Modeling and mapping of the environmental carrying capacity of the Sebuku and Sesayap watersheds based on food and water provision

Abstract

Agricultural practices and water availability are highly correlated with sustainable watershed management. The Sebuku and Sesayap  watersheds have a role to play for water conservation and support for agricultural practices. The research aimed to investigate, assess  and map the carrying capacity of the environment in the supply of fresh water and food. The method is carried out using a mathematical  model, Simple Additive Weighting to calculate the area of each carrying capacity category using ArcGIS 10.7 programs. This ecosystem  service approach is used to measure carrying capacity. The approach is based on the assumption that the higher the performance of  ecosystem services, the higher the carrying capacity of the environment. Carrying capacity is the maximum number of populations that  can be sustainably supported by a local ecosystem, meaning that it has a carrying capacity and assimilation capacity. The results show  that the application of the Simple Additive Weighting model has advantages over the expert-based valuation method which has been  widely used, which proves convenience in the investigation and assessment process. Investigations and assessments show that the  function of the Sebuku and Sesayap watersheds as a food providers is dominated by high category areas (Iecc 3.41 – 4.20) with an area of  1,178,843.93 ha. Meanwhile, the Sebuku watershed is dominated by the medium category area (Iecc 2.61 - 3.40) with an area of  850,633.60 ha. In addition, the environmental carrying capacity of the downstream watershed area in providing fresh water tends to be  low (Iecc 1.81 – 2.60) even though the environmental carrying capacity of the downstream area as a food provider is high (Iecc 3.41 –  4.20), because these areas are generally fluvial plains and coastal plains which are used as pond cultivation areas. Overall, watershed  conditions tend to experience a decrease in carrying capacity, both in terms of providing food and fresh water. Therefore, to achieve  sustainable watershed management, it is necessary to use a food commodity-based water conservation approach with the application of  dry land agroforestry practices in the middle region, and silvofishery in the downstream area.