Predicting Water Table Response to Rainfall Events,Central Florida

A rise in water table in response to a rainfall event is a complex function of permeability, specific yield, antecedent soil‐water conditions, water table level, evapotranspiration, vegetation, lateral groundwater flow, and rainfall volume and intensity. Predictions of water table response, however, commonly assume a linear relationship between response and rainfall based on cumulative analysis of water level and rainfall logs. By identifying individual rainfall events and responses, we examine how the response/rainfall ratio varies as a function of antecedent water table level (stage) and rainfall event size. For wells in wetlands and uplands in central Florida, incorporating stage and event size improves forecasting of water table rise by more than 30%, based on 10 years of data. At the 11 sites studied, the water table is generally least responsive to rainfall at smallest and largest rainfall event sizes and at lower stages. At most sites the minimum amount of rainfall required to induce a rise in water table is fairly uniform when the water table is within 50 to 100 cm of land surface. Below this depth, the minimum typically gradually increases with depth. These observations can be qualitatively explained by unsaturated zone flow processes. Overall, response/rainfall ratios are higher in wetlands and lower in uplands, presumably reflecting lower specific yields and greater lateral influx in wetland sites. Pronounced depth variations in rainfall/response ratios appear to correlate with soil layer boundaries, where corroborating data are available.     

Internet-based applications for interrogating 50 years of data from the South African national water quality monitoring network

ABSTRACT

National and regional water quality monitoring networks have been operated in South Africa since the early 1970s. These originally had text-based inventories that were convenient for specialists who were familiar with the national networks and knew the locations of their sites of interest. However, within two decades the networks had expanded in geographical extent and variables monitored to such an extent that users needed spatial context in order to locate sites that fitted their information requirements. Mapping applications running on the Internet, such as Google Earth and Leaflet, form the foundation of a system for providing online inventories and summaries of the data available on the water quality database. The interfaces were constructed using available software, mainly ArcInfo and R. A recent concern is a decrease in the collection of water quality data, which is reducing the value of data summaries for water resource management.     

Lutz Creek watershed,Barro Colorado Island,Republic of Panama

Lutz creek is a small (9.69 ha) catchment located on Barro Colorado Island (BCI), a 1500-ha island in Lake Gatún, the principal freshwater reservoir (425 ha, 26 m above sea level) of the Panama Canal watershed in central Panama. In 1972, a concrete V-notch weir was installed on the creek, located at 9°09′42.8358″N, 79°50′15.6699″W, and hydrological record keeping began. The island was first established as a research station in 1923 and precipitation data collection was initiated in 1925. A meteorological tower, installed in 1972 and located a few meters from the weir, is currently instrumented to collect air temperature, relative humidity, wind speed and direction, evapotranspiration and solar radiation. In addition, since 1972, gravimetric soil moisture has been measured at least biweekly at 10 sites located throughout the Lutz Catchment above the location of the weir. Data collection and the administration of BCI are the responsibility of the Smithsonian Tropical Research Institute (STRI; https://stri.si.edu ) which funds the data collection and storage. Data are in the public domain, entitled ‘Lutz Watershed And Meteorological Tower’ and are available at the STRI Physical monitoring website https://biogeodb.stri.si.edu/physical_monitoring/ .     

Horizontal Motions of Water in the Vicinity of a Tsunami Source

Because it is based on an initial seismic analysis and preset criteria, tsunami forecast often fails in assessment of tsunami danger. The level of danger can be determined more or less reliably only when observed sea level data became available. Along with the sea level data, i.e., vertical motions of free water surface, we suggest considering horizontal motions of water that accompany the formation and the propagation of a tsunami. The amplitude of horizontal motions is normally much higher than the amplitude of the vertical motions. Detection of the horizontal motions may provide tsunami warning centers with additional in situ data that can be used for estimation of tsunami strength. In this study, taking the 2011 Tohoku-Oki event as an example, horizontal motions of water in the vicinity of the tsunami source are theoretically examined by means of dynamic and static numerical models developed within the framework of linear shallow-water approximation. It is shown that in the vicinity of the tsunami source within a wide area of about 0.5 million square kilometers, the amplitude of horizontal motions exceeded 10 m, whereas in some shallow-water areas the amplitude amounted to hundreds of meters. Possible methods of in situ detection of the horizontal motions are discussed.     

利用瞬变电磁和多频电磁方法监测地下水位及其对Hawara遗址的影响

利用瞬变电磁（TEM）和地面电磁（GEM）方法,本文研究了埃及Hawara遗址区的地下水对遗址的影响.这个遗址包括Hawara金字塔、北区墓地、以及被称作“迷宫”的南区墓葬场所.现今Hawara遗址已经完全荒废,被耕作区和Bahr Wahba运河包围.地表水和地下水会破坏Hawara金字塔和“迷宫”遗址的地基,现在金字塔入口已被淹没至地面下约6 m深处.本文在耕作区、金字塔以及“迷宫”等三个地区进行了TEM勘察;在“迷宫”地区进行了GEM勘察.综合分析以上两种勘察数据,我们发现,农业灌溉是浸入到地下的水的主要来源;本地区地下水位随着观测点及海拔的不同,在地面以下2~7 m之间变化.     

Long term high frequency sediment observatory in an alpine catchment: The Arc-Isère rivers,France

We present a dataset on to the Arc-Isère long-term environmental research observatory, which is part of the Rhône Basin Long Term Environmental Research Observatory. This alpine catchment located in the French Alps is characterized by high Suspended Particulate Matter (SPM) in anthropogenized valleys. Suspended Sediment Concentrations (SSC) naturally observed in the river are very high, ranging from a few tens of milligrams per litre at low flow to tens of grams per litre during major natural hydrological events (floods, debris flows) or river dam hydraulic flushes. One research objective related to this site is to better understanding the SSC dynamics along the river using a system of nested catchments (Arvan, Arc, and Isère) in order to assess both temporal and spatial dynamics. The data allow the quantification of fine sediment yields and also the evaluation of possible morphological changes due to fine sediment deposition or resuspension. Additionally, the observatory database support studies on contaminants (either dissolved or particulate contaminants). Our monitoring includes six stations with high frequency (2–30 min) streamflow, SSC measurement using turbidity sensors, and associated automatic sampling. Discharge is measured via water level measurements and a rating curve. The oldest station (Grenoble-campus) started recording discharge and concentration data from April 2006 while others stations were built between 2009 and 2011. Data are available in an online data website called ‘Base de Données des Observatoires en Hydrologie’ (Hydrological observatory database, https://bdoh.irstea.fr/ARC-ISERE/ ) with a DOI reference for the dataset. The hydrological and sediment transport time series are stored, managed and made available to a wide community with unfettered access in order to be used at their full extent. This database is used as a data exchange tool for both scientists and operational end-users and there is an associated online tool to compute integrated fluxes.     

A simple and inexpensive turbidity meter for the estimation of suspended sediment concentrations

The relatively high cost of commercially available turbidity meters has inhibited detailed and intensive research on spatiotemporal patterns of suspended sediment transport. We describe here the electronic and physical design of an inexpensive turbidity sensor which is easy to construct, simple to interface with portable millivolt meters, dataloggers, computers, or chart recorders, consumes exceptionally small currents, and is robust and reliable. the very low individual cost allows a large number of sensors to be distributed throughout the water body of interest to facilitate turbidity mapping. Turbidity profilers to detect vertical or lateral turbidity changes in rivers, lakes, estuaries, or near-shore zones are also shown to be feasible. Test data are presented from a highly turbid glacial river in southern Iceland.     

Dynamic neuro-fuzzy local modeling system with a nonlinear feature extraction for the online adaptive warning system of river temperature affected by waste cooling water discharge

This paper proposes a dynamic modeling methodology based on a dynamic neuro-fuzzy local modeling system (DNFLMS) with a nonlinear feature extraction technique for an online dynamic modeling task. Prior to model building, a nonlinear feature extraction technique called the Gamma test (GT) is proposed to compute the lowest mean squared error (MSE) that can be achieved and the quantity of data required to obtain a reliable model. Two different DNFLMS modes are developed: (1) an online one-pass clustering and the extended Kalman filtering algorithm (mode 1); and (2) hybrid learning algorithm (mode 2) of extended Kalman filtering algorithm with a back-propagation algorithm trained to the estimated MSE and number of data points determined by a nonlinear feature extraction technique. The proposed modeling methodology is applied to develop an online dynamic prediction system of river temperature to waste cooling water discharge at 1?km downstream from a thermal power station from real-time to time ahead (2?h) sequentially at the new arrival of each item of river, hydrological, meteorological, power station operational data. It is demonstrated that the DNFLMS modes 1 and 2 shows a better prediction performance and less computation time required, compared to a well-known adaptive neural-fuzzy inference system (ANFIS) and a multi-layer perceptron (MLP) trained with the back propagation (BP) learning algorithm, due to local generalization approach and one-pass learning algorithm implemented in the DNFLMS. It is shown that the DNFLMS mode 1 is that it can be used for an online modeling task without a large amount of training set required by the off-line learning algorithm of MLP-BP and ANFIS. The integration of the DNFLMS mode 2 with a nonlinear feature extraction technique shows that it can improve model generalization capability and reduce model development time by eliminating iterative procedures of model construction using a stopping criterion in training and the quantity of required available data in training given by the GT.     

The Application of a Statistical Trend Analysis Model to Ground Water Monitoring Data from Solid Waste Landfills

A statistical trend methodology is used to compare ground water quality between eight landfill sites in western Michigan as a case study. Monitoring data were collected over a 15-year period on 36 parameters at an upgradient and downgradient well selected at each of the eight sites. This yielded a total of 576 monitoring data sets available for analysis. New trend and contamination indices are introduced that are used to compare ground water contamination between these eight sites. These indices are used to assess each landfill's relative potential for environmental harm.
Many questions remain unanswered, but what is demonstrated here is that this type of methodology has the potential to be used to assess trends of ground water chemistry concentrations at landfill sues in a region. A specific purpose of such an assessment could be to provide a quantified basis for the prioritization of funds allocated for cleanup of contaminated landfill sites. Having a technical capability to reduce large amounts of ground water monitoring data to appropriate summaries, which then can be used to assess environmental contamination between several sites, could also have important economic and health implications in other settings. Hopefully this paper will encourage further development of such technologies for these purposes.     

Variability and comparison of hyporheic water temperatures and seepage fluxes in a small Atlantic salmon stream

Ground water discharge is often a significant factor in the quality of fish spawning and rearing habitat and for highly biologically productive streams. In the present study, water temperatures (stream and hyporheic) and seepage fluxes were used to characterize shallow ground water discharge and recharge within thestreambed of Catamaran Brook, a small Atlantic salmon (Salmo salar) stream in central New Brunswick, Canada. Three study sites were instrumented using a total of 10 temperature sensors and 18 seepage meters. Highly variable mean seepage fluxes, ranging from 1.7 x 10(-4) to 2.5 cm3 m(-2) sec(-1), and mean hyporheic water temperatures, ranging from 10.5 degrees to 18.0 degrees C, at depths of 20 to 30 cm in the streambed were dependent on streambed location (left versus right stream bank and site location) and time during the summer sampling season. Temperature data were usefulfor determining if an area of the streambed was under discharge (positive flux), recharge (negative flux), or parallel flow (no flux) conditions and seepage meters were used to directly measure the quantity of water flux. Hyporheic water temperature measurements and specific conductance measurements of the seepage meter sample water, mean values ranging from 68.8 to 157.9 microS/cm, provided additional data for determining flux sources. Three stream banks were consistently under discharge conditions, while the other three stream banks showed reversal from discharge to recharge conditions over the sampling season. Results indicate that the majority of the water collected in the seepage meters was composed of surface water. The data obtained suggests that even though a positive seepage flux is often interpreted as ground water discharge, this discharging water may be of stream water origin that has recently entered the hyporheic zone.The measurement of seepage flux in conjunction with hyporheic water temperature or other indicators of water origin should be considered when attempting to quantify the magnitude of exchange and the source of hyporheic water.     

Evaluation of pore water pressure fluctuation around an advancing longwall face

Large deformations that accompany longwall mining result in complex spatial and temporal distributions of changes in undrained pore fluid pressures around the advancing face. These seemingly anomalous changes are recorded in the rapid water level response of undermined and adjacent wells, and may be explained in the short-term as a undrained poroelastic effect. A three-dimensional finite element model is applied to define anticipated pore fluid response both around the advancing mining face, at depth, and in the near surface region. The results are carefully verified against the response recorded at three well-instrumented longwall sites. Pore pressure changes are indexed directly to volumetric strains defining zones of significant depressurization in the caving zone and in zones of extension adjacent to the subsidence trough on the ground surface. Overpressurization occurs in the abutment region, at panel depth, and in the surface compressive zone immediately inside the angle-of-draw. These results are confirmed with available, short-term water level response data, defining the strongly heterogeneous spatial response and the significance of well depth on anticipated water level response.     

密云水库的构造磁实验

为探讨水库地区的构造磁效应,在密云水库周围布设了221个测点,测点间距为2——5km,测点离水库堤岸的距离为几十米至15km不等,使用G-816型与G-826型质子旋进磁力仪,在1983——1987年期间,每季度观测一次地磁场总强度.地磁与密云水库蓄水的资料分析得到,地磁变化与水库的水位变化、水容量变化的关系系数分别为-(0.280.22)nT/m与-(0.350.31)10-8nT/m3,表明地磁变化与该水库蓄水变化有着较强的负相关.这种较强的负相关可能是密云水库地区地下较强磁性岩石的压磁效应的反映.由于水库构造磁实验是地震磁现象的较好模拟,因此,根据实验结果可以相信,在地震活动区布设加密的高精度地磁观测,是能够捕捉到震磁前兆信息的.      

Stream discharge and water quality data for East Fork Poplar Creek beginning 2012

This data note describes 15-min discharge and in situ water quality data at two locations along East Fork Poplar Creek in east Tennessee, USA. Data records include temperature, gauge height, water surface elevation above mean sea level, and volumetric discharge. Water quality measurements include temperature, specific conductance, pH, dissolved oxygen (percent saturation and concentration), turbidity, and less extensive fDOM data at one site. The data records begin in 2012 at one site and 2015 at the second site; monitoring at both sites is ongoing (as of 2021). The goal of this data collection is to improve understanding of watershed functions, hydrologic dynamics, and material flux. The data will contribute to site conceptual and numerical models, exposure and risk evaluation, remediation selection and design, and performance monitoring. The data are publicly available and can be accessed via unique url or DOI.     

Sediment diffusive fluxes of Fe,Mn, and P in a eutrophic lake: Contribution from lateral vs bottom sediments

Water column data and porewater profiles are used to study the chemical evolution with time and with depth of a eutrophic lake. By using different approaches, diffusion fluxes for dissolved iron, manganese and phosphate are calculated and used to describe the processes occurring at the sediment-water interface as well as in the hypolimnion of the lake. These data are used in the elaboration of a qualitative model to describe the chemical behaviour of the sedimentary interface of an anoxic lake with emphasis on the Fe/P/S system. Acorona model is proposed to explain the evolution with time of the diffusion process by estimating the relative contribution of bottom and lateral sediment surfaces to the total fluxes of dissolved elements diffusing from the sediment to the overlying water. As the hypolimnion becomes more anoxic, it has been observed that lateral sediment surfaces (16 to 10 meters in depth) represents a larger supplier of diffusing dissolved components than the bottom sediment portion (bottom to 18 meters).     

Evaluation of time-space distributions of submarine ground water discharge

Submarine ground water discharge (SGD) rates were measured continuously by automated seepage meters to evaluate the process of ground water discharge to the ocean in the coastal zone of Suruga Bay, Japan. The ratio of terrestrial fresh SGD to total SGD was estimated to be at most 9% by continuous measurements of electrical conductivity of SGD. Semidiurnal changes of SGD due to tidal effects and an inverse relation between SGD and barometric pressure were observed. Power spectrum density analyses of SGD, sea level, and ground water level show that SGD near shore correlated to ground water level changes and SGD offshore correlated to sea level changes. SGD rates near the mouth of the Abe River are smaller than those elsewhere, possibly showing the effect of the river on SGD. The ratio of terrestrial ground water discharge to the total discharge to the ocean was estimated to be 14.7% using a water balance method.     

Water quality data for Fall Creek,New York,USA: 1972–1995

The 33 086 ha mixed land use Fall Creek watershed in upstate New York is part of the Great Lakes drainage system. Results from more than 3500 water samples are available in a data set that compiles flow data and measurements of various water quality analytes collected between 1972 and 1995 in all seasons and under all flow regimes in Fall Creek and its tributaries. Data is freely accessible at https://ecommons.cornell.edu/handle/1813/8148 and includes measurements of suspended solids, pH, alkalinity, calcium, magnesium, potassium, sodium, chloride, nitrate nitrogen (NO3-N), sulphate sulphur (SO4-S), phosphorus (P) fractions molybdate reactive P (MRP) and total dissolved P (TDP), percent P in sediment, and ammonium nitrogen (NH4-N). Methods, sub-watershed areas, and coordinates for sampling sites are also included. The work represented in this data set has made important scientific contributions to understanding of hydrological and biogeochemical processes that influence loading in mixed use watersheds and that have an impact on algal productivity in receiving water bodies. In addition, the work has been foundational for important regulatory and management decisions in the region.     

西洞庭湖沉水植物分布格局对环境因子及水文情势差异的响应

沉水植物是湖泊生态系统的重要组成部分,其生产力和分布格局受环境因子特别是水文情势决定.洞庭湖是长江流域重要的大型通江湖泊,近年来受人为干扰和气候变化影响,水文节律与水质等环境因子发生改变,导致沉水植物出现衰退现象,急需开展科学恢复,因此有必要对洞庭湖沉水植物深入研究.本研究选取西洞庭湖为研究区域,于2018年和2019年夏季调查了12处典型生境、98个样点的沉水植物与水深、透明度等11个环境因子,采用独立样本T检验和冗余分析方法对沉水植物与环境因子的关系进行分析,对比年际水文情势变化的影响.结果表明：1）西洞庭湖沉水植物主要在水深较浅、水质更优、水体更为稳定的半阻隔子湖和自由连通的湖湾区分布,在河道及水位波动较大的区域分布较少,有、无沉水植物分布样点间存在显著差异的环境因子为水深、透明度、底泥总磷和pH;2）在有沉水植物分布的样点,沉水植物生物量与pH、水深和水体总磷呈显著相关关系;3）自然连通的季节性淹没湖泊沉水植物生物量在2018年高于2019年,可能与2019年5—8月沉水植物关键生长期出现的涨水过程有关,持续的高水位对沉水植物的生长产生了不利影响.维持自然水文节律、湖泊生境异质性与自由连通性、健康的水质等是恢复西洞庭沉水植物的关键,建议在水深低于3 m、营养盐浓度适中、流速及风浪较小的湖湾区或半阻隔湖泊开展沉水植物恢复.     

唐山马家沟矿井水位异常分析

地下水动态受水文因素影响较大,对地震和构造活动具有较灵敏的响应。判别并排除各种水文干扰,确认地下水在地震前的异常变化,对提高地震分析预报能力,具有重要作用。马家沟矿井水位动态观测层与地下水开采层为同一含水层,井水位于2010年出现破年变异常,加速持续上升,截至2015年,最大上升幅度约30 m。依据该井水文地质环境特征,根据唐山市区2001-2015年地下水位、降雨量、地下水开采量实测资料,建立合理多元回归模型和三维地下水流动模型,发现地下水开采量减少应为影响马家沟矿井水位动态的可能因素。文中采取的异常识别与分析方法,可为其他类似井孔的地下水动态异常识别及判定提供一定借鉴。     

地电阻率年变化的一种物理解释——大柏舍台不同极距地电阻率观测结果

本文通过河北省隆尧县大柏舍地电台不同供电极距试验观测资料,与地下潜水水位动态的相关分析及数学模型计算结果,给出地电阻率年变化的一种物理解释,即认为大柏舍台地电阻率年变化是由于供电极距短,勘探深度浅,从而受潜水动态影响的结果。为消除大柏舍台地电阻率年变化,应采用不小于1500米的供电装置。     

Applying the HPT‐GWS for Hydrostratigraphy,Water Quality and Aquifer Recharge Investigations

The primary objective of this study was to evaluate use of the hydraulic profiling tool‐groundwater sampler (HPT‐GWS) log data as an indicator of water quality (level of dissolved ionic species) in an alluvial aquifer. The HPT‐GWS probe is designed for direct push advancement into unconsolidated formations. The system provides both injection pressure logs and electrical conductivity (EC) logs, and groundwater may be sampled at multiple depths as the probe is advanced (profiling). The combination of these three capabilities in one probe has not previously been available. During field work it was observed that when HPT corrected pressure (P_c) indicates a consistent aquifer unit then bulk formation EC can be used as an indicator of water quality. A high correlation coefficient (R ² = 0.93) was observed between groundwater specific conductance and bulk formation EC in the sands and gravels of the alluvial aquifer studied. These results indicate that groundwater specific conductance is exerting a controlling influence on the bulk formation EC of the coarse‐grained unit at this site, and probably many similar sites, consistent with Archie's Law. This simple relationship enables the use of the EC and P_c logs, with targeted water samples and a minimum of core samples, to rapidly assess groundwater quality over extended areas at high vertical resolution. This method was used to identify both a brine impacted zone at the base of the aquifer investigated and a groundwater recharge lens developing below storm water holding ponds in the upper portion of the same aquifer. Sample results for trace level, naturally occurring elements (As, Ba, U) further demonstrate the use of this system to sample for low level groundwater contamination.