ASSESSING THE VALUE OF GROUNDWATER REVENUES AND DETERMINATION OF OPTIMUM RATES IN MAKASSAR CITY

Ground water is defined as water that is in the ground and is water that moves and is present in the spaces between the grains of soil that make it up and rock crevices, where the initial part is called layer water and the latter is called fissure water. Water is one of the natural elements that are needed in the life activities of living things, especially humans. The purpose of this study is to assessing the value of groundwater revenues and determine of optimum rates in Makassar City. Data analysis method used is the analysis of groundwater value by referring to the Minister of Energy and Mineral Resources Regulation No.20 of 2017 concerning Guidelines for Establishing Groundwater Revenue Value and the marginal cost pricing method. The results showed that the average revenue of groundwater in Makassar City was IDR.690,276,939.35 with an average tax of IDR.138,055,387.87. The value of groundwater is quite high when compared to the revenue value of groundwater that has been determined by the Makassar City government at this time. The results of determining the optimum rates obtained for the user group 1 is IDR.9,661.96 per m3 per month, the user group 2 is IDR.13,973.63 per m3 per month, the user group 3 is IDR.10,866.67 per m3 per month, and the user group 4 is IDR.4,255.56 per m3 per month. Whereas the beneficiary group 5 has a higher average groundwater utilization cost when compared to the PDAM water rates. The results of research can become policy basis of the Makassar City local government in determining the value of groundwater.

The cost of ending groundwater overdraft on the North China Plain

Overexploitation of groundwater reserves is a major environmental problem around the world. In many river basins, groundwater and surface water are used conjunctively and joint optimization strategies are required. A hydroeconomic modeling approach is used to find cost-optimal sustainable surface water and groundwater allocation strategies for a river basin, given an arbitrary initial groundwater level in the aquifer. A simplified management problem with conjunctive use of scarce surface water and groundwater under inflow and recharge uncertainty is presented. Because of head-dependent groundwater pumping costs the optimization problem is nonlinear and non-convex, and a genetic algorithm is used to solve the one-step-ahead subproblems with the objective of minimizing the sum of immediate and expected future costs. A real-world application in the water-scarce Ziya River basin in northern China is used to demonstrate the model capabilities. Persistent overdraft from the groundwater aquifers on the North China Plain has caused declining groundwater levels. The model maps the marginal cost of water in different scenarios, and the minimum cost of ending groundwater overdraft in the basin is estimated to be CNY 5.58 billion yr−1. The study shows that it is cost-effective to slowly recover the groundwater aquifer to a level close to the surface, while gradually lowering the groundwater value to the equilibrium at CNY 2.15 m−3. The model can be used to guide decision-makers to economic efficient long-term sustainable management of groundwater and surface water resources.