Analysis of Small Hydropower Generation Potential: (1) Estimation of the Potential in Ungaged Basins

Abstract

Small hydropower (SHP) plants are advantageous as they have a short construction period and can be easily maintained. They also have a higher energy density than other alternative energy sources as environmentally-friendly energy sources. In general, hydropower potential is estimated based on the discharge in the river basin, and the discharge can be obtained from the stage station in the gaged basin. However, if there is no station (i.e., ungaged basin) or no sufficient discharge data, the discharge should be estimated based on rainfall data. The flow duration characteristic model is the most widely used method for the estimation of mean annual discharge because of its simplicity and it consists of rainfall, basin area, and runoff coefficient. Due to the characteristics of hydroelectric power depending on the discharge, there is a limit to guaranteeing the accuracy of estimating the generated power with only one method of the flow duration characteristic model. Therefore, this study assumes the gaged basins of the three hydropower plants of Deoksong, Hanseok, and Socheon in Korea exist as ungaged basins and the river discharges were simulated using the Kajiyama formula, modified-TPM(Two-Parameter Monthly) model, and Tank model for a comparison with the flow duration characteristics model. Furthermore, to minimize the uncertainty of the simulated discharge, four blending techniques of simple average method, MMSE(Multi-Model Super Ensemble), SMA(Simple Model Average), and MSE(Mean Square Error) were applied. As for the results, the obtained discharges from the four models were compared with the observed discharge and we noted that the discharges by the Kajiyama formula and modified-TPM model were better fitted with the observations than the discharge by the flow duration characteristics model. However, the result by the Tank model was not well fitted with the observation. Additionally, when we investigated the four blending techniques, we concluded that the MSE technique was the most appropriate for the discharge simulation of the ungaged basin. This study proposed a methodology to estimate power generation potential more accurately by applying discharge simulation models that have not been previously applied to the estimation of SHP potential and blending techniques were also used to minimize the uncertainty of the simulated discharge. The methodology proposed in this study is expected to be applicable for the estimation of SHP potential in ungaged basins.

Analysis of Small Hydropower Generation Potential: (2) Future Prospect of the Potential under Climate Change

“…The discharge was calculated using several runoff formulas and hydrologic models and blending techniques have been proposed to reduce the uncertainty of the results and to increase the usability of the results in the first part of the serial study. A previous study (Jung et al, 2021) confirmed that it is possible to estimate the reliable SHP potential through the application of the discharge simulation and blending technique that uses meteorological data even in ungauged basins without discharge data [8].…”

“…To calculate the potential, it is necessary to prepare standard coefficients for the number of resources (natural environmental conditions), geographic conditions, technical elements (e.g., energy efficiency, operation rate, and collection rate), environmental performance, and technological progress through long-term data accumulation. Many studies have been conducted on the estimation of the SHP potential [8].…”

“…To this end, calculating the accurate runoff is most important. In the first part of the serial study, Jung et al (2021) proposed a method of improving the accuracy of discharge data by applying four blending techniques after calculating the discharge using the Kajiyama formula, the modified-TPM model that calculates the runoff using hydro-meteorological data, and the Tank model that calculates the runoff based on the rainfall-runoff process [8]. For the next step, the SHP potential under climate change was predicted based on the results of Jung et al (2021) on the calculation of the SHP potential in ungauged basins in this study [8].…”

“…The flowchart of the serial study is shown in Figure 1. Part I shows the flow of the previous study [8], and part II shows the flow of this study.…”

Conjunctive Operation of Sand Dam and Groundwater Well for Reliable Water Supply during Drought Conditions

“…References [33][34][35] compared the Kajiyama formula and TPM in terms of the accuracy of runoff estimation. They analyzed the performance of the models against the observed data.…”