Quantifying and mapping of water-related ecosystem services for enhancing the security of the food-water-energy nexus in tropical data–sparse catchment

• Published in: The Science of the total environment 2019-01, Vol.646, p.573-586
• Main Authors: Sahle, Mesfin, Saito, Osamu, Fürst, Christine, Yeshitela, Kumelachew
• Format: Article
• Language: English
• Subjects: Africa, Eastern; Ecosystem; Environmental Monitoring - methods; InVEST; Quickflow; Rivers; Sediment retention; Tropical Climate; Water demand; Water management; Water yield
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.07.347

The food-water-energy nexus concept helps to produce an integrative solutions to secure the water-related ecosystem services sustainably. This study aims to quantify and map water provisioning and soil erosion regulating services from both demand and supply sides in a spatially explicit manner. It considers the Wabe River catchment of the Omo-Gibe Basin in tropical data-sparse region of East Africa as a case study and uses the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) annual and seasonal water yield and sediment delivery models. The water demands and biophysical parameters data were collected from primary and secondary sources and prepared according to the requirement of the models. The models output were validated after conducting sensitivity analysis of the input parameters. The result shows that the rainfall amount of the catchment is highly seasonal, which causes the surface water to vary according to the seasons. The high annual precipitation and low actual evapotranspiration of the catchment resulted high annual water yields. However, the people in the catchment did not satisfied their domestic water demand as result of inaccessibility and poor management of the rain water. The high net supply of water, especially in the rainy season, carries detached top soil via heavy rainfall in the upper catchment areas. Even though the existing land cover and management practices contribute to sediment retention, a large amount of sediment is exported to rivers, which jeopardizes the food and energy security. Thus, the management of water is essential for enhancing the security of the food-water-energy nexus in the catchment. The methods applied in this study can increase spatial understanding of the water-related ecosystem services especially in data–sparse catchments of the tropics, and lead to improvement of water management to enhance the security nexus. [Display omitted] •Losses in regulating capacities of ecosystem could lead to insecure the nexus food-water-energy.•High annual water yield catchment may not satisfy the community’s demand for water.•Loss of soil due to climatic factors can be prevented through cover and land management.•Management of water have a central role to improve the security of the nexus.•The net budgets of water-related ecosystem services can be quantified and mapped in data–sparse catchments.