Water Level Dynamics Research Articles

Numerical hydrodynamic model of the Lower Volga

The method of constructing a hydrodynamic model of a large river is described in the work using the example of a section of the Volga River south of the Volzhskaya HPP. The construction of reliable hydrodynamic models of real river systems requires actual digital elevation models (DEM). Natural changes in the characteristics of river bed with time require updating and subsequent verification of DEM. We consider 100-kilometers section of the Volga River south of the Volzhskaya HPP, which determines the hydrological regime of the entire Volga-Akhtuba floodplain (VAF) right up to the Caspian Sea. The algorithm for constructing the DEM of bottom topography, based on a comparative analysis of the results of numerical hydrodynamic modeling and data on the dynamics of water levels at gauging stations, is proposed. In order to reconcile the changes in the water level H(t) in the numerical hydrodynamic model with the observed dependence, we vary the characteristics of the local sectors of the bottom.

Water Level in a Shallow Highly Eutrophic Lake: Development Factor by Macrophyte or Phytoplankton Type: Case Study of Lake Nero, Yaroslavl Oblast

Long-term dynamics of water level in Lake Nero (1930–2011) has been analyzed. Pronounced trends, determined by the climate and anthropogenic components have been identified. Up to the 1970s, at a drop in lake water level, the ecosystem still showed the main features of a shallow water body overgrown with macrophytes. Water level rise caused a more intense development of phytoplankton, an increase in biogenic element concentrations, a decrease in water transparency and the contribution of cyanobacteria of S1 codon; pondweed disappeared almost completely. Step-by-step regression analysis of phytoplankton development indices and hydrological characteristics showed that water transparency in Lake Nero depends by 80% directly on water exchange and inversely on the concentration of chlorophyll a in seston. The main hypothesis of the study was confirmed: the key trigger in phytoplankton–macrophytes competition is water level rise.

Dendroindication of Lake Baikal level dynamics

This paper estimates and analyzes water level dynamics in Lake Baikal in the 15th-20th centuries by a method of dendroindication. The endrochronological material for the study was obtained in the Zabaikalsky National Park in 2007. Apart from the chronologies of 2007, the available temporal data sequence is extended by incorporating tree-ring chronologies collected in the 1950s by G. I. Galasy and published in a digest on “Dendrochronological Scales of Soviet Union”. The largest coefficients of positive correlation are found to be between the PinSib10 sample and the cumulative monthly precipitation of February and October and also between the PinSib2 sample and the precipitation of November and the cold season (November-March). A tighter relation between the annual ring increments and the lake level existed before the construction of the hydropower station in the city of Irkutsk. After the construction the increments have also been rather sensitive to changes in the level. The significant correlation between the increment variability and the Lake Baikal level allows the development of a quantitative model of reconstruction of the lake level. The model reproduces up to 60% of the known level variations. The reconstruction shows high level epochs as well as durable epochs of low level. A spectral Fourier analysis reveals cycles of 53, 33, 23, 17, and 11 years in the reconstructed series of the Lake Baikal water level.

Anatomy of simultaneous flood peaks at a lowland confluence

Abstract. Lowlands are vulnerable to flooding due to their mild topography in often densely populated areas with high social and economic value. Moreover, multiple physical processes coincide in lowland areas, such as those involved in river–sea interactions and in merging rivers at confluences. Simultaneous occurrence of such processes can result in amplifying or attenuating effects on water levels. Our aim is to understand the mechanisms behind simultaneous occurrence of discharge waves in a river and its lowland tributaries. Here, we introduce a new way of analyzing lowland discharge and water level dynamics, by tracing individual flood waves based on dynamic time warping. We take the confluence of the Meuse River (∼33 000 km2) with the joining tributaries of the Dommel and Aa rivers as an example, especially because the January 1995 flood at this confluence was the result of the simultaneous occurrence of discharge peaks in the main stream and the tributaries and because independent observations of water levels and discharge are available for a longer period. The analysis shows that the exact timing of the arrival of discharge peaks is of little relevance because of the long duration of the average discharge wave compared to typical time lags between peaks. The discharge waves last on average 9 days, whereas the lag time between discharge peaks in the main river and the tributaries is typically 3 days. This results in backwaters that can rise up to 1.5 m over a distance of 4 km from the confluence. Thus, local measures to reduce the impact of flooding around the confluence should account for the long duration of flood peaks in the main system.

Evaluating the Impaction of Coal Mining on Ordovician Karst Water through Statistical Methods

This study aims to reveal karst water trend change and the variation of affecting factors in the Heilongdong spring area due to long-term coal mining. In this study, five yearly recoded data over more than 40 years were collected, including underground water level dynamics, water flow, groundwater withdrawal for industrial and agricultural production and domestic production (groundwater withdrawal), mine drainage and rainfall. On that basis, we conducted linear regression, innovative trend analysis (ITA) and the Mann–Kendall method to quantitative analyze the trend and mutation sequence of the time series of environmental hydrological parameters in the study area. To determine the correlation of different affecting parameters under coal mining, as well as the trend of the correlation, we conducted multivariate linear regression analysis and exploited wavelet coherence. The results suggest: (1) under human influence, the annual value of underground water level in the Heilongdong spring area shows an insignificant decrease of 0.42 m/a; precipitation shows a significant downward trend of 2.34 mm/a, primarily the decrease of rainstorm; the spring flow shows a significant decrease of 9.41 × 106 m3/a, and springs with different flow show a significant decrease. (2) The abrupt changes of various factors affecting spring flow in the study area were successively delayed by rainfall, mine drainage rate, industrial and agricultural water consumption and underground water level. (3) Since the year of the start of dramatic changes, under the impact of increased manual mining and mine drainage, the amount of spring overflow has decreased, the groundwater level has decreased, and the groundwater dynamics have varied from meteorological type to meteorology-artificial type. Moreover, the factors affecting the dynamic changes of groundwater have been changed to rainfall and artificial mining and drainage. (4) As the results of Wavelet coherence analysis suggest, the spring flow resonates significantly with rainfall from the period of 3a to 15a. The correlation between the original spring flow and groundwater level is more obvious than that between the original spring flow and rainfall. The correlation between residual flow and groundwater level is less obvious than that between residual flow and rainfall. The above results provide a basis for comprehensively exploiting water resources in coal mining areas and regional groundwater resources protection measures.

Characteristics of Nitrogen and Phosphorus Concentration Dynamics in Natural Ditches Under an Irrigation-Drainage Unit in the Jianghan Plain

The paddy field in Jianghan Plain usually exists in the form of an irrigation-drainage unit, and the natural ditch is the main part of the unit. A continuous in situ monitoring of the natural ditch water level and water quality through the entire rice growing season in 2015 was conducted to investigate the dynamics of ditch water level and nitrogen and phosphorus concentration in the ditch. Another objective was to determine the effect of these factors. Results showed that during the entire rice growing season, the ditch water depth was maintained between 30 to 70 cm, and the water depth was higher during irrigation events than during rainfall events. Fertilization was the main factor affecting the nitrogen concentration in the ditch water. Two peaks of total nitrogen (TN) concentration appeared on June 18 and July 30 because of topdressing. In the early stage of rice growing, ammonia nitrogen (NH4+-N) concentration was higher than that of nitrate nitrogen (NO3--N). External disturbances (such as rainfall and irrigation events) were the main factors affecting the total phosphorus (TP) concentration in the ditch water. The dynamic of TP concentration in the ditch water was large, and it was consistent with that of the particulate phosphorus (PP) concentration. Drainage of the irrigation-drainage was mainly controlled artificially. The period from rice transplanting to 3 days after the first top dressing was critical in preventing the outflow of ditch water. During the rice harvest stage, the TN and TP concentration were 0.22 and 0.06 mg·L-1, and the water quality reached theⅡclass standard for surface water quality. This reduced the risk from drainage from the irrigation-drainage unit to the surrounding water environment.

Impact of River-Tide Dynamics on the Temporal-Spatial Distribution of Residual Water Level in the Pearl River Channel Networks

The behavior of the residual water level in estuarine environment is complex due to the highly nonlinear interaction between river flow and tide and the contributions made by these two external forcing to the dynamics of the residual water level are not yet fully understood. In this study, we investigate the effect of river-tide dynamics on the temporal-spatial changes of flow in terms of residual water level in the Pearl River channel networks, which is one of the complex channel networks in the world. Making use of a nonstationary tidal harmonic analysis, the continuous time series observations of water level covering a spring-neap cycle in 1999 (representing flood season) and 2001 (representing dry season) collected from around 60 stations in the Pearl River channel networks have been used to extract the temporal-spatial changes in stage and tidal properties (including amplitudes and phases) as a function of variable freshwater discharge and ocean tide. It was shown that the averaged residual water level during the flood season (ranging 0–5 m) is one order magnitude than that during the dry season (ranging 0–0.35 m). The distribution of the residual water level clearly indicates that the Pearl River channel networks feature two sub-systems, i.e., the central part of the channel networks being river-dominated with high value of residual water level and the eastern and western sides being tide-dominated with low value of residual water level. To understand the relative importance of river flow and tide on the temporal-spatial distribution of the residual water level, an idealized model is subsequently applied to the Modaomen estuary, which debouches the largest portion of river discharge into the South China Sea. Analytical results showed that the residual water level is mainly determined by the variation of the freshwater discharge for the flood season, while it is primarily controlled by the tidal forcing for the dry season and features a typical spring-neap cycle.

Effects of sea-level rise and freshwater management on long-term water levels and water quality in the Florida Coastal Everglades

Since the 1880s, hydrological modification of the Greater Florida Everglades has reduced water levels and flows in Everglades National Park (ENP). The Comprehensive Everglades Restoration Program (CERP) began in 2000 to restore pre-drainage flows and preserve the natural landscape of the Everglades. However, sea-level rise (SLR) was not considered in the development of CERP. We used long-term data (2001–2016) from the Florida Coastal Everglades-Long Term Ecological Research Program to quantify and model the spatial dynamics of water levels, salinity, and nutrients in response to changes in climate, freshwater management and SLR in the Shark River Slough (SRS), ENP. Results indicate that fresh-to-marine head difference (FMHD) was the single most important factor affecting marine-to-freshwater hydrologic connectivity and transport of salinity and phosphorous upstream from the Gulf of Mexico. Sea-level has increasingly exceeded ground surface elevation at the most downstream freshwater site in SRS, thereby reducing the FMHD. We showed a higher impact of SLR in the dry season when there was practically no freshwater inflow to raise FMHD. We also demonstrated effectiveness of inflow depends more on the monthly distribution than the total annual volume. Hence, the impact per unit volume of inflow is significantly higher in the dry season in preventing high salinity and marine-derived nutrient levels. We advocate that FMHD needs to be factored into water management decisions to reduce adverse and likely irreversible effects of SLR throughout the Everglades landscape.

Static and dynamic water wells levels of Kirkuk city represented by geo-statistical algorithms in GIS

Water is great importance for human life as well as for agriculture therefore, different scientific methods are used for curtailed the time and possibilities for well water sources investigation. Fresh water is the most importance for Human life and cannot be healthy without it. In the paper two different interpolation methods were used, which are the ordinary kriging and Inverse Distance Weighting (IDW) to predict static and dynamic water levels of wells in Kirkuk City, and the number of wells was 64. The data of wells were obtained from digging water wells in Directorate of Kirkuk. By using different methods different results were introduced. Furthermore, three wells were used as testing wells for interpolation algorithms.These are office of the Nation Mission, the Emergency department, and Wahid Athar district wells and it was found that the Emergency department well is the most accurate and nearest from the actual levels for both static and dynamic with RMSE of - 2.23 and - 1.35 in kriging method respectively as well as -2.97 and - 2.65 respectively in IDW method. However, the average of the three testing wells overall IDWinterpolation algorithm is the best, accurate and nearest from the true elevations in stable levels of wells.

Rhine Cities - Urban Flood Integration (UFI): German and Dutch Adaptation and Mitigation Strategies

Rhine Cities - Urban Flood Integration (UFI): German and Dutch Adaptation and Mitigation Strategies

Numerical Modelling of the 1995 Dinar Earthquake Effects on Hydrodynamic Regime of Egirdir Lake

The effect of earthquakes on closed and semi-closed
 water systems is a research topic that has been studied for many years. The
 lack of continuous measurement systems in closed and semi-closed water systems
 is insufficient to examine and investigate what has happened during the
 earthquake. The morphological structures of the lakes indicate the characteristics
 of the events that occurred during an earthquake. Due to the developing
 technology and research request, some monitoring, measurement stations are
 installed in some lakes, gulfs, estuaries, etc. systems. Today, both higher
 quality measurement and field data can be obtained, and more complicated
 processes are being explored with the help of faster computers. Computational
 fluid dynamics is currently used because of the difficulty in calculating
 hydrodynamic responses of lakes due to earthquake. Investigations on the
 effects of the earthquake condition on the desired closed / semi-closed water
 system studies by using numerical modelling have been continuing increasingly
 in recent years. Both the quality of the bathymetric data gathered from the
 field, the continuous acquisition of both dynamic water level measurement
 systems, and the use of new technologies and systems in the search for base
 materials contribute to the fact that we have more knowledge of the formation,
 behavior and effects of the sorts. In this study, 1995 Dinar Earthquake effects
 on Egirdir Lake hydrodynamic regime was investigated by numerical modelling
 approach.

Potential and limitations of satellite laser altimetry for monitoring water surface dynamics: ICESat for US lakes

Elevation measurements from the Ice, Cloud and Land Elevation Satellite (ICESat) have been applied to monitor dynamics of lakes and other surface water bodies. Despite such potential, the true utility of ICEsat--more generally, satellite laser altimetry--for continuously tracking surface water dynamics over time has not been adequately assessed, especially in the continental or global contexts. This study analyzed elevation derived from ICESat data for the conterminous United States and examined the potential and limitations of satellite laser altimetry in monitoring the water level dynamics. Owing to a lack of spatially-explicit ground-based water-level data, the high-fidelity land elevation data acquired by airborne lidar were firstly resorted to quantify ICESat’s ranging accuracy. Trend and frequency analyses were then performed to evaluate how reliably ICESat could capture water-level dynamics over a range of temporal scales, as compared to in-situ gauge measurements. The analytical results showed that ICESat had a vertical ranging error of 0.16 m at the footprint level—an lower limit on the detectable range of water-level dynamics. The sparsity of data over time was identified as a major factor limiting the use of ICESat for water dynamics studies. Of all the US lakes, only 361 had reliable ICESat measurements for more than two flight passes. Even for those lakes with sufficient temporal coverage, ICESat failed to capture the true interannual water-level dynamics in 32% of the cases. Our frequency analysis suggested that even with a repeat cycle of two months, ICESat could capture only 60% of the variations in water-level dynamics for at most 34% of the US lakes. To capture 60% of the water-level variation for most of the US lakes, a weekly repeated cycle (e.g., less than 5 d) is needed – a requirement difficult to meet in current designs of spaceborne laser altimetry. Overall, the results highlight that current or near-future satellite laser missions, though with high ranging accuracies, are unlikely to fulfill the general needs in remotely monitoring water surface dynamics for lakes or reservoirs. Keywords: ICESat, lidar, water resources, lake dynamics, water level, satellite laser altimetry, lake surfaces, repeat cycle DOI: 10.25165/j.ijabe.20171005.3426 Citation: Liu S, Jiang Q G, Zhang X S, Zhao K G. Potential and limitations of satellite laser altimetry for monitoring water surface dynamics: ICESat for US lakes. Int J Agric & Biol Eng, 2017; 10(5): 154–165.

A large‐scale medieval dam‐lake cascade in central Europe: Water level dynamics of the Havel River, Berlin–Brandenburg region, Germany

AbstractAn interdisciplinary study was carried out to trace the hydrological changes of the Havel River in northeastern central Europe over the last ca. 2000 years. This research was driven by the hypothesis that the present‐day riverscape is to a large degree a result of medieval and modern human transformation of the drainage system. The river system forms a series of dammed lakes and river sections that were greatly altered through hydraulic engineering in the past. Along the middle course of the Havel, 16 sedimentary sequences available for geoarchaeological and paleoecological research were analyzed in order to reconstruct regional water level dynamics. Chronological control was ensured through a multitude of palynological, dendrochronological, archaeological, and radiocarbon data. The sections upriver from the Brandenburg/H. and Spandau weirs, representing sites with historic watermills, reveal substantial water level changes during the late Holocene. Generally, lower water levels before and higher levels during the medieval German colonization of that area (ca. A.D. 1180/1250) can be inferred. This water level increase, which is primarily attributed to dams constructed for watermills and secondarily due to a multitude of fish weirs, took place rapidly and amounted to a relative height of ca. 1.5 m. It enlarged the river's cross‐sections and increased the size of existing lakes or initiated secondary lakes that previously aggraded, and thus caused flooding of large parts of land. The rising water level even influenced the settlement topography to a large degree. Several medieval rural settlements were abandoned due to flooding. In total, a ca. 150‐km long dammed lake cascade was formed.

Is pesticide sorption by constructed wetland sediments governed by water level and water dynamics?

Constructed wetlands (CWs) are used to reduce the pesticide inputs from tile drainage or run-off to surface water. Their effectiveness appears variable and remains to be better characterized and understood. The aim of this study was to assess the influences of two hydraulic parameters (i.e., dynamics and water level) on the sorption process occurring in CWs. Then, two solid/liquid ratios were studied (1/1 and 1/5) to mimic the water level variation in the field, and two agitation speeds were used (none and gentle agitation) to simulate different water dynamics (stagnation and flow pass, respectively). Sorption kinetics and isotherms were obtained for four pesticides with contrasting properties. The pesticide adsorption coefficients were classified as follows: boscalid (BSC) > cyproconazole (CYP) > isoproturon (IPU) ∼ dimethachlor (DMT) at any ratio or agitation, in agreement with their water solubilities and K ow values. The effect of the solid/liquid ratio was evidenced for all conditions. Indeed, the adsorption equilibrium time was reached more quickly for the 1/1 ratio (24-72h) than for the 1/5 ratio (96-120h). In addition, the adsorption coefficients (K fads) were larger for the 1/1 ratio (1.8-11.2Lkg-1) than for the 1/5 ratio (1.0-5.9Lkg-1). The agitation effect was more evidenced for the 1/5 ratio and for the more hydrophobic molecules, such as BSC and CYP, for which adsorption equilibrium time was never reached with agitation (>120h), while it was reached at 96h without agitation. Moreover, the K fads values were larger with agitation than without agitation for BSC and CYP, whereas they were similar for the two agitations for IPU and DMT. Our results demonstrated that the hydrodynamic function of CWs could influence pesticide sorption with variable effects according to the molecular properties and consequently influence the mitigation effect of CWs throughout the year.

Evaluation of Flooding in Sg Gita Catchment, Kuching

This paper outlines a methodology of flow routing with inclusion of downstream river water level applied to a Sg Gita urbanized catchment beside Sg Sarawak in Kuching city, Sarawak, Malaysia. Evaluations are done by demonstrating the modelling of flooding scenarios using InfoWorks River Simulation (RS) that stresses on different aspects specific to Sg Gita’s conditions, namely (1) impacts of high and low river water levels, (2) solely urban flooding and (3) the combination of the two. The outcomes indicate that the dynamics of downstream river water level influences the performance of the urban drainage that flowed into the river. Backwater is overriding the flows of urban drains. Therefore, the mentioned methodology is found superior than conventional methodology with only flow routing to represent the flow mechanism of urban catchment bounded by a downstream river.

Application of an unstructured 3D finite volume numerical model to flows and salinity dynamics in the San Francisco Bay-Delta

A linked modeling approach has been undertaken to understand the impacts of climate and infrastructure on aquatic ecology and water quality in the San Francisco Bay-Delta region. The Delft3D Flexible Mesh modeling suite is used in this effort for its 3D hydrodynamics, salinity, temperature and sediment dynamics, phytoplankton and water-quality coupling infrastructure, and linkage to a habitat suitability model. The hydrodynamic model component of the suite is D-Flow FM, a new 3D unstructured finite-volume model based on the Delft3D model. In this paper, D-Flow FM is applied to the San Francisco Bay-Delta to investigate tidal, seasonal and annual dynamics of water levels, river flows and salinity under historical environmental and infrastructural conditions. The model is driven by historical winds, tides, ocean salinity, and river flows, and includes federal, state, and local freshwater withdrawals, and regional gate and barrier operations. The model is calibrated over a 9-month period, and subsequently validated for water levels, flows, and 3D salinity dynamics over a 2 year period.Model performance was quantified using several model assessment metrics and visualized through target diagrams. These metrics indicate that the model accurately estimated water levels, flows, and salinity over wide-ranging tidal and fluvial conditions, and the model can be used to investigate detailed circulation and salinity patterns throughout the Bay-Delta. The hydrodynamics produced through this effort will be used to drive affiliated sediment, phytoplankton, and contaminant hindcast efforts and habitat suitability assessments for fish and bivalves. The modeling framework applied here will serve as a baseline to ultimately shed light on potential ecosystem change over the current century.

Characterization of Thin Alluvial Bed Aquifers in Manggar River Balikpapan East Kalimantan Indonesia

Abstract Manggar Village is suburban, located in District of East Balikpapan, East Borneo Indonesia. In dry season, clean water crisis always hit this area. Therefore in order to full fill the need of water for domestic use the inhabitant of this area use dug well water. Dug well water comes from the upper most ground water that is stored and transmitted by relatively thin layer of alluvium deposit. In this research surface elevation measurement was done to control the elevation of dug well so that the depth of dynamic water level ( DWL ) could be determined accurately. The equipotential map was made based on the DWL , then flow line can be drawn and gradient hydraulics ( i ) can be calculated. Coefficient of permeability ( k ) that were resulted from fall head test has shown value 1.284 x 10 -3 up to 11.45 x 10 -3 cm/sec which gradually increases toward beach. According to the results of serial test and calculation the ground water transmissibility and velocity increases toward the beach. Generally groundwater has high hardness. The groundwater close to the beach has been mixed with sea water.

Linkage between Water Level Dynamics and Climate Variability: The Case of Lake Hawassa Hydrology and ENSO Phenomena

Lake Hawassa is a topographically closed lake in the Central Main Ethiopian Rift Valley. The water level of this lake has been reported to dramatically rise without falling back to the original level. The cause of this rise is not yet sufficiently investigated and subjected to this study. This study argues that the general variability in the lake level and its resultant rise has significant linkage to the temperature variability at the Pacific Ocean. The linkage between water level dynamics and climate variability was analyzed through the application of diverse statistical techniques. It comprises the Mann-Kendall trend analysis to test monotonic variations over time; sequential regime shift index (RSI) to detect significant shifts in the mean values of time-series records of lake level; and coherence analysis to investigate the linear relationship between ENSO index and records of local hydrology. Despite the multiple rises and falls, the results of the trend analysis revealed that the lake level experienced a significant resultant upward trend with Mann-Kendall τ values of 0.558, 0.629, and 0.545 (at α = 0.05 and p < 0.01%) for monthly maximum, average and minimum values respectively. The sequential regime shift evidenced that most of the significant shifts coincide with the occurrences of ENSO events. Generally, the lake level tends to be high during El Niño and low during La Niña episodes. The typical examples are the coincidence of extreme historical maximum lake level to the strongest El Niño event of the century that occurred in 1997/98 and the lowest lake level record in the year 1975 with a strong La Niña year. The coincidence of climate regime shift in the Pacific Ocean in 1976/77 with an equivalent regime shift in the lake level is an additional confirmation for the possible climate-hydrology linkage. The likely involvement of anthropogenic factors (at least in modifying the effect of climate) is justified by the interplay between the non-trending rainfall and potential evapotranspiration and trending streamflow. The coherence analysis between 492 pairs of monthly step datasets of 3.4ENSO index and lake level changes is also found to have a significant linear relationship over frequencies ranging from 0.13 to 0.14 cycles/month or 1.56 to 1.68 cycles/year. This corresponds to a dominant average periodicity (coincident cycle) of about 7.4 months which is thought to be related to the time span of the two rainy season in the locality.

Relations between vegetation and water level in groundwater dependent terrestrial ecosystems (GWDTEs)

Alkaline wetlands and fens are groundwater dependent, terrestrial ecosystems (GWDTEs) existing throughout the temperate zone. They contain a large number of protected and endangered plant species and their ecological status is threatened by insufficient groundwater quality and quantity. However, management and conservation of fens are constrained by limited knowledge on the relations between vegetation and measurable hydrological conditions. This study investigates the relations between vegetation and water level dynamics in groundwater dependent wetlands in Denmark.A total of 35 wetland sites across Denmark were included in the study. The sites represent a continuum of wetlands with respect to vegetation and hydrological conditions. Water level was measured continuously using pressure transducers at each site. Metrics expressing different hydrological characteristics, such as mean water level and low and high water level periods, were calculated based on the water level time series. A complete plant species list was recorded in plots covering 78.5m2 at each site. Community metrics such as total number of species and the number of bryophytes were generated from the species lists and Ellenberg Indicator scores of moisture, pH and nutrients were calculated for each site.The water level correlates with the number of typical fen species of vascular plants, whereas bryophytes are closer connected to the stable water level conditions provided by groundwater seepage. The water level variability is proved to be a significant limiting factor for species diversity in wetlands, which should be considered along with the fertility in order to access the habitat quality. The study provides new insight in the water level preferences for GWDTEs which is highly needed in the management and assessment of anthropogenic damage to these ecosystems.

Multivariate analysis of ground water characteristics of Ajali sandstone formation: A case study of Udi and Nsukka LGAs of Enugu State of Nigeria

Multivariate statistical techniques were applied for the evaluation and interpretation of borehole characteristics of the Ajali sandstone geological formation of Enugu state of Nigeria to determine the latent structure of the borehole characteristics and to classify 9 borehole parameters from 33 locations into borehole groups of similar characteristics. Two chemometric data mining techniques used were, Cluster Analysis (CA) and Principal Component Analysis (PCA). PCA identified the borehole parameters responsible for variation in the borehole characteristic of the study area. Out of the nine parameters examined, the PCA identified borehole depth, borehole casing, static water level and dynamic water level as the most significant parameters responsible for variation in borehole characteristics. Hierarchical Cluster Analysis also grouped the 33 borehole locations into three clusters. The CA grouping of the borehole parameters showed similar trend with PCA hence validating the grouping of variations in the borehole characteristics in the geological zone. The results of the study indicate that PCA and CA are useful in offering reliable classification of the borehole characteristic of the study area.