Seasonal Inflow Research Articles

Hydrometeorological Conditions of the Volga Flow Generation into the Caspian Sea during the Last Glacial Maximum

The goal of this study is to evaluate annual and seasonal inflow from the Volga catchment area to the Caspian Sea during the Last Glacial Maximum (LGM ~21,000 years ago) using paleoclimate modeling data. The first approach is based on the LGM simulation by the general circulation models (GCMs) in the framework of the Paleoclimate Modelling Intercomparison Project (PMIP4) and the Coupled Modelling Intercomparison Project (CMIP6). We used four GCMs: INM-CM4-8, MIROC-ES2L, AWI-ESM1-1-LR, and MPI-ESM1-2-LR. The second approach is based on the spatially distributed process-based runoff generation model using PMIP4-CMIP6 model data as boundary conditions. The use of the hydrological ECOMAG model allows us to refine estimates of the Volga runoff in comparison to GCM calculations by considering seasonal features of runoff generation related to periglacial vegetation distribution, permafrost, and streamflow transformation along the channel network. The LGM is characterized by a high uncertainty in meteorological values calculated for the Volga basin using various GCMs. The share of runoff from the three most flooded months from the annual calculated in the LGM was 95%, according to INM-CM4-8, while other GCMs ranged from 69–78%. Three GCMs (MIROC-ES2L, AWI-ESM1-1-LR, and MPI-ESM1-2-LR) showed 83–88% of the present-day value of precipitation in the Volga basin during cooling for more than 10 °C, while INM-CM4-8 showed a two-fold decrease. According to hydrological modeling results using data from three models, the annual Volga runoff was significantly higher than the present-day value, and, when using data from INM-CM4-8, it was lower.

THE PROVISION OF EQUAL SHARING IN COMPOSING THE RULE CURVE FOR OPERATION PATTERN OF SERIAL CASCADES

This research intends to apply the provision of equal sharing in composing the rule curve as the operation pattern in a serial cascade reservoir. The increasing on the demand request of water, food, and energy, needs the dam development. The development of some dams in a river system can be carried out row or cascade. The operation pattern of the cascade reservoir is a design form of water usage from each reservoir optimally. However, the rule curve can be defined as a diagram that shows the saving rules for this time of year. Therefore, the rule curve gives a guide for operating the reservoir from day to day. Along the Way Sekampung river. It is planned to develop a cascade reservoir that are Batutegi Dam (existing), Way Sekampung Dam (existing), and Margatiga Dam (development processing). The ratio of reservoir capacity is as follow: the Batutegi is 90.4%, the Way Sekampung is 6.8%, and the Margatiga is 2.8%. However, the ratio of inflow discharge potency for each reservoir is as follow: the Batutegi is 32%, the Way Sekampung is 4%, and the Margatiga is 64%. Equal sharing is used in composing the rule curve. The difference between seasonal inflow and outflow cumulative in the dray year is -45.77 million m3, in the normal year is 912.64 million m3, and in the wet year is 2,251.41 million m3. The simulation results show that in the dry year, there is deficit in fulfilling the water need in the downstream dam, such as in the period of May 2, June 1–2, and July 2 (4 periods). The conclusion is that the rule curve of reservoir is the filling period from August 1 until December 2 for the Way Sekampung and Margatiga Dams. However, for the Batutegi Dam, it lasts from August 1 until April 2. The emptying period is from May 1 until July 2. The equal sharing method can be further developed for the reservoir with the function is PLTA (hydroelectric power) – multi-purpose – multi-purpose by the approach of simulation, optimization, and the other development that is suitable with the character of serial cascade reservoir storage.

Valuation and Pricing of Surface Water Supplies in Pakistan

Pakistan has the largest contiguous, well-articulated, and comprehensive irrigation system in the world, with 3 storage reservoirs, 68 small dams, 19 diversion barrages, and 45 canal commands with 12 Link Canals for inter-basin transfer of water. About 0.1 million outlets supply water to the farmers to irrigate land besides more than 600,000 tubewells. The whole irrigation network commands an area of 45 million acres (18.22 Mha) out of which 79 percent is irrigated by canals or tubewells/wells. More than half of the canal irrigated areas (58 percent) is irrigated perennially and 42 percent nonperennially [NWSR (2002)]. The average annual flow of Indus River System is approximately 151.58 million acre feet (MAF) of which presently 103.81 MAF (128.1 BCM) is being diverted to irrigate farm lands [NWSR (2002)]. The present live storage capacity of the reservoirs is about 12.5 MAF (13 percent of river flows) compared with the original capacity of 15.7 MAF. The hydropower generation is constrained by seasonal inflows to reservoirs and irrigation requirements by Indus River System Authority. The generation dictated by irrigation requirements is the highest in the months of July to October. Little more than half of the diverted flows (55 percent) become available at farm gate, 42 percent infiltrate to groundwater reservoir and balance 3 percent is lost as evaporation. Of the total water that seeps down to the groundwater reservoir, including some 27 percent of farm gate supply through field seepage, nearly 85 percent is being extracted. Groundwater owing its existence to operational canal system, supplies over 40 percent of crop water requirements of the country

Unfolding the relationship between seasonal forecast skill and value in hydropower production: a global analysis

Abstract. The potential benefits of seasonal streamflow forecasts for the hydropower sector have been evaluated for several basins across the world but with contrasting conclusions on the expected benefits. This raises the prospect of a complex relationship between reservoir characteristics, forecast skill, and value. Here, we unfold the nature of this relationship by studying time series of simulated power production for 735 headwater dams worldwide. The time series are generated by running a detailed dam model over the period 1958–2000 with three operating schemes: basic control rules, perfect forecast-informed operations, and realistic forecast-informed operations. The realistic forecasts are issued by tailored statistical prediction models – based on lagged global and local hydroclimatic variables – predicting seasonal monthly dam inflows. As expected, results show that most dams (94 %) could benefit from perfect forecasts. Yet, the benefits for each dam vary greatly and are primarily controlled by the time-to-fill value and the ratio between reservoir depth and hydraulic head. When realistic forecasts are adopted, 25 % of dams demonstrate improvements with respect to basic control rules. In this case, the likelihood of observing improvements is controlled not only by design specifications but also by forecast skill. We conclude our analysis by identifying two groups of dams of particular interest: dams that fall in regions expressing strong forecast accuracy and having the potential to reap benefits from forecast-informed operations and dams with a strong potential to benefit from forecast-informed operations but falling in regions lacking forecast accuracy. Overall, these results represent a first qualitative step toward informing site-specific hydropower studies.

Upper Limit and Power Generation Loss of Water Supplement from Cascade Hydropower Stations to Downstream under Lancang-Mekong Cooperation

In cross-border water supplement cooperation, the supplement water discharged from upstream hydropower stations is the key to improving downstream benefits, but will lead to upstream power generation loss, so the upstream hydropower stations have to be aware of how much water they can offer and how much power they will lose to make the water supplement cooperation more reasonable. Therefore, this study puts forward a model to calculate the upper limit flow of water supplement of cascade hydropower stations under firm power constraints and water level constraints and proposes a new optimization method called the “collaborative-independent” joint optimization method to calculate the power generation loss under water supplement constraints. The results show that the upper limit flow will increase with the increase of annual inflow, and the uncertainty of the distribution of inflow in the year will also affect the upper limit flow: the larger the proportion of non-flood season inflow, the higher the upper limit flow. In normal and wet years, delaying water supplement time can significantly increase the upper limit flow by about 5% per month. Additionally, the “collaborative-independent” joint optimization method newly proposed in this paper can significantly improve the local optimization problem compared to the traditional optimization method. The power generation loss increases with the increase of water supplement flow, and delaying water supplement time can significantly reduce the power generation loss. The results of this paper can provide essential data support for future water resources cooperation negotiations in the Lancang-Mekong river basin to promote efficient and orderly water resources cooperation in the basin.

Trend Detection in Seasonal Inflows and the Influence on Energy Generation in Goleşti Hydropower Plant

Among the multiple water uses, electricity generation is a factor strongly affected by alterations in the water cycle due to climate change. Long periods of drought followed by rainy periods lead to significant changes in the natural regimes of water flow in rivers. This paper aims to determine the long-term trends of seasonal inflows (spring, summer, autumn, winter) in Goleşti reservoir using daily data recorded over an 11-years period with the non-parametric Mann-Kendall test. The influence of tendency of increasing or decreasing was analyzed for the inflows in the Goleşti reservoir on the energy produced in associated hydropower plant.

Total organic carbon, heavy metal content and metal bioaccumulation in a freshwater wetland of Indo-Burmese province, India

ABSTRACT This study attempts to assess the spatio-temporal distribution of total organic carbon (TOC) and heavy metals in one of the Ramsar wetlands of Indo-Burmese province. Water samples were collected from 10 sampling points during the premonsoon, monsoon and postmonsoon season of 2016 and 2017. The general water parameters such as low DO, high BOD, and high fluoride imply the wetland water’s deteriorated quality. The mean TOC of water was estimated to be 2.4 ± 0.33 ppm, the first report from Deepor Beel. Pearson’s correlation coefficient showed a significant positive relation (> 0.7) between TOC, phosphate, and nitrate, which indicates the seasonal inflow of these parameters from a similar source. The computed heavy metal indices revealed that most of the water samples were highly contaminated by metals. The metal concentration recorded in the selected macrophytes and fishes species was far above the concentration of the respective metal in the water samples. Metal distribution in plant samples disclosed that Euryale ferox showed better accumulation ability than Hydrilla verticillata and Eichhornia crassipes. Among the fish species, the highest metal accumulation was recorded in Xenentodon cancila (zinc, iron, manganese, and nickel) and Channa punctatus (lead and cadmium). In the fish samples, metal accumulation was found to be higher in the organs (particularly in the kidney) than in the muscles. Bioconcentration factor revealed a high metal accumulation in the submerged type plants and surface feeder fishes.

Anaerobic digestion of urban wastes: integration and benefits of a small-scale system

ABSTRACT This work presents an integrated approach of anaerobic digestion (AD) at the urban scale, based on on-site collected wastes, experimentation in a pilot reactor, and model approach. To cope with urban waste limitations (season inflow, organic matter decrease, limited area), it was proposed a settlement of wastewater (WW), a drying of food waste (FW), and silage of green waste (GW). The results obtained highlight the performance of these pretreatments to concentrate and/or preserve the organic matter over time. Co-digestion in a 30-liter reactor was then successfully carried out, resulting in an 83% of volatile solids reduction and stable methane production of 321 ml CH4/g VSadd, in 35 days. Finally, we developed a standard neighbourhood model with AD based on these experimental results. It appears that 66% of the primary sludge (PS) and 28% of the FWs produced daily could be treated by the proposal process. 14% of the annual production of GW could thus be processed daily. From an energetic point of view, the process generates a surplus of respectively, 2500 MJ/year and 38,000 MJ/year in terms of electricity and heat. The generation of 15 times more heat energy than electricity, supports an installation of anaerobic digestion, close to homes. Moreover, if these results are encouraging, we suggest different scenarios of co-digestion ratios and operational parameters for their optimization.

Dynamic Regulation of Reservoir Drought Limit Water Level

Drought limit water level has been presented to guide reservoir drought resistance for years. However, current static drought limit water levels neglected the water transfer relationship among different periods. In this study, the Yuqiao Reservoir located in Tianjin, China, was taken as the study area. To avoid the excessive subjectivity brought by the conventional typical drought-year selection method, six indicators were used to analyse inflow intra-drought-season distribution characteristics, and a hierarchical agglomeration cluster method was used to propose a classification of the dry season inflow “shape.” To associate with the reservoir inter-month water transfer relationship, a number pair “early warning period/drought limit water level” format was proposed to represent the limit water level. The early warning period turned out to be related to initial water storage, inflow process in dry season and water supply rules. To overcome the uncertainty in inflow process during the dry season, a rolling computation mechanism was applied in determining the drought limit water level, thus dynamic regulation was realized. Finally, the dynamic reservoir drought limit water level was compared with the conventional method. The results suggest that drought limit water level has broad development potential in improving reservoir drought resistance guidance practices.

Analysis Of Perception Of Rural People Towards Socio-Economic Impact Of Financial Inclusion – A Case Study Analysis

The governments of India and other developing countries have made Financial Inclusion a priority – evidenced by policy development, regulatory reform and new funding vehicles. The government of India has set a target of reaching full inclusion by 2015. These objectives will be achieved through financial instruments, such as micro credit, which has achieved positive results, helping thousands of the world’s poor to lift themselves out of poverty. This paper examines the socio-economic impact of financial inclusion on rural people in Goa.
 
 It is now well understood that financial inclusion helps the poor in more viable and profitable way by providing them ability to do business with banks and other financial institutions. The provision of uncomplicated, small, affordable products can help bring low-income families into the formal financial sector. Taking into account their seasonal inflow of income from agricultural operations, migration from one place to another, and seasonal and irregular work availability and income, the existing financial system needs to be designed to suit their requirements. Mainstream financial institutions such as banks have an important role to play in this effort, not as a social obligation, but as a pure business proposition.

Subsurface characterization of a quick-clay vulnerable area using near-surface geophysics and hydrological modelling

Abstract. Quick-clay landslides are common geohazards in Nordic countries and Canada. The presence of potential quick clays is confirmed using geotechnical investigations, but near-surface geophysical methods, such as seismic and resistivity surveys, can also help identify coarse-grained materials associated with the development of quick clays. We present the results of reflection seismic investigations on land and in part of the Göta River in Sweden, along which many quick-clay landslide scars exist. This is the first time that such a large-scale reflection seismic investigation has been carried out to study the subsurface structures associated with quick-clay landslides. The results also show a reasonable correlation with radio magnetotelluric and travel-time tomography models of the subsurface. Other ground geophysical data, such as high magnetic values, suggest a positive correlation with an increased thickness of the coarse-grained layer and shallower depths to the top of the bedrock and the top of the coarse-grained layer. The morphology of the river bottom and riverbanks, e.g. subaquatic landslide deposits, is shown by side-scan sonar and bathymetric data. Undulating bedrock, covered by subhorizontal sedimentary glacial and postglacial deposits, is clearly revealed. An extensive coarse-grained layer (P-wave velocity mostly between 1500 and 2500 m s−1 and resistivity from approximately 80 to 100 Ωm) exists within the sediments and is interpreted and modelled in a regional context. Several fracture zones are identified within the bedrock. Hydrological modelling of the coarse-grained layer confirms its potential for transporting fresh water infiltrated in fractures and nearby outcrops located in the central part of the study area. The modelled groundwater flow in this layer promotes the leaching of marine salts from the overlying clays by seasonal inflow–outflow cycles and/or diffusion, which contributes to the formation of potential quick clays.

OMV Petrom starts up PolyFuel unit at Petrobrazi refinery in Romania

Detection and attribution of streamflow changes would be a standing point towards optimizing the management of basin-scale water resources. The Three Gorges Reservoir (TGR), the largest hydropower project worldwide, has recently experienced obvious inflow reduction, which has restricted its capability to achieve the designed electricity generation. This study considered the design period of TGR (1961–1990) as the baseline period for evaluating inflow variations during the subsequent impact period (1991–2015). Annual inflow reduced by 6%, and seasonal inflow significantly decreased by 16% in autumn, which is the main season for filling reservoir. A new stepwise procedure with the help of a water-use model, a lumped hydrological model, and a generic reservoir operation model is presented to unravel the causes of inflow reduction. Results revealed that the drier climate predominantly caused inflow decreases. Human activities have notably enhanced in recent decades, however, they have not posed significant threats to inflow deficiency. Climate variability, water consumption, and upstream reservoir operation contributed by 78%, 15%, and 7% to decrease annual inflow while they contributed by 63%, 4%, and 33% to reduce autumn inflow, respectively. The proposed procedure can quantitatively disentangle major human impacts including water consumption and reservoir regulation. Such information enriches policy makers' knowledge for framing delicacy management of regional human activities in response to changing streamflow pattern.

Attribution of decreasing annual and autumn inflows to the Three Gorges Reservoir, Yangtze River: Climate variability, water consumption or upstream reservoir operation?

Detection and attribution of streamflow changes would be a standing point towards optimizing the management of basin-scale water resources. The Three Gorges Reservoir (TGR), the largest hydropower project worldwide, has recently experienced obvious inflow reduction, which has restricted its capability to achieve the designed electricity generation. This study considered the design period of TGR (1961–1990) as the baseline period for evaluating inflow variations during the subsequent impact period (1991–2015). Annual inflow reduced by 6%, and seasonal inflow significantly decreased by 16% in autumn, which is the main season for filling reservoir. A new stepwise procedure with the help of a water-use model, a lumped hydrological model, and a generic reservoir operation model is presented to unravel the causes of inflow reduction. Results revealed that the drier climate predominantly caused inflow decreases. Human activities have notably enhanced in recent decades, however, they have not posed significant threats to inflow deficiency. Climate variability, water consumption, and upstream reservoir operation contributed by 78%, 15%, and 7% to decrease annual inflow while they contributed by 63%, 4%, and 33% to reduce autumn inflow, respectively. The proposed procedure can quantitatively disentangle major human impacts including water consumption and reservoir regulation. Such information enriches policy makers' knowledge for framing delicacy management of regional human activities in response to changing streamflow pattern.

Seasonal Inflow Forecasts Using Gridded Precipitation and Soil Moisture Information: Implications for Reservoir Operation

Reservoir inflow forecasts are important for guiding reservoir operation. This study proposes an integrated framework of incorporating different forms of seasonal inflow forecasts in identifying the optimal releases policy. Gridded precipitation forecasts from climate models have been widely used for forecasting inflow. Both precipitation forecasts and soil moisture estimates are used as predictors to provide one-season-ahead reservoir inflow forecasts by constructing a regression problem. Principal component analysis is used to reduce the dimension of the regression problem, and a Bayesian regression technique is employed to generate various forms of inflow forecasts such as deterministic, probabilistic and ensemble forecasts. Two optimization models are constructed to couple with different forms of inflow forecasts. The first model aims to maximize hydropower generation and the second one aims to minimize end-of-season reservoir storage deviation from the target storage. Both single-value inflow and ensemble forecasts are incorporated to find the optimal water releasing policy considering inflow uncertainty and end-of-season reservoir storage requirement. The proposed methodology is demonstrated for Huangcai Reservoir in southern China. Bayesian regression technique shows good performance of seasonal inflow forecasts with a Pearson correlation of 0.8 and rank probability score of 0.4, which outperforms climatology. The coupling of ensemble inflow forecasts and optimization models provides water managers a set of release policies considering inflow uncertainty.

Warm Water Is Rapidly Eroding Antarctica’s Ross Ice Shelf

The underside of the world’s largest ice shelf is melting—by meters per year in some places—because of the seasonal inflow of water heated by the Sun, observations of the White Continent reveal.�

Basal melting of Ross Ice Shelf from solar heat absorption in an ice-front polynya

Ice–ocean interactions at the bases of Antarctic ice shelves are rarely observed, yet have a profound influence on ice sheet evolution and stability. Ice sheet models are highly sensitive to assumed ice shelf basal melt rates; however, there are few direct observations of basal melting or the oceanographic processes that drive it, and consequently our understanding of these interactions remains limited. Here we use in situ observations from the Ross Ice Shelf to examine the oceanographic processes that drive basal ablation of the world’s largest ice shelf. We show that basal melt rates beneath a thin and structurally important part of the shelf are an order of magnitude higher than the shelf-wide average. This melting is strongly influenced by a seasonal inflow of solar-heated surface water from the adjacent Ross Sea Polynya that downwells into the ice shelf cavity, nearly tripling basal melt rates during summer. Melting driven by this frequently overlooked process is expected to increase with predicted surface warming. We infer that solar heat absorbed in ice-front polynyas can make an important contribution to the present-day mass balance of ice shelves, and potentially impact their future stability. High melt rates in a key location beneath the Ross Ice Shelf result from a seasonal inflow of water heated in the Ross Sea Polynya, according to in situ observations.

Complex biogeographical patterns support an ecological connectivity network of a large marine predator in the north‐east Atlantic

AbstractAimThe knowledge of a species biogeographical patterns greatly enhances our understanding of geographical ecology, which can improve identifying key conservation needs. Yet, this knowledge is still scarce for many marine top predators. Here, we aim to analyse movement patterns and spatial structuring of a large predator, the short‐finned pilot whale Globicephala macrorhynchus, over a wide geographical area.LocationNorth‐east Atlantic, in Macaronesian archipelagos (Azores, Madeira and Canaries) and Iberian Peninsula (Sagres).MethodsWe used likelihood techniques to estimate residency times and transition probabilities and carried out social analysis from individual photographic identification data, and analysed year‐round distribution from effort‐related sightings, collated between 1999 and 2015.ResultsThe best‐fitting models included emigration and reimmigration and showed different residency times within each archipelago. A total of 26 individual movements from 21 individuals (from a sample of >2,300 individuals) were recorded between Madeira and the neighbouring archipelagos, and heterogeneous transition probabilities were estimated within and between areas. A social network diagram showed associations from animals with distinct residency patterns. Higher significant sighting rates were recorded during autumn in the Azores and Madeira.Main conclusionsThe variation in site fidelity and year‐round occupancy among areas of the Macaronesia is consistent with some degree of population structuring, which combined with a connectivity network and seasonal inflows from animals inhabiting offshore waters, support the development of a complex social and geographical ecology in short‐finned pilot whales. The combination of techniques applied in this study was an effective way to estimate parameters of movement, which could be a good practice to be used for other scenarios and species.

Multi-tracer assessment of seasonal water source changes in coastal water systems along the southeastern coast of Ivory Coast (West Africa)

ABSTRACTProper management of coastal freshwater resources depends on an understanding of processes controlling their chemistry and seasonal flowpaths. A quantitative approach involving the coupling of major solutes and isotopes (δ18O, δ2H) of 180 samples in end-member mixing analysis (EMMA) was adopted to elucidate seasonal patterns of hydraulic exchanges amongst coastal waters along the Ebrié Lagoon catchment, Ivory Coast. The results show that the Ebrié Lagoon is a hydrologically dynamic system. In the dry season, evaporation and seawater inflow are the dominating processes, while in the wet season, river discharge is the main water source in the lagoon. Regional geology plays a significant role in aquifer recharge patterns. The Quaternary aquifer responds faster to precipitation, while the Mio-Pliocene aquifer is recharged indirectly via floodplain seepages. Salinization of over 90% of wells arises from hydrological exchanges with the Ebrié Lagoon. A diluted seawater effect was recorded in wells during the wet season owing to the relative increase in freshwater inflow.

An Optimal Operation Model for Hydropower Stations Considering Inflow Forecasts with Different Lead-Times

To make full use of inflow forecasts with different lead times, a new reservoir operation model that considers the long-, medium- and short-term inflow forecasts (LMS-BSDP) for the real-time operation of hydropower stations is presented in this paper. First, a hybrid model, including a multiple linear regression model and the Xinanjiang model, is developed to obtain the 10-day inflow forecasts, and ANN models with the circulation indexes as inputs are developed to obtain the seasonal inflow forecasts. Then, the 10-day inflow forecast is divided into two segments, the first 5 days and the second 5 days, and the seasonal inflow forecast is deemed as the long-term forecast. Next, the three inflow forecasts are coupled using the Bayesian theory to develop LMS-BSDP model and the operation policies are obtained. Finally, the decision processes for the first 5 days and the entire 10 days are made according to their operation policies and the three inflow forecasts, respectively. The newly developed model is tested with the Huanren hydropower station located in China and compared with three other stochastic dynamic programming models. The simulation results demonstrate that LMS-BSDP performs best with higher power generation due to its employment of the long-term runoff forecast. The novelties of the present study lies in that it develops a new reservoir operation model that can use the long-, medium- and short-term inflow forecasts, which is a further study about the combined use of the inflow forecasts with different lead times based on the existed achievements.

Long-Term Planning of Water Systems in the Context of Climate Non-Stationarity with Deterministic and Stochastic Optimization

Seasonal inflow variability, climate non-stationarity and climate change are matters of concern for water system planning and management. This study presents optimization methods for long-term planning of water systems in the context of a non-stationary climate with two levels of inflow variability: seasonal and inter-annual. Deterministic and stochastic optimization models with either one time-step (intra-annual) or two time-steps (intra-annual and inter-annual) were compared by using three water system optimization models. The first model used one time-step sampling stochastic dynamic programming (SSDP). The other models with two time-steps are long-term deterministic dynamic programming (LT-DDP) and long-term sampling stochastic dynamic programming (LT-SSDP). The study area is the Manicouagan water system located in Quebec, Canada. The results show that there will be an increase of inflow to hydropower plants in the future climate with an increase of inflow uncertainty. The stochastic optimization with two time-steps was the most suitable for handling climate non-stationarity. The LT-DDP performed better in terms of reservoir storage, release and system efficiency but with high uncertainty. The SSDP had the lowest performance. The SSDP was not able to deal with the non-stationary climate and seasonal variability at the same time. The LT-SSDP generated operating policies with smaller uncertainty compared to LT-DDP, and it was therefore a more appropriate approach for water system planning and management in a non-stationary climate characterized by high inflow variability.