects

The spatial and temporal controls on variability of the relative contributions of groundwater within and between flow systems to shallow lakes in the low-relief glaciated Boreal Plains of Canada were evaluated. Eleven lakes located in a coarse glacial outwash, of varying topographic positions and potential groundwater contributing areas, were sampled annually for stable O and H isotope ratios over the course of 8 years. It was demonstrated that landscape position is the dominant control over relative groundwater contributions to these lakes and the spatial pattern of the long-term isotopic compositions attributed to groundwater overrides interannual variability due to evaporative effects. Lakes at low landscape positions with large potential groundwater capture areas have relatively higher and more consistent groundwater contributions and low interannual variability of isotopic composition. Isolated lakes high in the landscape experience high interannual variability as they have little to no groundwater input to buffer the volumetric or isotopic changes caused by evaporation and precipitation. An alternative explanation that lake morphometry (area and volume) control long-term isotopic compositions is tested and subsequently refuted. Landscape position within coarse outwash is a strong predictor for relative groundwater input; however, surface-water connections can short circuit groundwater pathways and confound the signal. A hydrogeological case study for three of the study lakes is used to contextualize and further demonstrate these results.

Estimation of Dar-Zarrouk parameters and delineation of groundwater potential zones in Karlahi, part of Adamawa Massif, Northeastern Nigeria

Karlahi is largely underlain by granites and migmatites gneiss of the Adamawa Massif. The area lies west of Benue Trough and east of Cameroon volcanic line. The aim of this paper is to determine hydraulic properties of water bearing layer using parameters derived from Dar-Zarrouk equation and characterized them into groundwater potential zones. The resistivity values of the weathered and slightly weathered layers which make up the water bearing layers were added and an average was taken and used as the resistivity of the water bearing formation in computation of Dar-Zarrouk parameters in Karlahi area. The values of resistivity of water bearing formation ranged from 18 to 4963 Ωm with an average resistivity value of 549 Ωm and the thickness of the water bearing formation ranges from 21 to 32 m with an average thickness of 24.5 m. Conductivity values range from 0.000201 to 0.05509 (σ) while the longitudinal conductance range from 0.00483 to 1.2363 Ω-1, the transverse resistance ranges from 407 to 123504.3 Ωm2. The hydraulic conductivity and transmissivity values range from 0.14 to 25.87 m/day and 3.28 to 580.4 m2/day respectively. The longitudinal conductance values in Karlahi area revealed poor to good with an average longitudinal conductance value that is moderate. High transverse resistance values are located in the central and southern part of Karlahi area while low values are located in the eastern part. The spatial distribution map of transmissivity in the area revealed moderate to high transmissivity values in the north central part and a negligible to low transmissivity in southern part, extreme northeastern part. The groundwater potential map of Karlahi area shows negligible to weak potential groundwater zones in SW and SE, moderate potential in the central to northern part of Karlahi area.

Evaluating The Groundwater Potential of Wadi Al-Jizi, Sultanate of Oman By Intergrating Remote Sensing & GIS Techniques

Groundwater resources are highly stressed due to their overuse, especially in the arid region. This study is aimed at discovering potential groundwater resource zones using currently available data and state-of-the-art methods. This will lead to effective management of scarcely available and rapidly depleting groundwater resources in the Wadi Al-Jizi catchment, located in the Al-Batinah region. Data on terrain characteristics, geology, and geomorphology was integrated using remote sensing techniques and Geographical Information System (GIS). The result from this exercise was used for the identification of areas with a high potential for groundwater availability. These areas were classified into five types; namely; excellent, good, medium, low, and very low. The present study shows that the integration of all the weighted parameters shows promising results in the zonation of groundwater. This study shall be useful to the decision-makers in highlighting potential drilling as well as recharge sites in the area.

An Approach to Delineate Potential Groundwater Zones in Kilinochchi District, Sri Lanka, Using GIS Techniques

The scarcity of surface water resources in the dry season in the Kilinochchi district increases the demand for freshwater. Therefore, the existing groundwater resources should be managed to overcome the situation. Several authors worldwide have published studies on the delineation of potential groundwater zone. However, only a few studies addressed the delineation of potential groundwater zones in the Kilinochchi district. This study aims to delineate potential groundwater zones in Kilinochchi, Sri Lanka using integrated Remote Sensing, Geographic Information Systems, and Analytic Hierarchy Process techniques. Groundwater potential zones are demarcated for the Kilinochchi district by overlaying thematic layers: geology, geomorphology, land use/land cover, soil types, drainage density, slope, lineament, and rainfall. Saaty's scale was applied to the assigned weights of the chosen thematic layers and their features. The thematic layers were integrated into a Geographic Information System, and a weighted overlay analysis is carried out to delineate groundwater zones. Thus the resultant map is categorized into five different potential zones: very low, low, moderate, high, and very high. It was found that the very high groundwater potential zone is mainly found in the north-eastern part of the study area covering 111.26 km2. The upper north-western, middle, and eastern parts of the study area fall within the high groundwater potential zone covering about 507.74 km2. The moderate groundwater potential zones (309.89 km2) mainly occurred in the western part, and the extreme west part of the study area falls under low (207.78 km2) and very low (59.12 km2) zones. The groundwater potential map was validated with the existing seventy-nine wells, which indicated a good prediction accuracy of 81.8%. This research will help policymakers better manage the Kilinochchi district's groundwater resources and gives scope for further research into groundwater exploration in the area.

Modelling groundwater recharge, actual evaporation and transpiration in semi-arid sites of the Lake Chad Basin: The role of soil and vegetation on groundwater recharge

The Lake Chad Basin, located in the center of North Africa, is characterized by strong climate seasonality with a pronounced short annual precipitation period and high potential evapotranspiration. Groundwater is an essential source for drinking water supply as well as for agriculture and groundwater related ecosystems. Thus, assessment of groundwater recharge is very important although difficult, because of the strong effects of evaporation and transpiration as well as limited available data. A simple, generalized approach, which requires only a small number of field data, freely available remote sensing data, and well-established concepts and models, is tested for assessing groundwater recharge in the southern part of the basin. This work uses the FAO-dual Kc concept to estimate E and T coefficients at six locations that differ in soil texture, climate, and vegetation conditions. Measured values of soil water content and chloride concentrations along vertical soil profiles at these locations together with different scenarios for E and T partitioning and a Bayesian calibration approach are used to numerically simulate water flow and chloride transport. Average potential groundwater recharges and the associated model uncertainty at the six locations are assessed for the time-period 2003–2016. Model results show that interannual variability of groundwater recharge is generally higher than the uncertainty of the modelled groundwater recharge. Furthermore, the soil moisture dynamics at all locations are limited by water availability for evaporation in the uppermost part of the soil and by water uptake in the root zone rather than by the reference evapotranspiration.