Hydrologic Characterization Research Articles

Characterization of Ethiopian mega hydrogeological regimes using GRACE, TRMM and GLDAS datasets

Understanding the spatio-temporal characteristics of water storage changes is crucial for Ethiopia, a country that is facing a range of challenges in water management caused by anthropogenic impacts as well as climate variability. In addition to this, the scarcity of in situ measurements of soil moisture and groundwater, combined with intrinsic “scale limitations” of traditional methods used in hydrological characterization are further limiting the ability to assess water resource distribution in the region. The primary objective of this study is therefore to apply remotely sensed and model data over Ethiopia in order to (i) test the performance of models and remotely sensed data in modeling water resources distribution in un-gauged arid regions of Ethiopia, (ii) analyze the inter-annual and seasonal variability as well as changes in total water storage (TWS) over Ethiopia, (iii) understand the relationship between TWS changes, rainfall, and soil moisture anomalies over the study region, and (iv) identify the relationship between the characteristics of aquifers and TWS changes. The data used in this study includes; monthly gravity field data from the Gravity Recovery And Climate Experiment (GRACE) mission, rainfall data from the Tropical Rainfall Measuring Mission (TRMM), and soil moisture from the Global Land Data Assimilation System (GLDAS) model. Our investigation covers a period of 8years from 2003 to 2011. The results of the study show that the western part and the north-eastern lowlands of Ethiopia experienced decrease in TWS water between 2003–2011, whereas all the other regions gained water during the study period. The impact of rainfall seasonality was also seen in the TWS changes. Applying the statistical method of Principal Component Analysis (PCA) to TWS, soil moisture and rainfall variations indentified the dominant annual water variability in the western, north-western, northern, and central regions, and the dominant seasonal variability in the western, north-western, and the eastern regions. A correlation analysis between TWS and rainfall indicated a minimum time lag of zero to a maximum of six months, whereas no lag is noticeable between soil moisture anomalies and TWS changes. The delay response and correlation coefficient between rainfall and TWS appears to be related to recharge mechanisms, revealing that most regions of Ethiopia receive indirect recharge. Our results also show that the magnitude of TWS changes is higher in the western region and lower in the north-eastern region, and that the elevation influences soil moisture as well as TWS.

Hydrologic Characterization of Undrained Porous Pavements

Results of a simplified analysis of the hydrologic performance of undrained porous pavements, pavements without underdrains but that allow infiltration, are reported. The characterization of porous pavement behavior presented is appropriate for initial pavement design purposes. During any given storm, there are four distinct phases of porous pavement behavior: infiltration, accumulation, runoff, and drawdown. Analytical and graphical methods are presented for describing each of these phases from which a nonconvoluted approximate runoff hydrograph can be derived. This approach approximates peak runoff and time of that peak for a given storm depth, rainfall distribution, and pavement design. Second, a generalized method for calculating a porous pavement’s effective curve number (ECN) based on the National Resources Conservation Service (NRCS) [formerly Soil Conservation Service (SCS)] runoff curve number is presented. The analysis shows that for undrained porous pavements, the ECN is a function not only of the pavement and soil properties, but also of the storm depths and hyetographs used in the analysis. A standard calculation and presentation method is suggested that will allow local regions or municipalities to generate a local ECN design tool appropriate for their intensity-duration-frequency (IDF) data, which are only a function of the effective storage depth and the daily effective soil infiltration depth. A plot of the maximum ECN for all pavement depths and soil types is presented for each NRCS storm type as a reference for generating local ECN figures.

Evaluation of the capacitively coupled resistivity (line antenna) method for the characterization of vadose zone dynamics

The electrical resistivity survey, traditionally realized by the direct current (DC) resistivity method, has shown great value for characterizing vadose zone dynamics. Compared with the DC resistivity method, the capacitively coupled (CC) resistivity method has a higher ratio of measurement speed to data density, and thus is economically preferred for resistivity surveys that require high data density, e.g., hydrological characterizations. To test the applicability of the CC resistivity method to the study of vadose zone dynamics, we conducted time-lapse resistivity surveys using a commercial CC resistivity (line antenna) system, the OhmMapper, to monitor the water content change in an unsaturated zone due to artificial rainfall infiltration . Special considerations were paid to the inversion of CC resistivity (line antenna) measurements in order to increase the accuracy of inversion results. The derived resistivity of the subsurface clearly captures the water movement in the vadose zone and shows the applicability of the CC resistivity method. The experiment also showed a limitation of the equipment: when the ground surface became extremely conductive, the OhmMapper falsely interpreted the current level. If the wrong current level is identified in the measurement, the measured resistance should be corrected accordingly. The overestimation of the ground resistivity of the CC resistivity method, arising from the decrease in the ground resistivity, was also examined and discussed. Although the measurement bias was found to be negligible in our study, one should still be cautious about it when using the CC resistivity method for similar applications, especially when the measurement is made with a short dipole cable. • Water infiltration was monitored using the capacitively coupled resistivity method. • It proved the applicability of the method for vadose zone dynamics studies. • It revealed that the system sometimes falsely interpreted the current level. • The potential experimental bias of this study is examined and discussed.

Estimating annual groundwater recharge coefficient for karst aquifers of the southern Apennines (Italy)

Abstract. To assess the mean annual groundwater recharge of the karst aquifers in the southern Apennines (Italy), the estimation of the mean annual groundwater recharge coefficient (AGRC) was conducted by means of an integrated approach based on hydrogeological, hydrological, geomorphological, land use and soil cover analyses. Starting from the hydrological budget equation, the coefficient was conceived as the ratio between the net groundwater outflow and the precipitation minus actual evapotranspiration (P − ETR) for a karst aquifer. A large part of the southern Apennines, which is covered by a meteorological network containing 40 principal karst aquifers, was studied. Using precipitation and air temperature time series gathered through monitoring stations operating in the period 1926–2012, the mean annual P − ETR was estimated, and its distribution was modelled at a regional scale by considering the orographic barrier and rain shadow effects of the Apennine chain, as well as the altitudinal control. Four sample karst aquifers with available long spring discharge time series were identified for estimating the AGRC. The resulting values were correlated with other parameters that control groundwater recharge, such as the extension of outcropping karst rocks, morphological settings, land use and covering soil type. A multiple linear regression between the AGRC, lithology and the summit plateau and endorheic areas was found. This empirical model was used to assess the AGRC and mean annual groundwater recharge in other regional karst aquifers. The coefficient was calculated as ranging between 50 and 79%, thus being comparable with other similar estimations carried out for karst aquifers of European and Mediterranean countries. The mean annual groundwater recharge for karst aquifers of the southern Apennines was assessed by these characterizations and validated by a comparison with available groundwater outflow measurements. These results represent a deeper understanding of an aspect of groundwater hydrology in karst aquifers which is fundamental for the formulation of appropriate management models of groundwater resources at a regional scale, also taking into account mitigation strategies for climate change impacts. Finally, the proposed hydrological characterizations are also supposed to be useful for the assessment of mean annual runoff over carbonate mountains, which is another important topic concerning water management in the southern Apennines.

Hydrological and hydrogeological characterization of groundwater and river water in the North Hanoi industrial area, Vietnam

Degradation of groundwater quality by human activities is a widespread environmental problem in Vietnam. Groundwater there is a major source of water for domestic and industrial purposes. This paper reviews, compiles, and comprehensively analyzes spatiotemporal variations of hydrological and hydrogeological characteristics of shallow and deep groundwater aquifers in northern Hanoi industrial zones and in nearby Red River water. Groundwater level, electrical conductivity, and water temperature were measured in six monitoring wells, complemented by anion, cation, and stable isotope analyses of ground and surface water. The results show that the groundwater in both shallow and deep aquifers was fresh, but mainly calcium-bicarbonate type contaminants and human activities affect groundwater and surface water composition. With the goal of devising sustainable water use regulations, more research must be directed toward long-term monitoring of groundwater and surface water quality, as well as toward detailed investigation of the hydraulic characteristics of local aquifers in the study area.

Geoelectric and Geochemical Studies for Hydrological Characterization of Canning and Adjoining Areas of South 24 Parganas District, West Bengal

Abstract: Integrated geoelectric and geochemical investigation were carried out in the Canning and adjoining areas to assess the prevailing groundwater conditions and chemical quality of groundwater. Geologically, the area is constituted of alluvial sediments of Quaternary age. Vertical electrical soundings (VES) in the area of investigation mostly show six layers consisting of top soil, saline water, clay layer, brackish water, clay layer and fresh-water bearing zone of appreciable thicknesses at depths of 137 to 182 meter at six locations and from 370 to 430 meter for other two locations under confined conditions. The result of VES studies significantly correspond with the borehole litholog and well log data. A litho-resistivity relationship is established for this area of investigation A Fence diagram is constructed to show the spatial variation of the sub-surface lithology and hydrological characteristics. Chemically the ground water is fresh and mixed cation and anion type as revealed from Piper-Trilinear diagram with TDS ranging from 699 to 1547 mg/l. The geochemical parameters like Total hardness (TH), Sodium absorption ratio (SAR), Soluble sodium percentage (SSP), Percentage of sodium (PS), Kelley’s ratio (KR), Residual sodium carbonate (RSC), Corrosivity ratio (CR), Gibbs ratios (GR), Chloro alkaline indices (CAI), Sea water contamination (SWC) are also calculated for examining the quality of groundwater in the area. The depth of occurrences of freshwater bearing ground water zones for drinking and irrigation purposes are occurring at depths from 137 meter to 430 meter in this area.

Incorporating Pesticide Transport into the WEPP Model for Mulch Tillage and No Tillage Plots with an Underlying Claypan Soil

<abstract><title><italic>Abstract.</italic></title> Best management practice (BMP) tools that provide site-specific water quality assessment with limited input data are needed to assist soil and water managers as they work to target BMP placement and reduce dissolved and sediment bound pesticide loss from agricultural landscapes. BMP effectiveness largely depends on accurate characterization of dominant regional hydrologic processes. However, most BMP tools are region specific in their characterization of hydrology (e.g., most models capture either infiltration excess runoff or saturation excess runoff but cannot predict a combination of the two). In this study, we develop and couple a pesticide transport module with the Water Erosion Prediction Project (WEPP) model (v2012.8). The WEPP model realistically simulates infiltration excess and saturation excess runoff as well as dissolved pesticide loss from hillslopes in the Goodwater Creek Experimental Watershed (GCEW) in northeastern Missouri. Simulated runoff and dissolved atrazine concentrations were compared to observed data from mulch till (MT) and no till (NT) plots in the GCEW. The timing of runoff predicted by WEPP coincided well with observed events and simulated flow magnitudes were between minimum and maximum observations for replicate plots. Event-based Nash-Sutcliffe Efficiencies (NSE) are 0.84 and 0.79 for MT and NT runoff simulations, respectively. Both simulations and observations showed little difference in total growing season (planting to harvest) runoff between MT and NT. Event-based dissolved atrazine loads are well predicted for MT and NT with NSEs of 0.59 and 0.71, respectively. Consistent with observations, seasonal NT atrazine losses were greater than losses from MT plots. While this study only focuses on dissolved pesticide transport from the base of hillslopes using MT and NT conservation practices, the WEPP pesticide transport module is capable of predicting both dissolved and sediment bound pesticide loss from each section of the hillslope (i.e., top-slope, mid-slope, and toe-slope) for a wide range of BMPs. However, further field data are needed to evaluate these aspects of the model.

The hydrological characterisation and water budget of a South African rehabilitated headwater wetland system

This paper presents a synopsis of the findings of a valley bottom wetland monitoring study in which dominant hydrological processes maintaining the system are quantitatively defined. The Craigieburn-Manalana is a wetland subjected to technical rehabilitation, at the headwaters of the Sand River in the lowveld savanna region of South Africa. Findings include the identification of a rapid water delivery mechanism from the surrounding hillslopes to the wetland following a threshold-exceeding precipitation event, when hillslope-toe soil matric potential is close to 0, leading to a raising of the wetland water table by >0.7 m within 3 h. A summary of quantified fluxes and associated water budget of the wetland and its contributing catchment is developed. It is revealed that this wetland does not necessarily conform to the typical assumptions that wetlands augment low flows. Surface layer scintillometry shows actual wetland evapotranspiration to dominate the water budget during the dry season (2.3–3.5 mm/d) compared to its contributing catchment (0.9–2.2 mm/d), whilst stream discharge had ceased. Hydrograph separation, based on stable isotopes (18O), revealed that the wetland does not attenuate peak flows during the summer rains when the wetlands soil moisture deficit is close to 0, since more than 66% of stream discharge comprised event water. These results are discussed within the context of current hydrological understanding of southern African headwater wetlands, such as dambos. Keywords: hillslope processes, hydro-geomorphology, water budget, dambos, rehabilitation, wetlands

Application of the ReNuMa model in the Sha He river watershed: Tools for watershed environmental management

Models and related analytical methods are critical tools for use in modern watershed management. A modeling approach for quantifying the source apportionment of dissolved nitrogen (DN) and associated tools for examining the sensitivity and uncertainty of the model estimates were assessed for the Sha He River (SHR) watershed in China. The Regional Nutrient Management model (ReNuMa) was used to infer the primary sources of DN in the SHR watershed. This model is based on the Generalized Watershed Loading Functions (GWLF) and the Net Anthropogenic Nutrient Input (NANI) framework, modified to improve the characterization of subsurface hydrology and septic system loads. Hydrochemical processes of the SHR watershed, including streamflow, DN load fluxes, and corresponding DN concentration responses, were simulated following calibrations against observations of streamflow and DN fluxes. Uncertainty analyses were conducted with a Monte Carlo analysis to vary model parameters for assessing the associated variations in model outputs. The model performed accurately at the watershed scale and provided estimates of monthly streamflows and nutrient loads as well as DN source apportionments. The simulations identified the dominant contribution of agricultural land use and significant monthly variations. These results provide valuable support for science-based watershed management decisions and indicate the utility of ReNuMa for such applications.

Estuarine processes in macro-tides of Amazon estuaries: A Study of Hydrodynamics and Hydrometeorology in the Marajó Bay (Pará-Brazil)

ABSTRACT Bezerra, M.O.M.; Freitas, P.P.;Baltazar, L.R.S.; Rollnic, M., 2013. Estuarine processes in macro-tides of Amazon estuaries: A Study of Hydrodynamics and Hydrometeorology in the Marajo Bay (Para-Brazilyn: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.) The work carried out a hydrodynamic and hydrologic characterization in the estuary of the Para River (Marajo Bay), near the Colares and Guaras Islands (para, Brazil). The goal is to verify the behavior of the semi-diurnal macro-tide in large Amazon estuaries with an emphasis on hydrodynamic and hydrological characterization of the para River estuary. The work proposed as targets; to investigate the hydrodynamics as to stream and water level, and the physicochemical variations of the water body. The studies were conducted in quadrature and consisted of measurements of streams, salinity, temperature and tidal range. The main results showed that the para River estuary, as to the hydrological characteristics of the system, showed no s...

Development of a methodology for hydrologic characterization of faults - field validation project at Berkeley, California -

Development of a methodology for hydrologic characterization of faults - field validation project at Berkeley, California -

Optimization of CPMG sequences to measure NMR transverse relaxation time &amp;lt;i&amp;gt;T&amp;lt;/i&amp;gt;&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; in borehole applications

Abstract. Nuclear Magnetic Resonance (NMR) can provide key information such as porosity and permeability for hydrological characterization of geological material. In particular the NMR transverse relaxation time T2 is used to estimate permeability since it reflects a pore-size dependent relaxation process. The measurement sequence (CPMG) usually consists of several thousands of electromagnetic pulses to densely record the relaxation process and to avoid relaxation processes that are due to diffusion. These pulses are equidistantly spaced by a time constant tE. In NMR borehole applications the use of CPMG sequences for measuring the transverse relaxation time T2 is limited due to requirements on energy consumption. For measuring T2, it is state-of-the-art to conduct at least two sequences with different echo spacings (tE) for recording fast and slow relaxing processes that correspond to different pore-sizes. We focus on conducting only a single CPMG sequence and reducing the amount of energy while obtaining both slow and fast decaying components and minimizing the influence of relaxation due to diffusion. Therefore, we tested the usage of CPMG sequences with an increasing tE and a decreasing number of pulses. A synthetic study as well as laboratory measurements on samples of glass beads and granulate material of different grain size spectra were conducted to evaluate the effects of an increasing tE. We show that T2 distributions are broadened if the number of pulses is decreasing and the mean grain size is increasing, which is mostly an effect of a significantly shortened acquisition time. The shift of T2 distributions to small decay times as a function of tE and the mean grain size distribution is observed. We found that it is possible to conduct CPMG sequences with an increased tE. According to the acquisition time and increasing influence of relaxation due to diffusion, the sequence parameters need to be chosen carefully to avoid misinterpretations.

Hydrologic characterization of 56 geographically isolated wetlands in west-central Florida using a probabilistic method

Wetlands are important hydrological elements of watersheds that influence water storage, surface water runoff, groundwater recharge/discharge processes, and evapotranspiration. Understanding the cumulative effect wetlands have on a watershed requires a good understanding of representative water-level fluctuations and storage characteristics associated with multiple wetlands across a region. We introduce a probabilistic approach based on frequency analysis of water levels in numerous geographically isolated wetlands across the mantled karst terrain of west-central Florida, in the Tampa Bay region. This approach estimates the probabilities, or percentage of time, that water levels in a wetland or upland groundwater wells are at or below a specific elevation. We applied this hydrologic characterization to 56 wetlands in west-central Florida, and documented that standing water was present in the wetlands 61 % of the time and that these wetlands were groundwater recharge zones at least 50 % of the time over the 7 year study. Additionally, we demonstrated that various wetland types, classified according to vegetation community composition and structure, exhibit similar means, extremes and ranges in water-level behavior. We believe that this is the first paper to robustly quantify inundation frequency and recharge status in seasonally flooded wetlands at a regional scale. The analytical tool introduced in this manuscript could be used to detect, through changes in water-level frequency distribution, wetland hydrological response to different climatological or anthropogenic stressors. This tool is timely as changes in frequency distribution shape may provide early warnings of ecosystem regime change.

Ecological succession, hydrology and carbon acquisition of biological soil crusts measured at the micro-scale.

The hydrological characteristics of biological soil crusts (BSCs) are not well understood. In particular the relationship between runoff and BSC surfaces at relatively large (>1 m2) scales is ambiguous. Further, there is a dearth of information on small scale (mm to cm) hydrological characterization of crust types which severely limits any interpretation of trends at larger scales. Site differences and broad classifications of BSCs as one soil surface type rather than into functional form exacerbate the problem. This study examines, for the first time, some hydrological characteristics and related surface variables of a range of crust types at one site and at a small scale (sub mm to mm). X-ray tomography and fine scale hydrological measurements were made on intact BSCs, followed by C and C isotopic analyses. A ‘hump’ shaped relationship was found between the successional stage/sensitivity to physical disturbance classification of BSCs and their hydrophobicity, and a similar but ‘inverse hump’ relationship exists with hydraulic conductivity. Several bivariate relationships were found between hydrological variables. Hydraulic conductivity and hydrophobicity of BSCs were closely related but this association was confounded by crust type. The surface coverage of crust and the microporosity 0.5 mm below the crust surface were closely associated irrespective of crust type. The δ 13C signatures of the BSCs were also related to hydraulic conductivity, suggesting that the hydrological characteristics of BSCs alter the chemical processes of their immediate surroundings via the physiological response (C acquisition) of the crust itself. These small scale results illustrate the wide range of hydrological properties associated with BSCs, and suggest associations between the ecological successional stage/functional form of BSCs and their ecohydrological role that needs further examination.

Hydraulic and thermal response of groundwater–surface water exchange to flooding in an experimental aquifer

The effects of flooding on interactions between streams and shallow aquifers are poorly studied due to the unpredictable nature of flooding events. This study examines groundwater–surface water interactions in a constructed experimental meander over several simulated flood events using hydrologic and thermal monitoring. Detailed steady-state hydraulic head measurements were taken of the stream surface and in 59 piezometer nests during baseflow, bankfull flow, and overbank flooding conditions, allowing for three-dimensional hydrologic characterization. Additionally, a lithium tracer test was conducted, and pressure transducers and thermistors were deployed to capture transient behavior. Results demonstrate extensive coupling between the stream and adjacent alluvial aquifer under all discharge conditions. Water table elevation responds rapidly to changes in stream stage and re-equilibrates to order of magnitude increases in discharge within about 1 h. Though flooding elevates the water table, steady-state hydraulic gradients within the meander are independent of stream stage. This results from the flow boundary condition imposed by the stream, which deepens in response to flooding but has a slope that is essentially independent of discharge. In addition to the stream boundary, flow within the meander is also controlled by loss of stream water to the subsurface, which directs hydraulic gradients towards the base of the meander. Finally, the temperature distribution within the meander during normal and bankfull flow mimics the water table distribution and results from advected warm stream water being progressively cooled by vertical conduction in the direction of groundwater flow. These findings suggest that areas of high reaction rates within meanders (hot spots) will be sensitive to whether a stream reach is gaining or losing water to the subsurface. Further, the location of these hot spots of is likely independent of stream stage, though other controls on reaction rates may be affected.

Groundwater flooding in Irish karst: The hydrological characterisation of ephemeral lakes (turloughs)

Summary Ephemeral karst lakes (turloughs) are wetlands at the interface between groundwater and surface water, and are a characteristic feature of the Irish karst landscape. They are transient lakes resulting from a combination of high rainfall and, accordingly, high groundwater levels in topographic depressions in karstified limestone terrain. Turloughs are a valuable example of a Groundwater Dependent Terrestrial Ecosystem (GWDTE), providing a habitat for many floral and faunal species of both national and international importance. The extensive, recurring groundwater floods that originate at turloughs also represent the primary form of groundwater flooding found in Ireland. This study addresses the need for a comprehensive study of turlough hydrology based on quantitative hydrological and topographic parameters. In doing so it takes the first step towards the goals of ensuring the conservation status of these protected ecosystems, as well as providing a basis for determining the hazards associated with groundwater flooding in Ireland. The hydrodynamics of turloughs have been elucidated through the measurement of relevant hydrological parameters, the mapping of topography within turlough basins, and the analysis and interpretation of extensive hydrological datasets over a 3 year period. From this analysis a conceptual understanding of the hydrological operation of turloughs has been developed and the characteristic hydrological diversity of these habitats has been quantified.

Potential for hydrologic characterization of deep mountain snowpack via passive microwave remote sensing in the Kern River basin, Sierra Nevada, USA

Snow plays a critical role in hydrology and water resources, but snow properties in mountainous areas vary dramatically in space, making characterization difficult: in situ measurements represent a single point of spatially-variable snow properties. Spaceborne passive microwave (PM) remote sensing has spatially continuous coverage, but coarse spatial resolution. PM spatial footprints are nominally elliptical, with the spatial orientation changing relative to a given basin on the ground from one satellite pass to the next. The widely used Equal-Area Scalable Earth Grid (EASE-Grid) resamples the raw PM observations to a 25km×25km grid; this is far coarser than The Advanced Microwave Scanning Radiometer for EOS (AMSR-E) 37GHz Level 2A (L2A) footprints with an area of 87.9km2. This paper presents methods for processing the L2A data in order to illustrate that PM measurements contain information about snow accumulation and ablation cycles in mountainous regions. Methods are presented 1) to calculate the average Tb over a hydrologic basin for monitoring SWE accumulation amount, and 2) to interpolate Tb to a point for monitoring SWE ablation timing. Across the six-year study period, the range of the Tb was 50K, while the range of the air temperature was only 30K, indicating significant surface emissivity variations. The minimum Tb of each water year (WY), which starts from October 1 of a calendar year and ends at September 30 of the next, showed a strong inverse relationship to SWE measured in situ; the correlation coefficient between Tb and an in situ basin average SWE was −0.94. The L2A data is three times more sensitive to than the EASE-Grid data to in situ SWE. The diurnal amplitude variability (DAV, or difference between daytime and nighttime Tb) was used to identify the day of melt onset and compared with in situ estimates of onset derived from daily SWE measurements. L2A data corresponded well with the in situ onset dates with a correlation coefficient of 0.94 and an RMSE of 5.04days. When using EASE-Grid data, the RMSE in onset date was 11.7days. In addition, Tb DAV was found to be correlated with Tair DAV during winter, with an average correlation coefficient of 0.72. Future work will explore methods to extract this information in order to improve estimates of snow accumulation and ablation patterns.

High Resolution Mapping of Peatland Hydroperiod at a High-Latitude Swedish Mire

Monitoring high latitude wetlands is required to understand feedbacks between terrestrial carbon pools and climate change. Hydrological variability is a key factor driving biogeochemical processes in these ecosystems and effective assessment tools are critical for accurate characterization of surface hydrology, soil moisture, and water table fluctuations. Operational satellite platforms provide opportunities to systematically monitor hydrological variability in high latitude wetlands. The objective of this research application was to integrate high temporal frequency Synthetic Aperture Radar (SAR) and high spatial resolution Light Detection and Ranging (LiDAR) observations to assess hydroperiod at a mire in northern Sweden. Geostatistical and polarimetric (PLR) techniques were applied to determine spatial structure of the wetland and imagery at respective scales (0.5 m to 25 m). Variogram, spatial regression, and decomposition approaches characterized the sensitivity of the two platforms (SAR and LiDAR) to wetland hydrogeomorphology, scattering mechanisms, and data interrelationships. A Classification and Regression Tree (CART), based on random forest, fused multi-mode (fine-beam single, dual, quad pol) Phased Array L-band Synthetic Aperture Radar (PALSAR) and LiDAR-derived elevation to effectively map hydroperiod attributes at the Swedish mire across an aggregated warm season (May–September, 2006–2010). Image derived estimates of water and peat moisture were sensitive (R2 = 0.86) to field measurements of water table depth (cm). Peat areas that are underlain by permafrost were observed as areas with fluctuating soil moisture and water table changes.

Hydrological characterization of Mahd Ad Dahab Gold Mine, Saudi Arabia

Hydrological characterization of Mahd Ad Dahab Gold Mine, Saudi Arabia

Hydrological characterization of Mahd Ad Dahab Gold Mine, Saudi Arabia

The present study focuses on the gold mining in Mahd Ad Dahab region of Saudi Arabia. The study aims at the integrated use of existing meteorological information with the drainage basin morphometry of the mine catchment for determining the preferential flow path for the mine contaminants. The study reveals that the actual mining area lies at the headwaters of two watersheds: Watershed A and Watershed B. The streams in Watershed A drain in a North East - South West direction, whereas the streams of watershed B trend in a South East – North West direction. The peak runoff estimates show that in case of a heavy rainfall event, more surface discharge will be generated in Watershed A mainly due to its large surface area thus, leading to potential contamination in the south of the mining area. The runoff estimates for a maximum rainfall event of 104 mm/day is equal to 21.527 m3/s for Watershed A and 8.310 m3/s for Watershed B. Studies related to the investigation of the water pollution from mining activities should be concentrated towards the south of the mine. Key words: Mahd Ad Dahab Gold Mine, meteorology, drainage basin morphometry, runoff.