Water resources
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Onesmo Zakaria Sigalla
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30 June 2026
25
18
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Volume 3 Issue 1
Page 1 - 21
Valuing Water as an Economic Good in the Kilombero River Catchment, Tanzania: Where Does It Return the Most?
DOI:
https://doi.org/10.56542/wi.jwempo.v3.i1.a1.2026
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Keywords:
Computable General Equilibrium, Marginal Productivity of Water, Water Productivity, Water Allocation
Abstract
Across the world, the importance of water in production sectors is unparalleled. About 70% of freshwater withdrawals are used in agriculture, roughly 20% and 10% for industries and domestic uses respectively. These multiple strategic water users in a catchment such as Kilombero, presents managers with a daunting task to allocate the available water efficiently among sectors. This paper contributes to the knowledge of efficient water allocation mechanisms by evaluating water productivity (WP) and its marginal productivity (MP). The study employed summary statistics, water productivity metrics, correlation and regression methods for data analysis. The results revealed that WP for paddy and sugarcane are respectively 0.44Kg/m³ or 0.01US$/m³ and 6.18Kg/m³ or 0.10US$/m³, while hydropower generation yielded 2.05kWh/m³ or 0.19US$/m³. In addition, Sugarcane showed the highest MP, albeit elastic values over the years whereas, hydropower and paddy had lowest but more stable MP values. Notably, paddy exhibits diminishing returns observed post-2018. Despite the lowest WP of paddy compared to sugarcane, we advocate for prioritizing the former in water allocation due to its substantial contributions to the regional and local food and employment security. To enhance paddy production without additional water demand, implementation of an improved rainfed rice intensification system is recommended
