نتایج جستجو برای: earthen pond
تعداد نتایج: 7686 فیلتر نتایج به سال:
An experiment was conducted to assess the effect of different harvest draining techniques of fish ponds on water quality and fish growth in subsequent culture cycles. Fifteen tilapia ponds of 200 m2 were harvested using five different harvest draining techniques. After harvest, these ponds were stocked with Nile tilapia (Oreochromis niloticus) at 2 fish m-2. Fish with an initial size of 11 to 1...
This study was conducted in two phases on sturgeon larvae and fingerlings produced from artificial breeding of five pairs of the Persian sturgeon (Acipenser persicus) broodstocks in Shahid Beheshti Hatchery in spring and summer 2006. Initially, 600 larvae were collected on 3 post days hatching (pdh) and 5 days after the onset of exogenous feeding. The second phase was conducted with 450 specim...
production of new hybrids is important for growing aquaculture and protecting wild stocks of fish species. a hybrid between female asp × male kutum ( leuciscus aspius ♀ × rutilus frisii ♂) was produced and its growth performance was monitored in two rearing systems for 55 days. the fish held in earthen ponds exhibited higher performance compared to those held in concrete tanks. the results also...
We present in this paper a new inverse method for the study of the seepage from symmetrical earthen open channels. We map the half-strip from the complex potential domain onto the unit half-disk from an auxiliary ζ plane. We introduce Levi-Civitá’s function whose imaginary part vanishes on the diameter [−1, 1] of the half-disk by virtue of the boundary conditions imposed on the free lines. Then...
iran has limited water resources that require preservation and reducing water loss from reservoirs, especially in arid and semi arid regions. there are a number of methods available for to control water loss from reservoirs and canals. concrete linings in water reservoirs and ponds are durable, but their efficiency is limited. geomembrane sheets are another method of controlling leakage from wa...
Solar pond is a device which entraps the impinging solar radiation and stores it as thermal energy in its salty layers. Simple salt gradient solar pond consists of three basic layers: lower convective zone, non-convective zone and last is upper convective zone. In present study a simple working experimental setup of salt gradient solar pond was fabricated equipped with thermo siphon heat exchan...
The Prairie Pothole Region (PPR) is the most important waterfowl production area in North America. However, waterfowl populations there are predicted to decline because of climate-related drying of wetlands. Consequently, changes in the geographic focus of PPR waterfowl conservation have been recommended, which could have long-lasting and costly impacts. We used a 40-year dataset of pond counts...
The goal of this study was to use environmental sequencing of 16S rRNA and bop genes to compare the diversity of planktonic bacteria and archaea across ponds with increasing salinity in the Exportadora de Sal (ESSA) evaporative saltern in Guerrero Negro, Baja CA S., Mexico. We hypothesized that diverse communities of heterotrophic bacteria and archaea would be found in the ESSA ponds, but that ...
The paper aims at evaluating the effects of heavy groundwater withdrawal and artificial groundwater recharge of an exmining pond to the aquifer system of the Langat Basin through the three-dimensional (3D) numerical modeling. Many mining sites have been left behind from the massive mining exploitations in Malaysia during the England colonization era and from the last few decades. These sites ar...
Decision support systems (DSSs) are potentially valuable tools for assessing the economic and ecological impacts of alternative decisions on aquaculture production. This report discusses the latest design, functional modules, and application areas of POND©, a decision tool that has been developed to allow analysis of pond aquaculture facilities by the use of a combination of simulation models a...
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