Water chemistry of Mansar Lake (India): an indication of source area weathering and seasonal variability

The chemistry of major elements (Ca, Mg, Na, K and Si) and anions (HCO ₃, SO ₄ and Cl) in the water of Mansar Lake was studied, based on seasonal data. The results show that total dissolved solid (TDS) concentration in a particular season is similar, but varies slightly in different seasons with a variation factor of less than 2. This is because the collections were made in the dry seasons and the Ca-precipitation is the cause for the seasonal variability. The major element chemistry of Mansar Lake is mainly controlled by rock weathering, with HCO ₃ and Ca dominating the major ion composition because of the abundance of carbonate rocks in the basin. The results also indicate that the lake water is saturated with respect to calcite and/or dolomite during the spring season whereas it is undersaturated in the summer season. This contrast brings out seasonal variability. The lake shows disequilibrium with atmospheric CO ₂ as a result of carbonate dissolution in the drainage basin. The study also shows that physical weathering/erosion is dominant and that chemical weathering is incipient. This is consistent with the Chemical Index of Alteration (CIA) data.     

Flood susceptibility prediction using four machine learning techniques and comparison of their performance at Wadi Qena Basin,Egypt

Natural Hazards - Floods represent catastrophic environmental hazards that have a significant impact on the environment and human life and their activities. Environmental and water management in...     

Geospatial cryptography: enabling researchers to access private,spatially referenced,human subjects data for cancer control and prevention

Journal of Geographical Systems - As the volume, accuracy and precision of digital geographic information have increased, concerns regarding individual privacy and confidentiality have come to the...     

A parameter allocation approach for flow simulation using the WetSpa-Python model

Hydrologic models are simplified representations of natural hydrologic systems. Since these models rely on assumptions and simplifications to capture some aspects of hydrological processes, calibration of parameters is unavoidable. However, utilizing the philosophy of a recent modelling framework proposed by Bahremand (2016), we show how calibration of most model parameters can be avoided by allocating or presetting these parameters utilizing knowledge gained from sensitivity analyses, field observations and a priori specifications as a part of a parameter allocation procedure. This paper details the simulation of daily river flow of the Shemshak-Roudak watershed performed using the Python version of the WetSpa model. The WetSpa-Python model is a distributed model of hydrological processes applied at the watershed scale. The model was applied to the Shemshak-Roudak watershed of Iran with parameter allocation. Model calibration involved only two parameters. Straightforward methods were proposed for allocating model parameters, including three baseflow-related parameters and the determination of maximum active groundwater storage using a mass curve technique. Also, the Budyko curve was used to constrain a correction factor for potential evapotranspiration. The WetSpa-Python model was extended to include the influence of snowmelt. A failure to include snow in the hydrological processes of the WetSpa-Python model creates a significant discrepancy between the observed and simulated hydrographs during the spring. The results of daily simulations for 12 years (2002–2014) are in good agreement with observations of discharge (Kling-Gupta Efficiency = 0.84). These results demonstrate that it is feasible to simulate hydrographs with limited calibration given a knowledge of hydrological processes and an understanding of relationships between catchment characteristics and model parameters.     

FAO 56 Model and Remote Sensing for the Estimation of Crop-Water Requirement in Main Branch Canal of the Bhadra Command area, Karnataka State

Remote sensing and FAO 56 crop water model are used for estimating crop water requirement for paddy crop located in the main branch canal of Bhadra Command Area in Karnataka, India. The estimation of crop-water requirement depends on the meteorological factors, soil type and crop coefficients. The result obtained showed that water requirements of rabi crops higher than those of the kariff crops. The total irrigated area estimated from the IRS image is 29,353 ha. It is found that the total paddy crop acreage is 18,257 ha covering 62 % in the total irrigated area of the command area, Arecanut 20 %, coconut 15 % and sugarcane with other crops 3 %. The water requirement for paddy is 1180.4 mm for its entire growth period. The total water requirement for irrigation supply for crops in the entire command area is 5,790 at a demand of 0.10501 cusecs per ha.     

Natural radionuclide concentrations in thermal springs of east Algeria

The variation of the natural radionuclide concentrations depends on the chemical composition of each site. In this work, two thermal springs in the east of Algeria have been chosen to assess the activity concentration of natural radionuclide, mainly the three natural radioactive series ²³⁸U, ²³⁵U and ²³²Th, and ⁴⁰K. The high-resolution gamma ray spectroscopy was used to determine these concentrations. In these water samples, ²³⁵U, ²³⁴Th, ²¹⁰Pb, ²²⁶Ra radionuclides are less than the minimum detectable activity. The activity of ²³⁸U is dominant. The ²³⁸U activity was determined by taking the mean activity of two separate photo-peaks of daughter nuclides ²¹⁴Pb at 351.92 (37.2%) keV and ²¹⁴Bi at 609.31 (45%) keV. The measured activity concentrations of ²³⁸U in water samples obtained from the concentrations of ²¹⁴Bi and ²¹⁴Pb ranged from 0.56 ± 0.20 to 1.13 ± 0.20 Bq/L. The annual effective dose value due to the ingestion of the measured radionuclide ²³⁸U in 1 L of water, for an adult, ranged from 9.20 to 18.56 µSv.     

Prioritization of sub-watersheds based on morphometric and land use analysis using remote sensing and GIS techniques

Watershed prioritization has gained importance in natural resources management, especially in the context of watershed management. Morphometric analysis has been commonly applied to prioritization of watersheds. The present study makes an attempt to prioritize sub-watersheds based on morphometric and land use characteristics using remote sensing and GIS techniques in Kanera watershed of Guna district, Madhya Pradesh. Various morphometric parameters, namely linear and shape have been determined for each sub-watershed and assigned ranks on the basis of value/relationship so as to arrive at a computed value for a final ranking of the sub-watersheds. Land use/land cover change analysis of the sub-watersheds has been carried out using multi-temporal data of IRS LISS II of 1989 and IRS LISS III of 2001. The study demonstrates the significant land use changes especially in cultivated lands, open scrub, open forest, water bodies and wastelands from 1989 to 2001. Based on morphometric and land use/land cover analysis, the sub-watersheds have been classified into three categories as high, medium and low in terms of priority for conservation and management of natural resources. Out of the seven sub-watersheds, two sub-watersheds viz., SW1 and SW6 qualify for high priority, whereas SW7 has been categorised as medium priority based on the integration of morphometric and land use change analysis.     

A pan-sharpening method based on NSCT and formulated as compressive sensing problem

In this paper, a pan-sharpening method, using non-subsampled contourlet transform (NSCT) and the theory of compressive sensing (CS), is proposed. The NSCT is used for sparse image representation to perform a multiscale and directional decomposition of source images in order to express their detail and express the sparsity of their high frequency. The CS is used to merge the multispectral (MS) and panchromatic (pan) images from partial random measurements. Two different fusion rules are then applied. The final pan-sharpened image is obtained by inverse NSCT. Experimental results show the efficiency of the proposed method, compared with pan sharpening based on standard NSCT, in terms of visual quality and objective assessment. Moreover, the proposed technique is very effective when the storage and transmission bandwidth are limited.     

The effect of cemented soil strength on the frictional capacity of precast concrete pile–cemented soil interface

Acta Geotechnica - The pre-bored grouted planted (PGP) pile is a composite pile consisting of a precast concrete pile and the cemented soil around the pile. Thus, the PGP pile shaft capacity is...     

Groundwater Deterioration of Shallow Groundwater Aquifers Due to Overexploitation in Northeast Jordan

Groundwater is the major water resource in Jordan and most of the groundwater basins are already exploited beyond their estimated safe yield. Azraq basin is one of the most important groundwater basins in Jordan, which supplies Amman with drinking water. However, due to overpumping from the shallow groundwater aquifers, the water level dropped dramatically and signs of salinization and depletion are starting to occur. The severe drawdown in the Azraq well‐field caused a reverse in the hydraulic gradient and consequently, the saltwater in the center of the basin (Qa‐Azraq) started to move in the direction of the well‐field. The salinization in the shallow aquifer (basalt/B5/B4) is believed to result from one of the following scenarios: (i) a reverse flow from Sabkha to the AWSA well field, (ii) an upward leakage from the middle aquifer system (B2/A7) and the combined B3 Aquitard‐B2/A7 aquifer, (iii) a dissolution process between the water and rock matrix due to lowering of the dynamic water levels during pumping which reached the mineralized formations underlying the Basalt. The salinization trend of some AWSA wells represented by the gradual increase of major ions is associated with rather constant stable isotopic contents. This indicates that these constituents originate from the main minerals existing in the matrix of the aquifers and thus this scenario is the most likely to occur.