Author(s): Philip Nti Nkrumah
Linked Author(s):
Keywords: Frica; ASTER remote sensing; Atmospheric correction; Feasibility analysis; Water quality monitoring
Abstract: The traditional in-situ water quality monitoring methods that are normally used in Africa are complex with low spatial and temporal coverage. This results in inadequate estimation of the conditions in water bodies. These methods are also time consuming and expensive. However, the quality of inland water bodies in Africa continuous to deteriorate rapidly in varying degrees due to the enormous anthropogenic pressure on these water bodies. This has made water quality issues one of the crucial challenges to water management in Africa. Hence, there is the need for improved water quality monitoring techniques to ensure effective monitoring which is critical for water management and sustainability. Fortunately, remote sensing (RS) technique is a potential tool for monitoring inland water quality and other environmental phenomena. This technique provides efficient monitoring because it offers an opportunity for data collection on systematic, synoptic and temporal scales. The present study sought to assess the feasibility of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) RS technique in the effective monitoring of inland water quality in Africa. Specifically, a simplified step-by-step approach for the quantification of suspended particulate matter (SPM) concentrations in water bodies using the Integrated Land and Water Information System was presented. The study showed that water leaving reflectance (WLR) could be determined after a series of processes that included atmospheric correction. Once the WLR have been obtained, appropriate models could be employed to retrieve the spatial distribution of the concerned water quality parameters such as chlorophyll-a. For instance, the present study adopted the radiative transfer model to illustrate the retrieval of the spatial distribution of SPM concentrations. It was found that for SPM retrieval in inland water bodies, it is recommended to use band 2 for the ASTER data processing. This is because this band is where the sensitivity to suspended sediment concentration is high, while effects e. g. by chlorophyll and organic particles are limited. It must be emphasized that the focus on ASTER RS techniques used in this study lies in the fact that the high spatial resolution of ASTER has advantages for studying small aquatic areas, such as bay and lakes. This makes it highly applicable for the situation in Africa. It was evident in this study that ASTER RS is feasible in ensuring proper water quality monitoring in Africa. Hence, this technique could be taken as an independent measurement tool for effective water management in Africa and other parts of the world with similar challenges.
Year: 2013