Surface Water Diversions Research Articles

Impacts of water saving on groundwater balance in a large-scale arid irrigation district, Northwest China

Water saving practices are essential for sustainable use of water resources in semiarid regions. To understand the impacts of different water saving measures on groundwater resources, the Hetao Irrigation District in Northwest China was chosen in this study. Based on the data from 1991 to 2010, a groundwater balance model was calibrated and validated. The simulation results showed that irrigation-induced infiltration (92 % of the total groundwater recharge) and groundwater evaporation (92 % of the total groundwater discharge) were the primary factors controlling groundwater table fluctuations during irrigation seasons. The impacts of different water saving scenarios on groundwater balance components were then evaluated. The results revealed that the conjunctive use of water resources was the most effective way to improve water use efficiency (reducing surface water diversions by 52 %) and the depth to groundwater table increased by up to 79 cm. However, deeper groundwater tables may have a negative effect on crop growth due to reduced upward fluxes of groundwater into root zones. Therefore, future studies are needed to evaluate the impacts of different water saving measures on both water resources and crop yields. The results of this study provide further insights into effectively managing water resources in water-limited agricultural areas.

Diel Surface Temperature Range Scales with Lake Size.

Ecological and biogeochemical processes in lakes are strongly dependent upon water temperature. Long-term surface warming of many lakes is unequivocal, but little is known about the comparative magnitude of temperature variation at diel timescales, due to a lack of appropriately resolved data. Here we quantify the pattern and magnitude of diel temperature variability of surface waters using high-frequency data from 100 lakes. We show that the near-surface diel temperature range can be substantial in summer relative to long-term change and, for lakes smaller than 3 km2, increases sharply and predictably with decreasing lake area. Most small lakes included in this study experience average summer diel ranges in their near-surface temperatures of between 4 and 7°C. Large diel temperature fluctuations in the majority of lakes undoubtedly influence their structure, function and role in biogeochemical cycles, but the full implications remain largely unexplored.

Economic and Water Supply Effects of Ending Groundwater Overdraft in California's Central Valley

doi: http://dx.doi.org/10.15447/sfews.2016v14iss1art7 Surface water and groundwater management are often tightly linked, even when linkage is not intended or expected. This link is especially common in semi-arid regions, such as California. This paper summarizes a modeling study on the effects of ending long-term overdraft in California’s Central Valley, the state’s largest aquifer system. The study focuses on economic and operational aspects, such as surface water pumping and diversions, groundwater recharge, water scarcity, and the associated operating and water scarcity costs. This analysis uses CALVIN, a hydro-economic optimization model for California’s water resource system that suggests operational changes to minimize net system costs for a given set of conditions, such as ending long-term overdraft. Based on model results, ending overdraft might induce some major statewide operational changes, including large increases to Delta exports, more intensive conjunctive-use operations with increasing artificial and in-lieu recharge, and greater water scarcity for Central Valley agriculture. The statewide costs of ending roughly 1.2 maf yr-1 of groundwater overdraft are at least $50 million per year from additional direct water shortage and additional operating costs. At its worst, the costs of ending Central Valley overdraft could be much higher, perhaps comparable to the recent economic effects of drought. Driven by recent state legislation to improve groundwater sustainability, ending groundwater overdraft has important implications statewide for water use and management, particularly in the Sacramento–San Joaquin Delta. Ending Central Valley overdraft will amplify economic pressure to increase Delta water exports rather than reduce them, tying together two of California’s largest water management problems.

Comparative study of the composition and genetic diversity of the picoeukaryote community in a Chinese aquaculture area and an open sea area

Picoeukaryotes (<2–3 μm) perform key roles for the functioning of marine ecosystems, but little is known regarding the composition and diversity of picoeukaryotes in aquaculture areas. In this study, the Illumina MiSeq platform was used for sequencing the V4 variable region within the 18S rDNA gene to analyse genetic diversity and relative abundance of picoeukaryotic communities in the Qinhuangdao scallop cultivation area of the Bohai Sea. The community was dominated by three super groups, the alveolates (54%), stramenopiles (41%) and chlorophytes (3%), and three groups, dinoflagellates (54%), pelagomonadales (40%) and prasinophytes (3%). Furthermore, a contrasting station with open water away from the eutrophic aquaculture area was chosen. The communities collected from the two stations exhibited significant differences, with higher diversity in the aquaculture area. These results provide the first snapshot of the picoeukaryotic diversity in surface waters of the Qinhuangdao scallop cultivation area, and basic data for future studies on picoeukaryote community in an aquaculture region.

Effect of Fluctuating Salinity on Potential Denitrification in Coastal Wetland Soil and Sediments

The coastal wetlands of southern Louisiana provide an ideal environment for removing nitrate (NO₃⁻) from the Mississippi River before discharge into the Gulf of Mexico where it can contribute to hypoxia. However, denitrification, the primary mechanism of excess N removal, may be sensitive to the fluctuating salinities that characterize coastal wetlands. Salinity can shift from salt to fresh during river inflows, or from fresh to salt during storm surge events. This study investigated the impact of shifting salinity on potential denitrification rates in marsh soils and bayou sediments from the fresh and salt marshes of Brenton Sound estuary. Potential denitrification rates were quantified using bottle incubations for both short-term (2 d), and longer-term (11 d) studies. Fresh marsh sites had higher denitrification enzyme activity (DEA), but all soils and sediments achieved high denitrification when exposed to ideal conditions. Pulses of freshwater (0 ppt) in salt marsh soils decreased potential denitrification rates by 98% for an 11-d study, indicating the rapid opening of a freshwater diversion could significantly reduce that ability of coastal wetlands to provide significant nutrient-removal before discharge to the coastal ocean. Pulses of intermediate salinity (15 ppt) water stimulated denitrification rates in the fresh marsh soil by 75%, while full salinity seawater (35 ppt) suppressed potential denitrification by 73% for 11 d. This research demonstrates the sensitivity of the denitrifying microbial consortia to rapid shifts in salinity and this information can be used to guide water managers on maximizing NO₃⁻ removal in Mississippi River surface water diversions.

English

The distribution of trace metals (Zn, Cu, Ni, Mn, Fe, Co, V, Pb and Cd) in surface water and sediments from Imo River estuary in relation with the physicochemical variables were studied for both dry and wet seasons. The results obtained revealed that trace metal levels displayed marked spatial and seasonal variations in surface water and sediments, which is attributed to both anthropogenic natural processes in the environment. Trace metal levels were generally higher in the sediments than overlying water column. Seasonal variability in trace metal distribution was mostly observed in sediments than in the water phase of the relatively anoxic estuarine ecosystem. The highest average concentration of trace metal in the sediments was recorded for Fe (1101.18 mg/kg) during the dry season while the lowest was recorded for Cd (0.08 mg/kg) during the wet season. For the surface water, highest average concentration was recorded for Zn (0.04 mg/L) for the dry season and the lowest level was recorded for Cd (0.002 mg/L) for both seasons. The levels of trace metals in the water were within the permissible limits of some regulatory bodies. Pearson correlation analysis revealed that some of the physicochemical variables were associated with patterns of trace metals distribution. Based on trace metal concentrations, the health risk assessment based on the chronic daily intake (CDI) and hazard quotients (HQ) were calculated. Zinc and cadmium contributed most to the total intake through drinking water. As HQ for all trace metals were less than unity, it is suggested that there is little or no significant health risk to the exposed population. Key words: Trace metals, surface water, sediments, seasons, Imo River estuary, Nigeria.

浅水状態の桟粗度乱流場における水面変動のパターン変化に関する画像計測による検討

In shallow water conditions, open-channel flows are subject to the influence of channel bottom roughness because the boundary layer or vortices generated at the bottom interact with water surface. Such an influence become more pronounced when the bottom is composed of discrete roughness such as a strip roughness. In the present study, water surface variations were investigated experimentally by varying the water depth relative to the roughness height. Although the water surface is kept almost horizontal for a relatively large depth of water, it tends to show significant differences with decrease of water depth. As an example, the water surface exhibits three dimensional topographical features with various arrangement of lumps depending on hydraulic conditions. Moreover, water surface begins to oscillate quite periodically with a hydraulic jump under specific hydraulic conditions. A new image analysis technique was developed to capture such surface flow features.

Algae metabolism and organic carbon in sediments determining arsenic mobilisation in ground- and surface water. A field study in Doñana National Park, Spain.

A study has been performed to explore the origin, spatiotemporal behaviour and mobilisation mechanism of the elevated arsenic (As) concentrations found in ground water and drinking ponds of the Doñana National Park, Southern Spain. At a larger scale, 13 piezometers and surface water samples of about 50 artificial drinking ponds and freshwater lagoons throughout the National Park were collected and analysed for major ions, metals and trace elements. At a smaller scale, 5 locations were equipped with piezometers and groundwater was sampled up to 4 times for ambient parameters, major ions, metals, trace elements and iron (Fe) speciation. As was analysed for inorganic and organic speciation. Undisturbed sediment samples were analysed for physical parameters, mineralogy, geochemistry as well as As species. Sediment analyses yielded total As between 0.1 and 18mg/kg and are not correlated with As concentration in water. Results of the surface- and groundwater sampling revealed elevated concentration of As up to 302μg/L within a restricted area of the National Park. Results of groundwater sampling reveals strong correlation of As with Fe2+ pointing to As mobilisation due to reductive dissolution of hydroferric oxides (HFO) in areas of locally elevated amounts of organic matter within the sediments. High As concentrations in surface water ponds are correlated with elevated alkalinity and pH attributed to algae metabolism, leading to As desorption from HFO. The algae metabolism is responsible for the presence of methylated arsenic species in surface water, in contrast to ground water in which only inorganic As species was found. Temporal variations in surface water and groundwater are also related to changes in pH and alkalinity as a result of enhanced algae metabolism in surface water or related to changes in the redox level in the case of groundwater.

Wind and sunlight shape microbial diversity in surface waters of the North Pacific Subtropical Gyre.

Few microbial time-series studies have been conducted in open ocean habitats having low seasonal variability such as the North Pacific Subtropical Gyre (NPSG), where surface waters experience comparatively mild seasonal variation. To better describe microbial seasonal variability in this habitat, we analyzed rRNA amplicon and shotgun metagenomic data over two years at the Hawaii Ocean Time-series Station ALOHA. We postulated that this relatively stable habitat might reveal different environmental factors that influence planktonic microbial community diversity than those previously observed in more seasonally dynamic habitats. Unexpectedly, the data showed that microbial diversity at 25 m was positively correlated with average wind speed 3 to 10 days prior to sampling. In addition, microbial community composition at 25 m exhibited significant correlations with solar irradiance. Many bacterial groups whose relative abundances varied with solar radiation corresponded to taxa known to exhibit strong seasonality in other oceanic regions. Network co-correlation analysis of 25 m communities showed seasonal transitions in composition, and distinct successional cohorts of co-occurring phylogenetic groups. Similar network analyses of metagenomic data also indicated distinct seasonality in genes originating from cyanophage, and several bacterial clades including SAR116 and SAR324. At 500 m, microbial community diversity and composition did not vary significantly with any measured environmental parameters. The minimal seasonal variability in the NPSG facilitated detection of more subtle environmental influences, such as episodic wind variation, on surface water microbial diversity. Community composition in NPSG surface waters varied in response to solar irradiance, but less dramatically than reported in other ocean provinces.

Water availability and land subsidence in the Central Valley, California, USA

The Central Valley in California (USA) covers about 52,000 km2 and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and subsidence. During recent drought periods (2007–2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and subsidence that likely is mostly permanent. The subsidence has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued subsidence in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and subsidence monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated subsidence. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to subsidence while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.

Holocene sea subsurface and surface water masses in the Fram Strait – Comparisons of temperature and sea-ice reconstructions

Two high-resolution sediment cores from eastern Fram Strait have been investigated for sea subsurface and surface temperature variability during the Holocene (the past ca 12,000 years). The transfer function developed by Husum and Hald (2012) has been applied to sediment cores in order to reconstruct fluctuations of sea subsurface temperatures throughout the period. Additional biomarker and foraminiferal proxy data are used to elucidate variability between surface and subsurface water mass conditions, and to conclude on the Holocene climate and oceanographic variability on the West Spitsbergen continental margin . Results consistently reveal warm sea surface to subsurface temperatures of up to 6 °C until ca 5 cal ka BP, with maximum seawater temperatures around 10 cal ka BP, likely related to maximum July insolation occurring at that time. Maximum Atlantic Water (AW) advection occurred at surface and subsurface between 10.6 and 8.5 cal ka BP based on both foraminiferal and dinocyst temperature reconstructions. Probably, a less-stratified, ice-free, nutrient-rich surface ocean with strong AW advection prevailed in the eastern Fram Strait between 10 and 9 cal ka BP. Weakened AW contribution is found after ca 5 cal ka BP when subsurface temperatures strongly decrease with minimum values between ca 4 and 3 cal ka BP. Cold late Holocene conditions are furthermore supported by high planktic foraminifer shell fragmentation and high δ 18 O values of the subpolar planktic foraminifer species Turborotalita quinqueloba . While IP 25 -associated indices as well as dinocyst data suggest a sustained cooling due to a decrease in early summer insolation and consequently sea-ice increase since about 7 cal ka BP in surface waters, planktic foraminiferal data including stable isotopes indicate a slight return of stronger subsurface AW influx since ca 3 cal ka BP. The observed decoupling of surface and subsurface waters during the later Holocene is most likely attributed to a strong pycnocline layer separating cold sea-ice fed surface waters from enhanced subsurface AW advection. This may be related to changes in North Atlantic subpolar versus subtropical gyre activity. • Holocene sea subsurface temperatures after Husum & Hald (2012) estimated from planktic foraminifer fauna in E Fram Strait. • Biomarkers and IP25-derived indices (including DIP25) indicate surface water variability. • Delayed onset of early Holocene conditions in subsurface (∼10.6 ka) compared to surface (∼11.7 ka) water conditions. • Warm Atlantic layer likely occupied uppermost 200 m in eastern Fram Strait between 10 and 9 ka. • Diverging late Holocene trends in surface and subsurface conditions linked to presence of strong pycnocline/stratification.

Spatio‐Temporal Patterns of Open Surface Water in the Central Valley of California 2000‐2011: Drought, Land Cover, and Waterbirds

AbstractWe used Landsat satellite imagery to (1) quantify the distribution of open surface water across the Central Valley of California 2000‐2011, (2) summarize spatio‐temporal variation in open surface water during this time series, and (3) assess factors influencing open surface water, including drought and land cover type. We also applied the imagery to identify available habitat for waterbirds in agriculture. Our analyses indicated that between 2000 and 2011 open surface water has declined across the Central Valley during the months of July‐October. On average, drought had a significant negative effect on open surface water in July, September, and October, though the magnitude and timing of the effect varied spatially. The negative impact of a drought year on open water was experienced immediately in the southern Central Valley; however, there was a one year time‐lag effect in the northern Central Valley. The highest proportion of open surface water was on agricultural lands followed by lakes, rivers, and streams, yet the relative proportions varied spatially and across months. Our data were consistent with previous descriptions of waterbird habitat availability in post‐harvest rice in the northern Central Valley. Tracking water distribution using satellites enables empirically based assessments of the impacts of changing water policy, land‐use, drought, climate, and management on water resources.

Mediterranean Outflow and surface water variability off southern Portugal during the early Pleistocene: A snapshot at Marine Isotope Stages 29 to 34 (1020–1135 ka)

Centennial-to-millennial scale records from IODP Site U1387, drilled during IODP Expedition 339 into the Faro Drift at 558m water depth, now allow evaluating the climatic history of the upper core of the Mediterranean Outflow (MOW) and of the surface waters in the northern Gulf of Cadiz during the early Pleistocene. This study focuses on the period from Marine Isotope Stages (MIS) 29 to 34, i.e. the interval surrounding extreme interglacial MIS 31. Conditions in the upper MOW reflect obliquity, precession and millennial-scale variations. The benthic δ18O signal follows obliquity with the exception of an additional, smaller δ18O peak that marks the MIS 32/31 transition. Insolation maxima (precession minima) led to poor ventilation and a sluggish upper MOW core, whereas insolation minima were associated with enhanced ventilation and often also increased bottom current velocity. Millennial-scale periods of colder sea-surface temperatures (SST) were associated with short-term maxima in flow velocity and better ventilation, reminiscent of conditions known from MIS 3. A prominent contourite layer, coinciding with insolation cycle 100, was formed during MIS 31 and represents one of the few contourites developing within an interglacial period. MIS 31 surface water conditions were characterized by an extended period (1065–1091ka) of warm SST, but SST were not much warmer than during MIS 33. Interglacial to glacial transitions experienced 2 to 3 stadial/interstadial cycles, just like their mid-to-late Pleistocene counterparts. Glacial MIS 30 and 32 recorded periods of extremely cold (<12°C) SST that in their climatic impact were comparable with the Heinrich events of the mid and late Pleistocene. Glacial MIS 34, on the other hand, was a relative warm glacial period off southern Portugal. Overall, surface water and MOW conditions at Site U1387 show a strong congruence with Mediterranean climate, whereas millennial-scale variations are closely linked to North Atlantic circulation changes.

Free-Surface Flow Over River Bottom Sill: Experimental and Numerical Study

This paper reports on a laboratory study that was performed in an experimental model in the Technological Educational Institute of Thessaly. The current research work examines the water surface profile variation in abruptly altered open channel topography. The objective is to investigate the effects of river bottom sills on flow depth for river control protection against floods. A rectangular bottom sill with one edge rounded was placed on the bottom of a rectangular, horizontal, laboratory open flume and measurements were performed of free-surface flow depth over the bottom sill, under steady flow conditions, for different inflow discharges. Moreover, the HEC-RAS simulation model was used to numerically simulate the water surface variation over the rectangular bottom sill, under steady flow conditions. A mixed flow regime simulation was performed in order to validate the transition from subcritical to supercritical flow conditions. The computed flow depth variation over the rectangular bottom sill was compared with the obtained experimental measurements in order to demonstrate the accuracy of the performed measurements. The presented experimental data may be used to assist in the development of new and the verification and refinement of existing river hydraulic numerical simulation models, particularly those which use non-hydrostatic pressure distribution.

Seasonality in molecular and cytometric diversity of marine bacterioplankton: the re-shuffling of bacterial taxa by vertical mixing.

The 'cytometric diversity' of phytoplankton communities has been studied based on single-cell properties, but the applicability of this method to characterize bacterioplankton has been unexplored. Here, we analysed seasonal changes in cytometric diversity of marine bacterioplankton along a decadal time-series at three coastal stations in the Southern Bay of Biscay. Shannon-Weaver diversity estimates and Bray-Curtis similarities obtained by cytometric and molecular (16S rRNA tag sequencing) methods were significantly correlated in samples from a 3.5 year monthly time-series. Both methods showed a consistent cyclical pattern in the diversity of surface bacterial communities with maximal values in winter. The analysis of the highly resolved flow cytometry time-series across the vertical profile showed that water column mixing was a key factor explaining the seasonal changes in bacterial composition and the winter increase in bacterial diversity in coastal surface waters. Due to its low cost and short processing time as compared with genetic methods, the cytometric diversity approach represents a useful complementary tool in the macroecology of aquatic microbes.

Hydrologic Modeling in a Marsh–Mangrove Ecotone: Predicting Wetland Surface Water and Salinity Response to Restoration in the Ten Thousand Islands Region of Florida, USA

AbstractAt the fringe of Everglades National Park in southwest Florida, United States, the Ten Thousand Islands National Wildlife Refuge (TTINWR) habitat has been heavily affected by the disruption of natural freshwater flow across the Tamiami Trail (U.S. Highway 41). As the Comprehensive Everglades Restoration Plan (CERP) proposes to restore the natural sheet flow from the Picayune Strand Restoration Project area north of the highway, the impact of planned measures on the hydrology in the refuge needs to be taken into account. The objective of this study was to develop a simple, computationally efficient mass balance model to simulate the spatial and temporal patterns of water level and salinity within the area of interest. This model could be used to assess the effects of the proposed management decisions on the surface water hydrological characteristics of the refuge. Surface water variations are critical to the maintenance of wetland processes. The model domain is divided into 10 compartments on the b...

Spatial and temporal variability of surface water and groundwater before and after the remediation of a Portuguese uranium mine area

The old Senhora das Fontes uranium mine, in central Portugal, consists of quartz veins which penetrated along fracture shear zones at the contact between graphite schist and orthogneiss. The mine was exploited underground until a depth of 90m and was closed down in 1971. The ores from this mine and two others were treated in the mine area by the heap-leach process which ended in 1982. Seven dumps containing a total of about 33,800m3 of material and partially covered by natural vegetation were left in the mine area. A remediation process took place from May 2010 to January 2011. The material deposited in dumps was relocated and covered with erosion resisting covers. Surface water and groundwater were collected in the wet season just before the remediation, in the following season at the beginning of the remediation and also after the remediation in the following dry season. Before, at the beginning and after the remediation, surface water and groundwater have an acid-to-alkaline pH, which decreased with the remediation, whereas Eh increased. In general, before the remediation, uranium concentration was up to 83μg/L in surface water and up to 116μg/L in groundwater, whereas at the beginning of the remediation it increases up to 183μg/L and 272μg/L in the former and the latter, respectively, due to the remobilization of mine dumps and pyrite and chalcopyrite exposures, responsible for the pH decrease. In general, after the remediation, the U concentration decreased significantly in surface water and groundwater at the north part of the mine area, but increased in both, particularly in the latter up to 774μg/L in the south and southwest parts of this area, attributed to the remobilization of sulphides that caused mobilization of metals and arsenic which migrated to the groundwater flow. Uranium is adsorbed in clay minerals, but also in goethite as indicated by the geochemical modelling. After the remediation, the saturation indices of oxyhydroxides decrease as pH decreases. The remediation also caused decrease in Cd, Co, Cr, Ni, Pb, Zn, Cu, As, Sr and Mn concentrations of surface water and groundwater, particularly in the north part of the mine area, which is supported by the speciation modelling that shows the decrease of most dissolved bivalent species. However, in general, after the remediation, Th, Cd, Al, Li, Pb, Sr and As concentrations increased in groundwater and surface water at south and southwest of the mine area. Before and after the remediation, surface water and groundwater are contaminated in U, Cd, Cr, Al, Mn, Ni, Pb, Cu and As. Remediation caused only some improvement at north of the mine area, because at south and southwest part, after the remediation, the groundwater is more contaminated than before the remediation.

Effects of salinity variations on pore water flow in salt marshes

AbstractSpatial and temporal salinity variations in surface water and pore water commonly exist in salt marshes under the combined influence of tidal inundation, precipitation, evapotranspiration, and inland freshwater input. Laboratory experiments and numerical simulations were conducted to investigate how density gradients associated with salinity variations affect pore water flow in the salt marsh system. The results showed that upward salinity (density) gradients could lead to flow instability and the formation of salt fingers. These fingers, varying in size with the distance from the creek, modified significantly the pore water flow field, especially in the marsh interior. While the flow instability enhanced local salt transport and mixing considerably, the net effect was small, causing only a slight increase in the overall mass exchange across the marsh surface. In contrast, downward salinity gradients exerted less influence on the pore water flow in the marsh soil and slightly weakened the surface water and groundwater exchange across the marsh surface. Numerical simulations revealed similar density effects on pore water flow at the field scale under realistic conditions. These findings have important implications for studies of marsh soil conditions concerning plant growth as well as nutrient exchange between the marsh and coastal marine system.

Investigation of Ground Water Quality of Upstream Water Tanks in Coimbatore Using GIS: A Review

Coimbatore city, the head quarters of Coimbatore District is located on the bank of Noyyal River in Tamil Nadu state. It lies between 10 ° 13’ N and 11 ° 23’ N latitudes and 76 ° 39’ E and 77 ° 30’ E longitudes with a total geographical area of about 7469 km2.Water is the basic element of social and economic infrastructure and is essential for a healthy society and sustainable development .Coimbatore is one of the major developing citiesin India .Ground water is being the favourite alternative to water provided through taps,is facing threats due to anthropogenic activities in India, which has led to deterioration of ground water quality. In addition to the source contamination,urbanization and improper disposal of solid wastes lead to contamination of groundwater and surface water resources in this region. Municipal and industrial wastes of the city are presently disposed at four distinct open tanks namely Narasampathy, Krishnampathy, Selvampathyand Kumaraswamy/(muthannankulam) tanks. The leaches of these wastes directly contaminate the groundwater and surface water resources leading unsuitability of water for drinking at many places. Hence, a detailed study has been carried out using Geographical Information System (GIS) to understand the spatial variation of surface water and groundwater quality. About sixteen groundwater samples and sixteen surface water samples are to be collected during monsoon and post monsoon periods of the year – 2014&amp; 2015 from the study region, and the samples have to be analyzed for various physical and chemical parameters such as pH, Electrical Conductivity, Total Dissolved Solids, Alkalinity,Hardness, Na+, K+, Ca2+, Mg2+, Cl•, HCO3•, CO32•, SO4, NO3 and F. The concentrations of physical and chemical constituents inthe water samples are going to compared with the Bureau of Indian Standard (BIS) and World Health Organization (WHO) standard to know the suitability of water for drinking.The study indicates that the water quality parameters exceed the permissible limits fordrinking at many locations leading the water unsuitable for drinking. The spatial variation of groundwater quality parameters is also yet to be plotted using GIS.

Variations in China's terrestrial water storage over the past decade using GRACE data

Variations in China's terrestrial water storage from March 2003 to February 2013 were determined using data from the Gravity Recovery and Climate Experiment (GRACE) monthly gravity field model provided by the Center for Space Research. The results were compared with the variations in surface water estimated using the Global Land Data Assimilation System (GLDAS) hydrological model. The results indicated a decline in terrestrial water storage in the Shanxi and Xinjiang Tianshan regions over the past decade with a downward trend that reached −7.76 ± 0.71 mm/a and −5.8 ± 0.67 mm/a, respectively. Anthropogenic activities were considered to be the major cause of this terrestrial water loss (especially groundwater) in these regions. In contrast, the intersection of the Xinjiang and Tibet Autonomous Regions and the Qinghai Province showed an upward trend in the terrestrial water storage at a rate of 9.06 ± 0.37 mm/a, which is closely related to the high-quality local ecological environment and lack of human activities. At the intersections between the Chongqing, Guizhou, and Hunan Provinces and between the Jiangxi, Zhejiang, and Fujian Provinces, the terrestrial water storage increased at rates of 7.86 ± 0.9 and 8.68 ± 0.8 mm/a, respectively. These two regions received abundant annual precipitation; moreover, there was no considerable variation in the amount of groundwater storage over the past decade. In addition, the empirical orthogonal function (EOF) method used in this study could eliminate correlated errors in the GRACE monthly gravity field model more effectively than the traditional polynomial fitting method, and it did not generate false signals.