Application of Remote Sensing/GIS in Monitoring Typha spp. Invasion and Challenges of Wetland Ecosystems Services in Dry Environment of Hadejia Nguru Wetland System Nigeria

Abstract

Although, the threat posed by Typha invasion to wetland utilization has been widely acknowledged in the Hadejia Nguru wetlands, yet little or no monitoring has been done to quantify the extent and time analysis of the threat.  Remote sensing and GIS techniques were used in this study to monitor the Spatio-temporal dynamics of Typha spp. invasion in the dry environment of the Hadejia Nguru Wetlands of NE Nigeria. Satellite images of Band 1, 2, 3, and 4 from Landsat ETM+ were acquired between 2003 and 2015 and natural color from GeoEye-1 in 2016 where image classification, change detection and spatial statistics were performed. To evaluate the impact of Typha grass on the livelihood of the people, a field investigation involving administration of 200 questionnaires was conducted among the two major wetland users: the farmers and the fishermen. The result from the RS/GIS revealed that Typha grass recorded an astronomical growth of 1013% between 2003 and 2009 and another incremental of 32% in 2015. The ANOVA test on land cover change in 2003, 2009 and 2015 showed a significant variation in land cover and use changes at p < 0.05. The findings from field survey showed that Typha grass accounted for 70% decrease in land available for farmland and subsequent reduction in crop output by 90%. It also accounted for 80% reduction in total fish caught as compared to non Typha infested land and open water. Strategic and selective weeding by mechanical and manual techniques was therefore suggested as control measures to save the wetland ecosystem and wetland users’ livelihood.