Runoff optimization and control for basin water allocation

The water distribution plan for the three major irrigation districts (Changma, Shuangta, and Huahai) in the Shule River Basin in the planned year was analyzed in this study in an effort to resolve the insufficient natural endowment of water resources and contradiction between supply and demand throughout the basin. Based on this plan, and under the condition of satisfying the scheduling constraints of cascade reservoirs, the minimum total water supply shortage in the watershed was taken as the main goal coupled with the cascade reservoir runoff optimization control coefficient. An optimized dispatch model of the reservoir group was established accordingly. The large system coordination decomposition algorithm was called to solve the model and obtain the water scheduling scheme of each reservoir. After the optimal regulation of runoff, the water demand of the three major irrigation areas of Changma, Shuangta, and Huahai in the planned year is greater than the available water resources of the Shule River and the Petroleum River. The total surface runoff water shortage is 66.01 million m3, which cannot be satisfied. Among the reservoirs, Shuangta has the highest water shortage quota of 43.503 million m3, followed by Chijinxia with a water deficit quota of 22.18 million m3, and finally by Changma with a minimum water shortage quota of 0.3277 million m3. The results of this work may provide technical support for water resource allocation and regulations, as well as for the efficient usage of the Shule River Basin.

The Impact of River Regulation on Downstream Socio-Hydrologic Systems in Ethiopia

In recent years, a renewed interest in large-scale hydraulic interventions has developed, frequently justified by the premise of making the agricultural and energy sectors climate-resilient. Despite this important climate effort, hydraulic interventions are controversial and have far-reaching impacts on river-dependent communities and the environment. Drawing on gis analyses of remote sensing images and qualitative and quantitative empirical evidence from the field, this PhD dissertation focused on the impact of two large dams and one inter-basin water transfer (ibwt) on downstream socio-hydrologic systems (coupled human-water systems) in Ethiopia. The results indicated that (i) downstream hydrogeomorphic systems drastically altered after the implementation of the hydraulic interventions, (ii) small-scale farmer-led irrigation systems more efficiently increased crop productivities than several large-scale irrigation projects, (iii) the newly induced hydrologic regimes strongly altered downstream social interactions due to impeded river crossing and (iv) ill-prepared land redistributions and resettlements left thousands of households with a high risk of impoverishment.

Experimental Investigation on Finned Solar Still with Enhanced Thermal Energy Storage

In the present study, a novel solar still incorporated with fins and phase change material (PCM) based energy storage, was designed. To investigate the influence of fins and energy storage unit, four cases of stills were considered. In case I, a conventional type was considered, whereas square hollow fins were fitted over the basin liner of the still in case II. In addition to fins as in case II, case III employs energy storage unit wherein PCM was packed beneath the basin liner. Case IV was similar to case III except the extension of fins into the storage unit. The addition of fins above the base liner improved the absorber surface area and the extension of the same beneath the basin liner enhanced the storage efficiency. Experiments were carried out on all the four modules with a constant basin water depth of 2 cm. The maximum productivity of the conventional solar still was found to be 3.25 litre/m2/day. On the other hand, the results reveal improvement in productivity of 17.54%, 48.61% and 55.69% with cases II, III and IV, respectively. Although stills with energy storage unit exhibited higher exergy efficiency, the presence of fins in the PCM increases the internal irreversibilities. The cost of water yielded by modified solar still (MSS) used in case IV is proved to be less as compared to conventional solar still (CSS). Further, the payback period of MSS is found to be lesser than that of CSS.

Hydro-environmental response to the inter-basin water resource development in the middle and lower Han River, China

As one of the most important influencing factors, inter-basin water resource development has been exerting an increasingly evident impact on the hydro-environment of river basins. The Han River was selected as a case study to reveal the hydro-environmental response to China's inter-basin water resource development. The hydrological changes and water-quality variations resulted from the middle route of the South-to-North Water Transfer Project (SNWTP) and the Three Gorges Reservoir (TGR) operation were examined based on a hydro-environmental model. The results indicated that the runoff reduction is obvious after the SNWTP operation, and the low-flow duration significantly increased by 4–5 months. Consequently, the flow decrease significantly contributed to the water quality deterioration in the middle and lower Han River, while the Yangtze-Han Water Diversion Project (YHWDP) can not alleviate the situation completely. Moreover, the nutrient assimilative capacity decreased after water diversion, which agrees with the hydrological changes along the middle and lower Han River. The quantitative analysis performed in this study distinguishes the spatiotemporal variation in water quality variables using the integrated model. It provides insights into water quality management under the influences of inter-basin water resource development.

Multi-Objective Optimal Allocation of River Basin Water Resources under Full Probability Scenarios Considering Wet–Dry Encounters: A Case Study of Yellow River Basin

Wet–dry encounters between basins and regions have an important impact on the allocation of water resources. This study proposes a multi-objective allocation model for basin water resources under full probability scenarios considering wet–dry encounters (FPS-MOWAM) to solve the problem of basin water resource allocation. In the FPS-MOWAM model, the sub-regions were merged by precipitation correlation analysis. Next, the joint probability distribution of basin runoff and region precipitation was constructed using copula functions. The possible wet–dry encounter scenarios and their probabilities were then acquired. Finally, the multi-objective allocation model of water resources was constructed using the full probability scenario for wet–dry encounters in each region. The FPS-MOWAM is calculated by the NSGA-II algorithm and the optimal water resource allocation scheme was selected using the fuzzy comprehensive evaluation method. Using the Yellow River Basin as an example, the following conclusions were obtained: (1) the Yellow River Basin can be divided into four sub-regions based on precipitation correlations: Qh-Sc (Qinghai, Sichuan), Sg-Nx-Nmg (Gansu, Ningxia, Inner Mongolia), Sxq-Sxj (Shaanxi, Shanxi), and Hn-Sd (Henan, Shandong), (2) the inconsistencies in synchronous–asynchronous encounter probabilities in the Yellow River Basin were significant (the asynchronous probabilities were 0.763), whereas the asynchronous probabilities among the four regions were 0.632, 0.932, and 0.763 under the high, medium, and low flow conditions in the Yellow River Basin respectively, and (3) the allocation of water resources tends to increase with time, allocating the most during dry years. In 2035, the expected economic benefits are between 11,982.7 billion CNY and 12,499.6 billion CNY, while the expected water shortage rate is between 2.02% and 3.43%. In 2050, the expected economic benefits are between 21,291.4 billion CNY and 21,781.3 billion CNY, while the expected water shortage rate is between 1.28% and 6.05%.

Experimental Study of a Tilt Single Slope Solar Still Integrated with Aluminum Condensate Plate

The low freshwater productivity of a conventional solar still is considered a challenge for researchers due to the high temperature of the glass cover or basin water depth. In current work, a newly designed solar still was suggested according to the climatic conditions of Yekaterinburg/Russia, which included an enhanced condensation and evaporation process by spraying a thin water film on a hot absorber plate and then passing the generated water vapor by free convection over the aluminum plate (low temperature). The distillation system under study was tested during July 2020 and 29 July was chosen as a typical day from 08:00 a.m. to 8:00 p.m. The results showed that the largest amount of water vapor condenses on the aluminum plate (about 46%), and the rest condenses on the glass cover. This means that the aluminum plate effectively improved productivity due to the flow of humid air naturally (free convection) on the aluminum plate (its surface temperature was lower than that of the glass cover). The cost analytical calculations showed that the cost of producing one liter of distilled water from the suggested solar still was 0.063$.