Irrigation Dams Research Articles

Application of limit equilibrium and shear strength reduction techniques for stability assessment of slope cuts- A case study of Khalid-Dijo dam project, Southern Ethiopia

Dam failure can occur due to foundation instability, downstream and upstream slopes instabilities. This study assesses the stability of upstream and downstream slope cuts at Khalid-Dijo irrigation dam project, which is located in Southern Ethiopia, 3km south of Werabe town. Limit equilibrium and finite element shear strength reduction methods are adopted. Validation of results and comparisons between those methods are carried out. The analysis considers anticipated site conditions, including static dry, static saturated, dynamic dry and dynamic saturated conditions. Slope material properties are measured from insitu, laboratory tests and used as input parameters for the analysis to obtain factor of safety and critical strength reduction factors. The properties considered in the analysis include unit weight, cohesion, angle of internal friction, poison’s ratio, dilation angle and Young’s modulus. The analysis indicates that the factor of safety values for limit equilibrium methods and the critical strength reduction factor for finite element method are very similar across the three slope cuts under all anticipated conditions. The lowest factor of safety and critical strength reduction factor is 1.56 and 2.07 respectively. Generally, the proposed dam project is safe against upstream and downstream slope failures. These studies suggest that maintained the average safety factor values of both methods during the design stage are crucial to avoid unnecessary risk.

Using a Triple Sensor Collocation Approach to Evaluate Small-Holder Irrigation Scheme Performances in Northern Ethiopia

This study uses a triple-sensor collocation approach to evaluate the performance of small-holder irrigation schemes in the Zamra catchment of Northern Ethiopia. Crop water productivity (CWP), as an integrator of biomass production and water use, was used to compare the overall efficiencies of three types of irrigation systems: traditional and modern diversions, and dam-based irrigation water supply. Farmer-reported data often rely on observations, which can introduce human estimation and measurement errors. As a result, the evaluation of irrigation scheme performance has frequently been insufficient to fully explain crop water productivity. To overcome the challenges of using one single estimation method, we used a triple-sensor collocation approach to evaluate the efficiency of three small-scale irrigation schemes, using water productivity as an indicator. It employed three independent methods: remotely sensed data, a model-based approach, and farmer in-situ estimates to assess crop yields and water consumption. To implement the triple collocation appraisal, we first applied three independent evaluation methods, i.e., remotely sensed, model-based, and farmer in-situ estimates of crop yields and water consumption, to assess the crop water productivities of the systems. Triple-sensor collocation allows for the appraisal and comparison of estimation errors of measurement sensor systems, and enables the ranking of the estimators by their quality to represent the de-facto unknown true value, in our case: crop yields, water use, and its ratio CWP, in small-holder irrigated agriculture. The study entailed four main components: (1) collecting in-situ information and data from small-holder farmers on crop yields and water use; (2) derivation of remote sensing-based CWP from the FAO WaPOR open database and time series; (3) evaluation of biomass, crop yields and water use (evapotranspiration) using the AquaCrop model, integrating climate, soil data, and irrigation management practices; (4) performing and analysis of a categorical triple collocation analysis of the independent estimator data and performance ranking of the three sensing and small-holder irrigation systems. Maize and vegetables were used as main crops during three consecutive irrigation seasons (2017/18, 2018/19, 2019/20). Civil war prevented further field surveying, in-situ research, and data collection. The results indicate that remote sensing products are performed best in the modern and dam irrigation schemes for maize. For vegetables, AquaCrop performed best in the dam irrigation scheme.

Utilizing multi-criteria decision-making analysis and 3D visualization techniques for dam site selection and irrigation area identification in Gedeb River, Ethiopia

Irrigation dams and irrigation suitability analysis is important for optimal water management, crop selection and productivity, water conservation, environmental sustainability, and economic viability in agriculture arena. Thus, the main objectives of this study were to identify a suitable dam site and irrigation area in the Gedeb River, Ethiopia, using Multi-Criteria Decision-Making analysis and 3D Visualization techniques. To identify a suitable dam site, various parametrs such as rainfall, runoff, stream flow, mineral site, faulting areas, landslide site, rock types, elevation points, relief features, soil types were used while to identify a suitable irrigation area, different parametrs such as altitude, slope, soil, geological structure, distance, and land use land cover datasets were used. The necessary dataset which were used to identify a suitable dam site and irrigation area collected from Ethiopian Mapping Authority (EMA), Ethiopian irrigation and energy ministry freely. In addition, for the final irrigation dam site selection and suitable irrigation area in the Gedeb watershed, multi-criteria decision-making method with expert judgment were applied respectively. Based on the study's findings, a suitable irrigation water reservoir dam covering an area of 1886 ha, with a potential water holding capacity of 2,961,145,697 cubic meters was identified. The results also revealed a highly suitable area of 18,362.05 ha, a moderately suitable area of 19,204.05 ha, a marginally suitable area of 2095.25 ha, and a not suitable area of 2.89 ha for the aforementioned purpose. The methodological approach and research findings presented in this study can greatly assist government and non-governmental organization planners and decision-makers in the development of irrigation projects.

SMS based reservoir condition monitoring sensor system for pumped hydro storage in mini-grids

Solar mini-grids are a cost-effective and efficient method of improving energy access in sub-Saharan Africa, particularly in low-income communities. However, conventional battery storage systems have reduced the affordability of solar mini-grid-generated electricity, necessitating the development of alternative energy storage systems such as pumped hydro storage to replace lithium-ion batteries. This paper introduces a model for an SMS-based fluid parameter monitoring system to provide visibility of reservoir conditions during peak and off-peak periods. The model uses hardware such as voltage regulators, sensors, microcontrollers, and C- programming language software. Sensors monitor various parameters in the reservoir and penstock, transmitting signals to a microcontroller for analysis. The results are relayed to a display unit and personnel's mobile phones for alert notifications, ensuring precise and accurate reporting. Simulation results show the reliability of the design to monitor water levels, water temperature, flow rate, and transmission through SMS to mobile devices for timely reporting. The paper recommends the development and commercialization of this model for larger applications, such as monitoring dams for irrigation and power generation.

Construction of the water balance model for the Bontanga irrigation dam in Northern Ghana

ABSTRACT Freshwater resources are essential for the sustenance of all living things, for crop production and socio-economic activities. The objective of this study was to construct a water balance model aimed at optimizing reservoir management by analyzing variations in water availability in the reservoir. This model will help dam operators to adopt water allocation strategies, timing of water releases and storage decisions. An echo sounder was used to measure the depth of water. Crop water requirements were computed using FAO CROPWAT 8 software, and the InVEST-SDR model was used to estimate sediments exported downstream of the watershed. Model construction utilized multiple linear regression, and the results were tested at a level of significance α = 0.05. Model performance was evaluated using a coefficient of determination (R2) and the ratio of the root mean square error to the standard deviation of measured data (RSR). The results revealed a coefficient of determination (R2) of 0.743 and a ratio of the root mean square error to the standard deviation of measured data (RSR) of 0.67. The constructed model will provide essential information to stakeholders on drought preparedness and mitigation, including water conservation measures and the management of water releases during critical periods.

Physicochemical Characteristics of Water in the Bontanga Irrigation Dam in the Guinea Savannah Agro-Ecological Zone of Ghana

Fresh water resource is one of the most significant natural assets of a country. Irrigation dams are usually used for irrigation purposes and also often serve as a source of water for domestic use. Due to this, there is a need for proper maintenance, assessment, and sustainable use of irrigation dams. This study assessed the physicochemical properties of the water in the reservoir of Bontanga irrigation dam situated in the Guinea Savannah Agro-Ecological Zone of Ghana. The study assessed four (4) physical and fourteen (14) chemical water quality parameters of the water for irrigation to know whether they are within the acceptable threshold set by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO). Sampling techniques used in this study were stratified and purposive samplings. The reservoir of the dam was divided into nine (9) strata and in each stratum, 5 samples were taken making a total of 45 samples. Samples taken in each strata were composited making it a total of 9 samples. The water samples were collected into well-labelled polythene bottles and kept in an ice chest with ice cubes. The samples were transported to the Ecological Laboratory of the University of Ghana for analysis. The parameters analyzed were pH, electrical conductivity (EC), temperature, total dissolved solutes (TDS), chloride (Cl-), sulphate (SO42-), bicarbonate (HCO3-), carbonate, PO4-P, nitrites/nitrate (NO3-N), total dissolved solids (TDS), magnesium (Mg2+), calcium (Ca2+), sodium (Na+), boron, total alkalinity, ammonia (NH4-N) and potassium (K+). A greater percentage of the results obtained were within acceptable limits except potassium which was slightly higher. This could be the result of farming activities in the catchment of the dam. In general, the water in Bontanga irrigation dam can be considered suitable for irrigation purposes.

Dams for hydropower and irrigation: Trends, challenges, and alternatives

Hydropower and irrigation are essential for achieving human development objectives and for climate mitigation and adaptation. These sectors depend on the same grey infrastructure, such as dammed reservoirs, which has created negative socio-ecological externalities and sectoral conflicts in the past. Yet, future needs for infrastructure in both sectors and their interdependencies remain unclear. We address this gap by applying data-fusion and machine-learning approaches and provide a comprehensive global overview and a new dataset that elucidates the role of existing dams and reservoirs for hydropower and irrigation. We then review projected demands for irrigation storage and hydropower by 2050 and analyze how projected growth aligns with the identified potential for irrigation and hydropower dams. Globally, projections point to an increased demand for hydropower in the order of 400 GW by 2050, which amounts to around 60 %–64 % of the identified potential and around +35 % compared to today. For irrigation, fully leveraging sustainable water resources would require 460 km3/yr of stored water, or around +70 % compared to today. Projected demands for hydropower and irrigation are larger than what future grey infrastructure could provide in many regions, especially in Europe, South Asia, and Africa. In such conditions, both sectors will be increasingly in competition for infrastructure. Our findings also highlight the need to study alternative solutions, such as other forms of renewable energy and nature-based solutions for water storage, to meet societal demands while avoiding negative externalities associated with grey water infrastructure.

Estimation of water inflows to reservoirs of irrigation dams in the Guinea Savannah ecological zone of Ghana

ABSTRACT The study was carried out in the northern Ghana to estimate water inflows to nine reservoirs of irrigation dams for a period of 20 years (1999–2018) using the USDA Natural Resources Conservation Service Curve Number model. The key input parameters of the model were hydrologic soil group, rainfall amount, landuse/landcover, weighted curve number, antecedent moisture condition, and potential maximum soil moisture retention. The annual rainfall within the reservoir catchments was found to vary between 617.20 and 1,382.30 mm. The estimated annual runoff depths ranged from 54.10 to 125.55 mm. A high degree of positive correlation was found between rainfall and runoff depths with a coefficient of determination (R2) ranging from 79.80 to 90.70%. Hydrologic soil groups accounted for about 67.2 and 62.5% of the variation in runoff depth and percentage runoff, respectively. The estimated annual water inflows to the reservoirs ranged from 145,206 ± 125,814 m3/y at Gambibgo to 47,074,634 ± 4,395,860 m3/y at Tono. The variation in the annual water inflows and annual storage capacity recharge among the various reservoirs was noted to be influenced by reservoir size, catchment size, rainfall, and soil characteristics in the reservoir catchments.

Effects of irrigation dams on riverine biota in mountain streams

Mountain streams harbor unique biodiversity and provide essential ecosystem services to human societies. Yet, these ecosystems face numerous threats, such as the construction of dams and land use changes, leading to rapid habitat degradation, water pollution, and biodiversity loss. In this study, we assess the effect of irrigation dams on mountain riverine biota using traditional biotic indices and trait-based approaches. We selected diatom and macroinvertebrate communities surveyed between 2015 and 2017 in mountain streams located in different regions in northern Spain (Cantabrian Cordillera, Iberian System, and Pyrenees) under natural and altered flow conditions (i.e., downstream of irrigation dams). Hydrological and biological changes related to the presence of dams, the mountain range, and the interaction between these two factors were identified. Summer flows, frequency of high flow events, and minimum annual flows timing were significantly affected by irrigation dams, independently of the region. Winter flows, the magnitude of high flow extremes, and the number of flow rises and falls varied significantly with the dam-mountain range interaction. The frequency and duration of flow pulses depended on the mountain range only. In the Cantabrian Cordillera, a region with larger reservoirs (>150 hm3), impacted sites showed a marked inversion of the seasonal flow patterns (i.e., increased summer flows but reduced winter flows). In the other mountain ranges, reservoirs had smaller storage volumes and multiple purposes, causing significant flow change frequency variations. Diatom traits, taxonomic richness, diversity, and IPS score varied with dam presence and mountain ranges, while macroinvertebrate traits and biotic indices responded weakly. These findings suggest that diatom communities might be more sensitive to hydrological alteration, while macroinvertebrates might be more influenced by space-related factors, such as biogeography and dispersal, overriding dam-related impacts. Furthermore, dam-related changes in ecosystems may depend not only on the presence of dams and their characteristics (e.g., reservoir size and operation), but also on local conditions and biogeography. Our findings emphasize that, when using pre-existing biomonitoring datasets, although some dam-related patterns emerge (e.g., with diatoms), other patterns may be constrained by the datasets’ low spatio-temporal coverage and taxonomic resolution, highlighting the need of well-structured study designs.

Does dam-based irrigation affect the sustainability of natural capital ?: A doubly robust analysis

This study assesses the impact of dam-based irrigation on the adoption of management practices for sustaining the natural capital of a region, with a focus on soil and water resources, using survey data from 1020 farmlands in northwestern Tunisia. Because treatment effect estimates are frequently prone to misspecification in either the treatment or outcome models, we use the doubly-robust inverse probability weighted regression adjustment estimator on four soil and water sustaining agricultural practices. As a robustness check, we also apply propensity score matching, with both methods consistently indicating a positive impact of dam irrigation on the adoption of these practices. Overall, these findings emphasize the indirect positive ecological effects of dams on a region's natural capital sustainability.

Irrigation dams threaten Brazilian biodiversity.

Brazil is among the main contributors to global biodiversity, which, in turn, provides extensive ecosystem services. Agriculture is an activity that benefits greatly from these ecosystem services, but at the same time is degrading aquatic and terrestrial ecosystems and eroding Brazilian biodiversity. This conflict is growing, as emerging unsustainable legislative proposals that will benefit the agricultural sector are likely to accelerate the decline of biodiversity. One such initiative (Bill 1282/2019) would change Brazil's "Forest Code" (Law 12,651/2012) to facilitate construction of irrigation dams in Permanent Preservation Areas, a category that includes strips (with or without vegetation) along the edges of watercourses. Two other similar bills are advancing through committees in the Chamber of Deputies. Here we provide details of these three bills and discuss their consequences for Brazil's biodiversity if they are approved. Expected negative impacts with changes in the legislation include: increased deforestation; siltation; habitat fragmentation; introduction of non-native species; reduction in the availability of aquatic habitats; and changes in biogeochemical process. These proposals jeopardize biodiversity and may compromise the negotiations for an agreement between Mercosur and the European Union.

Impact of Irrigation Dams on Fish Diversity of Budhikhola in Bardiya, Lumbini Province of Nepal

This extensive study describes the current status of freshwater fish diversity in the Budhikhola which is an important branch of the Karnali River that runs through the western region of the Bardiya district covering about 30 km distance in the north-south direction. To examine the effects of irrigation dams on habitat modification and fish variety, fish were collected from the entire Budhikhola stretch, with four sampling stations established depending on habitat structure. The freshwater system of the Budhikhola harbors a diverse and ecologically complex fish community comprising 41 species from 6 orders and 13 families. The dominance of the Cyprinidae family, represented by Barilius barna, Chanda nama, Chagunius chagunio, etc., highlights its ecological significance. On the other hand, the loss of important fish species is proof that the building of irrigation dams has had significant ecological effects. Human-induced hazards such as damming and overexploitation, have adversely impacted the river environment, resulting in reduced water depth, habitat structure changes, and restricted nutrient flow. The majority of the riverbed had been observed to be silt-covered. Significant fish species loss indicates ecological instability brought on by human activity. Changes in the distribution of fish sizes and spatial differences between upstream and downstream areas highlight the complex link between habitat modifications and community functioning. The catch-per-hour seasonal tendency, which peaks in September and falls in March, is correlated with fishing patterns, environmental factors, or breeding seasons. The evenness value (0.96) and high Shannon-Weiner Diversity Index (H'= 3.57) show a diverse and harmonious fish community. The relevance of family-level distinctions in implementing effective conservation and management measures is highlighted by major differences among family groups (p<0.001). As the findings make clear, the long-term survival of the diversified fish ecosystem of the Budhikhola depends on addressing and reducing anthropogenic stressors. This study provides valuable insights for informed conservation efforts in the aquatic ecosystems of Nepal.

Reducing Poverty Through Irrigation Investment: A study of Palai Dam Irrigation Canal, District Charsadda

Reducing Poverty Through Irrigation Investment: A study of Palai Dam Irrigation Canal, District Charsadda

KEPERCAYAAN MASYARAKAT TERHADAP TEMPAT KERAMAT DI DESA SILAU MARAJA KECAMATAN SETIA JANJI KABUPATEN ASAHAN

Indonesian people still believe in places that they consider to have supernatural powers. In certain communities, such as the village of Silau Maraja, there are certain places and spaces that are considered by the community to have a special position, which is called the community of sacred places. The Silau Maraja community has carried out various ways to protect the sacred place where there is an irrigation dam in the belief that it will provide safety and peace to the community, which is called the "Nature of Bali" community. In this thesis, the purpose of this research is to look at the factors that society maintains belief in the place "Bali's nature as a sacred place. And to see the social function of this sacred place in the Silau Maraja community. In this study using a qualitative approach method. In this case, to obtain the intended data, the selection of research subjects in the Silau Maraja community was seven people, such as religious leaders, agricultural communities, community leaders and guardians of the Bali natural dam. Data collection techniques researchers conducted observations and interviews with informants and documentation. From the results of this study it was found that the community's belief system for sacred places is still maintained and becomes a source of livelihood for the community because they are a source of water for rice fields. The researcher uses Talcot Parsons Functionalism theory which says society is seen as an interconnected system and there is not a single part that does not have a function. Likewise in research related to functionalism theory that people's belief in sacred places has a relationship with each other that is interrelated and has a social function arising from sacred places to protect nature and protect the environment.

A Review on Significance and Failure Causes of Small-Scale Irrigation Dams in Arid and Semi-arid Lands (ASAL)

Water scarcity is increasingly becoming a significant challenge in arid and semi-arid lands. In these areas, small dams and reservoirs are important in providing water resources, supporting agricultural activities, and contributing to sustainable and resilient rural communities as they require an affordable investment. However, their frequent failures pose significant challenges to sustainable water management and agricultural development in these regions. This review study was developed based on the review of many international standards and guidelines from published studies in scientific journals in addition to information from practitioners. We examined the significance and causes of the failure of small dams and reservoirs; and discussed design criteria and considerations involved in their construction. The outcomes of this study offer valuable insights into the significance of small-scale irrigation dams and shed light on the multifaceted causes of their failure. A holistic approach to address the challenges identified are approach is required. Integrating engineering solutions such as improving design, and regular maintenance, with sustainable land management are crucial for optimising the small dams and ensuring that they adequately serve the needs of the community. The causes of failure were found to be multifaceted encompassing factors such as poor construction and maintenance practices and inadequate design considerations. Finally, this review highlighted the key elements in assessing structural conditions critical to the functionality and sustainability of small dams and reservoirs.

ASSESSMENT OF THE CONTRIBUTION OF GURARA DAM IRRIGATION SCHEME TO POVERTY REDUCTION AMONG FARMING HOUSEHOLDS IN KADUNA STATE, NIGERIA

The study assessed the contribution of Gurara dam irrigation scheme to poverty reduction among farming households in Kaduna State, Nigeria. Data on respondents’ poverty status, and the constraints faced by farming households in utilizing the Gurara irrigation facilities was collected using structured questionnaire during the 2019 cropping season. A four-sampling stage technique was employed in this study to select randomly 340 farming households made up of 170 each of beneficiary and non-beneficiary. The analytical tools used to achieve the objectives were descriptive statistics, Foster-Greer-Thorbecke (FGT) index, and Tobit regression models. The poverty headcount, poverty gaps and severity indices of the Gurara dam beneficiary farming households were 0.24, 0.03 and 0.005, respectively. Decomposition of poverty status of the Gurara dam beneficiary and non-beneficiary farming households based on socio-economic characteristics, institutional and living conditions characteristics was estimated using mean per adult equivalent household expenditure. The Tobit regression model showed that the marginal effects of household size (0.176), cooperative membership (-0.168), farm income (-0.157), farm size (0.404) and credit utilized (-0.193) for farm production were statistically significant determinants of the poverty status of household farmers. The result of analysis of constraints encountered by Gurara dam farming households were ranked from most critical to the least critical; these include inadequate irrigable land and water; excessive cost of irrigation equipment, inadequate inputs, inadequate and untimely supply of inputs, inadequate extension visits and research. Farming households should be encouraged by government and Non-Government Organization (NGO) as well as their cooperative empowerment to engage in small scale irrigation farming to enable increase production of food and alleviate their poverty status.

The Impact of Dam Construction on Downstream Vegetation Area in Dry Areas Using Satellite Remote Sensing: A Case Study

The assessment of ecosystem quality and the maintenance of optimal ecosystem function require understanding vegetation area dynamics and their relationship with climate variables. This study aims to detect vegetation area changes downstream of the Hali dam, which was built in 2009, and to understand the influence of the dam as well as climatic variables on the region’s vegetation areas from 2000 to 2020. The case study is located in an arid area with an average rainfall amount from 50 to 100 mm/year. An analysis of seasonal changes in vegetation areas was conducted using the Normalized Difference Vegetation Index (NDVI), and supervised image classification was used to evaluate changes in vegetation areas using Landsat imagery. Pearson correlation and multivariate linear regression were used to assess the response of local vegetation areas to both hydrologic changes due to dam construction and climate variability. The NDVI analysis revealed a considerable vegetation decline after the dam construction in the dry season. This is primarily associated with the impoundment of seasonal water by the dam and the increase in cropland areas due to dam irrigation. A significantly stronger correlation between vegetation changes and precipitation and temperature variations was observed before the dam construction. Furthermore, multivariant linear regression was used to evaluate the variations in equivalent water thickness (EWT), climate data, and NDVI before and after the dam construction. The results suggested that 85 percent of the variability in the mean NDVI was driven by climate variables and EWT before the dam construction. On the other hand, it was found that only 42 percent of the variations in the NDVI were driven by climate variables and EWT from 2010 to 2020 for both dry and wet seasons.

Seasonal forecast-informed reservoir operation. Potential benefits for a water-stressed Mediterranean basin

The increased seasonal demand for water puts pressure on Mediterranean water resources, which are often exploited in a non-renewable way. Besides, climate change can alter hydroclimatic patterns and exaggerate freshwater stress. Flexible operation of existing water reservoirs is one of the most cost-effective ways to mitigate water-related stress by storing water when it is abundant and releasing it when droughts persist. In this context, hydroclimatic forecasts can be central in properly informing reservoir operation. Nevertheless, the link between forecast skill and forecast value is neither easily predictable nor necessarily positive. Each system requires specific forecasts according to its characteristics, and the skill of existing forecast systems does not necessarily translate into a significant gain in system performance. In this work, we develop downscaled seasonal forecasts of reservoir inflow for the Faneromeni irrigation dam on Crete island. We then quantify the value of these seasonal forecasts in informing the reservoir operations. While the current operation of this reservoir is based on the available storage at the beginning of the irrigation season, we investigate alternatives by using the Evolutionary Multi Objectives Direct Policy Search method, which allows the design of flexible rules to cope with the variability of the hydrologic conditions as well as to include forecast information for conditioning operational decisions. Under historical climate conditions, results demonstrate a notable enhancement in performance solely by implementing more flexible operating policies. Incorporating perfect forecasts results in an additional improvement of 4% on average throughout the period from 1993 to 2019. However, when using actual forecasts, this gain diminishes to 1%. These outcomes support the exploration of potential trade-off solutions that effectively balance the competing demands within the region.

Assessment of irrigation water quality for vegetable production in the Bono and Bono East regions

Irrigation water quality is one of the key parameters for healthy plants growth and maintenance of healthy soils for abundant food production. This research examines the physicochemical parameters of irrigation water and its suitability for crop production in the Bono and Bono East regions. The suitability of irrigation water for vegetable production is to ensure that fresh vegetables produced are of good quality, since the vegetables are mostly eaten raw. Four irrigation dams in Subinja, Kaniago, Tanoso and Akrobi from the two regions were selected and water samples from each of the dams were collected during the dry and wet seasons. The samples were analysed for physical parameters, heavy metals and soluble cations and anions at the GWCL laboratory using standard laboratory procedures and techniques. The various parameters examined showed that EC, SAR, TDS, pH and the ionic concentrations (Ca2+, K+, Mg2+, Na+, Cl-, NO3-) were found within the WHO recommended limits and, therefore, suitable for irrigation of vegetables. However, Na+ values for dry and wet seasons were found to be above the permissible limits and, therefore, can only be suitable for salt tolerance crops. K+ was also found to be higher across all the dams. Elements such as Cu, Pb and As ions, which might cause toxicity of the irrigation water were low except Cr, which had no effect on the quality of the irrigation water. The study recommends further studies on the quality of vegetables produce from the dams and its impact on consumers.

Comparative Study on NACA-9405, NACA-9503 and NACA-9506 Airfoil Profiled Blade Open-Channel Flow Cross-Flow Turbine

Several agricultural areas in Indonesia are classified as underdeveloped rural areas, and challenging to acquire electricity from the primary grid. On the other hand, some pico hydropower potentials can be found in agriculture, especially at the irrigation dam spillway flows. However, no such technology can convert the energy inside the water open-channel flow through dam spillways into electricity. Crossflow turbines (CFT) are expected to utilize dam spillways’ power due to their ability to convert the kinetic energy of water. Prior studies found that airfoil profile could slightly increase CFT efficiency and affect the interaction between water and turbine. Using planar two-dimensional computational fluid dynamics (CFD) numerical simulation analysis, the current study investigated the energy conversion phenomenon inside different open-channel CFT blade profiles. This study simulates CFT working at 3 meters of total head and 0.04 m3/s of water discharge put into the dam spillway’s downstream. The turbine blade profiled with the National Advisory Committee of Aeronautics (NACA) standard airfoil numbered 9405, 9503, and 9506 are being compared and investigated in the present study. CFD numerical analysis results show that the forward direction NACA airfoil profiled blades deliver better efficiency than the reversed one. These findings contradict the prior study’s results which tested airfoil profiled CFT working as usual with nozzle. This phenomenon indicated differences in the energy transfer process between open channel CFT and the ordinary CFT with a nozzle. Furthermore, current work finds that forward NACA-9503 CFT has a higher efficiency than other tested airfoil profiles, with 57.05% efficiency. In addition, the present study finds that the NACA-95XX airfoil has a more suitable chamber curve with the original CFT blade’s curve than the NACA-94XX airfoil by velocity triangle analysis. Then, the NACA-9503 profile is thinner than the NACA-9506 profile, which eases water flowing through the turbine blades.