Stream channel and habitat changes due to flow augmentation

A previously ephemeral stream is being used to convey water and create fish habitat as part of mitigation for impacts of a transbasin water diversion project. This stream, the South Fork of Middle Crow Creek, is located in the Medicine Bow National Forest, Wyoming. After two years of increased flow to the 8.8 km study reach, the amount of stream channel had increased 32 per cent and the total area of beaver ponds had more than doubled. Brook trout (Salvelinus fontinalis) stocked into the beaver ponds are surviving and growing. Factors limiting fishery development in the augmented stream include interrupted flow, discontinuous channels, and summer water temperatures exceeding 25°C. Analysis using the Physical Habitat Simulation System indicated that a flow of 0.07m³s^?1 would maximize the amount of weighted usable area for brook trout under the channel conditions present in 1987.     

Water‐related bird assemblages in an urban pond ‘archipelago’: Winter patterns of bird species occurrence,abundance and richness

This study reports on the patterns of species occurrence, abundance and richness of a wintering water‐related bird assemblage in an ‘archipelago’ of 70 small artificial urban ponds (AUPs) embedded in a metropolitan landscape (Rome, central Italy). A total of 20 species in 26 AUPs were sampled. Only the largest AUPs (>0.1 ha) contained all these species, except for Gallinula chloropus. The highest total mean species abundance was observed in the largest ponds, with statistically significant differences evident among size classes. Two significant spatial thresholds in species abundance and richness were observed (between 0.01 and 0.1 ha; between 0.1 and 1 ha in size). The abundance of single species was correlated with their frequency of occurrence. Ponds in urban areas must be larger than 0.1 ha to host a rich winter assemblage of birds, with a further increase in richness noted with a surface area larger than 1 ha. The highest number of species was observed in the larger ponds (>1 ha). The species richness of each AUP is directly correlated to their size (log‐transformed species–area relationship: log S = 3.515 + 0.497 log A; R² = 0.76). Further research should be conducted to confirm these patterns and to implement information useful for planning and management of artificial ponds in urban areas for this purpose.     

Limnological characterization of interdune ponds of Curupu Island,Raposa – MA,Brazil

This study was conducted on four freshwater interdune ponds (Jacaré; Grande; Duna; Banho) located on Curupu Island within the municipality of Raposa (Maranhão State, Brazil). It focused on a diagnosis of the physical and chemical characteristics of the water and sediment in these water bodies, while at the same time obtaining basic data and information that could support the adoption of conservation strategies for the rational use of these ecosystems. Seasonal sampling of water from these ponds was conducted during the months of August, September and November 2008 and 2009 (dry period) and February, May, July 2009 and 2010 (rainy period), for the purpose of obtaining data on temperature, pH, electrical conductivity and dissolved oxygen, ammonium (NH₄), nitrite (NO₂), nitrate (NO₃) and phosphate ion (PO₄) concentrations in the pond water. Sediment sampling also was carried out to determine particle size, carbon, organic matter and phosphorus content. A large variation in most variables, especially the ammonia (NH₄), nitrate (NO₃) and phosphate (PO₄) concentrations, was observed during the study period. The pH values indicated the water in the ponds was mostly alkaline. Based on the average nitrate concentrations (137 μg L^?1 during the dry period; 123 μg L^?1 during the rainy period), the ponds exhibited primarily eutrophic conditions. The sediment samples exhibited a predominance of fine sand with low carbon and organic matter content, able to be classified by their mineral nature. Due to the fragile nature of the studied ecosystems, disciplinary control of grazing activities and tourism in the area is highly recommended, along with adoption of a basic sanitation infrastructure in the community for the purpose of rational and sustainable use of this ecosystem.     

Sustainability of Natural and Mechanized Aerated Ponds for Domestic and Municipal Wastewater Treatment in Palestine

Abstract

More than half of the current wastewater treatment facilities constructed in Palestine are waste stabilization ponds (WSP) and have several problems in their operation. This article evaluates three selected case studies on the various pond systems including WSP, algae- and duckweed-based ponds (ABP and DBP, respectively) and one mechanically aerated lagoon (AL) system. The effects of various design and operating parameters on the pond system' performance, with special emphasis on nitrogen removal, are discussed. The effluent quality of WSP and AL complies only with BOD limits, but not with microbiological limits prescribed for agricultural purposes, as determined by national standards. ABP and DBP achieved nitrogen removal only under high surface area demand (5-7 m2capita-1). Suitable plans for modifying existing aerated lagoons or for upgrading natural lagoons are suggested in order to comply with microbiological standards for effluent use in restricted irrigation. Finally, the suggested sustainability criteria for the evaluated pond systems may help the decision makers, as well as their designers and donor countries, to better select and design low-cost treatment options for sustainable wastewater management in developing countries.     

Pond sediments on nesting islands in eastern Lake Ontario provide insights into the population dynamics and impacts of waterbird colonies

Marked increases in ring-billed gulls and double-crested cormorants in the Laurentian Great Lakes during the last century have garnered attention over their ecological impacts, sparking debates about management strategies. However, monitoring data are generally sparse and of short duration for these colonies, hampering the ability to place recent changes within long-term context. Sediment records from ponds immediately surrounded by colonies on nesting islands can be used to track past bird populations, as they release wastes with geochemical signals that can be tracked using traditional paleolimnological methods, such as diatoms and stable isotopes of nitrogen (δ¹⁵N). Here, we provide new information about waterbird nesting histories on islands in eastern Lake Ontario that are of interest to wildlife managers. In all bird-impacted ponds, eutrophic diatom assemblages and elevated sediment chlorophyll-a coincided with high signatures of δ¹⁵N in the recent sediments, signifying bird influence. An absence of significant bird impacts in the oldest portion of one sediment core indicates that the current cormorant colony size (>2000 birds) is unprecedented over the ~150-year record. Diatoms and sediment chlorophyll-a also responded to even a small, short-duration cormorant nesting event on an actively managed reference island. Collating our findings with those from four previously studied sediment cores from nearby islands, we show that cormorants are unlikely to have occupied eastern Lake Ontario in their current numbers within the past ~150?years. However, ring-billed gulls have likely used several islands in the area for most of the 20th century (and perhaps earlier) until present.     

Effect of Climate Change on Streamflows in the Mahanadi River Basin,India

ABSTRACT

In wet tropical regions, study of climate warming effects on water resources is important due to the socioeconomic and ecological implications. Observed changes in river flows of a major Indian river basin called the Mahanadi during the period 1926–1980 arepresented in relation to climatic changes that have occurred there. The Mahanadi River Basin is located in the monsoon region of India; its area is 141,600 km² and its mean annual flow is 66,640 million m³ . An earlier study by the author revealed that the surface air temperature over the basin has increased at a rate of 1.1 C° per century, which is highly significant However there has been no considerable change in the precipitation regime, though a slight decreasing trend is observed. In this article, an analysis of the trends in the runoff of the upper catchment and the whole catchment gauged at Hirakud and Naraj is presented. The results show a steady decrease in the river flows at these locations during the 55 year period of the study; this is significant statistically at the 1 per cent level. In order to increase confidence in this result, the moisture indices for the catchment have been computed and examined. Time series of these indices also show a clear declining trend during the period 1901–80. The main result obtained here is that climate warming that occurred over the basin, without being offset by an increase in precipitation (in fact a slight decrease in precipitation was observed), has resulted in a gradual decrease of river flows of the upper catchment as well as of the entire basin during the period 1926–1980. As a backdrop to future climate change scenarios over the Indian region, studies related to its impacts on water resources in the basin are important. However General Circulation Models (GCMs) at present are not capable of simulating adequately at regional and subregional scales. Nevertheless, it is hoped that recent efforts toward development of nested regional climate models may soon make it possible to have acceptable climate simulations for regions and subregions of this scale. The results of this article may be useful at that stage in hydrological forecasting studies for the basin.     

Contrasting stream stability characteristics in adjacent urban watersheds: Santa Clara Valley,California

A comparative study of two adjacent stream channels in the Santa Clara Valley region of California provided an opportunity to study the relative effects of multi‐faceted watershed‐urbanization impacts on channel evolution and stability. Berryessa Creek (15.5 km²) and Upper Penitencia Creek (61.3 km²) have similar intrinsic watershed characteristics; however, urbanization processes have imposed distinctly different evolutionary trends in each watershed. The influences of drainage network manipulation, hydrologic routing and engineering infrastructure has resulted in Upper Penitencia Creek remaining relatively stable throughout the course of urbanization, while Berryessa Creek has experienced system‐wide channel instability problems. This study enumerates the many anthropogenic impacts and provides insight into basin alterations that can have either positive or negative feedbacks in maintaining or degrading channel stability throughout the course of urbanization. Results show that infrastructure that disrupts the bed material sediment continuity (such as large drop structures or sedimentation ponds) generate long‐term downstream channel instabilities leading to channel degradation and continued maintenance. Off‐line flow diversions (in this study percolation ponds) that do not disrupt bed material transport can emulate pre‐urbanization conditions offsetting channel degradation resulting from changes in hydrology. This study also demonstrates the degradational responses of a stream due to losses in riparian vegetation from water table lowering transforming a perennial stream into an ephemeral stream resulting in increased bank instability. The importance of maintaining floodplains for flood access and channel stability has also been identified and compared to conditions of channel encroachment to facilitate maintenance, which have further exacerbated downstream channel degradation, long‐term channel maintenance and dredging. Copyright © 2009 John Wiley & Sons, Ltd.     

Benefits of pan-sharpened Landsat imagery for mapping small waterbodies in the Powder River Basin, Wyoming, USA

Pan‐sharpened Landsat imagery was used to map waterbodies of a wide variety of sizes in the Powder River Basin (PRB) in northcentral Wyoming, USA. Coal bed natural gas extraction activities have been intensive in the PRB over the past decade, with abundant co‐produced water being discharged into retention ponds and small ephemeral channels. Although land management agencies are tasked with monitoring these waterbodies, traditional field survey methods might not be feasible during rapid development. Remote‐sensing applications could be used in such cases. Although Landsat and similar medium‐resolution datasets do not have detailed spatial information at fine resolutions required to map small waterbodies, they do contain rich spectral information. Panchromatic data collected by satellites have an appropriate spatial resolution, but lack detailed spectral information. Thus, image fusion techniques were used to create a pan‐sharpened image, by merging multispectral (30‐m resolution) and panchromatic (15‐m) bands from Landsat 7 imagery. Both the original and the pan‐sharpened images were used to map waterbodies and estimate their area, being compared to photo‐interpretation results. The accuracy of mapping waterbodies with pan‐sharpened imagery was significantly higher than the original Landsat data for waterbodies ranging in size from 901 to 8100 m². Large reservoirs (>8100 m²) were very accurately mapped, both images producing identical results (96%). Neither image was able to suitably detect very small waterbodies (<900 m²). Detailed analysis within 901–3600 m² size category revealed that the benefits of pan‐sharpened imagery were most pronounced (25% higher accuracy) for mapping waterbodies ranging in size from 1801 to 2700 m².     

基于地理探测器的菜子湖群湿地景观格局变化及驱动因子分析

选取1999年、2004年、2011年和2017年4期卫星遥感影像,采用网格分析法研究景观指数和人为干扰的时空分异规律,借助地理探测器和相关性分析相结合的方法,从人为活动和社会经济角度分析安徽菜子湖群湿地景观格局变化原因。结果表明:1999—2017年菜子湖群自然湿地面积减少,人工湿地面积增加;滩涂和沼泽草滩占比分别减少12.23%和13.84%,农田及养殖塘面积分别增加12.12 km²和20.71 km²,非湿地面积略有增加;湿地破碎化,景观斑块连通性下降,斑块形状趋于简单化,景观异质性增加;湿地人为干扰强度增加,较高、高干扰等级占比增大;农田、养殖、围网及围坝等人为活动对斑块数量分布的影响在时间及空间上存在明显差异,人为活动因子的交互作用较单个因子作用影响显著增强;景观指数与三大产业产值、国内生产总值、人口、渔业生产、耕地面积等社会经济因子有显著相关性。     

The thermal behaviour of French water bodies: From ponds to Lake Geneva

The management of French freshwater bodies (lakes, reservoirs, ponds, etc.) needs to face the challenges imposed by the effects of climate change and by legal requirements to develop standards for water temperature and other physicochemical indicators. While 1D hydrodynamical models could be helpful in improving the knowledge of the thermal and hydrodynamic behaviour of French water bodies, the scarcity of data for calibration and validation, in addition to the unavailability of some forcing data, makes their application difficult for most French water bodies. In this article we explore an alternative statistical approach that takes advantage of the available data in order to inform future modelling applications. We used official monitoring data and satellite measurements to study the thermal characteristics of more than 400 French water bodies (depth: 1–310 m, surface area: 0.1–577 km², volume: 0.1–89,000 hm³). The objective was to identify the importance of size on their thermal behaviour. For this we analysed the annual temperature cycle, the summer temperature profiles and within-lake spatial variability. Together with size, geography and transparency determine the thermal behaviour of water bodies through complex interactions. As a result of the analysis we propose a classification of French water bodies as a function of depth and surface area that reflects the summer vertical temperature gradient and the processes influencing the deepening of the thermocline.     

Assessment and Management of a Desert Basin in Kuwait

ABSTRACT

The study area, Umm Gudair, is located in the southwest corner of Kuwait. It occupies an area of ≈ 4.84 × 10⁹ ft². The brackish ground water is derived from the two main aquifers within the Cenozoic sequence. These are: the Kuwait Group aquifer (Miopleistocene) and the Dammam aquifer (Eocene). In the study area, the two aquifers are treated as a single reservoir Forty-one production wells, locally called “dual completion wells” were finished in the aquifers. This research identifies the hydrogeologic properties and the water quality of the aquifers. In addition, the article discusses the application of the surface electrical method Schlumberger configuration to correlate and delineate the areal distribution of the apparent resistivity with the aquifer salinity, and the occurrence of a water-bearing formation. The results will be use for assessment and management of the groundwater reservoir The water quality of the two aquifers is relatively poor The T.D.S. ranges between 3,130-4,740 mg/L. The hydrochemical facies are calcium-sodium cation facies and chloride-sulphate anion facies. The ground water is classified as a NaCl water type, however two genetic water types are identified: the MgCl₂ and CaCl₂ are of marine origin and are old marine formations. The aquifer is semiconfined to confined The average transmissivity, which increases toward the N and N-E, is 20,965 Igpd/ft. The geophysical studies conducted along seven profiles with 19 vertical electrical soundings reveal three distinct layers. The first layer is composed of dry gravel and has a resistivity of 80–220 m. For the second layer, the resistivity ranges between 5–9 Ωm. It is assumed to be a clayey layer saturated with brackish water; whereas the third layer corresponding to a limestone formation, has a resistivity of 25–700Ωm. The apparent resistivity decreases in the direction of the increasing salinity From the flow-net analysis, the amount of ground water entering the aquifer along the border with the Saudi Arabia is 2.3 × 10⁶ Igpd, while the average daily production from the Umm Gudair field is 13.5 × 10⁶ Igpd, It is obvious that the daily abstraction rate is higher than the daily flow toward the aquifer Therefore, in the future, if the daily abstractions continue to exceed the daily water flow through the aquifer a serious decline in the water level will result.     

Sedimentation in New Zealand Hydroelectric Schemes

ABSTRACT

Geologically young New Zealand catchments can produce large quantities of relatively coarse sediment which has caused problems in the design and operation of some hydroelectric schemes.

The general sediment producing characteristics of New Zealand catchments are described and are related to the measured sedimentation rates of four reservoirs.

A number of examples of sediment management problems and methods of dealing with them are given to illustrate some of the principles and practice in the design and operation of sediment handling facilities.

Generally sedimentation in New Zealand hydroelectric reservoirs has not been a problem mainly because development has concentrated on rivers where a large proportion of the sediment has been trapped by natural lakes upstream. Usually catchments of major schemes have had less than 200 t/km² sediment yield annually and this has caused no problems. However some smaller schemes in catchments where the annual sediment yield has exceeded 2000 t/km² have encountered problems and the cost of dealing with this has usually been less than 5% of the scheme income.

It is concluded that planning and management of sediment in New Zealand is a long-term problem which can be handled using the existing database and engineering techniques providing the problem is recognised.     

The Study and Planning of Reservoir Desilting in Taiwan

ABSTRACT

Taiwan is an island located in the western Pacific Ocean, about 36 000 km² in size. It has a banana shape with high mountains running roughly in the north-south direction with many peaks exceeding 3000 m in elevation. Consequently, the streams on the island are generally short and steep, many with high sediment loads. The climate is semitropical, with high precipitation between May and September and relatively dry during the rest of the year. In southern Taiwan nearly 70% of the annual rainfall occurs in the period of June through August, another 15% in the months of May and September.

In order to store the large amount of runoff water in the wet summer season for later use, 27 reservoirs have been constructed, some are under construction and several are being planned. For streams having a heavy sediment load such as those in southern Taiwan, the reservoir will be silted in a short time. One possible approach to prolong the useful life of the reservoir is to flush the sediment in the reservoir periodically by using sluice valves. Although the scheme is still under study, some tryouts have been implemented effectively. The proposed dam-reservoir project that adopts a special scheme will be presented in conjunction with the basic design procedures.     

湖泊水体营养状态对沉积物好氧氨氧化菌异质性的影响

采用荧光定量PCR(real-time fluorescence quantitative polymerase chain reaction)和末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)方法,对江苏7个湖泊沉积物中好氧氨氧化微生物进行分析,研究湖泊水体营养状态对沉积物好氧氨氧化微生物空间异质性的影响。综合营养指数分析结果表明,23个采样点中,61%的湖区为中营养状态,39%的湖区为轻度富营养状态。荧光定量PCR分析结果显示,每克底泥中氨氧化古菌(ammonia-oxidizing archaea,AOA)和氨氧化细菌(ammonia-oxidizing bacteria,AOB)amo A基因拷贝数虽然分别从中营养湖泊的3.91×10~6和3.82×10~6上升到轻度富营养湖泊的1.30×107和6.07×10~6,但湖泊水体营养状态并未显著影响沉积物AOA和AOB的丰度。T-RFLP分析结果表明,湖泊水体营养状态对AOA和AOB的优势种属及群落多样性也未产生显著影响。典范对应分析结果表明,湖泊水体营养盐浓度能解释AOA的群落结构差异的56.3%,而仅能解释27.2%的AOB的群落结构差异,TN和NO-3-N浓度是影响沉积物AOA分布异质性的主要环境因子,湖泊水体营养盐浓度比综合营养状态指数更能影响AOA和AOB的群落结构组成。     

A systems approach to validating the water vision of the Aral Sea Basin

Abstract:

The governments of the Aral Sea Basin countries, in cooperation with international organizations (UNESCO and World Bank) came up with a “water vision “for the region until 2025. The landlocked Aral Sea has been suffering from an imbalance in water evaporation, and, water inflow from its two main sources — Amu Darya and Syr Darya rivers, when the planners in the former Soviet Union from the 1960s diverted the river waters for irrigation. The irrigated area has increased from the 1960s by two‐thirds to 7 million hectares and the population by three‐fold to 50 million in the basin countries. Consequently the inflow to the Aral Sea from these two rivers decreased from 55 km³ in 1960 to a few km³ during the 1980s and 1990s. This has resulted in one of the worst man‐made ecological disasters of the century. In this paper, we examine different scenarios to achieve the vision goals and whether it is indeed feasible. Using IWMI basin‐oriented water accounting principles, we have shown that significant amount of water is being wasted in the region. Our analysis concludes that though not all the vision goals are likely to be met over the next 25 years, the inflow into the Aral Sea can be increased to over 20 km³ through better management and use of water resources.     

基于阻-导水通道的辽浑防洪保护区溃堤洪水淹没分析

为避免在影响水流运动的构筑物附近进行网格加密而导致计算效率降低的问题,本文采用阻水和导水通道数值模拟方法,以辽浑防洪保护区为研究对象,构建了基于阻-导水通道的水动力学模型,分析了超标准洪水下溃堤洪水的淹没过程及对研究区内社会经济的影响.结果显示:遇超标准洪水,陶家险工和偏养子堤段溃决后,保护区内将进入7.458亿m3和...     

生物接触氧化法净化供水原水现场试验

为了考察生物接触氧化法对供水原水的净化效果,以不同填料为基质构建了4组生物接触氧化池,开展野外现场试验。结果表明:组合填料、弹性填料、SDF阿科蔓和BDF阿科蔓4组生物接触氧化池对TP的平均去除率分别为59.4%、59.4%、44.7%和51.9%;对NH_4~+—N的平均去除率分别为36.5%、33.4%、35.0%和36.6%;对TN的平均去除率分别为21.6%、18.8%、22.3%和18.0%;对COD_(Mn)的平均去除率分别为13.9%、13.7%、14.5%和13.4%;对TOC的平均去除率分别为10.7%、13.6%、13.4%和11.5%;对UVA_(254)的平均去除率分别为31.1%、34.0%、25.3%和26.2%;对UVA_(410)的平均去除率分别为54.2%、62.0%、47.2%和49.3%。综合而言,组合填料生物接触氧化池对原水氮、磷营养盐的净化效果最好,弹性填料生物接触氧化池对原水有机物的净化效果最好,其次是组合填料生物接触氧化池。     

Numerical study of high-order Lagrangian structure functions in a turbulent channel flow with low Reynolds number

The scaling exponents of Lagrangian velocity structure functions from orders 1 to 10 in a low Reynolds number turbulent channel flow are investigated by using direct numerical simulation. The Reynolds number Re_τ is 80 (based on friction velocity on the wall). The Lagrangian velocity structure functions are shown to obey the scaling relations <Δv^q(τ)>∼τ^ζL(q). The scaling exponents are normalized by ζ_L(2) (so-called ESS procedure). The coincidence between the theoretical predictions and numerical calculations is very good for the longitudinal scaling exponent in the channel center. It is also found that the high-order longitudinal scaling exponents agree with theoretical values better than those for the transverse direction.

     

Evaluation of the Missouri River shallow water habitat using a 2D‐hydrodynamic model

Many of the Upper Missouri River dikes have been notched to create additional shallow water habitat (SWH, operationally defined as areas in the stream with depth < 1.5 m, and velocity < 0.75 m s^?1) for fish populations. The goal of this study was to quantify the additional SWH gained from notching these dikes and to evaluate their performance under different flow conditions. A coupled field and numerical study was performed on a reach of the Missouri River, near Nebraska City, NE, which contains a number of dikes notched in 2004. The numerical simulations showed that the SWH criterion for depth was more difficult to satisfy in the study reach than the SWH criterion for velocity. Notching the dikes resulted in a slight shift of the bankline due to local erosion in the vicinity of the dikes and the formation of scour holes downstream of the notches. Results from the study suggested that notching the dikes had limited impact on the SWH because the area gained from the bankline shift was offset by the area lost from the scour holes formation. The performance of the notched dikes in sustaining the minimum habitat suitability conditions for the Missouri River ecosystem was also investigated. These conditions corresponded to discharges < 709 m³ s^?1 for the period from mid‐July to mid‐August, or equivalently SWH areas > 5225 m² dike^?1 during the same period. Analysis of the Missouri River annual discharge records at the study site showed that the dikes can provide the minimum required SWH for mean annual discharges < 667 m³ s^?1. For mean annual discharges > 667 m³ s^?1, new alternative structures or restoration facilities were needed, in addition to the existing dikes, to sustain the minimum required SWH. The dikes were not effective in providing any SWH for mean annual discharges > 2000 m³ s^?1. Copyright © 2010 John Wiley & Sons, Ltd.     

Some Hydrogeological Problems In Sri Lanka

ABSTRACT

The environmental heavy stable isotopes of oxygen and hydrogen (¹⁸O and ²H or D) together with both natural and artificially introduced tritium, ³H or T, the radioactive isotope of hydrogen, were used to try to solve some hydrogeological problems in Sri Lanka. The approach proved useful in establishing the rate of recharge to a multi-aquifer system at Vanathavillu in the semi-arid Dry Zone of the island Here, and also in its Wet Zone, a value of almost1 00% wasdemonstrated Tritiated water (HTO) experiments around the country enabled apparent seepage velocitiesfrom canals and reservoirs to be calculated The rapid rise ofpopulation makes such investigations practically beneficial both in easing shortfalls ofpotable water and conserving scarce water resources.