水文学: 現在の研究

Water is the vital resource on which life sustains and water becomes more valuable in this cold desert part of the northernmost region of India, called Ladakh which comprises of two districts, Leh and Kargil. Groundwater since ancient times in the form of springs provided ample water for the region and its contribution has increased manifold in the wake of recent spurt in bore well installations, especially, in Leh-Town. Due to increasing urbanization, with surge in a huge floating population in the absence of a sewerage link in summer tourism boom season, puts extra stress on the limited water resources of the area and with the rising living standards, grey and black water is being disposed off in the ground-pit or in septic tanks without any treatment. This may lead to pollution of groundwater resources especially, in the densely populated residential areas. For insuring sustainable development of groundwater, in the absence of any observation wells for constant monitoring of quality or quantity of groundwater and the unregulated installation of bore-wells makes this quality characterization very significant and helps in future management. The physico-chemical parameters like pH, electrical conductivity, turbidity, total dissolved solids, hardness, alkalinity, nitrates, fluoride, and chlorides were analyzed to meet the objective of the study. The results revealed that in general, the present status of groundwater quality is suitable for drinking purposes and out of 20 total samples evaluated, 75% of samples had NTU above desirable limit while 10% samples each recorded TDS and EC above desirable limits.

Geographic Information Systems (GIS) were used to establish an information data base to characterize a watershed in Northern Greece, analyze the distribution of the drainage network according to the different characteristics of the watershed using a drainage density index based on GIS. The drainage network was delineated from ASTER GDEM and Landsat-8 OLI data. Digital image processing was based on enhancement techniques. GIS characterized the watershed easily and efficiently. The drainage density index, based on the number of pixels, was appropriate for analyzing the distribution of the drainage network in relation to other characteristics of the watershed. The possibility of using GIS to generate buffer zones around linear and area features helped to quantify sensitive areas close to streams. The problem of cell resolution was overcome by reference to the mapping scale and other factors. Landsat-8 OLI data gave promising results, closely accurate to those from a 1:50,000 topographic maps. The number of streams and total stream lengths of all orders from ASTER GDEM data were higher than from the other sources. Geometric characteristics of the watershed derived from ASTER GDEM data were almost the same as from the 1:50,000 topographic maps. Best results were from a new band index based on Bands 2 and 5. Both techniques, GIS and Remote Sensing, are suitable for application to watershed management in the Mediterranean region.

In the flood prone catchments, it is needful to estimate the discharge, standard lag time, time of peak, and flood response of each watershed in the basin. The SUH method offers considerable advantage over others, and thus, has been chosen for estimation of flood response, contribution of flooding potential, percentage of flood volume for 25 sub-watersheds. The discretion of sub-watershed for estimation of peak discharge, time of peak, alternate lag time, and width of SUH at 50% and 75% of peak found to offer advantages over other methods. This paper considers Snyder Unit Hydrograph (SUH) with GIS based spatial database for calculating discharge at Lower Tapi Basin (LTB). The hydrological parameters of each sub-watershed such as river length, length of centroid, spatial area, land use, lateral slope, and terrain and soil factors have been extracted from GIS database. The geo-data has been combined with topographical maps to produce a digital elevation model (DEM) of 50 m cell size. The analysis for all 25 subwatersheds exhibit that 35.07 m3/s and 4.55 m3/s and 13.23 hours and 4.33 hours have been highest and lowest peak flow and time of peak respectively. The SUH model has been validated for peak discharge at a gauge site Amli (E73023' N21023') where discharge data were collected during 2010 and 2011 monsoon. A comparison between measured and SUH modelled discharge shows good fit within a mean variability range of 5-7%. The SUH methods ability to estimate hydrological parameters including peak flow discharge shows wider replication for un-gauged catchments.

High chlorine dosages are used in some drinking water plants to overcome the deficiencies in the treatment to at least ensure a supply of microbiologically safe water to the population. This fact and the increment of natural organic matter (NOM) in the aquatic resources due to rainfall increases and anthropogenic activities are becoming a critical concern, due to the formation of chlorination by-products such as trihalomethanes (THM), which are carcinogenic substances. Egypt drinking water system using new treatments is essential to meet the quality guidelines. Trihalomethanes are carcinogenic by-products of disinfection that are present in drinking water. In the present research, adsorption was employed for the removal of THMs found in water supply systems. The effects of pH, contact time, adsorbents and adsorbate concentration on the adsorption system were investigated. The Langmuir and Freundlich adsorption isotherm models were used to analyse the resulting adsorption data. The kinetics of THM removal was found to follow the pseudo-second-order model rather than the Langmuir–Hinshelwood pseudo-first-order model.

Calibrated Win TR-20 model was validated and simulated to predict the peak runoff rates for 2, 5, 10, 25, 50 and 100 years for a small watershed area of 72 km2 in the southern region of Khyber Pakhtunkhwa of Pakistan. The catchment has a gauged spillway outlet at the downstream. The model was initially calibrated on the available known parameters from the grid survey and its derivatives, watershed physical features and other scales endorsed into the reservoir for monitoring. The calibrated model was tested and validated on physical data collected for duration of three months with a coefficient of determination of 98% among the observed and estimated runoff depths and peak runoff. After confirmation log-Pearson type III distribution was fitted to annual one day maximum rainfall upon which one day maximum rainfalls for 2, 5, 10, 25, 50 and 100 years return periods were simulated as 50, 80, 105, 144, 180 and 223 mm respectively. Run off depths for the same one day maximum rainfall of given returns period were further simulated as 10.34, 21.15, 30.3, 39.78, and 84.03 and 53.14 mm. Moreover the peak runoff rates for the return periods of 2, 5, 10, 25, 50 and 100 years were predicted as 11.3, 39.9, 77.7, 147.5, 221.9, and 320 m3s-1. Hence it was concluded that Win TR-20 provided satisfactory simulation of rainfall and their resultant runoffs and peak runoff rates which can be confidently recommended for use in small watersheds in the specific region of Khyber Pakhtunkhwa.

Mean long-term hydrologic budget components, such as recharge and base flow, are often difficult to estimate because they can vary substantially in space and time. Mean long-term fluxes were calculated in this study for precipitation, surface runoff, infiltration, total evapotranspiration (ET), riparian ET, recharge, base flow (or groundwater discharge) and net total outflow using long-term estimates of mean ET and precipitation and the assumption that the relative change in storage over that 30-year period is small compared to the total ET or precipitation. Fluxes of these components were first estimated on a number of real-time-gaged watersheds across Virginia. Specific conductance was used to distinguish and separate surface runoff from base flow. Specific-conductance (SC) data were collected every 15 minutes at 75 real-time gages for approximately 18 months between March 2007 and August 2008. Precipitation was estimated for 1971-2000 using PRISM climate data. Precipitation and temperature from the PRISM data were used to develop a regression-based relation to estimate total ET. The proportion of watershed precipitation that becomes surface runoff was related to physiographic province and rock type in a runoff regression equation. A new approach to estimate riparian ET using seasonal SC data gave results consistent with those from other methods. Component flux estimates from the watersheds were transferred to flux estimates for counties and independent cities using the ET and runoff regression equations. Only 48 of the 75 watersheds yielded sufficient data, and data from these 48 were used in the final runoff regression equation. Final results for the study are presented as component flux estimates for all counties and independent cities in Virginia. The method has the potential to be applied in many other states in the U.S. or in other regions or countries of the world where climate and stream flow data are plentiful.

Taiwan spent too much expenditure to remove not very toxic metals Cu and Zn. The biosorption mechanism of metal removal (copper, Cu and zinc, Zn) by four phytoremediation macrophytes biomasses including sunflower (Helianthus annuus), Chinese cabbage (Brassica campestris), cattail (Typha latifolia), and reed (Phragmites communis) was investigated in this study. The primary objectives were exploring the potential of reusing these bio-wastes after harvesting from phytoremediation operations. Based on the surface area, zeta potential, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) investigations, Chinese cabbage biomass presented the highest metal adsorption property while both cattail and reed revealed a lower adsorption capability for both metals tested. The equilibrium adsorption rate between biomass and metal occurred very fast during the first 10 min. The metal adsorption data were fitted with the Langmuir and Freundlich isotherms and presented that the Langmuir isotherm was the best fitted model for all biomass tested. All tested biomasses are fast growing plants with fairly high biomass production that are able to accumulate metals. The Langmuir model was used to calculate maximum adsorption capacity and related adsorption parameters in this study. The results revealed that the maximum metal adsorption capacity Qmax was in the order of Chinese cabbage (Cu: 2000; Zn: 1111 mg/kg)> sunflower (Cu: 1482; Zn:769 mg/kg)> reed (Cu: 238; Zn: 161 mg/kg)> cattail (Cu: 200; Zn: 133 mg/kg). The harvested sunflower, Chinese cabbage, cattail, and reed biomass possess the potential to be employed as biosorbents to remove Cu and Zn from aqueous solutions. Adsorption isotherms derived in this study might be crucial information for practical design and operation of adsorption engineering processes and prediction of relation between reused macrophyte biosorbents and heavy metal adsorbates.

Constructing dams around the city of Tabuk is an important solution to controlling flood events, as well as increasing surface water budget and creating ground water recharge spots. The success of this effort is mainly based on locating the best site for a dam in the area. The aim of this study is to demonstrate the use of remote sensing, and geographic information system in dam site selection within the context of a catchment scale. Digital Elevation Model was used from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER 30m) to characterise the catchment area. Enhanced Thematic Mapper Plus images (ETM+) from LandSat 7 were used to classify the land cover in the study area. Several software packages such as ERDAS 11, Global Mapper 15.2 and ArcGIS 10.1 were used to construct and process the basic database. In addition, model builder from ArcGIS 10.1 was employed to construct a simplified model and integratesraster and vector datasets. The parameters of this model were: catchment slope (less 3%), delineation network order more than or equal to 7 and Runoff Coefficient (0.4). Six suitable locations were chosen: Wadi Dam in connection with Wadi Al Baqqr, Wadi Na’am, Wadi Atanah, Wadi Abu Nishayfah A, Wadi Abu Nishayfah B and Qa’a Sharawra.

This study is an initial stage in an effort to conserve groundwater by employing skills and self-reliance of groundwater user farmers where the groundwater is utilized to irrigate farm. Before carrying out community empowerment, specifically for marginal community, the researcher shall be able to recognize some factors that affect target's empowerment. Accordingly, empowerment model formulation which can be made representatively shall in conformity with reality to empowered target community. To examine level of influence of every observed factor in this study, it applies instrument through Gutmann scale. Scales of applied instrument in the study is answers of YES or NO. The instrument is adapted by vary educational background of the farmers. For all identified factors in the study, there are 6 factors that affect significantly groundwater user farmer empowerment level in their effort to conserve groundwater independently and collectively. Factors indicating significant influence are: (1) agricultural input, (2) environmental potential, (3) technical aid, (4) farmer organization, (5) farmers' rights and (6) democratization of farmers.

The present short review is an attempt to explain the importance and uses of arsenic. It also explains different researches which have been conducted for treatment of arsenic contamination; particularly the botanical tools or the plants. The paper also deals with the future prospects of the topic, guiding the future aspects.

Most water management methodologies require comprehensive studies and thus, entail voluminous data, time, and scientific expertise. Sensorial evaluation techniques were thus, considered as these represent methods with minimal cost and can involve the local communities. This study applied the Sarno River Visual Assessment Protocol (SRVAP), a modified version of the Stream Visual Assessment Protocol developed by the United States Department of Agriculture, to Sarno River, Italy and tested its reliability as a river assessment tool. SRVAP scores has a statistically significant positive correlation with Chemical Oxygen Demand (COD) and shows that local knowledge is important and increases the viability of incorporating public participation in the evaluation. Correlation between SRVAP and organic content greatly increased barring seasonal variability and a significant positive relationship was found between SRVAP score and Biochemical Oxygen Demand (BOD) and COD during spring, as well as during summer. The resulting regression equations may be used as rapid estimates of COD and BOD levels in Sarno River for the seasons of spring and summer.

The Nubian Sandstone complex in the western desert is a part of the major regional Nubian aquifer system comprising West Africa. The different rock strata deposited in localities forming the units of the aquifer system. Farafra Oasis lies in the northern part of the Dakhla basin. In its southern region, the Nubian Sandstone (deep aquifer) is overlained by Dakhla shale but in the central and northern regions by fissured chalky limestone (shallow aquifer). The two overlaying aquifers in Farafra Oasis represent a typical hydrogeological model of a huge multi-layered artesian basin extending over the territory of Egypt. The Post Nubian aquifer played an essential role in the development of Farafra Oasis for a long time through the many springs issued from this aquifer. The rapid drilling process of deep wells started in 1960s led to stop flowing of many springs and wells plus the depletion in discharges and pressure of many others. Therefore, there is a real danger of either dewatering or increasing the water depths to uneconomic lifting depths for both the shallow and deep aquifers. A two-dimension flow model GMS (Groundwater Modeling System) was used to investigate this problem. Application of the present conditions indicated that drawdowns in the Post Nubian aquifer range from 5 m to about 9 m. The second scenario tries to sustain the groundwater utilities in the Post Nubian aquifer through a group of procedures. Accordingly, drawdowns are expected to range from 5 m to 8.6 m in the Post Nubian aquifer. According to this scenario, 3 m decline in the Nubian Sandstone aquifer followed by declining in the Post Nubian by about 1 m.