Floodplain Mapping and Risks Assessment of the Orashi River Using Remote Sensing and GIS in the Niger Delta Region, Nigeria

Abstract

Residents along the shoreline of the Orashi River have yearly been displaced and recorded loss of lives, farmland, and infrastructures. The Government’s approach has been the provision of relief materials to the victims instead of implementing adequate control measures. This research employs Shuttle Radar Topographic Mission and Google Earth imagery in developing a 3D floodplain map in ArcGIS 10.4. The result indicates the drainage system in the study area is observe to be dendritic with catchment of 79 subbasin with 76 pour point indicating the area is floodplain including 3D slope > 8 contain 1.15% and < 8 has 98.85% indicating floodplain area, aspect indicate west-facing slope are dark blue,3D hillshade indicate yellow is very low area and high area is pink and also the buffer analysis result reveals waterbodies reflecting blue with estimated area of 1.88 km2, yellow indicate 0.79 km2 of the shoreline, red indicate 0.81 km2 of the minor floodplain and pink contain 0.82 km2 with length of 32.82km. The result from google earth image in 2007 indicate absent of settlement ,2013 indicate minimal settlement and 2020 indicate major settlement in the study area when correlated with 3D Floodplain mapping before and during the flood in other to analyze and manage flooding for further purpose and majority of the area are under seize with flood like in 2020. Therefore, Remote Sensing and GIS techniques is useful for Floodplain mapping, risk analysis for control measures for better flood management.

GIS & Remote Sensing Based Morphometric Parameters and Topographic Changes of the Lower Orashi River in Niger Delta

“…in addition, the area is accessible by roads and the river and lies between longitude 006 0 20'0 and 006 0 40'0 "East and latitude 04 0 50'0" and 05 0 10'10" North in the Niger Delta (Figure 1), with altitude below sea level on the region 39 m further inland [4] . The average rainfall and temperature of the area are 2,899 mm and 26.7°C [3] . Several settlements in the area are close to hydrocarbon flow stations owned by the SPDC and NAOC, and the area is drained by tributaries that connect to the lower Orashi River [5] geologically described the research area as the south-western flank of the Niger Delta Region.…”

“…rains. According to Eteh and Okechukwu [3] proper planning and management of the flood situation is essential to avoid major effects on flooding during the rainy season in the Niger Delta. It is therefore important to study the terrain of the area by investigating the hydrological property and the depth of the river to monitor the statue of the area, especially in terms of the drainage system, making decisions for the construction of structures mainly along the riparian communities and including roads, agriculture, buildings construction, Because most of the topography has poor drainage system due to lack of planning, structures and roads are built on drainage canals, resulting in flooding during the rainy season.…”

“…Consequential environmental impacts such as flooding, erosion, etc. have been detected and monitored using remote sensing and geographic information system (GIS) technologies [3] . This study focuses on the morphometric evaluation of the Lower Orashi River to comprehend the drainage basins by assessing their morphometric values, which incorporate the state of the morphometric framework including the shape of the basin, the length of the stream, the area, the stream order, the length of stream segments, bifurcation ratio, density of drainage, and frequency.…”

Shoreline Change Assessment in the Orashi River, Rivers State, Nigeria, using the Digital Shoreline Analysis System (DSAS)

“…The complexity and dynamic nature of environmental and social processes in coastal areas make shoreline change particularly impactful on both the environment and human communities. In the context of Nigeria, the Orashi River region stands out as a prime example of the intricate interplay between human activities and natural processes, making it a focal point for the study of shoreline change [3] Situated in the Niger Delta region of Nigeria, the Orashi River area is not only teeming with biodiversity but also holds immense economic importance due to its oil and gas resources, fisheries, and agricultural potential. Nevertheless, this region faces formidable challenges stemming from a growing population and anthropogenic activities such as urbanization, industrialization, and deforestation [3].…”

“…In the context of Nigeria, the Orashi River region stands out as a prime example of the intricate interplay between human activities and natural processes, making it a focal point for the study of shoreline change [3] Situated in the Niger Delta region of Nigeria, the Orashi River area is not only teeming with biodiversity but also holds immense economic importance due to its oil and gas resources, fisheries, and agricultural potential. Nevertheless, this region faces formidable challenges stemming from a growing population and anthropogenic activities such as urbanization, industrialization, and deforestation [3]. As a result, shoreline change analysis assumes a pivotal role in coastal protection planning, disaster management, sea-level rise assessments, hazard zone development, numerical method calibration, and the policy-making processes related to coastal development.…”