Water Level Recorder Research Articles

Evaluation of repeat bathymetric surveys on water surface elevations on the Saint Clair River

The Great Lakes contain 20 percent of the world’s fresh surface water, a drinking source for 30- million people. The system is vital to manufacturing, largely due to efficient transportation of commodities and an abundance of natural resources. Understanding the water balance and predicting future water levels is important for many industries including commercial navigation, the tourist industry, hydropower and shoreline property owners, just to name a few. These predictions require an understanding of both the hydroclimate drivers across the Great Lakes as well as physical changes in the connecting channels that pass water between each lake. Since the International Upper Great Lakes Study began, the St. Clair River has been the topic of conveyance change investigations. This study tests the sensitivity of water surface elevations to small differences in bathymetric changes. Greater than 80 percent of the surveyed points had less than 0.24 m of change between any combination of survey years. Repeat bathymetric surveys collected in 2007, 2012 and 2021, along with hydrodynamic modeling, find changes in water surface elevations associated with bathymetric change are on the sub-centimeter scale. These changes are put into perspective and compared to known anthropogenic and naturally occurring conveyance changes. While these surveys represent a short duration in the observed water level record of the Great Lakes, they represent an important documentation of the geomorphic state of the St. Clair River. These changes can and should be compared to similar future surveys of the river over longer engineering and geomorphic timescales.

Development and Field Testing of the Technical Implementation Unit for Lowland Automatic Water Level Recorder (AWLR BTR) for Water Level Measurement in Jejangkit Lowland Irrigation Area, South Kalimantan

Observation of water levels using tide gauge is typically conducted by designated personnel or observers. However, its on-field implementation is deemed to be less effective due to the relatively low accuracy of readings. Additionally, hourly water level readings are necessary to generate detailed tidal patterns. Hence, Automatic Water Level Recorder (AWLR) plays a crucial role as an alternative to tide gauge. The utilization of AWLR is considered more practical, yielding more accurate reading data. Furthermore, readings can be conducted continuously, ensuring data acquisition in all conditions. The development of the AWLR BTR system involved literature reviews, software development, hardware assembly, device testing, field trials, and data comparison with the Valeport Tide Gauge. Field trials were conducted at DIR Jejangkit, South Kalimantan. The conducted trials involved operating the AWLR BTR and comparing it with the Valeport AWLR data for validation. Through calculations, the comparison of data between AWLR BTR and AWLR Valeport demonstrates similar water level values, where the average value from AWLR BTR data is 39,69 and Valeport is 39,55. Meanwhile, the Pearson correlation coefficient between the water levels of AWLR BTR and AWLR Valeport is found to be 0,9976, indicating a strong positive correlation between these two data variables.

Land use change analysis and the impact on the streamflow of the Keureuto River

The increasing of population is proportional to the natural resource’s exploitation. Over the past few decades, the activity has converted the natural land into agricultural and plantation fields, urbanized areas, and other types of use. In some watershed systems, land use conversion has reduced the system’s capability both in sustaining water resources and in preventing extreme runoff. Such is the case of the 302 km2 Krueng Keureuto Watershed which supports the water supply for the North Aceh District, both for irrigation and municipal use. Therefore, this study aims to investigate the land use change in the system and its impact on the streamflow. The land use is classified based on the Landsat satellite images of the year 2015 and 2021, using the Supervised Classification tool in ArcGIS. The impact is investigated using a Hydrologic Modelling System (HEC-HMS). The outlet is defined based on the Automatic Water Level Recording (AWLR) station downstream of the Keureuto River. A significant reduction of the forest is estimated at 27.67% in seven years. In contrast, the land use types such as urbanized areas, agricultural fields, and shrubs are increasing to 6.34%; 4.75%; and 5.75%, respectively. Based on the model simulation it is confirmed that the changes in land use have altered the river flow regime.

Flood peak estimation for the keureuto watershed using the hydrological modeling system HEC-HMS

The Keureuto watershed has been the water resource used mainly for irrigation and municipal use. Extreme rainfall along with changes in the system may trigger rainfall excess causing flood at downstream. The occurrences may impact the usability of the system that supports the water resources supply. Investigating the impact of the floods requires initial research on the rainfall-runoff process of the watershed system. Rainfall-runoff modeling is an approach widely used for estimating the discharge hydrograph of the river as the result of the processes. The HEC-HMS rainfall-runoff model tool is applied in this study to estimate the peak flood discharge for the Keureto watershed located in the North Aceh region. The data used are satellite Global Precipitation Measurement (GPM) data and Automatic Water Level Recorder (AWLR) data at the watershed outlet. The 302 km2 Keureuto Watershed is divided into 23 sub-basins for the HEC-HMS model. The SCS Curve Number is applied to the model. The simulated freturncompared to the observed flow using the Nash Sutcliffe Efficiency criteria which returns the NSE value of 0.38 for seven years simulation, based on data of year 2015 to 2021. At an event based on October 2020 to March 2021, the NSE value returns 0.52, satisfactory for the simulation data range. The highest peak of the event is captured by the model simulation in the timing and the magnitude which value lower 20% from the observed flow.

Flood hazard comparison based on geomorphic flood index and hydraulic HEC-RAS (Case study in Ciliwung Watershed, Jakarta)

The Jakarta Special Capital Region is a highly vulnerable area to floods due to its location on wetlands laced by 13 major rivers and borders the Java Sea, with more than 40% of its land below sea level and groundwater extraction leading to the ground sinking. The city has experienced several major flood disasters, and climate change has increased the risk, frequency, and severity of flooding in Jakarta. The present study aims to identify areas with flood potential in the Jakarta Special Capital Region (Provinsi DKI Jakarta) using the Geospatial Flood Index (GFI) method recommended by the National Disaster Management Agency (BNPB). The GFI method is an alternative rapid assessment that utilizes the Digital Elevation Model for National Spatial (DEMNAS) data with an 8-meter spatial resolution and employs ARCGIS and QGIS software to identify areas with high potential for flooding and the extent of inundation. To assess the effectiveness of this method, a comparison is made with the Hydraulic HECRAS model for the section from the Automatic Water Level Recorder (AWLR) MT. Hartono to the Manggarai Flood Gate, considering flood return periods Q50 and Q100. The modeling results indicate that the inundation area estimated by the conventional GFI modeling is 150% larger than that the HECRAS Hydraulic model predicted.

Rating curve development and uncertainty analysis in mountainous watersheds for informed hydrology and resource management

Accurate measurement of continuous stream discharge poses both excitement and challenges for hydrologists and water resource planners, particularly in mountainous watersheds. This study centers on the development of rating curves utilizing the power law at three headwaters of the lesser Himalayas—Aglar, Paligaad, and Balganga—through the installation of water level recorders for stage measurement and salt dilution for discharge measurement from 2014 to 2016. The stream stage–discharge relationship, crucially known as the rating curve, is susceptible to numerous factors in mountainous watersheds that are often challenging to comprehend or quantify. Despite significant errors introduced during the rating curve development, such as stemming from observations, modeling, and parameterization, they are frequently overlooked. In this study, acknowledging the inherent uncertainty, we employ the maximum-likelihood method to assess uncertainty in the developed rating curve. Our findings reveal substantial inconsistency in the stage–discharge relationship, particularly during high flows. A novel contribution of this study is introducing a weighing factor concept that correlates uncertainty with the morphological parameters of the watershed. The higher value of the weighting factor in Paligaad (0.37) as compared to Balganga (0.35) and less in the case of Aglar (0.27) will have more uncertainty. The authors contend that precise rating curves and comprehensive uncertainty analyses can mitigate construction costs, foster robust decision-making, and enhance the perceived credibility of decisions in hydrology and water resource management.

Low-cost system of automatic water level recorder tools based on microcontroller Arduino

Low-cost system of automatic water level recorder tools based on microcontroller Arduino

Potensi Pembangunan Pembangkit Tenaga Mini Hidro (PLTM) pada Sungai Batang Kenaikan Kabupaten Pasaman Barat

Rivers that flow from hilly or mountainous areas can be used for various purposes including; sources of drinking water, irrigation, fisheries, power plants, and downstream shipping lanes. West Sumatra Province is mostly a mountainous area and has many rivers flowing east and west from the Barisan hills. This condition allows the development of hydroelectric power plants that utilize the head and discharge of rivers. One potential development of a mini hydro power plant (PLTM) is in Batang Panggang, which is located in Paraman Ampalu Village, Gunung Tuleh District, West Pasaman Regency. The potential for developing a PLTM on the Batang Panggang River is based on topographic conditions that allow for adequate head height and river flow that can produce electrical energy. For this reason, it is necessary to study the potential by selecting the planned discharge so that it can produce several power production values. These various power productions can be taken into consideration in relation to development costs and operating patterns agreed with PT. PLN (Persero). In this study, the data used includes daily discharge data from automatic water level record (AWLR) recording over the last 15 years. From the discharge data, a Flow Duration Curve (FDC) can be drawn to determine the relationship between discharge and the probability of its occurrence, and this is used as a basis for selecting generator discharge plans and annual energy production. Based on the topographic conditions of the location, the elevation of the lighthouse weir is planned at an altitude of +200 m above sea level, the calming tank is at an altitude of +197 m and the location of the power house is at an altitude of +150 m, while the length of the carrier channel is 2400 m. From this elevation, the height of the fall, H, is 50 m. Assuming the effective fall height, Heff is 90%xH, then Heff is obtained as 45 m. By trying the planned discharge used is Q40% to Q80%, from the FDC we get Q40% = 17.97 m3/s, Q50% = 14.99 m3/s, Q60% = 12.98 m3/s, Q70% = 11.17 m3/s, and Q80% = 9.54 m3/s. Based on the fall height and design discharge, the appropriate type of turbine is a French turbine and the generator efficiency is 0.95, then the annual energy for each Qplan is obtained, namely; W40 = 40413.97 MWh, W50 = 37108.22 MWh, W60 = 34744.17 MWh, W70 = 31296.90 MWh, and W80 = 27606.57 MWh.

LAND CONSERVATION FOR REHABILITATION OF CRITICAL WATERSHEDS: CASE IN WAY CENGKAAN, WAY BESAI SUB-WATERSHEDS, LAMPUNG, INDONESIA

Land and water conservation are the keys to success in controlling the rate of sedimentation. The sediment runoff rate represents the catchment area that increases erosion. This study was conducted to analyze the sedimentation rate in the upstream part of the Way Cengkaan, Way Campang tributary rivers located in Pekon Karang Agung, Way Tenong District, West Lampung Regency. It was carried out from January to December 2020. The research equipment included: a current meter, a stopwatch, a rollmeter, a rainfall recorder, an automatic water level recorder (AWLR), a peiscal, sediment bottles, scales, ovens, and cups. While the materials used are sediment samples, discharge measurement results, and water level. The calculation of flow was carried out at two observation points, upstream and downstream of the Cengkaan River before entering the Way Campang River. Calculation of flow rate using the velocity-area methods using the current meter and the float method. During the observation period from January to July 2020, the sediment velocity increased in line with the trend of the sediment velocity map. The sediment velocity curve for upstream stations is steeper than for downstream stations. The sediment volume decreased relatively in December 2020, and the slope of the sediment velocity graph at the downstream observation point is larger than that at the upstream observation point. This finding reflected that in the one-year observation period from January to December 2020, the evaluation resulted from a decreasing trend of sedimentation in the Way Cengkaan River. Based on these conditions, the implementation of a land conservation program carried out in collaboration between farmer groups and beneficiary stakeholders has a positive impact and effectively contributes to improving the quality of the watershed by reducing the sedimentation rate.

Design and implementation of an IoT-based Automatic Water Level Recorder (AWLR) as a tool to mitigate the risk of tidal flood disasters in the coastal area of Jakarta

Jakarta’s land continues to sink, and rising sea levels pose a high risk of tidal flooding in Jakarta Bay. From 2022 until May 2023, three tidal floods in Jakarta have been recorded due to high-intensity rainfall, causing the sea level to rise above normal. This threat is of public concern due to its material and immaterial losses. To address this issue, a real-time monitoring system that can provide accurate information on sea level heights on the coast of Jakarta needs to be developed. The research aims to develop a web-based Automatic Water Level Recorder (AWLR) system tool to support flood disaster mitigation in Jakarta’s coastal areas. This system integrates several sensors to measure sea level heights, temperature, humidity, and data transmission through a telemetry system. Based on running tests conducted from December 2022 to February 2023, the AWLR recording had been validated with BMKG’s Tide Gauge data installed in the same waters. The results show the data recording performance with high accuracy (98%). The successful performance of the sensors in this device is supported by monitoring devices involving temperature and humidity sensors. The initial calibration stage also shows significant accuracy test results with an error range of 2 -5%. The measurement accuracy of the pressure, temperature, and humidity sensors are 98%, 97%, and 95%, respectively, so the data obtained is reliable. This IoT-based AWLR data recording can be an input for coastal management decision-making, especially for monitoring coastal disasters.

Design of mechanical digitalization automatic water level recorder for river water level monitoring

The Welang River Pasuruan has an Automatic Water Level Recorder (AWLR) tool that measures water levels at that location. This tool operates using mechanical movement to rotate the roller on the AWLR, causing the float to move up and down. This movement results in ink marks on the water level validator paper. The recorded water level data is then processed into an Excel chart. This study aims to digitize the AWLR tool so that the monitoring and calculation of the water level is more precise and can be monitored in online. The water level detector will work in real time using a rotary encoder sensor and data will be sent to database and monitor water level monitoring through a series of data processing which later the data will be sent via MiFi. The method of testing the 2-component connecting system is the accuracy of reading the water level and the accuracy of sending data. The results will be displayed every 1 second on the monitoring dashboard and a standard deviation of 0.0002792 and an error of 0.43% is obtained which indicates the accuracy of the reading is quite accurate and real time.

Sedimentology and stratigraphy of the Jordan River Dureijat archeological site reveal subtle late Pleistocene water-level changes at Lake Hula, Jordan Valley, Israel

AbstractSedimentary records of environmental conditions retrieved from archeological sites provide valuable insight into the milieux of ancient humans and context to understand societal and cultural changes. At Jordan River Dureijat, an open-air site in Israel’s Hula Valley documenting the entire Epipaleolithic period as well as the Early Neolithic, sediments exposed on the walls of the excavation pit reveal a sequence of lacustrine deposits accumulated continuously between c. 21.1 and 11.3 cal ka BP near the southeast margin of Paleolake Hula. Through sediment-grain-size, geochemical, and paleontological analyses, we describe the nature of the Paleolake Hula from the Last Glacial Maximum (LGM) to the start of the Holocene. Until c. 17.2 cal ka BP, Paleolake Hula existed as a relatively large and well-buffered waterbody. A rapid and substantial drawdown of the lake occurred at 17.2 cal ka BP, followed by more frequent changes in the position of the shoreline in a smaller and shallower lake, resulting in the deposition of alternating near-shore and deeper lacustrine facies. Since the LGM, seven beds of structureless, silty sediments preserve archeological artifacts belonging to three Epipaleolithic cultures as well as the Early Neolithic pre-pottery Neolithic A culture. These sediments were deposited during phases of low lake level during which times humans waded into the shallow part of the lake, leaving behind stone and bone tools such as bladelets, lunates and burins, fishing hooks, line weights and net sinkers. Using radiocarbon-dated charcoal and a Bayesian statistical model, we produced a chronostratigraphic model for the archeological site, which enables the comparison of proxy paleoclimate records produced from this site’s sediments with regional archives as well as with global trends and changes in the Northern Hemisphere climate. Periods of low lake stands are correlated with the end of the LGM, Heinrich Event 1, and the beginning of the Younger Dryas Stadial. High water stands occurred contemporaneously with the peak of the LGM and during the Bølling–Allerød interstadial. This new water-level record from Lake Hula confirms that lake-level changes here broadly paralleled those of the Dead Sea and Sea of Galilee during the late Pleistocene, highlighting the importance of northern water sources to the overall water balance of the lakes along the Dead Sea Transform.

Analysis of Water-Surface Oscillations Upstream of a Double-Right-Angled Bend with Incoming Supercritical Flow

This study deals with the free-surface supercritical flow through a double-right-angled bend (DRAB), which can be found in storm drainage networks in steep terrains. Laboratory experiments showed that strong backwater effects and water-surface oscillations are generated upstream of the DRAB, especially in supercritical flow conditions. This paper investigated the DRAB hydraulic behavior and water-surface heading up (backwater), and oscillations under supercritical flow conditions. Thirty-four lab experiments were conducted with Froude numbers ranging between 1.03 and 2.63. Dye injection and video analysis were used to visually capture the flow structure and to record water-surface oscillations. A tracker package was utilized to analyze the collected visual data. Time series and spectral analysis were used to identify the statistical characteristics of recorded water level time series and the dominant frequencies. It was found that the dominant frequencies of water-surface oscillations upstream of the DRAB range between 1.6 and 4.6 Hz with an average value of about 3 Hz. The Strouhal number of the water-surface oscillations is more sensitive to the Froude number than to the Reynolds number. The Strouhal number ranged between 0.03 and 0.3 for Froude numbers ranging from 2.63 to 1.03. The study confirms that near critical flow conditions exhibit the highest water oscillation, and that the maximum nondimensional water depth upstream of the DRAB is underestimated by both the Grashof formula and Knapp and Ippen (1939) model. A new formula is proposed to estimate the maximum water depth upstream of the DRAB.

Extreme Value Analysis of Ocean Still Water Levels along the USA East Coast—Case Study (Key West, Florida)

This paper provides an Extreme Value Analysis (EVA) of the hourly still water level (SWL) record at Key West, Florida dating back to 1913 to understand the statistical likelihood of the combination of high predicted tides and the more dynamic influences (predominantly hurricane induced storm surges) that can drive ocean water levels higher at the coast. The impact of hurricane ‘Wilma’ in 2005 dominates the records, producing a super-elevation of the SWL above Mean Sea Level (MSL) of 1155 mm with an estimated return period of around 147 years. This paper explores the duality of increasing risks of oceanic inundation due to extreme events and increasing mean sea level over time, whilst also providing a range of recommendations for ensuring improved predictive model fitting and robustness of EVA for SWLs measured at tide gauges. When integrated with future IPCC AR6 sea level projections, the return level plots from the EVA provide decision makers with key guidance for design, strategic planning and climate change adaptation purposes at Key West, Florida.

GIS-based Spatial Variability and Water Quality Index (WQI) Modeling of Trace Elements in Groundwater of Jamshedpur, Eastern India

Abstract The present study investigated the spatial variability and water quality index (WQI) modeling of groundwater for drinking purposes. Thus, the sample from 30 locations in Jamshedpur city was collected to explore the hydrochemical characteristics. The range of values of trace elements was well complied with the Bureau of Indian Standards (BIS) except Co (0.1 to 13.87 µg/L), Cu (0.12 to 64.62 µg/L), Mn (20 to 1461 µg/L), and Sr (30 to 544 µg/L).The water table of this region showed tremendous variation (0.44 to 4.90 mbgl) as monitored by a sensor-based water level recorder. The WQI model revealed that only 4% of the water in this region is under the excellent categories, followed by good (86%) and poor (10%). Human health risk assessment of trace elements in contaminated groundwater was also performed according to the United States Environmental Protection Agency (USEPA). The estimated hazard index (HI) value (4.85E-02 to 1.61E+00) indicated the non-carcinogenic risk. The study provides immense help for public health decision-makers to prevent the communities health risks.

Discharge Monitoring in Open-Channels: An Operational Rating Curve Management Tool.

An aspect correlated with climate change is certainly represented by the alternation of severe floods and relevant drought periods. Moreover, there is evidence that changes in climate and land cover are inducing changes in stream channel cross-sections, altering local channel capacity. A direct consequence of a significant change in the local channel capacity is that the relationship between the amount of water flowing at a given point in a river or stream (usually at gauging stations) and the corresponding stage in that section, known as a stage-discharge relationship or rating curve, is changed. The key messages deriving from the present work are: (a) the more frequent and extreme the floods become, the more rapid the changes in the stream channel cross-section become, (b) from an operational point of view, the collection and processing of field measurements of the stage and corresponding discharge at a given section in order to quickly and frequently update the rating curve becomes a priority. It is, therefore, necessary to define a control system for acquiring hydrological data capable of keeping river levels and discharges under control to support flood early warnings and water management. The proposed stage-discharge management system is used by the Civil Protection Service of the Marche Region (east-central Italy) for the monitoring of river runoff in the regional watersheds. The Civil Protection Service staff performs stage-discharge field measurements using water level sensors and recorders (e.g., staff gauges, submersible pressure transducers, ultrasound and radar sensors) and a current meter, acoustic doppler velocimeter, acoustic doppler current profilers, portable mobile radar profiler and salt dilution method equipment, respectively. Power functions are fitted to the stage-discharge field data. Furthermore, extrapolation is performed to cover the full range of flow measurements; in general, extrapolation is not an easy task because of sharp changes in the stream cross-section geometry for very high or very low stages. In the present work, we also focused attention on the application problems that occur in practice and the need for frequent updating.

Flood Modelling due to Dam Failure Using HEC-RAS 2D with GIS Overlay: Case Study of Karalloe Dam in South Sulawesi Province Indonesia

A dam is one of the water structures that have many benefits for humans. However, flood disasters caused by dam break may have a very bad impact on human life. This study specifically analyzed the impact of flooding caused by the failure of the Karalloe dam in Bone Regency, South Sulawesi Province, Indonesia. For the first time, the selected flood discharge used in the dam break analysis was verified using the Creager graph by comparing the calculated discharge from several synthetic unit hydrograph methods (HSS) with the flood discharge measured on the automatic water level recorder (AWLR) at the monitoring point. The impact of flooding due to dam break was simulated using HEC-RAS 2D combined with ArcGIS for mapping. The calculation results of the design flood discharge based on rainfall data using the methods of HSS Nakayasu, HSS ITB I, HSS ITB II, and HSS SCS (HEC-HMS) as well as the calculation of the designed flood discharge based on the discharge data showed that the design flood discharge value which is closest to the measured discharge value and Q1000 Creager was the HSS SCS method. The flood discharge values obtained based on the HSS SCS method for Tr (return period) 2 years, Tr 5 years, Tr 10 years, Tr 20 years, Tr 25 years, Tr 50 years, Tr 100 years, and Tr 1000 years were 322.70 m³/s, 464.10 m³/s, 560.40 m³/s, 658.40 m³/s, 682.70 m³/s, 787.00 m³/s, 885.70 m³/s, and 1202.60 m³/s, respectively. The simulation results showed that 22 villages will be affected by flooding due to the failure of the Karalloe dam and the fastest standby time of the flood is 12 minutes, namely at Lookout Point 7 in Paitana Village. This result suggests that early warning system should be installed at the downstream of the dam and flood disaster mitigation should be adopted and applied to these threatened area.

Surface Water-Groundwater Connections as Pathways for Inland Salinization of Coastal Aquifers.

Coastal agricultural zones are experiencing salinization due to accelerating rates of sea-level rise, causing reduction in crop yields and abandonment of farmland. Understanding mechanisms and drivers of this seawater intrusion (SWI) is key to mitigating its effects and predicting future vulnerability of groundwater resources to salinization. We implemented a monitoring network of pressure and specific conductivity (SC) sensors in wells and surface waters to target marsh-adjacent agricultural areas in greater Dover, Delaware. Recorded water levels and SC over a period of three years show that the mechanisms and timescales of SWI are controlled by local hydrology, geomorphology, and geology. Monitored wells did not indicate widespread salinization of deep groundwater in the surficial aquifer. However, monitored surface water bodies and shallow (<4 m deep) wells did show SC fluctuations due to tides and storm events, in one case leading to salinization of deeper (18 m deep) groundwater. Seasonal peaks in SC occurred during late summer months. Seasonal and interannual variation of SC was also influenced by relative sea level. The data collected in this study data highlight the mechanisms by which surface water-groundwater connections lead to salinization of aquifers inland, before SWI is detected in deeper groundwater nearer the coastline. Sharing of our data with stakeholders has led to the implementation of SWI mitigation efforts, illustrating the importance of strategic monitoring and stakeholder engagement to support coastal resilience.

Leachate delineation and aquifer vulnerability assessment using geo-electric imaging in a major dumpsite around Calabar Flank, Southern Nigeria.

A near-surface resistivity investigation was undertaken to investigate soil contamination and aquifer vulnerability due to leachate percolation in a major dumpsite in Calabar. The study was undertaken using 2-D electrical resistivity tomography (ERT) and vertical electrical sounding. Ten traverse lines were created within and outside the dumpsite and geo-electric measurement was conducted using dipole-dipole and Schlumberger electrode configurations. Interpretation of the measured data was carried out using DIPROWIN and WinResist program. 2-D resistivity structures were produced, showing four resistivity layers. Conductive layers with a resistivity of less than 14Ωm were delineated as leachate infiltrated and soil-contaminated zones. The study has shown that leachate has spread across all the survey lines except the two control stations outside the dumpsite. The investigation has further revealed that leachate has percolated the subsurface up to 25m in the area. Subsequently, twenty vertical electrical soundings were carried out to evaluate aquifer protective capacity/vulnerability in the area. The interpretation shows the area is underlain by four to five geo-electric layers. Total longitudinal conductance values were calculated. Two VES points (14 and 19), representing 10% of the sounding points, showed a weak protective capacity rating; eight VES points (1, 7, 9, 11, 12, 13, and 18), representing 35% of the soundings, showed a moderate protective capacity rating; ten VES points (2, 3, 4, 5, 6, 8, 10, 15, 16, 17, and 20), representing 55% of the total soundings, showed a good protective capacity rating. Three (3) hand-dug wells were sampled with the view to obtaining the groundwater and leachate flow direction within the dump vicinity. An electric water level recorder was used to determine the static water level (SWL) of the three wells, and the leachate flow direction was determined to be north-easterly.

Hydrology of Acidic Mine Pit Lake: A Case Study of ex-Copper mine Pit Lake, Mamut, Sabah Malaysia.

Hydrological study of pit lake was carried out in ex-Mamut Copper Mine (MCM), Ranau Sabah. Gauging stations were established to measure surface inflows and outflows of the pit lake. Each station was equipped with a continuous water level recorder to record water level data at 10–minutes intervals. Rainfall and evaporation were measured respectively using storage gauge and evaporation pan. Over the entire study period, surface inflow accounted for 32.11% of the water entering the lake, the rest being provided by direct precipitation on the lake surface. Surface outflow discharges 53.13% of the water from the lake. Evaporation from the lake contributed 30.10% of water loss to the atmosphere. Changes of storage ranged from 61.09 mm to 241.56 mm per month. Simple linear regression analysis showed that, changes in lake level can be explained through rainfall and resulting tributary inflows, rate of surface outflow and evaporation, which would allow projections of possible future levels to be made by analysis of these components.