Standing Water Level Research Articles

Forecast of changes in the beach condition of the Yuzhne city under the influence natural factors

The study of the factors of degradation and the forecast of the state of recreational areas of the coast to prevent their negative changes is relevant. Purpose. Forecast of changes in the condition of the Yuzhne beach, provision of general proposals for its protection from degradation. Methods. Mathematical statistics, linear analysis and mathematical modeling, comparative analysis, cartographic and grapho-analytical studies. Results. The beach of Yuzhne is located on the coast of the Black Sea. Its length is approximately 700 m. The southern direction in the sector 180±22.5⁰ is dangerous for waves. The distance from the beach to the opposite shore (wave acceleration) is 540-610 km. The boundary between the shallow and deep water zones is at a distance of approximately 200 km with a depth of 75 m. With southerly winds, recurring once every 25 years, on the approach to the shallow water zone with a depth of 50-75 m, a developed disturbance with extreme wave parameters is formed, which, transforming in the shallow water zone, significantly affects the coast. A profile of relative dynamic equilibrium with a length of 1,200 m and a depth at this distance of 11.2 m is formed during the calculated disturbance. From the water cut, the boundary between the near-cut and surf zones is located at a distance of 220 m with a depth of 3.6 m. Regardless of the standing water level, the calculated storm destroys the original shore at the extreme parts of the beach. When the sea level is high, the disturbance moves the destroyed material with the beach material into the cut-off zone, while the water cut at the 0.0 m BS mark does not change its planned location. The amount of beach material on the upper part of the coastal slope may decrease significantly. At an average level of the sea, the washing away of destroyed and beach material is accompanied by the advance of the water cut toward the sea for a distance of up to 20 m, but at the same time, a decrease in beach material on the above-water part of the coastal slope is also observed. Conclusion. Without taking special protection measures, the beach of the Yuzhne city will degrade in the future. In areas of the beach, in order to prevent its erosion, it is necessary to erect a retaining wall with a backfilling layer. An option for an active method of protection can be the construction of permeable bunkers on the beach or an intermittent breakwater at a distance from the shore. Such protection will not impede the alongshore transport of sand. Dunes or waves will contribute to the accumulation of sand on the beach. At the same time, after strong storms from the southern direction, with high sea level, episodic additions of sand to the beach are necessary

Relating groundwater to geology in Sokoto basin, north-western Nigeria using multivariate and regression analysis: implications for groundwater availability

Background: Geological formation's variability is responsible for spatial distribution and volume of groundwater stored in the aquifer. Groundwater availability is also determined by topography, geology, and climate, accountable for numerous natural surface indicators and groundwater availability. Objective: This paper evaluates the empirical relations between geology and sporadic groundwater levels over three geographical locations in the Sokoto basin by assessing the variability of static water level, pumping test, pumping water level and estimated yields from boreholes. Method: Hydrogeological data comprising of standing water level (Swl), pumping water level (Pwl), pumping test (Pt), and estimated yield (Ey) were derived from 612 boreholes in the Basement complex section (n=103), central Sokoto basin (n=113) and western Sokoto basin (n=396). The result shows that the Swl, Pt, and Ey were higher in the central Sokoto basin, whereas, Pwl was higher in the western Sokoto basin. Multivariate statistical analysis (Factor Analysis) was further applied to analyse the data. Results: Factor analysis indicates that most of the variability in groundwater availability in the western Sokoto basin is explained by Swl and Pwl as contained in Factor 1. Factor 2 revealed that Pt and Ey are responsible for groundwater variability in the central Sokoto basin. Factor 3, connected to the basement complex, explained 12.57%, had no high positive loadings on any hydrogeological variable. It suggests that most groundwater variability in the Sokoto basin is influenced by the Cretaceous and Tertiary sediments. The Hierarchical Cluster Analysis (HCA) revealed three types of aquifers: those aquifers with high Swl and Pwl in western Sokoto basin; those aquifers with high pumping test in the central Sokoto basin, and those aquifers having high yields comparable to the aquifers in both western and central Sokoto basin. Lastly, the general regression model shows that Swl is the significant hydrogeological parameter influencing groundwater levels. Conclusion: Even with the variability in groundwater conditions, the Sokoto basin sits on very rich aquifers to sustain different water supply programs. However, this study presents only a spatial assessment. Therefore, studies comparing groundwater conditions with geology over broader spatial and temporal scales are recommended.

MITIGATION YIELD SCALED METHANE EMISSION FROM RICE GROWN IN WATER STRESS CONDITIONS WITH BIOCHAR AND SILICATE AMENDMENTS

Climate change and water scarcity may badly affect existing rice production system in Bangladesh. With a view to sustain rice productivity and mitigate yield scaled CH4 emission in the changing climatic conditions, a pot experiment was conducted under different soil water contents, biochar and silicate amendments with inorganic fertilization (NPKS). In this regard, 12 treatments combinations of biochar, silicate and NPKS fertilizer along with continuous standing water (CSW), soil saturation water content and field capacity (100% and 50%) moisture levels were arranged into rice planted potted soils. Gas samples were collected from rice planted pots through Closed Chamber technique and analyzed by Gas Chromatograph. This study revealed that seasonal CH4 emissions were suppressed through integrated biochar and silicate amendments with NPKS fertilizer (50–75% of the recommended doze), while increased rice yield significantly at different soil water contents. Biochar and silicate amendments with NPKS fertilizer (50% of the recommended doze) increased rice grain yield by 10.9%, 18.1%, 13.0% and 14.2%, while decreased seasonal CH4 emissions by 22.8%, 20.9%, 23.3% and 24.3% at continuous standing water level (CSW) (T9), at saturated soil water content (T10), at 100% field capacity soil water content (T11) and at 50% field capacity soil water content (T12), respectively. Soil porosity, soil redox status, SOC and free iron oxide contents were improved with biochar and silicate amendments. Furthermore, rice root oxidation activity (ROA) was found more dominant in water stress condition compared to flooded and saturated soil water contents, which ultimately reduced seasonal CH4 emissions as well as yield scaled CH4 emission. Conclusively, soil amendments with biochar and silicate fertilizer may be a rational practice to reduce the demand for inorganic fertilization and mitigate CH4 emissions during rice cultivation under water stress drought conditions.

Space-time modelling of groundwater level and salinity

Soil salinization resulting from shallow saline groundwater is a major global environmental issue causing land degradation, especially in semi-arid regions such as Australia. The adverse impact of shallow saline groundwater on soil salinization varies in space and time due to the variation in groundwater levels and salt concentration. Understanding the spatio-temporal variation is therefore vital to develop an effective salinity management strategy. In New South Wales, Australia, a hydrogeological landscape unit approach is generally applied, based on spatial information and expert operators, classifying the landscape in relation to landscape and climate. In this paper, a data science approach (random forest model) is introduced, based on historical groundwater quality and quantity data providing predictions in a 4-dimensional space. As a case study, we demonstrate the spatio-temporal factors impacting standing water levels (SWL) and associated salinity and predict the spatial and temporal variability in the Muttama catchment (1059 km2), in NSW, south eastern Australia. The random forest model explains 77% of the variance in the groundwater salinity (electrical conductivity) and 65% of the SWL. Spatial factors were the most significant variables determining the space-time variation in groundwater salinity and the occurrence of groundwater at the surface. Drilled piezometer depth and elevation are dominant factors controlling SWL, while salinity is mainly determined by underlying geology. The methodology in this study predicts salinity and SWL in the landscape at fine scales, through time, improving options for salinity management.

Dynamics of Soil Moisture under Different Water Levels and Various Dosages of Organic Fertilizer

The study aimed to determine the dynamics of soil moisture in various standing water levels and dosages of organic fertilizer. The experiment was arranged in a Completely Randomized Block Design (CRBD) with a 3 × 3 factorial treatment in 3 replicates. The first factor was 3 different water levels, namely 10 cm (T1), 20 cm (T2), and 30 cm (T3). The second factor was 3 levels of dosages of organic fertilizer, namely 0 g pot-1(P1), 35 g pot-1 (P2), and 70 g pot-1 (P3). The highest of soil moisture was obtained in the 10 cm water levels and 70 g organic fertilizer (T1P3) and the lowest in the 30 cm water levels and without organic fertilizer (T3P1). The highest infiltration rate was obtained in the 30 cm water levels and 70 g pot-1 organic fertilizer (T3P3), the 30 cm water levels and 35 g pot-1 organic fertilizer (T3P2), the 20 cm water levels and 70 g pot-1 organic fertilizer (T2P3), and the lowest in the combination of the 10 cm water levels and without organic fertilizer (T1P1). The highest capillary rate was obtained in the combination of the 30 cm water levels and 70 g organic fertilizer (T3P3) and the lowest in the combination of the 30 cm water levels and without organic fertilizer (T3P1).

Effect of standing water levels on methane gas emission and yield performance of transplanted Aman rice (Oryza sativa L. cv. BRRI dhan51)

An experiment was conducted to investigate the effect of standing water levels on methane gas emission and yield of transplanted Aman rice (cv. BRRI dhan51) during July to December 2015 at medium low-lying area of Mohangonj upazila under Netrokona district. The experiment comprised five standing water levels on surface paddy soil viz., 5 cm, 10 cm, 15 cm, 20 cm and 25 cm. Methane (CH4) gas emission, yield components and yield of transplanted Aman rice were significantly affected by standing water levels on surface paddy soil. CH4 emission was gradually increased with rising standing water levels and remained static condition at 20-25 cm water level. The highest CH4 emission was observed at 20 cm standing water level and the lowest CH4 emission was recorded at 5 cm water level. The highest CH4 peak recorded at 85 days after transplanting (DAT). The highest CH4 flux (36.59 mg/m2/h) was observed in treatment 20 cm water level whereas the lowest CH4flux (21.17 mg/m2/h) was observed in 5 cm water level. Finally, the CH4 emission dropped at 108 DAT. On and average, the CH4 emission rate during rice cultivation followed 20 cm > 25 cm> 15 cm > 10 cm > 5 cm water level. Soil Eh gradually decreased with progress of time and plant growth and at 85 DAT highly reduced condition developed in all treatments. The maximum reduced condition was observed (-238.67 mV) in treatment 20 cm water level and minimum one (- 214.667 mV) was found in 5 cm water level. The highest grain (5260 kg ha-1) and straw (6725.0 kg ha-1) yields were obtained at 10 cm standing water level while the lowest grain (4191.6 kg ha-1) and straw (5050.0 kg ha-1) yields were recorded in 5 cm and 15 cm water level, respectively. It may be concluded that 10 cm standing water level is beneficial for transplant Aman rice (cv. BRRI dhan51) cultivation in low lying area in respect of grain yield and environmental issues.

Reconciling Police Power Prerogatives, Public Trust Interests, and Private Property Rights Along Laurentian Great Lakes Shores

The United States has a north coast along its ‘inland seas’—the Laurentian Great Lakes. The country enjoys more than 4,500 miles of Great Lakes coastal shoreline, almost as much as its ocean coastal shorelines combined, excluding Alaska. The Great Lakes states are experiencing continued shorefront development and redevelopment, and there are growing calls to better manage shorelands for enhanced resiliency in the face of global climate change. The problem is that the most pleasant, fragile, and dangerous places are in high demand among coastal property owners, such that coastal development often yields the most tenacious of conflicts between public interests and private property rights. Indeed, those conflicts implicate fundamental debates over the state’s authorities and prerogatives to regulate privately owned shoreland (the police power), the public’s interest in coastal resources (the public trust doctrine), and private property owners’ rights to use and to exclude others from their shorelands (referred to collectively here as the private property doctrine). While not tidal, standing water levels of the Great Lakes fluctuate over time substantially. As a result, the lakes have beaches much like ocean coasts, and the public trust doctrine is aptly applied to them, albeit awkwardly. All of the eight Great Lakes states have long acknowledged the applicability of the public trust doctrine to their Great Lakes bottomlands and shorelands. In doing so, they have accepted the now-conventional understanding that the doctrine originated in ancient Roman law. Even so, recent critiques of the public trust doctrine assert that it has been misinterpreted and that its historical pedigree is not so strong or aptly applied to American coasts, especially along Great Lakes coasts. These critiques do not address the historical pedigree and robustness of the police power doctrine, or, more importantly, the pedigree and robustness of contemporary notions of private property rights. If the public trust doctrine is indeed lacking upon reconsideration, how does it fare in comparison to these other doctrines? This Article lays the foundation for an extended study of the public trust doctrine as it applies to Great Lakes shores. We provide an overview of the public trust doctrines of all eight Great Lakes states, noting for illustration and, where appropriate, particulars for the State of Michigan, which enjoys more than 60% of the combined U.S. Great Lakes coastline. To explain our motivations in undertaking this study, the Article first briefly reviews the importance of the lakes to the State of Michigan and the other Great Lakes states more broadly and then frames shoreland management as one of the resource management imperatives those states face. The Article then reviews the historical origins, the contemporary contours, and the ongoing debates surrounding the police power, public trust, and private property doctrines separately. Building on that foundation, we then analyze how courts and legislatures have reconciled those doctrines through application in coastal settings broadly. First, we find that the public trust doctrines of the Great Lakes states fall well within the boundaries of the origins and application of that doctrine throughout the nation’s history, even though the Lakes are not tidal. Second, we find that the concept of a ‘moveable freehold’ inherent in the public trust doctrine—that the boundary separating state-owned submerged public trust land from privately owned upland along the shore—reflects natural dynamic shoreline processes, not arbitrary governmental rulemaking, and is well established and accepted by all Great Lakes states. Finally, and most importantly for the purposes of this Article, we find that all three doctrines—public trust, police powers, and private property rights—trace their roots to English common law and even ancient Roman law, but all are in fact distinctly American doctrines. All three doctrines were first fully articulated in the context of unique American institutions, values, and conflicts. Each has evolved over time as American institutions, values, and conflicts have similarly evolved. Thus, despite detractors’ assertions to the contrary, the public trust doctrine is no less robust or aptly applied to Great Lakes coasts than is either the police power or private property rights doctrine. In fact, despite case law and commentary rhetoric that can be dogmatically extreme, efforts to understand and reconcile these doctrines in practice generally strike a pragmatic balance between the private rights inherent in shoreland property ownership and the public interest in common access to and use of submerged lands and the foreshore. Following our analysis of these doctrines from a broad perspective, we conclude by providing a brief overview of the several public trust doctrines as adapted by all of the Great Lakes states and finally identifying a number of questions for further study.

Patterns of vegetation and soil properties in a beaver-created wetland located on the Coastal Plain of Virginia

This study investigated vegetation and soil properties in a beaver-created freshwater wetland located on the Coastal Plain of Virginia near Washington, DC. We focused on the associations among floristic quality, soil physicochemistry, denitrification, and hydrologic conditions of the wetland to understand links between the effects of beaver engineering and ecosystem function. The floristic quality assessment index (FQI) and denitrification are two important indicators often used to examine overall habitat quality and ecosystem functioning of a wetland. Samples were collected from ten plots (10 m × 10 m each) in August 2014. Vegetation attributes included total percent cover, species richness (S), diversity, FQI, and prevalence index (PI). Soil attributes included organic matter (OM), total carbon, total nitrogen, gravimetric moisture (GM), pH, bulk density (Db), and denitrification potential (DP). FQI was greater in the higher of the two standing water level categories, where Db was lower, and was negatively associated with Db but no other soil nutrient properties. DP was positively associated with soil nutrients, OM, and GM, but not with measured vegetation attributes nor standing water levels. We found higher soil GM, lower plant community PI, and lower plot S in this study compared to our previous study, with no changes to other vegetation or soil attributes, indicating enduring beaver activity and a resilient plant community. The outcome of the study includes regression models that best explain the association between structural and functional attributes of the ecosystem, which can be applicable to the study of other beaver-created wetlands. The study also provides partial evidence for the notion that low-lying areas dug out by beaver positively impact the FQI of wetlands.

Effect of Water Management Practices on Rice Yield, Water Productivity and Water Savings under Irrigated Rice Paddy Ecosystem

A field experiment was carried out during the Boro season 2013 to find out the effects of water management practices on rice yield performance and water productivity index at Old Brahmaputra flood plain paddy land, Muktagacha, Mymensingh. The experiment was laid out in randomized complete block design (RCBD) with six (6) irrigation treatments. Two treatments, T1 and T3 were kept under continuous standing water levels (10 cm and 5 cm respectively) while in treatment T5 irrigation water was supplied for 1st 3 weeks then followed mid season drain out and re-flooded at flowering stage. Three alternate wetting and drying irrigation treatments, T2, T4 and T6 were selected in which irrigation water was applied when water level dropped 20cm, 10cm and 15cm below ground level, respectively. All the irrigation treatments significantly affected the rice yield and yield contributing parameters. The study revealed that the highest grain yield (5950 kg ha-1) was found in treatment T5 which was identical with AWDI treatment T4 (5820 kg ha-1) followed by AWDI treatment T6 (5460 kg ha-1). On the contrary, rice yield of 3350 kg ha-1, 4470 kg ha-1 and 4810 kg ha-1 were found in the treatment T1, T2 and T3, respectively. It was found that AWDI treatment T2 showed maximum water savings (15.1%) followed by T6 (11.3%), T4 (7.59%) and T5 (3.8%), however rice yield in the treatment T2 (4470 kg ha-1) was significantly lower compared to T6, T4 and T5 treatment. Therefore, it may be inferred that treatment T4 (AWDI; irrigation when water level fell 10 cm from ground level), T5 (Irrigation for 1st 3 weeks, then mid-season drain out and re-flooding at flowering) and T6 (AWDI; irrigation when water level fell 15cm from ground level) would be the feasible choice for the water savings, higher rice yield as well as maximum water productivity index (0.478, 0.472 and 0.467, respectively) for sustaining rice farming during the dry Boro season in Bangladesh.J. Environ. Sci. & Natural Resources, 9(2): 79-84 2016

Groundwater Visualisation System (GVS): A software framework for integrated display and interrogation of conceptual hydrogeological models, data and time-series animation

Summary Management of groundwater systems requires realistic conceptual hydrogeological models as a framework for numerical simulation modelling, but also for system understanding and communicating this to stakeholders and the broader community. To help overcome these challenges we developed GVS (Groundwater Visualisation System), a stand-alone desktop software package that uses interactive 3D visualisation and animation techniques. The goal was a user-friendly groundwater management tool that could support a range of existing real-world and pre-processed data, both surface and subsurface, including geology and various types of temporal hydrological information. GVS allows these data to be integrated into a single conceptual hydrogeological model. In addition, 3D geological models produced externally using other software packages, can readily be imported into GVS models, as can outputs of simulations (e.g. piezometric surfaces) produced by software such as MODFLOW or FEFLOW. Boreholes can be integrated, showing any down-hole data and properties, including screen information, intersected geology, water level data and water chemistry. Animation is used to display spatial and temporal changes, with time-series data such as rainfall, standing water levels and electrical conductivity, displaying dynamic processes. Time and space variations can be presented using a range of contouring and colour mapping techniques, in addition to interactive plots of time-series parameters. Other types of data, for example, demographics and cultural information, can also be readily incorporated. The GVS software can execute on a standard Windows or Linux-based PC with a minimum of 2 GB RAM, and the model output is easy and inexpensive to distribute, by download or via USB/DVD/CD. Example models are described here for three groundwater systems in Queensland, northeastern Australia: two unconfined alluvial groundwater systems with intensive irrigation, the Lockyer Valley and the upper Condamine Valley, and the Surat Basin, a large sedimentary basin of confined artesian aquifers. This latter example required more detail in the hydrostratigraphy, correlation of formations with drillholes and visualisation of simulation piezometric surfaces. Both alluvial system GVS models were developed during drought conditions to support government strategies to implement groundwater management. The Surat Basin model was industry sponsored research, for coal seam gas groundwater management and community information and consultation. The “virtual” groundwater systems in these 3D GVS models can be interactively interrogated by standard functions, plus production of 2D cross-sections, data selection from the 3D scene, rear end database and plot displays. A unique feature is that GVS allows investigation of time-series data across different display modes, both 2D and 3D. GVS has been used successfully as a tool to enhance community/stakeholder understanding and knowledge of groundwater systems and is of value for training and educational purposes. Projects completed confirm that GVS provides a powerful support to management and decision making, and as a tool for interpretation of groundwater system hydrological processes. A highly effective visualisation output is the production of short videos (e.g. 2–5 min) based on sequences of camera ‘fly-throughs’ and screen images. Further work involves developing support for multi-screen displays and touch-screen technologies, distributed rendering, gestural interaction systems. To highlight the visualisation and animation capability of the GVS software, links to related multimedia hosted online sites are included in the references.

Habitat associations of invertebrates in reedbeds, with implications for management

ABSTRACT Reedbeds in Europe and Asia have undergone substantial fragmentation and habitat degradation. Conservation action for reedbeds in the UK has focused on restoration and management. At present there is little evidence of how reedbed invertebrates respond to such changes. This study sampled Diptera and moths in three English reedbed nature reserves using pan traps and light traps. The aim was to elucidate habitat attributes that support a reedbed invertebrate fauna of conservation value. Habitat variables were tested for their relationship with (a) number of reedbed specialist Diptera and moths, (b) conservation importance of the invertebrates sampled, and (c) species richness of the invertebrates sampled. The fauna of old and recently created or restored reedbed was compared. Reedbed specialist Diptera and moths and species with a conservation status tended to be trapped more at points with lower standing water levels. Points with deeper litter also tended to trap more reedbed specialist Diptera and moths. Greater total numbers of moth species were trapped at points with partial flooding of the litter layer compared with total flooding. Pan traps in all hydrological categories trapped species of conservation importance at Ham Wall and species unique to each hydrology category were found. Recently restored or created reedbed hosted similar numbers of reedbed specialist moths to adjacent older reedbed at both Hickling Broad and Stodmarsh. The number of reedbed specialist Diptera species was comparable between restored and older reed at Hickling Broad. It is concluded that management aimed at maintaining a range of successional stages should maximize invertebrate conservation value and species richness. This involves keeping the ecosystem dynamic, maintaining the transitions between different habitats, and avoiding permanent long‐term flooding. The authors recommend phasing restoration spatially and temporally and taking into account the existing value of older reedbeds before any invasive restoration. Copyright © 2012 John Wiley & Sons, Ltd.

Recovery of the red-finned blue-eye: an endangered fish from springs of the Great Artesian Basin

The red-finned blue-eye (Scaturiginichthys vermeilipinnis) is endemic to a single complex of springs emanating from the Great Artesian Basin, Australia. The species has been recorded as naturally occurring in eight separate very shallow (generally <20 mm) springs, with a combined wetland area of ~0.3 ha. Since its discovery in 1990, five red-finned blue-eye (RFBE) populations have been lost and subsequent colonisation has occurred in two spring wetlands. Current population size is estimated at <3000 individuals. Artesian bores have reduced aquifer pressure, standing water levels and spring-flows in the district. There is evidence of spatial separation within the spring pools where RFBE and the introduced fish gambusia (Gambusia holbrooki) co-occur, although both species are forced together when seasonal extremes affect spring size and water temperature. Gambusia was present in four of the five springs where RFBE populations have been lost. Four out of the five remaining subpopulations of RFBE are Gambusia free. Circumstantial evidence suggests that gambusia is a major threat to red-finned blue-eyes. The impact of Gambusia is probably exacerbated by domestic stock (cattle and sheep), feral goats and pigs that utilise the springs and can negatively affect water quality and flow patterns. Three attempts to translocate RFBE to apparently suitable springs elsewhere within the complex have failed. Opportunities to mitigate threats are discussed, along with directions for future research to improve management of this extremely threatened fish and habitat.

Post-depositional 137Cs Mobility in the Sediments of Three Shallow Coastal Lagoons, SW England

We present 137Cs profiles for three low lying coastal lagoons in Southwest England that show a decline in activity with sediment depth. 137Cs inventories are lower than expected by comparison with local reference inventories despite the fact that sampling was undertaken in the deep-water zone of each lake where sediment and 137Cs focusing would be expected. At all three locations, lake sediment 7Be and unsupported 210Pb (210Pbun) inventories are not significantly lower than the local reference inventory. 137Cs inventories in the study cores range from 38 to 95% of local reference inventories. The standing water level and mud: water interface at two sites are below maximum tide level and, at all three sites, salinity increases significantly in the water columns between low and high tide and in the pore waters of the underlying sediments. We suggest that the difference in hydrostatic pressure between sea level and standing water levels in the lagoons forces salt water up through the sediment column and that monovalent cations (especially Na+ and K+) replace 137Cs on exchange sites leading to the upward migration and loss of 137Cs. Rising sea levels may therefore contribute to remobilisation and release of 137Cs to the aquatic environment from the sediments of coastal lagoons.

Effect of Ground Water Irrigation on Paddy Rice Yield in Maligaya, Philippines

Air and water temperatures are important climatic variables influencing rice yields through the interaction of pests and nutrients. The Philippine Rice Research Institute (PhilRice) in Maligaya, central region of Luzon island, stated that the Philippines could attain rice sufficiency if farmers' average yield increases to at least 1 t/ha. It is generally said that decreasing the minimum air temperature in the rice canopy could make a yield increase possible in the Philippines. Instead, results showed that the timing of irrigation water application using a shallow tubewell pump in Maligaya could not decrease canopy air temperature. However, the temperature of the standing or flooding water in the field was reduced using pumped water or ground water irrigation compared with the conventional irrigation where water came from irrigation canals, and the lower temperature of the standing water resulted in an increase in rice yield from 7.27 to 8.58 t/ha for PSB Rc28 rice cultivar and from 3.08 to 4.02 t/ha for New Plant Type IR66106-5-3-2-3. Based on this result, this study recommends that rice growers irrigate using pumped water or ground water from 15: 00 to 17: 00 with a standing water level of 5 cm during the reproductive stage to have a lower water temperature at night for better efficiency of water and resistance to white heads.

Plant communities along environmental gradients of high‐arctic mires in Sassendalen, Svalbard

Abstract. The wet to moist bryophyte‐dominated vegetation of Sassendalen, Svalbard, was classified into seven communities. These communities were grouped into (1) Cardamino nymanii‐Saxifragion foliolosae marsh; (2) Caricion stantis fen; (3) Luzulion nivalis snowbed – including manured vegetation corresponding to moss tundras. All communities have a basically arctic distribution. Marshes are developed in habitats with a water table above the bryophyte vegetation surface and fens on sites with a water table level high above the permafrost but below the bryophyte surface. Moss tundras normally have no standing water table, but in Sassendalen they have a low water table due to their development on less steep slopes than in their normal habitat near bird cliffs.CCA confirms that the standing water level is the prime differentiating factor between the alliances, while aspect favourability and permafrost depth differentiate between the fen communities and temporary desiccation is important for the Catoscopium nigritum community. Carex subspathacea is a characteristic fen species in the absence of other Carex species dominating elsewhere in the Arctic. Arctic marshes are linked to an extremely cold environment. They have a very low species diversity with a few species dominating; Arctophila fulva, Pseudocalliergon trifarium, Scorpidium scorpioides and Warnstorfia tundrae are character species. Moss tundra as defined here appears to be restricted to Svalbard and, probably, neighbouring Novaya Zemlya. This may be due to the absence of rodents and the high seabird density, which is related to the mild sea currents reaching further to the north here and which implies manuring of surrounding ecosystems. Manuring in a very cold environment produces moss carpets with a thin active layer and accumulation of thick peat layers without a standing water level. In Sassendalen the role of arctic seabirds is replaced by Svalbard reindeer which are nonmigratory and are concentrated to favourable grazing areas where their manuring effect is intense. Their long‐term manuring effect probably explains the occurrence of moss tundras in this weakly rolling landscape where seabird colonies are absent.

Plant communities along environmental gradients of high-arctic mires in Sassendalen, Svalbard

Abstract The wet to moist bryophyte-dominated vegetation of Sassendalen, Svalbard, was classified into seven communities. These communities were grouped into (1) Cardamino nymanii-Saxifragion foliolosae marsh; (2) Caricion stantis fen; (3) Luzulion nivalis snowbed – including manured vegetation corresponding to moss tundras. All communities have a basically arctic distribution. Marshes are developed in habitats with a water table above the bryophyte vegetation surface and fens on sites with a water table level high above the permafrost but below the bryophyte surface. Moss tundras normally have no standing water table, but in Sassendalen they have a low water table due to their development on less steep slopes than in their normal habitat near bird cliffs. CCA confirms that the standing water level is the prime differentiating factor between the alliances, while aspect favourability and permafrost depth differentiate between the fen communities and temporary desiccation is important for the Catoscopium ni...

An individual-oriented model of a wading bird nesting colony

An individual-oriented model for a colony of nesting wading birds during a breeding season is described. The birds in the colony are modeled as an assemblage of individuals. Their behaviors, such as foraging, bioenergetics, interactions with conspecifics, and reproduction, as well as spatial movements, are modeled separately for each bird. The individual behavior of each bird is described by decision rules which specify what particular action the bird performs at any given time. The paper gives an overview of the most important behavioral rules used in the model and also briefly describes how the physical and resource environments are taken into account. Simulations of a breeding colony of wood storks ( Mycteria americana ) in a heterogeneous landscape and under a variety of environmental conditions (e.g., changes in standing water level and prey concentration through the breeding season) illustrate their effect on reproductive success of individuals in the colony.

Wellbore Refluxing in Steam Injection Wells

SPE Members Summary Most deep steam injection wells are completed with insulated tubulars to reduce heat loss. Due to various circumstances, the annular space between the tubing and casing is usually filled with water prior to the beginning of steam injection. Although most of the water is "boiled off" after injection commences, a small fraction of the water remains in the wellbore in the form of refluxing steam. Heat losses in a refluxing wellbore are considerably higher than would be expected if the annulus was dry. Refluxing was studied to determine the mechanisms which drive the process and to identify methods to eliminate refluxing. The analysis indicates that vaporization from bare surfaces such as subs and expansion joints located above the packer is the principle source of wellbore heat loss that drives the refluxing process. Although vaporization can occur when condensate contacts uninsulated couplings, such occurrences are transient and of short duration. Vaporization caused by heat losses from uninsulated couplings cannot sustain the process in the absence of vaporization from heated surfaces below. Therefore, insulating the couplings will not prevent wellbore refluxing. Other methods of controlling refluxing such as evacuation of the annulus, pressurization of the annulus with inert gas, and continuous injection of gas in the annulus were investigated. Both evacuation of the annulus and continuous injection of gas can prevent wellbore refluxing. Introduction The use of insulated tubing to reduce wellbore heat loss in steam injection wells began in the mid-1960's with the development of prestressed tubulars to prevent casing failure during steam stimulation of wells not designed to tolerate thermal stresses . In the last 15 years, insulated tubing has become widely used in steam injection wells spurred by the simultaneous growth of steamflooding projects as well as a significant rise in oil prices, and thus the cost of fuel to generate steam. In addition, there were technological developments in insulating materials that reduced the effective thermal conductivity of the insulating system from 0.03 Btu/hr/ft / F/ft to 0.01 Btu/hr/ft /F/ft. The evaluation of insulating tubing strings is usually done assuming the tubing string is run on a packer into a well with some standing water level. Water remaining in the annulus is assumed to be boiled off by heat transfer from uninsulated surfaces such as collars, subs, expansion joints and the packer body, leaving a dry annulus. Under these conditions, wellbore heat loss calculations show that heat losses from insulated tubing can be as low as 80–100 Btu/hr/ft. The economics of using insulated tubing strings are quite favorable with these heat loss rates even though the capital investment for the insulated tubing is significant. Recent field experience has shown that the annulus does not dry out in insulated steam injection wells. Data were presented demonstrating the existence of refluxing in the wellbore which maintained the casing temperature at a constant value consistent with the annulus pressure. Casing temperatures under refluxing conditions were maintained at 212F when the annulus pressure was 1 atm while the casing temperature in a dry annulus was expected to be about 130F. Because of this, heat losses were higher than anticipated which offset some of the economic benefits of using an insulated tubing string. P. 95^

Design and application of a borehole flowmeter

Abstract A borehole flowmeter has been developed to measure low flow rates in NX (76 mm) boreholes. The instrument can be used to determine the standing water level and permeability of a test section of the borehole. The borehole flowmeter is a short, lightweight wireline packer which is inflated pneumatically and contains a turbine flowmeter transmitter unit. The useful flow range of the standard instrument is approximately 0.7 cm 3 /s to 70 cm 3 /s. The unit was originally designed to measure small axial flow rates in an array of boreholes which was thought to intersect a series of perched aquifers. Experimentation showed that an increased rate of flow could be induced through the unit by piping water into the top of the borehole, the flow rate being proportional to the excess head of water above the unit. Using this principle, a form of in situ falling head permeability test was devised. The corrected head of water at a zero flow rate was found to correspond to the standing water level in a borehole, and the linear relationship between applied head and flow rate was used to calculate the permeability of the section of borehole below the unit. The results are compared with those of packer tests carried out in the same test sections. The method has several advantages over packer testing in many conditions. The wireline equipment is light and can be operated by one man. The permeability test results are repeatable and are completed on average within one hour, though a satisfactory relationship between flow and head is usually established within ten minutes in a moderately permeable formation.

Results of an experimental programme of in situ permeability testing in rock

Abstract In an earlier pilot programme of tests in shallow drillholes (Pearson & Money, Quarterly Journal of Engineering Geology, 1977) it was shown that significant improvements could be made at low cost to packer testing in rock, which lead to greater reliability in test performance and interpretation. It was also demonstrated that non-equilibrium flow occurred in some tests which, if not recognised, could lead to anomalies in test results. A second programme of tests has been completed under commercial conditions using significantly deeper arrays of 76 mm drillholes in two rock masses, one in the Old Red Sandstone, and the other a set of basalt flows. Single packer tests were carried out as drilling proceeded using a standard mechanically-expanded packer with continuous autographic recording of flows and of input pressures. Some of the holes were also tested after drilling with a prototype double packer system instrumented with transducers to measure pressure within, above and below the test section. Results of the two methods are compared and individual test behaviour has been examined and it has been found that results were affected by changes in groundwater level produced by drilling. In any test it is unwise to assume that the effective piezometric level in the rock mass at the time and position of a test is necessarily the same as that observed in a completed drillhole. The tests have produced further practical evidence of the need to consider the scale of tests and observations in relation to the inhomogeneity of the rock mass under investigation. At these test sites there were marked variations in standing water levels, and in measured permeabilities in adjacent closely spaced drillholes.