Optimal Operation of Nashe Hydropower Reservoir under Land Use Land Cover Change in Blue Nile River Basin

Abstract

Changes in LULC (land use land cover), which significantly influence the spatial and temporal distribution of hydrological processes and water resources in general, have a substantial impact on hydropower generation. The utilization of an optimization approach in order to analyze the operation of reservoirs is an important concern in the planning and management of water resources. The SWAT (Soil and Water Assessment Tool) and the HEC-ResPRM (Hydrologic Engineering Center reservoir evaluation system Prescriptive Reservoir Model) were combined to model and optimize the Nashe hydropower reservoir operation in the Blue Nile River Basin (BNRB). The stream flow into the reservoir was determined using the SWAT model, considering the current and future impacts of LULC changes. The HEC-ResPRM model has been utilized in order to generate the optimal hydropower reservoir operation by using the results of the SWAT calibrated and validated stream flow as input data. This study proposes a method for integrating the HEC-ResPRM and SWAT models to examine the effects of historical and future land use land cover change on the watershed’s hydrological processes and reservoir operation. Therefore, the study aimed to investigate the current and future optimal reservoir operation scenarios for water resources management concerning hydropower generation under the effect of LULC changes. The results reveal that both the 2035 and 2050 LULC change scenarios show the increased operation of hydropower reservoirs with increasing reservoir inflows, releases, storage, and reservoir elevation in the future. The effects of LULC change on the study area’s hydrological components reveal an increase in surface runoff until 2035, and its decrease from 2035 to 2050. The average annual reservoir storage and elevation in the 2050 LULC scenario increased by 7.25% and 2.27%, respectively, when compared to the current optimized scenario. Therefore, changes in LULC have a significant effect on hydropower development by changing the total annual and monthly reservoir inflow volumes and their seasonal distribution. Reservoir operating rule curves have been commonly implemented in the operation of hydropower reservoirs, since they help operators to make essential, optimal decisions with available stream flow. Moreover, the generated future reservoir rule curves can be utilized as a reference for the long-term prediction of hydropower generation capacity, and assist concerned authorities in the successful operation of the reservoir under the impact of LULC changes.

Investigation of climate change impact on the optimal operation of koka reservoir, upper awash watershed, Ethiopia

“…With the exception of the inflow during the 2020s under the RCP4.5 scenario, the peak inflow has shifted from August during the reference period to September during the 2020s, 2050s, and 2080s periods. The result is also consistent with the findings of Abera et al [ 10 ]; Adera and Alfredsen [ 16 ], and Leta et al [ 52 ]. Therefore, climate change on the Koka reservoir will most likely increases the magnitude of the inflow and shift its temporal distribution.…”

“…(2) to Eq. (4) , which is a special form of linear programming algorithm in HEC-ResPRM to simulate the optimal solution of flow, storage, release, and hydropower [ 52 ].…”

Concern Condition for Applying Optimization Techniques with Reservoir Simulation Model for Searching Optimal Rule Curves

“…The impact of the initial reservoir capacity was considered by ranging from 10% of the capacity to the full capacity. The reservoir simulation model was integrated with an optimization technique to search for the optimal rule curves [81][82][83]. Following the optimization process, the obtained rule curves were subjected to an assessment to evaluate the occurrences of water shortage and excess release.…”

Parameter Uncertainty Analysis for Streamflow Simulation Using SWAT Model in Nashe Watershed, Blue Nile River Basin, Ethiopia

“…e Nashe watershed is the principal tributary and is mainly used for hydropower generation for the country. e watershed area is classified as having intensive irrigable fields downstream, huge water potential sites upstream, and a high head of hydropower potential [28]. Agriculture is the watershed's most important financial activity and the primary source of income for the local population.…”