Percolation pond as a method of managed aquifer recharge in a coastal saline aquifer: A case study on the criteria for site selection and its impacts

Percolation ponds have become very popular methods of managed aquifer recharge due to their low cost, ease of construction and the participation and assistance of community. The objective of this study is to assess the feasibility of a percolation pond in a saline aquifer, north of Chennai, Tamil Nadu, India, to improve the storage and quality of groundwater. Electrical resistivity and ground penetrating radar methods were used to understand the subsurface conditions of the area. From these investigations, a suitable location was chosen and a percolation pond was constructed. The quality and quantity of groundwater of the nearby area has improved due to the recharge from the pond. This study indicated that a simple excavation without providing support for the slope and paving of the bunds helped to improve the groundwater quality. This method can be easily adoptable by farmers who can have a small pond within their farm to collect and store the rainwater. The cost of water recharged from this pond works out to be about 0.225 Re/l. Cleaning the pond by scrapping the accumulated sediments needs to be done once a year. Due to the small dimension and high saline groundwater, considerable improvement in quality at greater depths could not be achieved. However, ponds of larger size with recharge shafts can directly recharge the aquifer and help to improve the quality of water at greater depths.     

Salinization and arsenic contamination of surface water in southwest Bangladesh

To identify the causes of salinization and arsenic contamination of surface water on an embanked island (i.e., polder) in the tidal delta plain of SW Bangladesh we collected and analyzed water samples in the dry (May) and wet (October) seasons in 2012–2013. Samples were collected from rice paddies (wet season), saltwater ponds used for brine shrimp aquaculture (dry season), freshwater ponds and tidal channels (both wet and dry season), and rainwater collectors. Continuous measurements of salinity from March 2012 to February 2013 show that tidal channel water increases from ~0.15 ppt in the wet season up to ~20 ppt in the dry season. On the polder, surface water exceeds the World Health Organization drinking water guideline of 10 μg As/L in 78% of shrimp ponds and 27% of rice paddies, raising concerns that produced shrimp and rice could have unsafe levels of As. Drinking water sources also often have unsafe As levels, with 83% of tubewell and 43% of freshwater pond samples having >10 μg As/L. Water compositions and field observations are consistent with shrimp pond water being sourced from tidal channels during the dry season, rather than the locally saline groundwater from tubewells. Irrigation water for rice paddies is also obtained from the tidal channels, but during the wet season when surface waters are fresh. Salts become concentrated in irrigation water through evaporation, with average salinity increasing from 0.43 ppt in the tidal channel source to 0.91 ppt in the rice paddies. Our observations suggest that the practice of seasonally alternating rice and shrimp farming in a field has a negligible effect on rice paddy water salinity. Also, shrimp ponds do not significantly affect the salinity of adjacent surface water bodies or subjacent groundwater because impermeable shallow surface deposits of silt and clay mostly isolate surface water bodies from each other and from the shallow groundwater aquifer. Bivariate plots of conservative element concentrations show that all surface water types lie on mixing lines between dry season tidal channel water and rainwater, i.e., all are related by varying degrees of salinization. High As concentrations in dry season tidal channel water and shrimp ponds likely result from groundwater exfiltration and upstream irrigation in the dry season. Arsenic is transferred from tidal channels to rice paddies through irrigation. Including groundwater samples from the same area (Ayers et al. in Geochem Trans 17:1–22, 2016), principal components analysis and correlation analysis reveal that salinization explains most variation in surface water compositions, whereas progressive reduction of buried surface water by dissolved organic carbon is responsible for the nonconservative behavior of S, Fe, and As and changes in Eh and alkalinity of groundwater.     

森林水文生态效应若干争论问题讨论

对国内外若干森林水文生态效应的部分争论焦点问题进行了阐述,指出容量饱和与平衡变化是导致不同森林水文生态效应存在的根本原因.截留量可以用林冠截留率或林冠饱和度计算.对森林水文生态效应的研究方法进行了探讨,指出某些研究结论相反的原因可能是由于实验方法的问题.必须结合水文循环过程的机理,加强森林生水文生态效应机制的研究,要建立不同空间尺度的分布式水文模型,从而准确的回答流域或区域的森林生态水文效应.     

SCS-CN and GIS-based approach for identifying potential water harvesting sites in the Kali Watershed,Mahi River Basin,India

The Kali sub-watershed is situated in the semi-arid region of Gujarat, India and forms a part of the Mahi River Watershed. This watershed receives an average annual rainfall of 900mm mainly between July and September. Due to high runoff potential, evapo-transpiration and poor infiltration, drought like situation prevails in this area from December to June almost every year. In this paper, augmentation of water resource is proposed by construction of runoff harvesting structures like check dam, percolation pond, farm pond, well and subsurface dyke. The site suitability for different water harvesting structures is determined by considering spatially varying parameters like runoff potential, slope, fracture pattern and micro-watershed area. GIS is utilised as a tool to store, analyse and integrate spatial and attribute information pertaining to runoff, slope, drainage and fracture. The runoff derived by SCS-CN method is a function of runoff potential which can be expressed in terms of runoff coefficient (ratio between the runoff and rainfall) which can be classified into three classes, viz., high (>40%), moderate (20–40%) and low (<20%). In addition to IMSD, FAO specifications for water harvesting/recharging structures, parameters such as effective storage, rock mass permeability are herein considered to augment effective storage. Using the overlay and decision tree concepts in GIS, potential water harvesting sites are identified. The derived sites are field investigated for suitability and implementation. In all, the accuracy of the site selection at implementation level varies from 80–100%.     

Physico-chemical characterization of saline subsurface system near small endorheic ponds in Thailand

The problem of salt-ravaged lands is reported in many parts of the world and could be exacerbated by the presence of an endorheic pond normally associated with a saline low-lying area. An endorheic or playa pond accumulates dissolved salts which can be carried primarily by groundwater before discharging into the pond; then, intense evaporation produces salt residues which can wreak havoc on the adjacent areas. The objective of this study is to investigate the subsurface conditions and groundwater interactions beneath two endorheic saline ponds of Thailand’s Great Mekong Basin to have a better understanding and thereby efficiently manage the resources. A comprehensive analysis of the physical and geochemical properties (limited to pH, specific conductance and salinity) of the subsurface system was performed to determine the processes that regulated the migration of dissolved salt. The data collected from the deep and shallow groundwater of the basin were analyzed to determine their physical and chemical properties. Soil samples of various depths were examined to determine their respective geologic, chemical and unsaturated properties. The groundwater near the salt ponds was different from that of other areas in that its groundwater table was closer to the surface soil and its deep groundwater, which is of high pressure, was more saline than its shallow groundwater. As the capillary rise influences the topsoil, particularly in the saline pond areas, the vertical upward flow and the capillary force are thus the additional mechanisms of salt transportation to the endorheic ponds. Since these surface water bodies are the discharge sites for saline groundwater and are not perennial, a practical solution is to localize the saline groundwater.     

Assessing the acidic potential of waste rock in the Akara gold mine,Thailand

Acid mine drainage (AMD) is the environmental issue that generates the greatest public concern regarding the mining industry. Thus, characterization of mine waste rock according to acid generation potential is necessary for mining operations to ensure proper waste rock storage and to avoid future adverse environmental effects. Therefore, this study was conducted to estimate the potential of AMD generation in the largest operating gold mine in Thailand by using acid base accounting and net acid generation tests. Representative samples of six types of waste rock classified by mining geologists for mineral processing and waste dumping were collected for this study: volcanic clastic, porphyritic andesite, andesite, silicified tuff, silicified lapilli tuff, and sheared tuff. Under various conditions, experimental results indicate that only silicified lapilli tuff and shear tuff are potentially acid-forming materials. The results indicate that AMD generation may possibly occur a long time after mine closure due to the lag time of the dissolution of acid-neutralizing sources. Acidic generation from some waste rocks may occur in the future based on environmental conditions, particularly the oxidation of sulphide minerals by the combination of oxygen and water. Therefore, a proper design for waste rock dumping and storage is necessary to reduce the risk of AMD generation in future. It is advisable to install a surface management system to control the overland flow direction away from the waste dump area and tailing storage facility and to install a second water storage pond next to the main storage pond to store the spilled water during storms and the rainy season. A water quality monitoring plan that focuses on disturbed areas such as water storage ponds and mine pits should be put in place.     

Regional modelling of rainfall-induced runoff using hydrological model by incorporating plant cover effects: case study in Kelantan,Malaysia

The objective of this paper is to develop a spatial temporal runoff modelling of local rainfall patterns effect on the plant cover hilly lands in Kelantan River Basin. Rainfall interception loss based on leaf area index, loss/infiltration on the ground surface, and runoff calculation were considered as the main plant cover effects on the runoff volume. In this regard, a hydrological and geotechnical grid-based regional model (integrated model) was performed using Microsoft Excel^® and GIS framework system for deterministic modelling of rainfall-induced runoff by incorporating plant cover effects. The infiltration process of the current model was integrated with the precipitation distribution method and rainfall interception approach while the runoff analysis of integrated model was employed based on loss/infiltration water on the ground surface with consideration of water interception loss by canopy and the remaining surface water. In the following, the spatial temporal analysis of rainfall-induced runoff was performed using 10 days of hourly rainfall events at the end of December 2014 in Kelantan River Basin. The corresponding changes in pressure head and consequent rate of infiltration were calculated during rainfall events. Subsequently, flood volume is computed using local rainfall patterns, along with water interception loss and the remaining surface water in the study area. The results showed the land cover changes caused significant differences in hydrological response to surface water. The increase in runoff volume of the Kelantan River Basin is as a function of deforestation and urbanization, especially converting the forest area to agricultural land (i.e. rubber and mixed agriculture).     

高密度电法勘探数据在Voxler平台的三维可视化展示——及其在尾矿库隐患勘查中的应用

尾矿库内堆放的有污染的固体和液体废物若得不到合理妥善的处理,会对周边的环境造成严重的污染.为了确定尾矿库的稳定性,分析尾矿库内的固、液废弃物对周边土壤和地下水的影响,急需查明尾矿库的形态特征和库容规模.高密度电法作为一种常规的物探方法,以其简便、快捷、高效等特点,在确定尾矿库形态特征方面成为现场探测的首选技术手段.本研究运用高密度电法反演得到尾矿库的底界面范围,并结合钻孔验证,在Voxler平台构建了尾矿库的可视化三维模型,从而更加精确计算尾矿砂的方量,证明了高密度电法在确定尾矿库形态特征中的可行性.     

北极巴罗地区海冰消融初期表面特征及光谱反射率观测研究

北极海冰消融初期,上覆积雪急剧消融,融池开始形成,海冰表面物理特征异常复杂。由于观测资料缺乏,对这一时期海冰变化的研究仍存在较大不确定性。利用2015年5月份在巴罗Elson Lagoon海域观测的海冰表面物理特征和光谱反射率数据,分析了巴罗地区海冰消融初期表面积雪、裸冰和融池反射率特性及其影响因素。结果表明：消融初期,海冰表面异质性强,积雪、裸冰和融池相间分布。在积雪覆盖的区域,积雪对海冰光谱反射率起决定性作用,观测到不同雪深（3~23 cm）的反射率变化在0.53~0.85之间,平均反射率为0.76且反射率与雪深呈正相关。在表面积雪厚度相同的情况下,积雪底层含水量越大,表层反射率越小。观测还显示,在融池形成的区域,海冰的反射率急剧降低,融池初形成时反射率为0.206,略低于裸冰（0.216）。随着融池的发展,当其深度达到10 cm时,反射率仅为0.04,与开阔海域海水接近。     

Distribution of stable isotopes in arid storms

 Temporal distributions of the isotopic composition in arid rain storms and in the associated runoff were investigated in a small arid rocky basin in Israel. Customized rain and runoff samplers provided sequential water samples hermetically sealed in high-density PVC bags. In several storms where the runoff was isotopically depleted, compared with the rainfall, the difference could not be explained by fractionation effects occurring during overland flow. A water-balance study relating the runoff discharge to rainfall over a rocky watershed showed that the entire discharge is produced by a very small segment (1–2 mm) of the rain storm. The major objective, therefore, was to provide quantitative relations between segments of rainfall (rain showers and rain spells) and runoff. The time distribution of the composition of stable isotopes (oxygen and hydrogen) was used to quantify the correlation between the rain spell's amount and the consequent runoff. The aim of this work was to (a) utilize the dynamic variations in the isotopic composition in rainfall and runoff and model the magnitude of surface-storage capacity associated with runoff processes of overland flow, and (b) characterize the isotopic composition of the percolating water with respect to the isotopic distribution in rainfall and runoff events. The conceptual model postulates an isotopic mixing of overland flow with water within the depression storage. A transport model was then formulated in order to estimate the physical watershed parameters that control the development of overland flow from a certain rainfall period. Part I (this paper) presents the results and the assessment of the relative depression storage obtained from oxygen-18 and deuterium analyses that lead to the physical and mathematical formulation of a double-component model of kinematic-wave flow and transport, which is presented in Part II (accompanying paper). Received, February 1997 · Revised, September 1997 · Accepted, September 1997     

Using digital mapping techniques to evaluate beneficiation potential in a coal ash pond

Coal-fired power plants produce energy and many by-products (unburned carbon, fly ash, and bottom ash) that are normally stored in permitted ponds and landfills. When the storage facility fills to capacity, it is necessary to haul material off-site for disposal, construct a new storage facility, or find a use for some of the material. Because certain criteria must be met to successfully beneficiate the ash, mapping the ash reserve provides data that shows where the most promising recovery sites will be.The University of Kentucky Center for Applied Energy Research (CAER) in conjunction with Western Kentucky Energy (WKE) and the US Department of Energy are constructing an ash beneficiation plant to recover high quality fuel and lightweight aggregate from the ash ponds at WKE's Coleman Station in Hawesville, KY. To determine the locations of the most productive areas, an extensive sampling and mapping project is underway. An amphibious ATV-mounted hydraulic drill has been employed to take core samples throughout the pond. These samples are then evaluated for particle size distribution, carbon content, chemical and leaching properties. With this information as well as each drill-hole's GPS coordinates and aerial photographs of the plant site, digital maps have been produced showing trends of deposition of material in the pond. Using a Geographical Information System to compile the data, the feasibility of removing ash for beneficial re-use can assessed.     

Geotechnical modeling of fractures and cavities that are associated with geotechnical engineering problems in Kuala Lumpur limestone,Malaysia

This study presents a modified geotechnical model of subsurface cavities and fractures that are associated with foundation and pilling problems. The topographical model was used to automatically extract minimum surface curvature, slope, and pits. The image processing shows that more than fourteen regional faults, trending NE, SW, and WNW affect the Kuala Lumpur limestone bedrock and the surface topography from South to North. These fractures often show higher probability of piling and constructions problems. The faults are tensional, low lying, and wrench of length 10–20 km. Opencast ex-mining pond floors (bathymetry) are good indicators of subsurface fractures and cavities that affect the limestone bedrock. The LANDSAT image (band one) shows that the fractures of opencast ex-mining pond floors have the same trend as the regional faults. These techniques can help geotechnical engineers to predict subsurface fractures and cavities, especially in areas adjacent to ex-mining ponds. In brief, most of the subsurface cavities and ex-mining ponds, for example the Phong Fatt pond, are located on and along fault zones.     

渭河源区典型小流域水沙演变规律分析

根据渭河源区清源河典型小流域实测水文资料,分析了流域水文要素的年内和年际变化规律,流域降水、径流和泥沙主要集中在汛期,5-9月降水量占全年的78.5%,5-10月径流占全年的78.7%,5-8月输沙量占全年的88.9%。受上游修建水库、水土保持等人类活动的影响,流域汛期径流和泥沙1997-2013年比1980-1996年均减少了5.9%。流域面平均降水量、平均流量、平均输沙量年际变化不稳定,总体呈减少趋势,序列最大可能变异点分别为1995年、1994年和1997年。建立了流域年降水量与年径流深、次降水量P+Pa与次径流深相关模型,相关系数达到0.902和0.860。以年最大洪峰流量为参数,分别建立了流域年径流量与年输沙量、次径流量与次输沙量关系模型,相关系数达到0.835和0.917,公式模拟值与实测值接近,误差较小,可以作为以径流推算泥沙的重要依据。通过定性定量分析人类活动对流域径流、泥沙的影响程度,对区域抗旱防洪减灾、水资源管理、小流域治理及生态环境保护具有重要意义。     

The effect of low-rate sand filtration and modified feed management on effluent quality,pond water quality and production of intensive shrimp ponds

Pond water in intensive shrimp ponds is typically high in nutrients, solids, and BOD and may have an adverse environmental impact when discharged to natural waters. As part of ongoing research to develop intensive production technologies that minimize the potential for environmental impact, a study investigated the effect of lowrate, coarse-grain sand filtration on the quality of effluent being discharged from an intensive shrimp pond receiving 5% d^?1 water exchange. The effect of sand filtration on a recirculating no-exchange pond was also examined. For comparison, a third pond received no water exchange and no filtration. Sand filtration removed some particulate matter, but levels of dissolved and particulate organic and inorganic nutrients were changed little and were sometimes higher as the result of in situ decomposition. Low-rate sand filtration is not seen as a cost-effective method of increasing the carrying capacity of no-exchange shrimp ponds or drastically improving the effluent quality of ponds with water exchange. Compared to previous studies with decreased or no water exchange, the application of feed in these ponds was more stable with small portions fed at frequent intervals with a constant rate of 80 kg ha^?1 d^?1. These ponds, stocked with 40 m^?2 juvenilePenaeus vannamei, had excellent survival and normal growth, resulting in productions levels approaching 7,000 kg ha^?1 crop^?1 without water exchange. This indicates that intensive shrimp farming may be possible in static no-exchange systems, thereby minimizing the potential impact of effluent as long as feed inputs do not overwhelm the assimilative capacity of the pond ecosystem. *** DIRECT SUPPORT *** A01BY069 00011     

The processes affecting oxytetracycline contamination of groundwater in a phreatic aquifer underlying industrial fish ponds in Israel

Oxytetracycline (OTC) is an antibiotic that is regularly added to fish ponds used in industrial- scale fish-farming along the Mediterranean coast of Israel. It is not found in unpolluted water. The ponds are constructed upon porous sands that are also the host rock of the local aquifer. These ponds leak. Monitoring for OTC was carried out in a fish pond and three surrounding water wells that exploit the local aquifer. The local groundwater is composed of the native groundwater and the leakage additions. Two wells, P-204 P-205 are used to insure that the water levels in the ponds are maintained. A frequently pumping well, M-2, is located closest to the main source of OTC input at pond B. It is used to supply drinking water and OTC was found in it. This contaminant is related to leakage from the nearby fish pond. OTC is generally assumed to be immobile and effectively removed by soil and sediments. In this case, continuous leakage of the pond has created preferential saturated flow paths that bring the contaminants directly to groundwater, bypassing the immobilizing sorption processes that usually take place in the unsaturated zone. In the absence of such conduits OTC is effectively excluded from reaching other producing wells.     

一个网格型松散结构分布式水文模型的构建

根据流域降雨径流的基本过程,以蓄满产流理论为基础,建立了一个网格型松散结构的分布式流域水文模型。模型将流域离散为包含河道与不包含河道两种类型的单元格,以协克里金方法插值得到空间离散的降雨输入,考虑的产汇流物理过程包括降雨、植被截留及蒸散发、单元格产流、单元格汇流及河网汇流。模型结构简单,参数较少,在充分利用植被覆盖类型图及土地利用类型图的基础上,能够获得大部分参数的选用值。通过在长江三峡区间沿渡河流域的实际应用,模型计算成果令人满意。     

Carbonate pond deposits related to semi-arid alluvial systems: examples from the Tertiary Madrid Basin, Spain

Carbonate pond deposits occur associated with alluvial sediments in Miocene sequences of the Madrid Basin, central Spain. The ponds developed near the basin margins, either in floodplain environments (north) or mud-flat settings (south). Three main facies assemblages are recognized: (1) floodplain/mud-flat, (2) palaeosols and (3) pond deposits. In the northern part of the basin, ponds developed on the floodplain of terminal fluvial systems. The floodplain facies are typically red mudstones with interbedded sandstones and siltstones. Palaeosols associated with the ponds show a pedofacies relationship, the maturity of soils increasing with distance from the main channel. Carbonate pond deposits consist mainly of limestones, which display typical ‘palustrine’features. The formation and further accumulation of carbonate in the ponds took place in periods of reduced clastic sediment input and it is suggested that recharge into the pond areas was mainly from groundwater. In the south, ponds developed on mud-flats located between sheet-flood-dominated alluvial fans and evaporite lakes. Mud-flat facies consist of red mudstone that exhibits evidence of progressive soil development near both edges and beneath the carbonate pond lenses. Carbonate in the ponds is mainly dolomite and comprises two subfacies, mottled and laminated dolomicrites. This mineralogy, together with the presence of gypsum crusts below and in the lower part of the carbonate body, suggests higher evaporation rates and/or more saline waters filling the ponds in this part of the basin. In spite of differences in depositional setting and, to some extent, climatic conditions between the two areas of the basin, both facies associations and the sequential arrangement of the ponds show strong similarities that allow the proposal of a facies model for carbonate pond deposits related to semi-arid alluvial systems. The sequences recognized from the pond deposits record a set of facies clearly different to those forming in swampy lakes associated with many permanent fluvial systems developed in more humid climates.     

红壤丘陵区地表水资源动态与合理调蓄利用研究

以红壤丘陵景观中相对独立且整体性强的集水区为基本单元,重点研究了集水区内降水、蒸散、水量蓄存等地表水资源的年变化。结果表明,降水资源在集水区内的陆面拦截蒸散、塘堰蓄存、排出集水区三者中的分布比例约为7:2:1,在水土保持型坡地的植被拦截、土壤渗流、地表径流三者中的分布比例约为3:5:2;每公顷1m土体中的土壤贮水量,在丰水季节,水土保持型坡地要比非水保坡地高出864.0～1067.0m3,少水季节则高出647.0～855.0m3。研究结果还表明,以集水区为单元的农业灌溉用水量,一般为年降水量的12%左右,蓄存此水量的塘堰面积应占集水区土地总面积的11%左右,对于塘堰面积已占土地总面积10%左右的红壤丘陵区而言,抗御季节性干旱依靠扩大塘堰蓄水已不现实,其主要途径应是充分发挥水库工程和"土壤水库"的巨大抗旱潜力。     

Epitaxial salt reefs and mushrooms in the southern Dead Sea

Salt usually accumulates in shallow ephemeral brines as simple flat beds. However, in permanent brines deepening in solar evaporation ponds in the southern Dead Sea, salt accumulation is complicated by the growth of isolated vegetable-like salt structures and networks of polygonal salt walls. These walls divide large salt ponds, which are easily homogenized by wind, into thousands of small compartments that are less easy to mix. Instead, brines in the compartments stratify when a surficial layer about 10 cm thick supersaturates and floats above the cumulate floors on brines that are merely saturated. Salt reef growth in the southern Dead Sea has previously been attributed to mixing of ions common to brines already in the ponds and those pumped in from the northern basin (with or without subsurface brines rising through the pond floors). A new factor is emphasized here that, whatever the origins of the brines, salt reefs remain emergent by epitaxis, the in situ growth of crystalline substrates already in the surficial supersaturated layer. Epitaxis can be invisible in crystal clear brines and prolongs the obvious crystallization season by replacing sedimentation of grains nucleated and grown on the brine surface as the dominant mechanism of deposition. Salt reefs develop botryoidal overhangs that can merge into salt platforms that roof over deep brines. Salt shallows on the reef platforms and around the pond shores are both characterized by the deposition of the thin flat beds with vertical palisade textures well known from other ephemeral brines. Salt reefs are interpreted as tepee structures which have grown by epitaxis as fast as saturated brines have deepened around them. Epitaxis may also account for the rapid deposition of thick beds of pure salt in rifts that open to oceans. Local histories of salt reef compartmentalization can be read from the shapes of reefs that record their relative rates of growth and drowning. Rather than diminish evaporation area, damp emergent salt reefs act as giant transpirative pumps that accelerate salt crystallization and reconfigure the evaporation ponds into areas smaller than thought necessary by chemical engineers. The natural end of reef formation may be when shallow brines on hollow reef platforms become ephemeral on solid salt flats. Former salt reefs are likely to be distinguishable in the undeformed geological record by their botryoidal layers of nonvertical chevron crystals.