Capacity Of Ponds Research Articles

Diminished storage capacity of ponds caused by sedimentation weakens their nitrogen removal efficiency

Though their small size, ponds play a disproportionately crucial role in eliminating nitrogen (N) transporting to downstream freshwaters. As significant water infrastructures, ponds are non-sustainable due to loss of storage capacity resulting from sedimentation. However, the effects of pond sedimentation on N removal is widely neglected in landscape N processing. The NUFER (Nutrient flows in Food chains, Environment and Resources use) model was employed to estimate N runoff from 1960 to 2018. We reconstructed the dynamic of number and storing capacity of about 14 million ponds due to construction and sedimentation from 1960 to 2018, projecting these trends into the year 2060. Our approach incorporated first-order kinetic reactions, including water residence time (HRT), to estimate N removal of ponds, utilizing data 6 monitoring ponds and 81 ponds from literature studies. Our analysis reveals a fourteen-fold increase in N runoff over the past six decades, rising from 0.8 Mt N in 1960 to 11.4 Mt N in 2018. Due to the initial rapid expansion of ponds, N removal by ponds increased from 6.4 % in 1960 to 13.6 % in 1990. Sedimentation is prevalent in ponds, particularly in small ponds with a sedimentation accumulation rate of 2.96 cm yr−1. Pond sedimentation, which reduces HRT, resulted in a decrease in pond N removal percentage to 11.2 % in 2018 and a projected 7.4 % by the year 2060, assuming similar sediment accumulation rates persist in the future. Overall, our findings underscore the non-negligible role of ponds as landscape nodes in N cycling. Urgent mitigation measures are needed to extend the lifetime of existing ponds and sustain their critical role in water quality management.

Suitability and Carrying Capacity of Aquatic Environment for Shrimp Culture in Sarjo District, Pasangkayu Regency West Sulawesi

The potential of coastal and marine resources in Indonesia is so diverse both in terms of quantity and quality, should be able to contribute greatly to the economic growth of the State of Indonesia. The purpose of this stydy is to assess the level of land suitability and carrying capacity of the pond environment for shrimp culture in Sarjo District Pasangkayu Regency. The research was conducted using survey method, measuring biological, physical and chemical parameters. The observed data consisted of temperature, turbidity, TSS, current direction and speed, tides, pH, salinity, dissolved oxygen, ammonia, nitrate, nitrite, phosphate, BOD, COD, BOT, and plankton. Based on biological, physical and chemical data, an analysis of the suitability of the pond area was carried out using the geographic information system (GIS) Arc View GIS Application Version 3.3. The results of the level of suitability of land for shrimp culture in Sarjo District was very suitable 154.88 hectare; 2) Suitable 77.16 hectare and quite suitable 27.26 hectare. Overall land for aquaculture in each area is traditional 732.95 hectare, semi-intensive 1,589.12 hectare and intensive 247.83 hectare. The environmental carrying capacity of intensive shrimp cultivation ponds with an estimated maximum production of 42.63 tons ha-1, with a permitted pond area that does not exceed the environmental carrying capacity is 166.07 ha; semi-intensive cultivation with a maximum production of 153.49 tons ha-1 MT-1, the permitted pond area so as not to exceed the environmental carrying capacity is 597.85 hectare, traditional cultivation with a maximum production of 3.4 tons MT-1 with a supported pond area of 2,569 ha in Sarjo District, Pasangkayu Regency.

IDENTIFIKASI, EVALUASI DAN REKOMENDASI LAYANAN LUMPUR TINJA DI KOTA BANJARBARU KALIMANTAN SELATAN

The feces waste treatment installation (IPLT) pond capacity of Banjarbaru is 20 M3/ day, while the maximum amount per month in 2022 is only 11 M3 of household fecal waste that goes into IPLT. This shows that the excrement that enters the IPLT is below the IPLT capacity of Banjarbaru because currently, the sludge service has yet to be scheduled and is still using the on-call system. Meanwhile, Banjarbaru Regional Regulation No. 1 of 2021 regarding scheduled sludge services in Banjarbaru already exists. This study aims to identify and evaluate the existing conditions of the sludge service in Banjarbaru and develop recommendations for improving the sludge service in Banjarbaru. The method used in this research is a descriptive method using a questionnaire and conducting interviews with people who have used sludge services in 2022. Calculation of the results of the questionnaire uses a Likert scale, validity, and reliability tests. The results of the identification through the questionnaire revealed that the IPLT had been actively carried out with the on-call system; if implementing the scheduled feces sludge service (LLTT), several processes had to be improved, and the results of the evaluation stated that the community did not agree with the fees charged for the LLTT. Recommendations for sludge services are increasing the number of fleets, promoting sludge services, and improving the administration system.

Research on the purification enhancement of ecological ponds: Integrating water cycle optimization and plants layout

The hydrodynamic conditions of ponds are generally poor, which seriously affects the long–term water quality guarantee. In this research, the numerical simulation method was used to establish an integrated model of hydrodynamics and water quality for the simulation of the plant purification effect in ponds. Based on the flushing time using the tracer method, the purification rate of plants was introduced to consider the purification effect of plants on water quality. In–situ monitoring was carried out at the Luxihe pond in Chengdu, and the model parameters such as the purification rate of typical plants were calibrated. The degradation coefficient of NH3–N in the non–vegetated area was 0.014 d−1 in August and 0.010 d−1 in November. In areas with vegetation, the purification rate of NH3–N was 0.10–0.20 g/(m2·d) in August and 0.06–0.12 g/(m2·d) in November. The comparison of the results in August and November showed that due to the higher temperature in August, the plant growth effect was better, and the degradation rate of pollutants and the purification rate of pollutants by plants were higher.The flushing time distribution of the proposed Baihedao pond under the conditions of terrain reconstruction, water replenishment, and plant layout was simulated, and the frequency distribution curve of flushing time was used to evaluate the results. Terrain reconstruction and water replenishment can significantly improve the water exchange capacity of ponds. The reasonable planting of plants can reduce the variability of the water exchange capacity. Based on this combined with the purification effect of plants on NH3–N, the layout plan of Canna, Cattails, and Thalia in ponds was proposed.

Hydrological Investigations in Red Soils of a Micro Catchment Area for Dugout Farm Pond at UAS Raichur Campus

Aims: To measure and characterize storm wise runoff for the catchment area of the farm pond and to correlate rainfall intensity and runoff relationship for the catchment area will help to design the appropriate size of the farm pond and waste weirs of the bunding system.
 Place and Duration of Study: The study was conducted in a micro catchment (field sized area) of a dugout farm pond, having an area of 6 ha located in the new area of UAS campus Raichur, which comes under Zone II in Region-I of Karnataka state. Geographically it is located at 16° 12′ N latitude and 77° 20′ E longitude and at an elevation of 389 m above the mean sea level (MSL). The study was conducted for a period of one year during 2019.
 Methodology: The existing farm pond constructed was used for conducting hydrological studies. The detailed soil and rainfall characterization of the study area has been made through appropriate methods. The rainfall intensity for each storm has been measured using self-recording rain gauge. The runoff has been measured at the out let of the field sized micro catchment area of farm pond using hydraulic structures coupled with automatic runoff recorder. The event wise rainfall, rainfall intensity and runoff have been measured and analysed to see the relationship between rainfall intensity and runoff with prevailing soil and topographical characteristics of the study area.
 Results: The percent runoff varied from 6.79 to 50.42 and highest was 50.42 per cent occurred on 25-10-2019 followed by 44.03, 39.36 and 37.46 per cent. The data shows that the individual storm wise percent runoff was quite high as compared to annual percent runoff of 15.99 per cent. The storm wise high runoff percent was due to the fact that high intensity of rainfall followed by high AMC in the soil. Further the minimum runoff yield of 142.66 m3 was observed on 18-07-2019 against the rainfall of 35.00 mm and maximum of 2985.48 m3 was yielded on 25-09-2109 against rainfall of 113.00 mm and followed by 1086.64 m3, 944.24 m3, 665.61 m3 and 431.25 m3 against rainfall of 46.00 mm, 42.00 mm, 22.00 mm and 48.00 mm respectively. The total annual runoff yield was found to be 6255.90 m3 against the rainfall of 651.50 mm. Therefore, there is a scope for harvesting excess quantity of runoff which is going as a waste. The existing pond capacity of 547.77 m3 is insufficient to store prevailing runoff generated in the catchment area and hence, pond capacity may be enhanced. The maximum intensity of rainfall and runoff during six events were showed statistically insignificant relationship with R2 value of 0.370. There is no correlation between intensity of rainfall and runoff.

A review of Open Channel Design for Mine Dewatering System Based on Environmental Observations

The purpose of mine dewatering system is to control runoff water that enters mine openings so that the mining process is not disturbed. The rainfall discharge (Q) is 0.0951 m³/second and the runoff discharge (Q) is 0.69 m³/second, making the total mining discharge entering the location 0.781 m³/second. The open channel design has dimensions of Channel wall slope (α) = 60°, Water depth (h) = 0.73 m, Channel depth (d) = 0.83 m, Channel base width (B) = 0.73 m, Surface width (b) = 1.57 m, Wet cross-sectional area of channel (A) = 0.92 m², and Channel wall length (a) = 0.97 m. The sedimentation pond has the following dimensions and compartments: Total length (l) = 104 m; width (b) = 8 m; depth (H) = 4 m; partition width = 4 m; partition depth = 4 m; partition length = 7 m. It consists of 3 compartments: conditioning compartment, separation between solids and mine water, and flow with an area of 277 m² per compartment. The sedimentation pond volume is 3094 m³ with a total area of 830 m². The results of the study obtained information that to control runoff water entering mine openings, a pond capacity as a settling site was needed of more than 3094 m³ with a maximum dredging time of settling pond particles that can be done once every 10 months.

Factors influencing the use of rainwater for agricultural irrigation: the case of greenhouse agriculture in southeast Spain

Abstract The availability and quality of water resources for agricultural irrigation are being increasingly compromised by different factors. In this context, the installation of rainwater harvesting (RWH) systems for use in agricultural holdings can contribute to mitigating this problem. However, the use of these systems by farmers continues to be very low. This paper analyses the factors that influence a farmer's decision to adopt these systems to take advantage of rainwater. Greenhouse agriculture in southeast Spain is the case studied. For this, a binary logistic regression model based on a survey administered to farmers was used. Among the variables found to be significant, the most important variables are the quantity of water in the pond, the pond capacity and environmental awareness. The variables that least affect the adoption decision are age, education level and income. These results have allowed the development of the main lines of action for policy-makers to intervene in order to promote the adoption of these systems. These measures focus on enhancing the training of farmers, providing them with financial support and boosting their environmental awareness. The results of this study lead to improved research on farmers’ behaviour and sustainable management of water resources in agriculture.

Erosion-control interventions associated with pond-catchment rehabilitation on the Borana plateaus, Southern Ethiopia

Among the major problems of Borana pastoralists are scarcity of potable water inside dry season and gully erosion in a widespread on the Borana plateau. Gullies are the main pathway for sediment accumulation in community ponds, which reduces pond capacity. Ponds are therefore a critical source of water during dry seasons the Borana rangelands. However, most ponds rapidly fill with sediment from eroding catchments after rainfall events and hence, their water holding capacity gradually get reduced. Much work is then required each year from the communities to remove sediment manually. Erosion of pond catchments is the consequence of uncontrolled grazing that causes heavy grazing and trampling by livestock. Sediment movement in gullies can be substantially reduced by installation of sieve structures that slow down water flows and allow sediment to settle out of suspension. Sieves can be easily constructed from trees by community labour at low cost. Yabello researchers have demonstrated that a series of sieve structures down a secondary gully in Bunaka and Liban Jatani pond that effectively trap sediment. When gully head treatments are accompanied by a series of sieves in the main channel, gully erosion can be arrested, gully floor and walls re vegetated and sediment captured. Overall, protection of grazing land from livestock reach for only one year led to a 55.45% increase in ground cover. Similarly, increases in cover tended to be greater (118.1 % more) at Liban Jatani pond that had less cover at the beginning when compared to Bunaka pond. Protection from livestock grazing led to substantial increases in ground cover. Within the Liban Jatani pond enclosure, ground cover steadily increased at each sampling period by 7.1% in June 2019, 11.13% in November 2019.

Retention Pool As Alternative For Flood Control Case Study Of Bapertarum Housing, Sumenep Regency

Indonesia is a water country with thousands of rivers and hundreds of deep seas. This causes Indonesia to become a country that is very prone to flooding. But basically, there are several factors that cause this to happen, namely: natural events, drainage damage and environmental degradation caused by human activity itself. Geographically, Bapetarum Housing is an area located in a rainwater catchment area so that it is prone to flood events. High rainfall intensity can cause flood inundation as high as 30 cm. The purpose of this study is to calculate the adequacy of the retention pond to cope with flooding. The procedure for collecting research data begins with analyzing the flood, namely primary and secondary data. Meanwhile, the data analysis techniques used are planning rain analysis, rainfall intensity, flood discharge analysis, retention pond capacity. The retention pond capacity is sufficient because the dimensions of the retention pond are larger than the volume of the retention pond capacity when the flood is 6750m3>6447m3. The retention pond is planned in the downstream area of the residential river with a pool area of 50 x 40 meters and a depth of 4.5 m. The bottom condition of the pond is saturated because it is always inundated with water, the infiltration rate is constant (fc). The constant infiltration for clayey soil type is 0.5 m/day, the infiltration volume rate that occurs at the bottom of the pond is 179 m3/hour, the volume is below the threshold 8283.21 m3, infiltration time is 46 hours.

Tropical Asian mega‐delta ponds: Important and threatened socio‐ecological systems

AbstractThis paper uses multimedia to showcase the narratives and lived experiences of those who live and work in tropical Asian mega‐deltas, and as such is the first journal article of its kind in the field of Regional Geography. Using videos, photography and audio this paper describes the characteristics of ponds and their place in the intrinsically connected human‐environmental fabric of these delta regions. The aim is to bring to life descriptive inventories and provide greater weight in support of our conclusion that tropical Asian mega‐delta ponds are important and threatened systems. River deltas comprise just 1% of land cover worldwide but support the livelihoods of more than 500 million people. Delta research has historically focused on the major river channels and the socio‐ecological role of ponds has been overlooked despite their large number and surface area. Ponds are intrinsically linked to daily life (potable water, sanitation, bathing, washing), industry (aquaculture, agriculture) and the natural‐cultural heritage (religion, folklore) of deltas. In contrast to the larger river channels, ponds are likely to be significant stores and processors of nutrients, including carbon, and pollutants at annual to decadal scales, on account of their heavy anthropogenic use and smaller individual sizes. Consequently, they are severely polluted water sources and pose significant public health risks. In this review, we use case studies from three Asian mega‐deltas (the Red River Delta and the Mekong River Delta, Vietnam, and the Ganges‐Brahmaputra‐Meghna Delta, India and Bangladesh) to highlight the importance of Asian mega‐delta ponds as important socio‐ecological systems in their own right. We discuss future environmental challenges, knowledge gaps on the ecological function and biodiversity of these habitats, management and policy practices, and the capacity of ponds to achieve the UN Sustainable Development Goals.

Development of Sustainable Detention Ponds for Flood and Sediment Control in Urban Areas

Muddy floods often occur in Indonesia as a side effect of urban development. Flood and sediment control facilities have been so far developed separately. Flood is controlled by reservoirs, while sediment is trapped by checkdam. The objective of this paper is to develop an integrated system between flood control and sediment trap analytically. The system consists of detention pond equipped with perforated spillway tower. Optimization is carried out on the dimensions of spillway tower, the diameter, number and layout of perforation orifices to obtain the highest trapped sediment and flood peak reduction for a certain pond capacity. The research was conducted in the Meteseh sub-watershed, located in Semarang. The results indicated that the position and arrangement of the orifices in the spillway tower affect sediment trap, while their size and number affect the reduction in peak discharge. The proper size, number, posistion and arrangement of orifices on the spillway tower be able to trap sediment and reduce flood discharge as high as 80%, and 24% consecutively.

Investigation of Highway Stormwater Management Pond Capacity for Flood Detention and Water Quality Treatment Retention via Remote Sensing Data and Conventional Topographic Survey

Stormwater management ponds are common best management practice (BMP) and green infrastructure (GI) for flood attenuation and water quality treatment in highway projects. Originally designed to provide storage volume for flood detention, stormwater ponds today often employ additional retention volume at pond bottom in a hope to improve water quality via sedimentation and other pollutant-removal mechanisms. It is commonly assumed that sediment accumulation and topographic variations (such as erosion, channelization, and in-pond plant growth and decay) over time often decrease the capacity of stormwater ponds. However, differences between design capacities and field capacities over time have never been verified and quantitatively analyzed before. This study presents such analysis using conventional topographic survey techniques and remote sensing data (topographic light detection and ranging digital elevation model [LIDAR DEM]) for 10 highway stormwater ponds along Interstate Highway-95 (I-95) systems in Baltimore City, Cecil County, and Harford County, Maryland, United States, with facility service life ranging from 14 to 26 years (1990–2015). Data derived from LIDAR DEM were compared with those from topographic survey; the LIDAR DEM data appear to be effective in measuring flood detention capacities and identifying silted ponds, but not in estimating the remaining retention volume for water quality treatment. Data from topographic survey indicate that the total volume in the ponds was relatively unchanged compared with the design, with increases in some instances. The increase typically occurred at the pond’s upper stages. Nonetheless, the water quality treatment capacity at pond bottom (wet pool volume) was drastically less (up to 100% of the design). As current maintenance practice of stormwater ponds relies heavily on visual inspection, the storage volume variations are often overlooked. As such, the findings prompt uncertainty on the long-term effectiveness of watershed implementation plan and models in the Chesapeake Bay watersheds, as many of them depend on wet pool volume design in BMP and GI.

The Integration of Retention Pond And Composite Sluice in Flood Prevention in Makassar City

in 2018, Badan Pengkajian dan Penerapan Teknologi (BPPT) has developed composite sluice for controlling flood goals. The integration of retention pond and composite sluice deemed necessary to be analyzed as the integrated system as a flood disaster mitigation effort. This study aims to give a brief overview of the suitable retention pond capacity, which is integrating with composite sluice as a flood prevention effort. The retention pond designed in this study requires rainfall data, land use data and topography map. This study method uses empirical formulation based on statistical parametric on hydrology analyze and hydraulic analyze as a basis of retention pond capacity calculation and composite sluice as flood controller. The result of this study are; the maximum flood discharge in 10 years return period is 103,28 m3/s, while the riverbed discharge capacity with 8 meters width is 68,29 m3/s. To prevent flooding the retention pond volume with capacity volume in 1.117.214,24 m3 has required. In sluice practical width calculation for the retention pond, the resulting amount is 28,70 meters. It takes 32 units of composite sluice if the current needs to be maintained. The side composite sluice width has obtained 1 meter while the total composite sluice building width with four units for the retention pond is 6,4 meters.

Utilization of a pond in East Jakarta for a sustainable urban drainage system model

High population growth in the area of East Jakarta has led to more construction of settlements, including in several areas of East Jakarta, which includes Jalan Pengantin Ali in Ciracas Sub-District. When very heavy rains fall in the rainy season, this place is often flooded, while in the dry season there is a scarcity of raw water or clean water. This study examines the application of sustainable drainage systems with the technique of making a retention pond as a flood control alternative. The purpose is to hold water runoff during the rainy season so that it does not enter the river directly, and so that some of the collected water could be used to meet the clean water supply needs of the people. The calculation of rainwater potential used the height of the monthly average rainfall. The retention pond capacity was determined by the pool simulation method during the rainy season. The planned flood discharge was calculated using the Nakayasu HSS method. The obtained results indicated a peak discharge value with a return period of 2 years that amounted to 8.84 m3/sec. The planned retention pond area is 6380.94 m2, with a retention pond height of 4 m, a dike slope of 1:1, and the elevation of the overflow base being at an altitude of 38.5 meters above sea level (masl). From the results of the HEC-RAS 5.0.6 software, an optimal overflow width of 2 m was obtained, with an outflow discharge of 4.55 m3/sec and a pond volume of 19530 m3. With the retention pond, flood peak discharge could be reduced by 4.29 m3/sec. This will allow the flood discharge in the rainy season to be reduced and increased clean water needs in the dry season to be met.

Optimal Water Resources Regulation for the Pond Irrigation System Based on Simulation-A Case Study in Jiang-Huai Hilly Regions, China.

Due to the importance and complexity of water resources regulations in the pond irrigation systems of the Jiang-Huai hilly regions, a water allocation simulation model for pond irrigation districts based on system simulation theory was developed in this study. To maximize agricultural irrigation benefits while guaranteeing rural domestic water demand, an optimal water resources regulation model for pond irrigation districts and a simulation-based optimal water resources regulation technology system for the pond irrigation system were developed. Using this system, it was determined that the suitable pond coverage rate (pond capacity per unit area) was 2.92 × 105 m3/km2. Suitable water supply and operational rules for adjusting crop planting structure were also developed the water-saving irrigation method and irrigation system. To guarantee rural domestic water demand, the multi-year average total irrigation water deficit of the study area decreased by 4.66 × 104 m3/km2; the average multi-year water deficit ratio decreased from 20.40% to 1.18%; the average multi-year irrigation benefit increased by 1.11 × 105 RMB (16,128$)/km2; and the average multi-year revenue increased by 6.69%. Both the economic and social benefits were significant. The results of this study provide a theoretical basis and technological support for comprehensive pone governance in the Jiang-Huai hilly regions and promote the establishment of a water allocation scheme and irrigation system for pond irrigation districts, which have practical significance and important application value.

A Simulation-Optimization Model for Conjunctive Use of Canal and Pond in Irrigating Paddy Fields

In this study, a new methodology is presented for conjunctive use of canal and pond to assess the role of ponds in saving local water and optimizing use of them in supplying irrigation water requirement of paddy fields. Evapotranspiration, runoff, irrigation water requirement, irrigation interval and pond water balance were simulated and then number of canal intake, storage volume and released volume of pond were optimized by binary genetic algorithm. Minimizing the number of canal intake and limitations of no deficit irrigation and storage volume of pond was defined as objective function and constraints, respectively. The effectiveness of the proposed methodology is examined through applying it for Fashtam pond in Sangar, Guilan province in Northern part of Iran. The results showed that 60, 54 and 46% of irrigation requirement of paddy fields were supplied by precipitation and runoff water saved in Fashtam pond and the rate of overflow of pond to maximum pond volume were 100, 74 and 34% in wet, normal and dry years, respectively. The model develops a scenario to increase pond capacity in selected case study for Fashtam pond located in Guilan province in Iran. It demonstrates how supply of irrigation to paddy fields has been increased to 100, 91 and 61% in wet, normal and dry years, respectively through simulation-optimization approach.

Capturing temporal and spatial variability in the chemistry of shallow permafrost ponds

Abstract. Across the circumpolar north, the fate of small freshwater ponds and lakes (< 1 km2) has been the subject of scientific interest due to their ubiquity in the landscape, capacity to exchange carbon and energy with the atmosphere, and their potential to inform researchers about past climates through sediment records. A changing climate has implications for the capacity of ponds and lakes to support organisms and store carbon, which in turn has important feedbacks to climate change. Thus, an improved understanding of pond biogeochemistry is needed. To characterize spatial and temporal patterns in water column chemistry, a suite of tundra ponds were examined to answer the following research questions: (1) does temporal variability exceed spatial variability? (2) If temporal variability exists, do all ponds (or groups of ponds) behave in a similar temporal pattern, linked to seasonal hydrologic drivers or precipitation events? Six shallow ponds located in the Hudson Bay Lowlands region were monitored between May and October 2015 (inclusive, spanning the entire open-water period). The ponds span a range of biophysical conditions including pond area, perimeter, depth, and shoreline development. Water samples were collected regularly, both bimonthly over the ice-free season and intensively during and following a large summer storm event. Samples were analysed for nitrogen speciation (NO3−, NH4+, dissolved organic nitrogen) and major ions (Cl−, SO42−, K+, Ca2+, Mg2+, Na+). Across all ponds, temporal variability (across the season and within a single rain event) exceeded spatial variability (variation among ponds) in concentrations of several major species (Cl−, SO42−, K+, Ca2+, Na+). Evapoconcentration and dilution of pond water with precipitation and runoff inputs were the dominant processes influencing a set of chemical species which are hydrologically driven (Cl−, Na+, K+, Mg2+, dissolved organic nitrogen), whereas the dissolved inorganic nitrogen species were likely mediated by processes within ponds. This work demonstrates the importance of understanding hydrologically driven chemodynamics in permafrost ponds on multiple scales (seasonal and event scale).

Evaluation of Design and Operational Parameters of Pilot Single Stage Stabilization Pond for Treatment of Brewery Waste Water Effluent

The suitability of waste stabilization pond (WSP) as a cheaper alternative in the treatment of brewery wastewater effluent was investigated. A pilot WSP was designed and constructed and test run for the treatment brewery wastewater effluent. Wastewater effluents were collected from an operating brewing industry in Kudenda light industrial layout, Kaduna. The influent pond flow rate of 0.2 m3/day was chosen for the design of the pilot pond. Kinetic model design procedure of a facultative pond was used to design a rectangular shaped pond to reduce the BOD loading by 90%. The pond capacity was 4.7 m3 (4700 litres) with a retention time of 25 days. The parameters that were analyzed for the raw and treated wastewater include: Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total suspended solids (TSS), Turbidity and Electrical conductivity (EC). It was observed that aerobic degradation occurred at the upper layer of the pond favoring the activities of aerobic bacteria. At the middle layer however favored the activities of the facultative bacteria, while at the lower level where there is virtually little or no presence of dissolved oxygen, anaerobic decomposition of the wastewater predominate. These combined mechanisms yielded the total the total decomposition of the wastewater by the pond. The BOD removal rate constant was 0.088 per day and the BOD-COD correlation was BOD=0.531COD-1.960. The BOD removal regression model was: BOD=0.0001t5-0.0034t4-0.1419t3+6.6096t2-102.09t+1114.5 and the pond performance efficiencies for the reduction/removal of the tested parameters 69% 68.9%, 81%, 67.2% and 71.6% respectively. The pond performance was found to be satisfactory and the kinetic parameter obtained can be utilized in the scale up design for industrial scale WSP.

Runoff Harvesting and Storage for Rice Crop at Hamelmalo, Semiarid Region of Eritrea

Rice is staple food in Eritrea but it is not cultivated in the country due to semiarid conditions. However, possibilities exist for growing rice using runoff produced from nonagricultural hilly lands, which occupy >50% - 80% area of all agricultural watersheds in Eritrea. Study was undertaken in 6 ha watershed at Hamelmalo to design and develop waterway for safe harvesting of runoff from 5.5 ha catchment into a pond for facilitating runoff farming of rice in 0.5 ha field at the outlet end receiving recurrent floods. Slope of the catchment ranged from 1% to 6%. The waterway was designed to intercept and carry runoff from two major drains in nonagricultural land together and delivering into a pond made adjacent to rice field. The waterway was about 323 m long with 3 m top width, 1.5 m bottom width and 0.3 - 0.8 m depth from surface. The pond was 60 m long, 9 m wide and 1 m deep with 1.5 m high earthen dam towards rice field using soil excavated from the pond. Embankment on the remaining sides was mango orchard land slopping towards pond. The dam base width was 4 m, top width was 2.5 m and height was 1.5 m from the ground surface. Two spill ways were provided in the dam at ends at the ground level to facilitate release of runoff from the pond for irrigation. Gross capacity of pond was >1000 m3. Combined effect of river water, percolation from pond and wetter rice field raised groundwater table from 3.25 m depth in June to 1.4 m by mid-crop season. This resulted in soil wetness exceeding field capacity below 0.7 m depth and greener crop. Rice yields exceeding 2000 kg·ha-1 were harvested under runoff farming conditions. Soil puddling was more conducive to rice crop than compaction under available soil and water resources.

Sediment Flushout from Pond of River Diversion Barrages by Gate Operation

Construction of river diversion barrages produces a shallow reservoir, called the pond, which is used more often for flow balancing between the inflows of the river and the outflows of the off-taking canal. However, deposition of sediment in the pond due to the relatively low velocities reduces the pond capacity. The current study investigates the effectiveness of gate operation and variations of other parameters in flushing out these sediment mounds, or shoals, from the barrage pond. Data from laboratory experiments on a scaled model of a prototype barrage is used to train and test different Artificial Neural Network (ANN) models of the system. The models map the relationship between flushing efficiency of a sediment shoal from the upstream of a barrage, and the parameters river discharge, barrage pond depth and area of gate opening, position of the sediment shoal with respect to the barrage. The ANN models are then used to study the effect of different parameters on the sediment flushing efficiency. Apart from river discharge and net area of gate opening, upstream pond depth is also found to have a significant effect on flushing efficiency, with a general trend of decrease in efficiency with increase in pond depth becoming apparent. Efficacy of different gate opening pattern is also tested, with the ‘inverted arch’ gate opening pattern proving to be the most efficient when compared with ‘arch’ and ‘uniform’ gate opening.