Geospatial Techniques, a Superlative Method to Assess Urban Heat Island Intensity: The Case of Abuja Municipal, Nigeria

Most cities around the world, including Abuja Municipal are being faced with an undesirable increased in air temperature. This is indicated by an increase in non-porous, non-evaporating, highly thermal conductive surfaces such as concrete and asphalt, which has replaced the vegetation biomass resulting to the formation of urban heat island. There is an increasing need for studies on the changing trend of UHI intensity in cities. This research employed geospatial techniques to determine the urban heat island intensity in Abuja Municipal. Temperature characteristics over twenty selected rural and urban locations in Abuja, FCT were derived from the satellite image of 1986, 2001 and 2016 using the “Extract Multi Values to Point” tool in ArcGIS 10.4. These transects pass over various landscapes with different environmental settings, with the aim of understanding the factors shaping the city’s thermal landscape. The intervals of +15 years were deliberately chosen to ensure uniformity between the datasets. The results of this analysis indicate that UHII has been increasing, from 1986-2016, giving credence to the results of the spatial and temporal analysis of the land surface temperature, indicating the development phases had hit full stride. The different periods under study (1986, 2001 and 2016) were also tested using the student “t” test to determine the significant difference in the land surface temperature values to acknowledge the presence of a substantial urban heat island within the study area. The result reveals the calculated “t” values of 2.50, 3.34, 5.57 of 1986, 2001 and 2016 respectively, are higher than the critical value of “t” at 0.05 being 1.73, thus, revealing the temperature differences between the urban and rural stations to be highly significant, indicating the presence of a strong urban heat island. Also, a slide difference in the temperature was observed with the Rubuchi and Karmajiji rural areas having higher temperature readings than their counterparts in the urban areas, Asokoro and Garki, with readings of −0.4°C and −1.3°C. Since effectiveness of a surface in reducing daytime urban air temperatures depends strongly on the amount of heating avoided, the study recommends preserving and replicating greenery, light coloured facades as measures to reduce the effects of urban heat island.

Modelling tropical cyclone risks for present and future climate change scenarios using geospatial techniques

Tropical cyclones and their devastating impacts are of great concern to coastal communities globally.An appropriate approach integrating climate change scenarios at local scales is essential for producing detailed risk models to support cyclone mitigation measures.This study developed a simple cyclone risk-modelling approach under present and future climate change scenarios using geospatial techniques at local scales,and tested using a case study in Sarankhola Upazila from coastal Bangladesh.Linear storm-surge models were developed up to 100-year return periods.A local sea level rise scenario of 0.34 m for the year 2050 was integrated with surge models to assess the climate change impact.The resultant storm-surge models were used in the risk-modelling procedures.The developed risk models successfully identified the spatial extent and levels of risk that match with actual extent and levels within an acceptable limit of deviation.The result showed that cyclone risk areas increased with the increase of return period.The study also revealed that climate change scenario intensified the cyclone risk area by 5–10%in every return period.The findings indicate this approach has the potential to model cyclone risk in other similar coastal environments for developing mitigation plans and strategies.

Assessment of water resources in Yarmouk River Basin using geospatial technique during the period 1980–2020

It is common knowledge that Yarmouk River Basin(YRB)is shared between Jordan and Syria.Management of YRB trans-boundary water resources is attracting increasing interest because it is a strategic water resource for the riparian countries.Actually,lack of sharing information regarding hydrological flows and basin’s water management between partners’countries makes it difficult to distinguish between natural and man-made factors affecting the water body.Therefore,this study seeks to address and assess the main on-site changes that exert on YRB.Geospatial technique and arithmetic equations were combined to carry out an assessment of the changes on water resources in YRB.Data,information and field measurements of the basin were aggregated,compiled and presented to determine the extent of changes during the period 1980-2020.Remarkable findings showed that precipitation amount in the basin significantly declined during the period 1980-2020 in particularly after the year 1992.Pumping rate of groundwater was 550 x 103 m3/a,exceeding the basin’s safe yield.Draw down of static groundwater level over time approached the value of-3.2 m/a due to the over abstraction in the aquifer body.Additionally,the evaporation rate reached more than 99%in some regions in the basin.Moreover,the number of private wells has increased from 98 wells in 1980 to 126 wells in 2020,showing the excessive extraction of groundwater.These findings indicate that the study area is subjected to a considerable groundwater depletion in the near future due to extensive abstraction,continuous drilling of illegal wells and decreased annual precipitation under the shadow of the rapid population growth and continuous influx of refugees.Therefore,decision makers-informed scenarios are suggested in the development of water resource portfolios,which involves the combination of management and infrastructural actions that enhance the water productivity of the basin.Further studies are recommended to evaluate the on-site changes on water resources in YRB in collaboration with riparian countries and to establish monitoring system for continuous and accurate measurements of the basin.

Effectiveness of hybrid ensemble machine learning models for landslide susceptibility analysis:Evidence from Shimla district of North-west Indian Himalayan region

The Indian Himalayan region is frequently experiencing climate change-induced landslides.Thus,landslide susceptibility assessment assumes greater significance for lessening the impact of a landslide hazard.This paper makes an attempt to assess landslide susceptibility in Shimla district of the northwest Indian Himalayan region.It examined the effectiveness of random forest(RF),multilayer perceptron(MLP),sequential minimal optimization regression(SMOreg)and bagging ensemble(B-RF,BSMOreg,B-MLP)models.A landslide inventory map comprising 1052 locations of past landslide occurrences was classified into training(70%)and testing(30%)datasets.The site-specific influencing factors were selected by employing a multicollinearity test.The relationship between past landslide occurrences and influencing factors was established using the frequency ratio method.The effectiveness of machine learning models was verified through performance assessors.The landslide susceptibility maps were validated by the area under the receiver operating characteristic curves(ROC-AUC),accuracy,precision,recall and F1-score.The key performance metrics and map validation demonstrated that the BRF model(correlation coefficient:0.988,mean absolute error:0.010,root mean square error:0.058,relative absolute error:2.964,ROC-AUC:0.947,accuracy:0.778,precision:0.819,recall:0.917 and F-1 score:0.865)outperformed the single classifiers and other bagging ensemble models for landslide susceptibility.The results show that the largest area was found under the very high susceptibility zone(33.87%),followed by the low(27.30%),high(20.68%)and moderate(18.16%)susceptibility zones.The factors,namely average annual rainfall,slope,lithology,soil texture and earthquake magnitude have been identified as the influencing factors for very high landslide susceptibility.Soil texture,lineament density and elevation have been attributed to high and moderate susceptibility.Thus,the study calls for devising suitable landslide mitigation measures in the study area.Structural measures,an immediate response system,community participation and coordination among stakeholders may help lessen the detrimental impact of landslides.The findings from this study could aid decision-makers in mitigating future catastrophes and devising suitable strategies in other geographical regions with similar geological characteristics.

Spatiotemporal variability of channel and bar morphodynamics in the Gorai-Madhumati River,Bangladesh using remote sensing and GIS techniques

Bangladesh is a riparian country that is criss-crossed by the many tributaries and distributaries of the mighty Ganges,Brahmaputra,and Meghna river systems.Gorai-Madhumati,a distributary of the Ganges River is an example where morphological development of the river is associated with frequent channel shifting within the catchment area.The main objective of this research is to quantify the extent of channel migration,erosion-accretion,river width,sinuosity,and charland morpho-dynamics from 1972 to 2018 using geospatial techniques combined with satellite images and hydrological data.The study also addressed the impacts of Farakka Barrage construction in India on the shifting,flow behavior,and siltation of Gorai-Madhumati River.The study shows that bar surface areas have abnormally increased in both segments after 1975 due to the construction of Farakka Barrage.Water flow in the Gorai-Madhumati has dropped remarkably in the downstream and instigated huge sedimentation in this region.Analysis of the time series satellite images revealed that the morphology of the river channel experienced huge changes simultaneously with the changes in the seasonal flow and sedimentation all over the study period.Migration trend has frequently shifted and taken place in the NW and NE direction in the observed sections of the river.Throughout the study period,total amount of accretion was greater than the net percentage of erosion on both banks of the river.River discharge,bar accretion,and erosion history show that the Gorai-Madhumati River will no longer exist with the present flowing condition without attention and proper river management.