Pond Depth Research Articles

In silico study of the microalgae−bacteria symbiotic system in a stagnant pond

A rigorous mathematical modeling of the symbiotic interaction between microalgae and bacteria in a stagnant pond is applied to analyze the effect of the operating conditions on the bioprocess kinetics. The microbial co-culture is described by a partial differential equations system, which is solved by a combined numerical method based on the Lagrangian Particle Tracking for microalgae transport equation and the Orthogonal Cubic Hermite Collocation for remaining transport equations. The effect of the temperature and light intensity, alkalinity, turbidity, initial ratio of biomasses, algal cell size, pond depth on the algal biomass productivity and the substrates removal is analyzed. It was found that all of them significantly affect the biomass production and the substrates removal, which is discussed in detail. Besides, a strong symbiotic interaction between cell growth of microalgae and bacteria is observed; specifically, bacterial growth was restricted by the microalgal growth, due to the limitation of dissolved oxygen.

Aspects influence leachate characteristics on leachate treatment plants in Temesi Landfill Gianyar Regency, Bali Province, Indonesia

This paper revealed aspects that influenced leachate characteristics in leachate treatment plants located in Temesi landfill. Four aspects observed refers to Law Number 3/2013 Ministry of Public Works: landfill operation; rainfalls; treatment plant designs; operation and maintenance. Data collected by observation and field survey to identify leachate characteristics. Leachates were collected by grab sampling from inlet through outlet of the treatment plants, to be laboratory analysed to meet the standards set by Ministry of Environmental and Forestry Number 59/2016 and compared to the standards. Leachate discharge calculated using Thornthwaite method to be compared to criteria designed. The result shown that leachate discharge is 0.45 L/sec exceeding the designed discharge 0.42 L/sec. Laboratory test result from leachate sampling shown that the BOD, COD and TSS value exceeding the regulation standard in range of > 2000 mg/L. Findings revealed that the depth of maturation ponds is 2.9 meters exceeded the designed criteria. It is found that the landfill operated with open dumping system and the treatment lagoons has never been regularly drained and recirculate. Those practices increase the leachate volume and degenerate the treatment functions. It can be concluded that the 4 aspects mentioned significantly influenced the leachate characteristics.

Scaling factors in HYDRUS to simulate a reduction in hydraulic conductivity during infiltration from recharge wells and infiltration basins

AbstractManaged aquifer recharge (MAR) represents a promising technique to cope with increasing water stress worldwide. However, it can be challenging to operate MAR systems, especially concerning clogging. Clogging reduces the infiltration capacity and system efficiency of a MAR facility. Processes that cause clogging are difficult to quantify and assess, and their simulations in MAR schemes have so far been limited. The variably saturated water flow model HYDRUS‐2D was therefore modified to include time‐variable hydraulic conductivities to more realistically represent clogging at the infiltration interface of infiltration basins and recharge wells. An exponential function with a time‐variable scaling factor was implemented into HYDRUS to vary the soil hydraulic conductivity over time during simulations. The new approach was tested, in combination with the reservoir boundary condition, by simulating two‐dimensional cross‐sections of two three‐dimensional laboratory experiments representing recharge from infiltration basins and injection wells. With the help of the time‐variable scaling factor, the increasing ponding depth in both experiments due to progressive clogging was reproduced. Hypothetical simulations with various well configurations, soils, and injection rates indicate that clogging influences the infiltration volumes and subsurface infiltration area, which should be considered during the planning of MAR systems. The approach can be used to evaluate the resulting infiltration capacity numerically and to help with the operation and design of MAR facilities. However, further research is required to fully understand and integrate the processes that lead to clogging at MAR facilities into numerical simulations.

Small population size and low genomic diversity have no effect on fitness in experimental translocations of a wild fish.

Little empirical work in nature has quantified how wild populations with varying effective population sizes and genetic diversity perform when exposed to a gradient of ecologically important environmental conditions. To achieve this, juvenile brook trout from 12 isolated populations or closed metapopulations that differ substantially in population size and genetic diversity were transplanted to previously fishless ponds spanning a wide gradient of ecologically important variables. We evaluated the effect of genome-wide variation, effective population size (Ne), pond habitat, and initial body size on two fitness correlates (survival and growth). Genetic variables had no effect on either fitness correlate, which was determined primarily by habitat (pond temperature, depth, and pH) and initial body size. These results suggest that some vertebrate populations with low genomic diversity, low Ne, and long-term isolation can represent important sources of variation and are capable of maintaining fitness in, and ultimately persisting and adapting to, changing environments. Our results also reinforce the paramount importance of improving available habitat and slowing habitat degradation for species conservation.

The effects of rearing water depths and feed types on the growth performance of African catfish ( Clarias gariepinus )

African catfish (Clarias gariepinus) has been growing in popularity as a culture species globally. Although considerable research has been carried out on this species’ feeding preferences, no research has been carried out on optimum water level for growth. This is particularly surprising given this species' benthic nature. This study assessed the effect of different combinations of water levels and types of feed on the growth performance of African catfish. The study employed a 3 × 2 factorial design with three ponds of different water levels (0.5, 1 and 1.5 m) and two types of feeds (floating and sinking). Twelve earthen ponds (1 × 2 m) were each stocked with 16 catfish fingerlings (mean weight ~100 g), and their growth was monitored for 12 weeks. The fish cultured in the shallowest water grew significantly faster than those cultured in the deepest ponds. At the same time, fish cultured in the shallowest ponds had the lowest feed intake rates and consequently the lowest feed conversion ratios. Catfish fed sinking pellets grew faster than those fed floating pellets although the difference was not significant. There was no significant interaction between pond water depth and feed type. The results of this study suggest that the growth and feeding efficiency of C. gariepinus can be optimized by culturing in fairly shallow ponds (0.5 m).

Exploring optimal nitrogen management strategies to mitigate nitrogen losses from paddy soil in the middle reaches of the Yangtze River

Excessive fertilization in rice paddy fields leads to surface water eutrophication, groundwater contamination and air pollution. Determining optimum nitrogen (N) management is essential for maintaining rice yield while reducing the environmental risk caused by N loss. A two-year field experiment (2017–2018) was carried out in a typical paddy field in the middle reaches of the Yangtze River. The WHCNS (soil Water Heat Carbon Nitrogen Simulator) model was calibrated and evaluated for simulations of measured ponding water depth, evapotranspiration, aboveground dry matter, yield, runoff and crop N. The model was then used to evaluate the effects of different N fertilizer rates and split-N application ratios (SNR) practices on crop growth and N losses. Results showed that the model performed well in simulating rice growth and N losses in the region. Ammonia volatilization and denitrification were the mainly pathways of N loss in paddy field, and their two-year average losses were 34% and 38% of the total N loss, respectively. N leaching accounted for 23%, and runoff N loss accounted for 5% of total N loss. N losses were evaluated for two different scenarios and simulated ratios of ammonia volatilization, denitrification, N leaching, and runoff to total N loss under different N management scenarios were 15%–53%, 33%–55%, 6%–30%, and 4%–8%, respectively. Ammonia volatilization and N runoff exponentially increased with an increase of N fertilizer rate, whereas denitrification and N leaching showed an increasing and then a decreasing trend. Yield increased by 36 kg ha−1, and the total N loss decreased by 32.6 kg N ha−1 when the N fertilizer rate was reduced from 231 kg N ha−1 to 155 kg N ha−1 and the SNR was changed from 5:3:1 to 1:1:4. Therefore, reducing the N fertilizer rate and increasing the SNR in the late rice growing season can significantly reduce N loss and effectively improve N use efficiency.

Two-dimensional Analytical Derivation of Incipient Desaturation Criterion in Stream-aquifer Flow Exchange

A criterion for incipient desaturation for a stream and an aquifer initially in saturated hydraulic connection is derived analytically. The riverbed acts as a clogging layer. Such a criterion cannot be derived using a one-dimensional analysis. At least a two-dimensional analysis is required. It applies for a variety of shape of cross-sections. The formulae are algebraic and show explicitly the various factors that affect the initiation of desaturation such as river width, thickness of the aquifer, thickness of the clogging layer, conductivities of the clogging layer and of the aquifer, (drainage) entry pressure of the aquifer, ponded depth over the riverbed and aquifer head at some distance from the river bank. It is shown also that neglecting the change in thickness of the capillary fringe due to flow, as opposed to its hydrostatic value, has little impact on the accuracy of the criteria for incipient desaturation.

Lessons from Assessing Uncertainty in Agricultural Water Supply Estimation for Sustainable Rice Production

Agricultural water supply (AWS) estimation is one of the first and fundamental steps of developing agricultural management plans, and its accuracy must have substantial impacts on the following decision-making processes. In modeling the AWS for paddy fields, it is still common to determine parameter values, such as infiltration rates and irrigation efficiency, solely based on literature and rough assumptions due to data limitations; however, the impact of parameter uncertainty on the estimation has not been fully discussed. In this context, a relative sensitivity index and the generalized likelihood uncertainty estimation (GLUE) method were applied to quantify the parameter sensitivity and uncertainty in an AWS simulation. A general continuity equation was employed to mathematically represent the paddy water balance, and its six parameters were investigated. The results show that the AWS estimates are sensitive to the irrigation efficiency, drainage outlet height, minimum ponding depth, and infiltration, with the irrigation efficiency appearing to be the most important parameter; thus, they should be carefully selected. Multiple combinations of parameter values were observed to provide similarly good predictions, and such equifinality produced the substantial amount of uncertainty in AWS estimates regardless of the modeling approaches, indicating that the uncertainty should be counted when developing water management plans. We also found that agricultural system simulations using only literature-based parameter values provided poor accuracy, which can lead to flawed decisions in the water resources planning processes, and then the inefficient use of public investment and resources. The results indicate that modelers’ careful parameter selection is required to improve the accuracy of modeling results and estimates from using not only information from the past studies but also modeling practices enhanced with local knowledge and experience.

Hydraulic investigation of the impact of retrofitting floating treatment wetlands in retention ponds.

This paper describes the laboratory experimental investigations undertaken to analyse the influence of floating treatment wetlands (FTWs) on the hydraulic performance of a stormwater retention pond. Two experimental series were conducted, each focussed on investigating the influence of placing an FTW in a pond with firstly the inflow entering the retention pond from an inlet positioned 0.25 m offset from the longitudinal axis of the pond, and secondly the inlet positioned at the longitudinal axis of the pond. For both series of experiments, tests were undertaken at 1 l/s and 1.5 l/s, and with and without an artificial FTW installed. This study is the first to investigate the hydraulic impact of FTWs and their root systems on the performance of stormwater retention ponds. The results presented in this study suggest that FTWs are a viable method to minimise hydraulic inefficiencies, thereby increasing retention time and optimising hydraulic performance of stormwater retention ponds. The results highlight the importance of plant root characteristics. The optimal arrangement of root length is LR/DP = 0.5, where LR = root length and DP = pond depth. The results also indicate that the spatial variability of vegetation has a significant impact on the hydraulic performance of the pond.

Laboratory evaluation of falling-head infiltration for saturated soil hydraulic conductivity determination

Falling-head one-dimensional infiltration procedures, such as the simplified falling-head (SFH) technique, yield estimates of saturated soil hydraulic conductivity, Ks, with parsimonious and rapid experiments. Factors that can influence determination of Ks by the SFH technique were tested in the laboratory on three repacked soils differing by particle diameter ranges (0-2000, 0- 105 and 105-2000 mm, respectively). Using the theoretically calculated depth of ponding on the infiltration surface, D, instead of the measured one had a small impact on the Ks calculations (means differing by a factor of 1.1-1.2, depending on the soil). For the finest soil, Ks decreased by 3.1 times as D increased from 40 to 135 mm but D did not affect Ks for the coarsest soil, yielding in general the highest Ks values. The abrupt increase of the infiltration rate close to the end of the run did not influence appreciably Ks calculations since it determined an increase in Ks by a mean factor never exceeding 1.1. The most frequent result of the developed procedure for estimating the α* parameter was failure of the experiment although the valid α* calculations were plausible, being higher for the coarse textured soil (17 m–1) than the finer soils (9.2-9.3 m–1). The depth of the wetting front at the end of the run was 1.1-1.2 times deeper than that calculated theoretically before the run, depending on the soil. In conclusion, the method used to determine D should not affect very much Ks determination but larger D values can yield smaller Ks values in fine-textured soils. Air escapes from the sampled soil volume when almost all water had infiltrated but this circumstance does not have a great impact on calculation of Ks. A falling-head one-dimensional ponded infiltration process is not recommended to estimate α*. The theoretical depth of the wetting front can approximately be predicted before the run. The SFH technique appears a rather robust method to simply and rapidly determine Ks.

Evaluasi Usaha Pembudidayaan Ikan di Desa Matungkas Kabupaten Minahasa Utara

The purppuse of research was to study the feasibility of fish culture technically and economically. Primary data was gathered by interview to fish farmer and secondary data was obtained from related references. Data analyzed were break even point and foof conversion ratio. Water source of pond was spring water and the pond depth was 0.50 – 1.75 m. Juveniles were obtained fron Tatelu Freshwater Aquaculture Board and other palces. Fish was fedr pellet for 3-4 months. Pond conctruction did not match the criteria . Fish farmer did not used capital from bank and farmers did not use book account in running the business. Food conversion ratio was 2.5 – 3.5. The price of pellet was Rp. 8.500/kg ang fish price was Rp. 25.000/kg. Fish farmer dit not receive enough profit in running fish culture Keywords: feasibility study, pond construction, fish culture, Matungkas Village

Trait-Environment Relationship of Aquatic Vegetation in a Tropical Pond Complex System

The relationship between organisms’ traits and the characteristics of their habitats has been a central theme in ecology. Using two complementary approaches to analyze three-matrices of species composition, functional trait, and environment data (RLQ and fourth-corner analyses), we tested if environmental gradient determines aquatic plant traits in ponds in the Pantanal wetland. Furthermore, we tried to understand if plant composition is spatially structured and if environmental gradient is correlated with taxonomic and functional community properties. We sampled aquatic plants coverage in 20 ponds and measured pond size, depth and pH to represent the environmental gradient. We found significant turnover of several traits of aquatic plants along the environmental gradient, being niche partitioning the most probable process structuring plant communities. There was no evidence of spatial autocorrelation determining species composition in the scale of the study, which may indicate that the annual flooding can act as homogenizing factor that promotes species co-occurrence along the ponds. Taxonomic abundance and functional richness were positively related with environmental gradient. Larger and deeper ponds provide higher resource availability thus supporting more functional attributes and vegetation cover. Our results support the hypothesis that niche process is the main driver of aquatic plants in the Pantanal.

Review: Toward management of urban ponds for freshwater biodiversity

AbstractMany cities around the world are expanding and this trend in urbanization is expected to sharply increase over coming decades. At the same time, the integration of green and blue spaces is widely promoted in urban development, potentially offering numerous benefits for biodiversity. This is particularly relevant for urban waterbodies, a type of ecosystem present in most cities. However, site managers often lack the knowledge base to promote biodiversity in these waterbodies, which are generally created to provide other ecosystem services. To address this, our review presents guidelines for promoting biodiversity in urban ponds. We found a total of 516 publications indexed in ISI Web of Sciences related to this topic, of which 279 were retained for the purposes of our review. The biodiversity of urban ponds, measured by species richness, appears to be generally lower than in rural ponds; however, urban ponds often support threatened species. Furthermore, if well managed, urban ponds have the potential to support a much greater biodiversity than they currently do. Indeed, this review shows that a range of urban factors can impair or promote pond biodiversity, including many that can easily be controlled by site managers. Local factors include design (surface area, pond depth, banks and margins, shade, shoreline irregularity), water quality (conductivity, nutrients, heavy metals), and hydroperiod and biotic characteristics (stands of vegetation, fish, invasive species). Important regional factors include several indicators of urbanization (roads, buildings, density of population, impervious surfaces, car traffic), and the presence of other wetlands or green spaces in the surrounding landscape. We considered each of these factors and their potential impact on freshwater biodiversity. Taking into account the management measures listed in the publications reviewed, we have proposed a framework for the management of urban ponds, with guidelines to promote biodiversity and other ecosystem services, and to avoid ecosystem disservices or the creation of ecological traps. At the city scale, the biodiversity of a pondscape benefits from a high diversity of pond types, differing in their environmental characteristics and management.

Hydrus-1D model for simulating water flow through paddy soils under alternate wetting and drying irrigation practice

Alternate wetting and drying (AWD) irrigation practice in paddy cultivation requires a safe soil moisture stress level in the root zone for which irrigation water savings can be maximized without compromising the yield. Determining safe soil moisture stress level in AWD practice experimentally is challenging and involves time and money. Mathematical models can be alternate tools for determining the safe soil moisture stress with least experimental data. In this study, field experiments were conducted on rice crop using thirty lysimeter plots during rabi seasons (January to April) of 2015–2016 and 2016–2017. Three irrigation treatments including irrigation under no-soil moisture stress, mild soil moisture stress (MS: 450 cm matric potential head) and severe soil moisture stress (SS: 700 cm matric potential head) were considered, and each treatment was replicated ten times. The ponding depth and matric potential head at 10, 40 and 70 cm soil depths were measured daily from all lysimeter plots. The measured field data were used to calibrate and validate Hydrus-1D model and simulate water flow under different soil moisture stress treatments. The water saving in MS and SS treatments was 23 and 27%, respectively. The deep percolation in MS and SS treatments was reduced by 27–30% and 30–35%, respectively. The safe ponding water depth required to minimize deep percolation loss in MS and SS treatments was 5 and 7 cm, respectively. The required ponding water depth was observed to be increased with the increased matric potential head.

Microbial Augmentation on Intensive Grow Out Shrimp Culture to Improve Water Quality, Growth and Shrimp Production

The objective of this study is to evaluate the microbial augmentation on intensive shrimp culture to improve water quality, growth, and shrimp productivity. This study was conducted on intensive shrimp grow out ponds of the farmers in Pangkep Regency, South Sulawesi. There were four grow out ponds used for study with different pond size. All ponds used zero or minimal water exchange systems. All inputs used in this study such as high quality of commercial feed, seed, intensive aeration with paddle wheels, vitamins and minerals. Treatment with a consortium of flock forming bacteria as a starter each given every week. Shrimp growth ponds used intensive culture system with condition water depth of ponds 120 – 130 cm, feeding rate was four time a day. Water quality parameters measured are salinity, pH, water temperature, dissolved oxygen (DO) and turbidity. Survival rate (SR), average daily gain (ADG), feed conversion ratio (FCR), and MBW were measured every week. The results of this research showed that shrimp production 1,600 – 5,600 kg. Growth rate: ADG 0.34 – 0.45; survival rate 90 – 97 %; FCR 1.02 – 1.1 and MBW 22.8 – 29.40. Water quality parameters such as dissolved oxygen, water temperature, water depth, salinity, pH and water transparency were 2.8 – 5.5 mg L−1; 26 – 31°C; 75 – 125 cm; 15-30 mg L−1; 6.8 – 9.6 and 15 – 30 cm; respectively. In summary, shrimp production increased significantly with microbial augmentation, and water quality parameters were a suitable condition.

Development of an empirical formula for estimation of bioretention outflow rate

Urbanization of a watershed affects both surface water and groundwater resources. When impervious area increases, the excess runoff and volume of water collected at the downstream end of the watershed also increases, due to the decrease in groundwater recharge, depression storage, infiltration and evapotranspiration. Low-impact development (LID) methods have been developed in order to diminish adverse effects of excess stormwater runoff. Bioretention is one of the LID types which is used to prevent flooding by decreasing runoff volume and peak flow rate, and to manage storm-water by improving water quality. In this study, an empirical formula is derived to predict the peak outflow out of a bioretention column as a function of the ponding depth on bioretention, hydraulic conductivity, porosity, suction head, initial moisture content and height of the soil mixture used in the bioretention column. Coefficients of the empirical formula are determined by using metaheuristic algorithms. For analyses, the experimental data obtained from rainfall-watershed-bioretention (RWB) system are used. The reliability of the empirical formula is evaluated by calculating the absolute per cent error between the peak value ofthe measured outflow and the calculated outflow of the bioretention columns. The results show that the performance of the empirical formula is satisfactory.

Fuzzy-set-based real-time reservoir operation using genetic algorithm

ABSTRACT A short-term reservoir operation model is developed for irrigation wherein the soil moisture of crops at grids and the reservoir storage are considered as fuzzy sets. The distinguished main features of the model as compared to the former fuzzy short-term reservoir operation model are the consideration of real-coded genetic algorithm and the implementation of the satellite-based gridded soil moisture of crops. The water is released from the reservoir at 10-day time periods by maintaining storage balance and the available water for the irrigation is distributed between the crops at grids by considering ponding depth for paddy, soil moisture continuity and root depth of the crops. The irrigation area is discretized into a number of grids (1º × 1º) to consider the spatial variations of rainfall and soil moisture of the crops. The fuzzy short-term reservoir operation model is optimized by the real-coded genetic algorithm by minimizing soil moisture deficits using forecasted inflow and rainfalls at grids from the present to last periods. The fuzzy short-term reservoir operation model using genetic algorithm performs better as compared to the conceptual reservoir operation policy and is faster than the short-term reservoir operation model using dynamic programming.

Carbon Dioxide Concentrations and Efflux from Permanent, Semi-Permanent, and Temporary Subalpine Ponds

Small ponds account for a disproportionately high percentage of carbon dioxide emissions relative to their small surface area. It is therefore crucial to understand carbon flow in these ponds to refine the current global carbon budget, especially because climate change is affecting pond hydrology. High elevation ponds in the Elk Mountains of western Colorado are drying more frequently as the timing of snowmelt advances. We compared CO2 concentrations and fluxes among ponds of different hydroperiods over diel sampling periods during the course of the 2017 open-water period. CO2 concentrations were significantly negatively correlated with pond depth and averaged 77.6 ± 24.5 μmol L−1 (mean ± S.E.) across all ponds and sampling events. Ponds were up to twenty times supersaturated in CO2 with respect to the atmosphere. Flux was highly variable within individual ponds but correlated with time of sampling and was highest at night. Flux averaged 19.7 ± 18.8 mg CO2 m−2 h−1 across all ponds and sampling events. We also compared flux values obtained using modeled and empirical methods and found that widely-applied models of gas exchange rates using wind-based gas exchange (K) values yielded estimates of CO2 flux that were significantly higher than those obtained using the floating chamber approach, but estimates of CO2 flux using globally averaged convection-based K values were lower than those obtained using the floating chambers. Lastly, we integrated soil vs. water efflux measurements with long-term patterns in hydrology to predict how total season-long efflux might change under the more rapid drying regimes and longer seasons that are already occurring in these systems. Because soil CO2 efflux averaged 277.0 ± 49.0 mg CO2 m−2 h−1, temporary ponds emitted 674.1 ± 99.4 kg CO2 m−2 over the course of the 2017 season from ice-out to refreezing, which was over twice as much as permanent and semi-permanent ponds. Our results emphasize that contributions of CO2 from small ponds to the global carbon budget estimates will vary with pond hydroperiod and sampling methodology, which have been overlooked given that most previous estimates were collected from limited sampling periods and from pond waters alone. Furthermore, pond CO2 contributions are predicted to increase over time as pond areas transition from efflux from water to efflux from soil.

Concept of Triple Heat Exchanger-Assisted Solar Pond Through an Improved Analytical Model

Abstract A new three-zone heat extraction system and its analytical model for maximizing the thermal power output of salt gradient solar ponds against a given volume is proposed. The present study considers internal heat exchangers installed within the non-convective zone (NCZ), lower-convective zone (LCZ), and the ground below the pond. The work is validated against a simplified version of the model (eliminating ground and bottom-zone heat extractions) available in the existing literature. Contrary to the conventional practice of optimizing only the middle-zone pond thickness, here, the newly proposed expression is used to find ideal values of both the middle- and bottom-zone thicknesses of the pond along with its cross-sectional area. The present work acknowledges that although the three-zone heat extraction system is the best, yet if a choice for two-zone heat extraction is to be made between the NCZ–LCZ and ground–LCZ, then the former is a better alternative. The power output is observed to increase asymptotically with mass flow rates of the three heat exchangers. However, their values must lie much below their theoretical asymptotic limits and their selection is regulated by constructional and operational constraints. These involve a minimum pond depth to offset surface evaporation, ground seepage water loss, and constraints preventing turbulent flow in heat exchangers to reduce friction loss and pumping power. This work recommends using three heat exchangers instead of either one or two and provides cardinal guidelines to extract heat in an ideal manner for a fixed solar pond volume.

Effect of organizational paddy water management by a water user group on methane and nitrous oxide emissions and rice yield in the Red River Delta, Vietnam

To mitigate the emissions of greenhouse gases from paddy fields and solve water shortage problems, sustainable and eco-friendly water management systems for rice cultivation urgently need to be constructed. Alternate wetting and drying (AWD) water management is effective and saves water. However, practical examples of AWD at the district or on-farm level are limited. We aimed to investigate the feasibility of AWD in experimental block units (conventional, weak-dry, and strong-dry) in paddy fields of about 44 ha in the Red River Delta area of Vietnam by examining the effects of intermittent irrigation (i.e., AWD) on the ponding depth, CH4 and N2O emissions, and rice yield in blocked experimental plots. Intermittent irrigation was expected to be achieved through the operation of irrigation pumps and sluice gates of water division works by the water management organization (water user group) of the district. However, the ponding depth was not controlled as initially planned because of frequent rainfall and low rate of decrease of the ponding depth in the study area. It was, however, confirmed that the period during which the ponding depth decreased below the soil surface was mostly (but not always) longer in the dry-type blocks. CH4 emissions decreased with an increase in drying period and this reduction was large in the summer-autumn season. There appeared to be no relationship between N2O emissions and water management. Rice yield decreased due to extreme drying in the summer-autumn season but was not affected by drying in the winter-spring season. This study demonstrated that CH4 emissions can be reduced and rice yield can be maintained by achieving a maximum drying index (i.e., ratio of the period during which the ponding depth is below the soil surface) of 0.6 in the summer-autumn season in the paddy fields of the target area.