Agricultural Reservoirs Research Articles

Assessment of Overflow Risk in Agricultural Reservoir Based on Water Balance Theory

The unexpected climate changes are causing rainfalls to exceed the design frequency, which complicates the management and operation of agricultural reservoirs and increases the risk of overflow. According to the “Planning and Design Standards for Agricultural Prediction Infrastructure Maintenance Project (Fill Dam Section),” agricultural reservoirs were originally designed without flood control functions, with the standard being to directly discharge incoming flood. Based on this foundation, this study assesses the overflow risk of agricultural reservoirs using the concepts of inflow and outflow theories as well as storage capacity. The balance when inflow and outflow are at their maximum was analyzed for prioritized areas, focusing on the flood management area (the area between the full water level and crest elevation) relative to the basin area, to examine the feasibility of balance through flood routing. The proposed method is easily accessible to facility managers, enabling them to assess the risk of reservoirs for efficient management and operation during floods.

Development and Applicability Assessment of an Hourly Water Level Prediction Model for Agricultural Reservoirs Using Automated Machine Learning

Objectives:This study aims to develop and evaluate hourly water level prediction models for agricultural reservoirs using an automated machine learning (AutoML) approach, specifically, employing TPOT.Methods:The study focuses on the Baekrok and Baekryeon reservoirs using rainfall forecast data from the Korea Meteorological Administration, along with observed rainfall and reservoir water level data. TPOT, which utilizes genetic algorithms to automate the generation of optimal machine learning pipelines, was used to build models. Additionally, Random Forest (RF) was implemented as a benchmark to evaluate TPOT’s applicability. Predictions were generated with lead times of 1, 3, 6, and 12 hours, and model accuracy was evaluated using the Nash-Sutcliffe Efficiency (NSE), coefficient of determination (R2), and root-mean-square error (RMSE).Results and Discussion:The predictions from both TPOT and RF showed high accuracy for shorter lead times, with NSE values exceeding 0.99 for the 1-hour predictions. However, predictive accuracy decreased as lead time increased, likely due to greater uncertainty in rainfall forecast data, particularly for the 12-hour predictions. Despite this trend, TPOT-derived models maintained more stable and accurate performance compared to RF models across all lead times.Conclusion:This study demonstrates the applicability of TPOT-based AutoML techniques in predicting hourly water levels in agricultural reservoirs. Future work should explore strategies to mitigate the decline in accuracy for longer lead times.

Assessing Irrigation Efficiency Improvements in Paddy Fields Using Granular SWMM Simulations

As water scarcity intensifies due to climate change, improving the efficiency of agricultural water use has become increasingly critical. Current irrigation systems often experience significant water losses, especially in paddy fields in South Korea that largely rely on open-channel water supply networks. However, previous studies have simulated irrigation improvement strategies by aggregating multiple paddy fields into larger unites rather than modeling them individually, which limits the accurate representation of field conditions. To address this limitation, we applied a granular simulation approach, collecting detailed input data through field surveys. Using this granular model, the study evaluated strategies to enhance irrigation efficiency in paddy fields serviced by the Baekma Agricultural Reservoir in South Korea. We assessed four scenarios: the current open-channel system, conversion of open channels to closed conduits, installation of farm ponds, and a combination of closed conduits and farm ponds. These scenarios were simulated using the Strom Water Management Model (SWMM), meticulously configured to represent individual paddy fields and channel networks. The results show that converting open channels to closed conduits increased irrigation efficiency by 5.4% compared to the current open-channel system. Combining closed conduits with farm ponds achieved the highest efficiency, although the independent effect of farm ponds was minimal. These findings suggested that converting open-channels to closed conduits was a highly effective solution for reducing water losses, while farm ponds played a limited role. This study provides valuable insights into the development of precise irrigation strategies, offering a detailed assessment of real-world conditions in paddy fields.

Trade-Off and Synergy Mechanism of Agricultural Water Resource Spatial Allocation in Monsoon Climate Areas Based on Machine Learning: A Case Study of Reservoir Layout Optimization in Shandong Province, China

Influenced by increasing global extreme weather and the uneven spatiotemporal distribution of water resources in monsoon climate areas, the balance of agricultural water resources supply and demand currently faces significant challenges. Conducting research on the spatial allocation trade-offs and synergistic mechanisms of agricultural water resources in monsoon climate areas is extremely important. This study takes the spatial layout of reservoir site selection in water conservancy projects as an example, focusing on Shandong Province as the research area. During the site selection process, the concept of water resource demand is introduced, and the suitability of reservoir siting is integrated. It clarifies ten influencing factors for suitability degree and five influencing factors for demand. A bi-objective optimization model that includes suitability degree and demand degree is established. Utilizing machine learning methods such as the GA_BP neural network model and the GA-bi-objective optimization model to balance and coordinate the supply and demand relationship of agricultural water resources in the monsoon region. The study found that: (1) in the prediction of suitability degree, the influencing factors are most strongly correlated with the regulatory storage capacity (regulatory storage capacity > total storage capacity > regulating storage coefficient); (2) compared with single-objective optimization of suitability degree, the difference between water supply and demand can be reduced by 74.3% after bi-objective optimization; (3) according to the spatial layout optimization analysis, the utilization of water resources in the central and western parts of Shandong Province is not sufficient, and the construction of agricultural reservoirs should be carried out in a targeted manner. This study provides new ideas for promoting the efficient use of water resources in monsoon climate zones and the coordinated development of humans and nature, reflecting the importance of supply and demand balance in the spatial allocation of agricultural water resources, reducing the risk of agricultural production being affected by droughts and floods.

A survey on the application of ICTs in automated water level gauges for agricultural reservoirs

A survey on the application of ICTs in automated water level gauges for agricultural reservoirs

Hydrological Analysis of Agricultural Reservoir Watersheds Based on Water Utilization System Using the Catchment Hydrology Cycle Analysis Tool Model

In this study, the catchment hydrology cycle analysis tool (CAT) model was used to conduct a comprehensive hydrological analysis of the water balance of agricultural reservoirs. Data from 2010 to 2017, including precipitation, water level data in the reservoir, groundwater usage, and wastewater discharge, were collected and compiled for the upper reaches of the Hantan River Dam. The current conditions and content curves of the 11 reservoirs within the watershed were investigated and recorded. The results were analyzed by simulating three scenarios: treating the entire watershed as 1 unit, dividing the watershed into 5 sub-watersheds according to the standard watershed criteria, and further subdividing it into 27 watersheds, taking into account the presence of agricultural reservoirs. In cases where watershed information is lacking, it is deemed that subdividing the watershed can enhance efficiency. The highest model efficiency was observed in the 27 sub-basins, particularly when accounting for agricultural reservoirs. This study proposed an efficient method for hydrological analysis of watersheds including ungauged areas.

Spatiotemporal patterns of water volume and total organic carbon concentration of agricultural reservoirs over South Korea

Lacking of available water quality data causes the limited understanding of the coupled dynamics of hydrologic and nutrient cycles in lakes and reservoirs and along river streams. This study conducts the rotated Principal Component Analysis (rPCA) of water volume and total organic carbon (TOC) concentration data from ∼2200 agricultural reservoirs in South Korea to extract the major modes of their spatiotemporal variability. Over 2020–2022, the total TOC load in the reservoirs ranges between 1,165 and 1,492 tons (289 and 360 Mtons of water storage volume; 3.54 and 4.60 mg/L of TOC concentration). The first rPCA mode is assoicated with a decreasing trend of water level (38 % of the explained variance) and increasing trend of TOC concentration (27 %) over the southern Korea region, where the TOC concentration increased during the 2022 drought. The second rPCA mode is associated with interannual variability of water level (25 %) and TOC concentration (18 %) over the central Korea region. This study found a marginal relationship between paddy field area and TOC concentration and their regime shift to high TOC concentration during the 2022 drought, which was a potential cause of the increased TOC concentration in 2022. This study provided observational evidence of interactions between water volume and TOC concentration during a severe drought, suggesting a possible shift of the role of agricultural reservoirs to carbon source.

Shading solutions for sustainable water management: impact of colors and intensities on evaporation and water quality

This study investigated the effectiveness of suspended shade covers in reducing evaporation rates and improving evaporation suppression efficiency. The experiment tested different shading colors (black, white, and green) and intensities (50, 70, and 90%) while considering ecological and economical aspects. Evaporation was determined using class-A evaporation pans, and various microclimatic variables were measured below the shade covers. Additionally, water quality parameters such as EC, phosphate, nitrate, and chloride concentrations were monitored. The results showed that black covers had the highest evaporation suppression efficiency with values of 56.8, 53.6, and 51.7% observed under 90% shading intensity for the black, green, and white covers, respectively. Despite variations in water quality parameters which all met Jordanian and FAO standards for irrigation water, the economic feasibility of installing these covers was found to be viable due to the resulting benefits in water conservation and crop production. However, selecting the best shading cover should consider the multipurpose use of agricultural reservoirs, including aquaculture, and further studies are recommended to investigate other overlapping aspects on a reservoir scale.

Experimental Ecosystem Eutrophication Causes Offsetting Effects on Emissions of CO2, CH4, and N2O from Agricultural Reservoirs.

Despite decades of research and management efforts, eutrophication remains a persistent threat to inland waters. As nutrient pollution intensifies in the coming decades, the implications for aquatic greenhouse gas (GHG) emissions are poorly defined, particularly the responses of individual GHGs: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The biogeochemical controls of each gas can differ, making it difficult to predict the overall effect of nutrient pollution on the net radiative forcing of aquatic ecosystems. Here, we induced eutrophication of small nitrogen (N)-limited agricultural reservoirs and measured changes in diffusive GHG emissions within a before-after-control-impact (BACI) study design during June to September 2021. Each gas exhibited a unique response to 300% increases in primary production, with a shift from an overall CO2 source to a sink, a modest increase in N2O flux, and, unexpectedly, no significant change in CH4 emissions. The lack of net directional change in CO2-equivalent GHG emissions in fertilized reservoirs during the summer contrasts findings from empirical studies of eutrophic lakes. Our findings illustrate the difficulty in extrapolating among different sized ecosystems and suggest that forecast 2-fold increases in agricultural N fertilization by 2050 may not result in consistently elevated GHG emissions during summer, at least from small reservoirs in continental grassland regions.

Effects of aeration on water quality in agricultural reservoirs in the northern Great Plains

Lerminiaux J, Norton B, Wilson RJ, Rimas R, Lavender TM, Finlay K. 2024. Effects of aeration on water quality in agricultural reservoirs in the northern Great Plains. Lake Reserv Manage. 40:264–284. Aeration of agricultural reservoirs is an encouraged practice in the northern Great Plains of Canada as it can improve water quality by reducing pathogenic bacteria and algal abundance. Cattle also prefer aerated water, resulting in greater weight gain. Despite its known benefits, agricultural reservoir aeration is still not uniformly adopted, largely given its cost of installation and maintenance. Wind powered aeration has been shown to be an eco-friendly and sustainable way to increase oxygen levels in agricultural reservoirs, but the mechanisms by which this aeration can improve water quality are not well documented. By comparing 5 aerated agricultural reservoirs to 5 unaerated agricultural reservoirs, we evaluated whether wind-powered aeration improves water quality. We measured dissolved oxygen, nitrogen, and phosphorus, algal biomass (as chlorophyll a), cyanobacteria abundance, and algal toxins (microcystin, anatoxin-a, and β-N-methylamino-L-alanine) in the aerated and unaerated agricultural reservoirs on a weekly basis over a 12-week period from mid June through August 2022. We found that the aerators were able to mix the water column and add oxygen to deeper regions of the agricultural reservoir, but this did not result in consistent improvements to any measured water quality parameter. The observed lack of a strong response to aeration suggests that this practice may provide only minimal water quality benefits, but aeration may still prove beneficial for deep (>2 m) and sheltered agricultural reservoirs that do not regularly mix from wind effects alone.

Sources and transformation of nitrate in an agricultural riverine reservoir watershed of the Sichuan Basin

Elucidating the origins and transformations of nitrate in groundwater and surface water within agricultural regions is imperative for effectively managing watershed contamination and environmental improvement. This study conducted a comprehensive geochemical investigation using multiple stable isotopes (δD-H2O and δ18O–H2O, δ15N–NO3- and δ18O–NO3-, and δ15N–NH4+) and hydrogeochemical characteristics to explore the potential sources and transformation of nitrate in groundwater and reservoir water within an agricultural riverine reservoir watershed. The results indicated that nitrate pollution in groundwater exhibited a higher severity compared to the reservoir water within this watershed, thereby posing potential risks to the quality of the reservoir water through hydraulic connection. The integration of δ15N–NH4+ and dual-isotopes of nitrate, combined with hydrogeochemical analyses, revealed that the presence of NO3− in groundwater and reservoir water primarily originated from manure/sewage sources. Moreover, intricate biogeochemical processes containing denitrification, nitrification, and DNRA were identified within this watershed. The findings of the Bayesian stable isotope mixing model (SIAR) further corroborated the conclusion that manure/sewage was the primary source of nitrate. It revealed that manure/sewage accounted for an average of 46 % of groundwater NO3− concentration, followed by atmospheric precipitation (25 %), soil nitrogen (18 %), and chemical fertilizer (11 %). There were no distinct differences in nitrate source contributions between groundwater and reservoir water. For reservoir water, manure or sewage (45 % on average) > atmospheric precipitation (28 %) > soil nitrogen (16 %) > chemical fertilizer (11 %). This study demonstrates the effectiveness of incorporating δ15N–NH4+ with dual isotopes of nitrate and hydrogeochemical analyses, serving as a reliable methodology that yields valuable insights into the origins and transformations of NO3− in an agricultural reservoir watershed, with potential applicability to other regions.

A Case Study on Simulation of Water Cycle in a Watershed Considering Artificial Elements such as Agricultural Reservoirs

The National Fire Agency in Korea has implemented various stress management programs for firefighters. However, few studies have focused on the actual effectiveness of these programs. This study thus aimed to explore problems in the psychological counseling system for firefighters, focusing on the case of Jeju Island, and to prepare an efficient operation plan for the system. Survey results indicate that counselors’ lack of understanding of firefighting results in low satisfaction with counseling services, and that firefighters with short service periods require counselors who understand the firefighting profession more than other groups do. In order to overcome these limitations, it is proposed that a counselor’s education program be introduced and that retired firefighters be hired for the psychological counseling program.

농업용 저수지 안전점검 및 등급 체계 개선방안 연구

Accidents in agricultural reservoirs continue to occur due to heavy rain caused by abnormal weather conditions. To prevent reservoir accidents, it is necessary to identify factors affecting collapse and manage them safely through prior inspection and repair. For reservoirs with a total storage capacity of less than 50,000㎥, which accounts for 81% of reservoirs nationwide, regular inspections conducted at least once a quarter are the only safety inspection procedures, and the conduct of regular inspections can be seen as a measure of safety inspections. As a result of the survey, it was determined that the implementation status of regular inspection was low at 46%, and problems were analyzed and improvement measures were proposed. Additionally, if the factor affecting collapse is a member with a low score, it is difficult to reflect the results of regular inspection in the safety grade. In this study, we analyzed the problems with the regular inspection grading system and proposed an improvement plan by borrowing and applying the condition evaluation method of precise safety diagnosis, assessing overflow risk, and considering downstream impacts.

Evaporation Loss From Small Agricultural Reservoirs in a Warming Climate: An Overlooked Component of Water Accounting

AbstractSmall agricultural reservoirs support water demands during dry spells. However, evaporative losses that are often overlooked in water accounting and management diminish the storage efficiency of these popular but un‐inventoried resources. We developed a predictive framework to identify the spatio‐temporal extent of small reservoirs (900–100,000 m2) and quantify their evaporative losses using a physically‐based model. Focusing on water‐stressed regions of Europe (Italy, Spain, and Portugal), our results indicate that the total number and cumulative area of small reservoirs in drier areas of Europe almost doubled in two decades from about 6,200 reservoirs with the cumulative area of 46 km2 in 2,000 to 11,800 reservoirs with the cumulative area of 93.5 km2 in 2020. We observed climate‐driven trends in the expansion of agricultural reservoirs and their evaporative losses which exceeded 72 million cubic meters during warm months (April to September) accounting for 38% of their total storage capacity.

Arrangement of Agricultural Reservoir Along Rill Erosion: Case Study in the Sumbing Volcanic Landscape, Java, Indonesia

Arrangement of Agricultural Reservoir Along Rill Erosion: Case Study in the Sumbing Volcanic Landscape, Java, Indonesia

Hydrological Analysis Before and After Embankment-Raising Project of Agricultural Reservoir Watershed: A Case Study of Suyang Reservoir

We selected the SWAT hydrological model to analyze the hydrological changes before and after an embankment-raising project in agricultural reservoirs. The model was calibrated and validated from 2015 to 2016 using discharge data from the Songsan gauge station, which serves as a watershed outlet that includes the Suyang Reservoir. The dam height of Suyang Reservoir was raised from 13.5 m to 15.1 m, which resulted in a total storage capacity increase from 7.472 million cubic meters to 11.926 million cubic meters. The calibrated model demonstrates an efficiency of 0.9. Scenarios for pre- (2001-2012) and post-embankment raising (2014-2016) were simulated, and the results for various hydrological components (precipitation, runoff, infiltration, evapotranspiration, percolation, soil moisture, groundwater evaporation, and groundwater recharge) were summarized. The model results revealed average precipitation, runoff, infiltration, evapotranspiration, and groundwater recharge for the pre-embankment raising period (2001-2012) as 1,479.3 mm, 864.1 mm, 550.8 mm, 584.2 mm, and 165.0 mm, respectively. For the post-embankment raising period (2014-2016), the simulated values were 1,290.4 mm, 678.0 mm, 494.0 mm, 587.9 mm, and 145.9 mm, respectively. Below-average precipitation during the post-embankment raising period did not have a significant impact on the operation of the agricultural reservoir. The increased reservoir capacity through the embankment-raising project suggests the potential for additional water supply in the face of future water shortages and abnormal drought conditions. Additional research, including the determination of an appropriate water storage rate, will be necessary through long-term investigations and analyses, and climate change scenarios should be incorporated.

농업용 저수지 조기경보시스템 현황 분석 및 개선방안

Of the 17,160 agricultural reservoirs nationwide, 96% are aged more than 30 years after construction. Aging reservoirs are at risk of deterioration and potential collapse. The torrential rains between July and August 2020 caused 26 collapse and loss filure across the country. Preemptive and comprehensive response plan is needed to prevent damage to life and property caused by such a reservoir collapse, and this study analyzes the early warning system of agricultural reservoirs as part of a preemptive and comprehensive countermeasure plan to diagnose the current situation and come up with improvement measures. Using bathymetric data, real-time water level change through water level-rainfall linkage analysis and early warning standard setting according to rainfall were proposed. Using bathymetric and aerial survey data, a three-dimensional reservoir collapse simulation was used to predict the arrival time and submerged range of the collapsed flow, suggesting early warning standards and positioning methods.

Evaluation of future flood probability in agricultural reservoir watersheds using an integrated flood simulation system

In agricultural reservoir watersheds, the presence of various agricultural hydraulic structures combined with the influence of climate change necessitates effective flood risk analysis. This study aims to develop a flood risk evaluation technique for agricultural basins by incorporating the low temporal resolution of climate change scenarios. The approach utilizes flood probability as a key component and incorporates the Multiplicative Random Cascade model as a probability-based rainfall time decomposition model to capture the inherent uncertainty in climate change data. Reliability analysis with the limit state equation is employed for probability-based risk evaluation. Given that agricultural watersheds typically consist of agricultural reservoirs and farmland, the study develops a hydraulic and hydrological linkage model to comprehensively calculate flood probability, simulating from the agricultural reservoir in the upper side to the farmland located at the bottom edge of the watershed. The flood risk assessment is applied to the Yedang Reservoir watershed in Korea, using the Shared Socio-economic Pathways climate change scenario. Results indicate that flood probability is the highest in river levees during future precipitation events, converging to nearly 100% under 24-hour duration rainfall, irrespective of the rain frequency. Despite the hydraulic structures at the farmland being designed for a lower frequency of rain events, the average probability of flooding in the farmland have reached 50%. The agricultural reservoir exhibits a low risk of flooding even under climate change conditions. The proposed method not only enables the establishment of flood countermeasures but also facilitates the evaluation and prediction of future flood risk for each hydraulic structure located in rural areas affected by climate change.

Climate-associated risks for reliability, resilience, vulnerability and sustainability of irrigation reservoirs in small ungauged watersheds

Climate change poses an existential threat to the functional integrity of the network of agricultural reservoirs responsible for sustaining rice production in South Korea. Anthropogenic interventions have triggered a cycle of droughts and floods by magnifying the already existing supply–demand gap, which is seriously hampering reservoir performance. The watersheds of most agricultural reservoirs in South Korea are ungauged, and inflow and outflow data are not measured. In this study, recorded volumetric water storage data from five reservoirs were used to derive observed inflow data based on the hydrological reasoning and reservoir operation rule curves. These data were then used to evaluate the performance of a lumped rainfall-runoff model in simulating the runoff generated in upstream ungauged watersheds. A water balance analysis was conducted for 400 major agricultural reservoirs spread throughout the country during 1973–2017. Performance indices were estimated based on inflow availability in the reservoirs and downstream irrigation demands. Empirical relationships were derived to predict performance indices by using the reservoirs’ physical characteristics as input variables. Generally, reservoirs received substantially higher inflows compared to irrigation demands, suggesting sufficient water availability during the rice growing season (Apr−Sep). An out-of-phase cycle of peak inflow generation and water demand periods induced frequent failure events during the rice nursery transplanting period (May−Jun), and reservoir sustainability was minimal in these months. Southern and southwestern major agricultural regions with a higher density of small- to medium-sized reservoirs would be at higher risk of climate-induced water scarcity. Upsizing storage capacity could alleviate the water deficit in reservoirs associated with watersheds featuring higher means and lower standard deviations of runoff. A watershed-to-irrigated area ratio > 5 indicated acceptable reservoir sustainability.

Stability and Economic Evaluation of Agricultural Reservoirs with PV Systems

In Korea, the majority of agricultural reservoirs have been in use for over 50 years. Hence, there is an urgent need for maintenance and reinforcement to safeguard against potential collapses caused by unforeseen natural disasters. This study assessed the stability and economic viability of applying solar panels to these agricultural reservoir embankments. The Slope/w program was used to analyze the stability of embankments fitted with solar panels, considering reinforcement techniques and the load from the photovoltaic (PV) system. The economic feasibility of the PV system was determined using the RETScreen program, factoring in the unit cost of solar modules, lifespan of solar panels, and specific climatic conditions of the target reservoir. The findings indicate that the PV system and reinforcement techniques enhanced the stability of the reservoir embankments. Furthermore, economic benefits, such as production of electricity and reduction of greenhouse gas, can be expected.