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1.
Lake Qinghai, the largest saline lake with an area of 4,260 km2 (2000) and average depth of 21 m (1985) in West China, has experienced severe decline in water level in recent decades. This study aimed to investigate water balance of the lake and identify the causes for the decline in lake level. There was a 3.35-m decline in water level with an average decreasing rate of 8.0 cm year−1 between 1959 and 2000. The lake water balance showed that mean annual precipitation between 1959 and 2000 over the lake was 357 ± 10 mm, evaporation was 924 ± 10 mm, surface runoff water inflow was 348 ± 21 mm, groundwater inflow was 138 mm ± 9 and the change in lake level was −80 ± 31 mm. The variation of lake level was highly positively correlated to surface runoff and precipitation and negatively to evaporation, the correlation coefficients were 0.89, 0.81 and −0.66, respectively. Water consumption by human activities accounts for 1% of the evaporation loss of the lake, implying that water consumption by human activities has little effect on lake level decline. Most dramatic decline in lake level occurred in the warm and dry years, and moderate decline in the cold and dry years, and relatively slight decline in the warm and wet years, therefore, the trend of cold/warm and dry climate in recent decades may be the main reasons for the decline in lake level.  相似文献   

2.
The Lebanese coast is highly subject to seawater intrusion and groundwater deterioration. The study is carried out in Byblos district (Jbeil Caza) 35 km north of Beirut. It aims to investigate the seawater intrusion, to determine the regional water balance of the region and finally to estimate the economic value of that water for agricultural use. The monitoring of the aquifer was achieved through samples from different wells chosen randomly. As for the regional water balance, it was determined with use of a GIS model. The economic evaluation was carried out, using the contingent valuation method to estimate the willingness to pay of farmers to contribute to the improvement of groundwater quality; two alternative scenarios were proposed and compared with the current situation. The annual regional water balance is positive, which means that the region is rich in water. The monitoring results show that the coastal part of the region is slightly contaminated by seawater intrusion due to the excess of pumping from the aquifer. The economic evaluation estimated that farmers would contribute by 102 US$ yr − 1 for the first proposal and 166.67 US$ yr − 1 for the second.  相似文献   

3.
Treated wastewater (TWW) reuse has increasingly been integrated in the planning and development of water resources in Tunisia. The present study aimed the evaluation of the environmental and health impact that would have the reuse of TWW for crops direct irrigation or for the recharge of the local aquifer in Korba (Tunisia). For this purpose water analyses were carried on the TWW intended for the aquifer recharge and on underground water of this area. As for underground water before recharge, no contamination by organic matter or heavy metals is shown but high salinity, nitrate, potassium and chloride concentrations are detected. The bacteriological analyses show the occurrence of faecal streptococcus, thermo-tolerant coliforms, total coliforms and E coli, but absence of salmonella. These results indicate that this water is not suitable for irrigation worse still for drinking purpose. The monitoring of TWW pollutants has demonstrated that oxygen demands (COD and BOD) do not exceed the Tunisian standards for TWW used in agriculture (NT 106.03) except for August when samples reach high values (COD = 139 mg O2 L − 1, BOD = 34). It is also the case for temperature, electrical conductivity (EC), salinity and pH. Heavy metal concentrations are under the detection limit. The determination of nutrients shows relatively low concentrations of nitrates, nitrites and orthophosphate (the maxima in mg L − 1 are respectively 6.6, 5.6 and 0.92) whereas the potassium levels are high (up to 48.8 mg L − 1) and the ammonia levels very high, reaching 60.6 mg L − 1. As for bacteriological pollution, while no salmonella and intestinal nematods are detected, high concentrations of total coliforms, thermo-tolerant coliforms, faecal streptococci and E. coli are analysed. Consequently, the better use of TWW in this region would be the use of infiltration basins for the recharge of the deteriorated aquifer by TWW. It would give the opportunity to better the quality of the TWW reaching the groundwater by an additional treatment for bacteriological and suspended solid (TSS) contaminants while being an alternative water for the aquifer recharge and a coastal barrier against seawater intrusion.  相似文献   

4.
An estimation of the crop water requirements for the Pontina Plain, Central Italy, was carried out through the use of remote sensing land classification and application of a simple water balance scheme in a GIS environment. The overall crop water demand for the 700 km2 area was estimated at about 70 Mm3 year − 1, i.e. 100 Mm3 year − 1 irrigation requirements when considering an average irrigation application efficiency of 70%. The simplest and least demanding available methodology, in terms of data and resources, was chosen. The methodology, based on remote sensing and GIS, employed only 4 Landsat ETM+ images and a few meteorological and geographical vectorial layers. The procedure allowed the elaboration of monthly maps of crop evapotranspiration. The application of a spatially distributed simple water balance model, lead to the estimation of temporal and spatial variation of crop water requirements in the study area. This study contributes to fill a gap in the knowledge on agricultural use of water resources in the area, which is essential for the implementation of a sustainable and sound water policy as required in the region for the application of the EU Water Framework Directive.  相似文献   

5.
A dynamic systems simulation model of water resources was developed as a tool to help analyze alternatives to water resources management for the Piracicaba, Capivari and Jundiaí River Water Basins (RB-PCJ), and used to run six 50-year simulations from 2004 to 2054. The model estimates water supply and demand, as well as contamination load by several consumers. Six runs were performed using a constant mean precipitation value, changing water supply and demand and different volumes diverted from RB-PCJ to RB-Alto Tietê. For the Business as Usual scenario, the Sustainability Index went from 0.44 in 2004 to 0.20 by 2054. The Water Sustainability Index changed from 74% in 2004 to 131% by 2054. The Falkenmark Index changed from 1,403 m3 person − 1 year − 1 in 2004 to 734 m3 person − 1 year − 1 by 2054. We concluded that sanitation is one of the major problems for the PCJ River Basins.  相似文献   

6.
In this study, the revised Remote Sensing-Penman Monteith model (RS-PM) was used to scale up evapotranspiration (ET) over the entire Yukon River Basin (YRB) from three eddy covariance (EC) towers covering major vegetation types. We determined model parameters and uncertainty using a Bayesian-based method in the three EC sites. The 95 % confidence interval for the aggregate ecosystem ET ranged from 233 to 396 mm yr−1 with an average of 319 mm yr−1. The mean difference between precipitation and evapotranspiration (W) was 171 mm yr−1 with a 95 % confidence interval of 94–257 mm yr−1. The YRB region showed a slight increasing trend in annual precipitation for the 1982–2009 time period, while ET showed a significant increasing trend of 6.6 mm decade−1. As a whole, annual W showed a drying trend over YRB region.  相似文献   

7.
A regional hydrogeological study was carried out in the Maritimes provinces, in one of the main aquifer systems in Canada. The study area covers a land surface of 10,500 km2, of which 9,400 km2 is over Carboniferous and younger rocks. The sedimentary fractured bedrock is composed of a sequence of discontinuous strata of highly variable hydraulic properties, and is overlain by a thin layer of glacial till (mostly 4 to 8 m). Depending on areas, 46 to 100% of the population relies on groundwater for water supply. Almost all residential wells are shallow (28 m on average) open holes that are cased only through the surficial sediments. This paper describes a regional hydrogeological investigation based on targeted fieldwork, the integration of a wide variety of existing multisource datasets and groundwater flow numerical modelling. The aim of this paper is to present the current state of understanding of the aquifer system in a representative area of the Maritimes Basin, along with the methodology used to characterize and analyze its distinct behaviour at the regional, local and point scales. This regional hydrogeological system contains confined and unconfined zones, and its aquifer lenticular strata extend only a few kilometers. Preferential groundwater recharge occurs where sandy tills are present. The estimated mean annual recharge rate to the bedrock aquifers ranges between 130 and 165 mm/year. Several geological formations of this Basin provide good aquifers, with hydraulic conductivity in the range of 5 × 10−6 to 10−4 m/s. Based on numerical flow modelling, faults were interpreted to play a key role in the regional flow. Pumping test results revealed that the aquifers can locally be very heterogeneous and anisotropic, but behave similarly to porous media. Work performed at the local scale indicated that most water-producing fractures generally have a sub-horizontal dip along a north-east (45°) strike.  相似文献   

8.
Integrated water resources management at river basin scales and evaluation of effects of climate change on regional water resources require quantitative estimates of space-time variability of monthly discharges within a river network. This study demonstrates that such estimates, which can be called stream water availability, for regional river basins with meager or nonexistent gauge data, can be obtained by combining continuity models of hydrological processes, flow routing, and topology of the river basin. The hydrologic processes can be adequately modeled using high quality databases of hydrologic significance. A stream water availability model is presented for Upper Indus Basin (UIB) utilizing the most up-to-date datasets for topography, temperature, precipitation, net radiation, land cover, soil type, and digital atlas. Multiple datasets have been evaluated and the ones with best accuracy and temporal coverage have been selected for the final model. Upper Indus River and its major tributaries are highly significant in regional water resources management and geopolitics. However, UIB is a poorly studied and largely ungauged river basin with an area of 265,598 km2 and extremely rugged topography. Several factors, the chief ones being the challenging terrain and the trans-boundary nature of the basin, have contributed to this knowledge gap. Hydro-climatologically it is a complex basin with a significant cryospheric component. The spatial and temporal variation of the principal climatic variables, namely precipitation, net radiation, and temperature has been thoroughly accounted for in the development of a stream water availability model based on a process model coupled with a topologic model and a linear reservoir model of river flow routing. Model calculations indicate that there are essentially two hydrologic regimes in UIB. The regime that is truly significant in contributing stream flows, originates from the UIB cryosphere containing outstanding glaciers and snowfields. The other regime, generated from wet precipitation and melt water from seasonal snow covers is insignificant due to high rates of infiltration and evaporation in the semi-desert environment prevailing at elevations below perennial snow and ice covers. In general, the modeled stream flow characteristics match with the sparse discharge measurements that are available. Flow in the Indus considerably increases at its confluence with Shyok River and further downstream where other tributaries form the north join the main stem. At or near the outlet of the basin stream flow can vary from less than 800 m3 s − 1 in the winter and spring to nearly 8,000 m3 s − 1 in the peak summer and can persist to over 1,500 m3 s − 1 in the autumn. The importance of snow and glacial melt in Indus River discharge is apparent and any global or regional climate change affecting the equilibrium line elevation of the snow fields in the Karakoram will have a profound influence on the water availability in the Indus. Estimates are made for per capita water availability in Ladakh and Gilgit-Baltistan territories, controlled by India and Pakistan respectively. Geopolitical significance and climate change effects are discussed briefly.  相似文献   

9.
In arid and semiarid areas, bimodal and high rainfall leads to infrequent flood that can be extremely damaging. To reduce the impacts of persistent intra-seasonal drought and also to reduce flood damaging in arid and semiarid areas, rainwater storage is a prerequisite that keeps water far from evapotranspiration, increases groundwater level and decreases flood hazards modification to exchange between surface water and groundwater through flood spreading, dams, etc. The purpose of this paper is to delineate and explain variations in groundwater recharge and groundwater quality along an ephemeral stream that has been modified by flood spreading. Groundwater samples were collected from 14 deep wells located at different distances from flood spreading projection area (FSPA) in 1 month interval during September 2005 to September 2008. Groundwater quality was followed via Na+, K+, Ca2+, Mg2+, Cl-, Hco3- SO42-, Electrical Conductivity (EC) and pH measurements for two time periods between 2005 and 2008. The results show significant impact of flood spreading in groundwater table and groundwater salinity variation. Groundwater table decreased in all study wells, but groundwater drawdown increased by increasing the distance to FSPA (during 4 years study, 11.02 m in the well located at 20 m of FSPA versus 38.88 in the well located at 1,825 m). Also ion concentration increased in all of the wells during the study period, but the increasing ion concentration was significantly less important in FSPA closeness.  相似文献   

10.
Bangladesh has a large and growing population that will demand more food and place greater pressure on resources. Dry season irrigated Boro rice production is important for national food security. Dry season irrigation mainly uses groundwater, but the extent of its use is not well known. We assessed groundwater use and water productivity of Boro in the northwest region of Bangladesh using remote sensing based energy balance modelling, crop classification and secondary statistics. The energy balance modelling shows a large spatial variation in the actual evapotranspiration (ETa) from about 325 to 470 mm, with an overall spatial average of 365 mm during dry season. The estimated values of ETa correspond well with independent values from field and regional scale soil and water balance modelling results. From spatial estimates of ETa and effective rainfall, we computed regional net groundwater use for Boro production in 2009 as 2.4 km3. Groundwater is being used unsustainably in some areas, and a spatial time series (1990 to 2010) of pre- and post-monsoon groundwater depth changes in the northwest region of Bangladesh suggests that, with the current level of groundwater use, falling groundwater levels may pose a long term threat to the sustainability of irrigated agriculture in much of the region. Boro water productivity varies from 0.95 to 1.35 kg/m3, allowing the identification of high performing “bright” and low performing “hot” spots and the development of strategies to reduce crop yield/productivity gaps and ensure future food security.  相似文献   

11.
基于2006—2007年中巴资源卫星(ZY01/ZY02)影像数据,采用统计经验法估算盘山风景名胜区的蒸散发量为3 273.1万m3,在此基础上建立区域水平衡模型。结果表明:地下水补给量1 111 m3的保证率为60%,反推入渗系数为0.2,区域地下水资源利用量占补给水量的56.6%,其中农业用水量占总用水量的55.5%以上,水资源利用效率低,且农业面源污染对地下水水质构成威胁。指出该地区的地下水资源保护应强化大气降水的节流,增加地下水补给量;降低农业用水量,提高用水效率;解决农业面源污染和工业点源污染。  相似文献   

12.
This study determines the spatial and temporal distribution of nitrate content within the water-supply wells in the Mancha Oriental System (MOS) for the period 1998–2003 and presents an example of the multiple nitrate pollution sources in the El Salobral–Los Llanos Domain (SLD, southwestern Albacete). The groundwater resources of the MOS are used to maintain approximately 800 km2 of irrigated crops and are the sole water supply for a total population of 275,000 inhabitants. The average nitrate content varies from <0.5 mg l − 1 (detection limit) to 125 mg l − 1. In some areas of the MOS statistical analyses show a growing tendency between 2001 and 2003. Nitrate content shows a heterogeneous spatial distribution but the highest levels can be associated with large areas of irrigated crops. However, there are also points in which nitrate has been detected in significant quantities which are not found to be spatially linked to this kind of crop. The presence of nitrate in these areas can be explained considering other sources of pollution, such us wastewater, or due to pollutant transport from contaminated areas through groundwater flow in a multiple-layered karstic aquifer. These results lead necessarily to reconsider the agricultural-derived nitrate as the sole source of pollution and to analyze the effectiveness of the current wastewater treatment practices from effluents in the MOS.  相似文献   

13.
This study concerns the development of a methodology using modern techniques of data generation (Modeling) and interpretation (GIS) to compute groundwater plausibly at regional scale, alternate to previously established norms. The approach is centered on quantitative estimation of two main parameters-input and output. GIS techniques along with soil vegetation model (CropSyst) have been demonstrated for the calculation of groundwater balance components. Using the developed methodology water resources of the Ludhiana district for the period between, 2000 and 2010 were estimated. The temporal changes in water balance components indicated that the major inputs to the hydrologic system are rainfall and canal water and the major out component are evapotranspiration (ET). Multi-annual (2000 to 2010) average of 719 mm rainfall, 88 mm canal water, 74 mm of groundwater inflow, with annual loss 974 mm as ET, caused 123 mm of net negative groundwater recharge in Ludhiana district. The annual computed rise/fall with the developed methodology closely matched the observed values.  相似文献   

14.
地下水是指储存在地面以下饱和岩土孔隙、裂隙及溶洞的水。地下水资源量是指某时段内地下含水层接收降水、地表水体、侧向径流及人工回灌等项渗透补给量的总和。其中,地表水体渗透补给量由湖泊(水库、坑塘)周边渗透补给量、河道及渠系渗透补给量和田间灌溉入渗补给量组成。对无资料地区通常采用临近站地形、地貌等相似的地区借用其现有的水文资料来计算地下水资源量。文章对此进行探讨研究。  相似文献   

15.
Irrigation of pasture forms the greatest single use of irrigation water in Australia yet there has been little monitoring of its spatial extent and water demands across southeast Australian coastal catchments where irrigated dairy farming forms an important rural livelihood. This paper provides an analysis of spatio-temporal patterns in the extent of irrigated pasture in the Bega–Bemboka catchment on the south coast of New South Wales from Landsat imagery, and establishes quantile regression relationships between metered monthly irrigation abstraction volumes, evaporation and rainfall. Over the metering period (2000–2007), annual water usage averages 4.8 ML ha − 1 year − 1, with January being the month of highest demand with an annualised usage of 10.4 ML ha − 1 year − 1. Analysis of Landsat imagery indicates that the spatial extent of irrigated pasture across the catchment has increased from 1266 ha in 1983 to 1842 ha by 2002, together with amalgamation of smaller holdings along less reliable streams into larger parcels along the trunk stream. Quantile regressions to estimate monthly mean and maximum abstraction volumes from monthly evaporation and rainfall data indicate that abstraction volumes are more closely correlated with evaporation. When combined with Landsat analyses of the spatial extent of irrigated areas, such relationships enable estimation of catchment-scale hydrological effects of irrigation abstractions that in turn can help guide regional-scale assessments of the ecological effects and sustainability of spatially and temporally changing irrigation abstraction volumes.  相似文献   

16.
Gully erosion is one of the most complicated and destructive forms of water erosion. In order to prevent this erosion, the important factors controlling gully heads must be understood. This paper examines gully head advancement in the Hableh Rood Basin, Iran by (1) observing gully head advance between 1957 and 2005 using field studies, aerial photography and GIS analysis and: (2) applying and evaluating widely used experimental models including the, Thompson (Trans ASAE 7(1):54–55, 1964), SCS (I) and SCS (II) models, for estimating migrating headcuts over the study period. The results showed that the highest mean gully advancement (0.26 m year − 1) took place during the 1956–1967 period, with most gullies having lower and steady headcut retreat rates between 1967–2000 (0.21 m year − 1) and 2000–2005 (0.15 m year − 1). This suggests that the majority of gullies in the study area were still in the early stages of formation in the first study period and their formation may be linked to land use or climatic changes pre 1956. Analysis of the correlation between environmental characteristics of the study area and gully advancement indicated that the upslope area of head cuts and soluble mineral content of the soil were the two most important factors influencing the spatial and temporal variation of gully longitudinal development. Results of multiple regression revealed that the simple relation including upslope area and soluble minerals can explain 93% of total variance and relatively reflects the effects of runoff and waterfall process for headcut retreat. Application of statistical error analysis to evaluate the four gully advancement models showed that in comparison to other models, the second model of SCS has more reliable results for predicting longitudinal gully advancement in this study area and other similar regions. However, this study indicates that future modelling in the region should consider the role of soil soluble mineral content in predicting gully advancement.  相似文献   

17.
A tank cum open dug well system suitable for plateau region of eastern India has been developed for providing reliable irrigation to croplands. The system comprises of a series of tanks with open dug wells in the recharge zone of the tank that reharvest back the seepage water. Thus, the rainwater remaining in the tank as well as partial seeped water is used for providing round the year full irrigation. This system was evaluated in field in Keonjhar district of Orissa of eastern India with six tanks and five wells in two drainage lines. The total command area of the system of six tanks and five wells in both drainage lines is 23 ha and the total irrigation potential is 44.5 ha. The total cost of the system is US $19,180 making the cost of irrigation resource creation as US $426 per ha which is much less than about $2,220 per ha for major and medium irrigation projects in the last decade of 20th century. The system increased the rice yields from 1.92 t ha − 1 to a range of 2.25 to 3.8 t ha − 1 depending upon the package of practices or the amount of inputs. The farmers went for crops in post-monsoon and summer season and the cropping intensity rose to 112% in the first year, 126% in the second year and 132% in the third year. The internal rate of return from the system was 13.4% at the present level of utilization, which is about 2.4% more than the prime-lending rate of Indian banks, and 3.4% more than the lending rate for agricultural purposes.  相似文献   

18.
This work demonstrates significant vertical variability in the chemical composition of groundwater (Cl −  from 150 to 550 mg/L, NO3-{\rm{NO}}_{3}^{-} from 3 to 70 mg/L, trichloroethene from 350 to 55,000 μg/L and CrTotal from 3 to 2,900 μg/L) along a 130 m thick vertical section passing through two subaquifers of the Costal Plain aquifer of Israel. Water samples were obtained by multilevel sampler under natural gradient flow conditions from a monitoring well which penetrates the entire aquifer. The vertical chemical variability detected at a single point in time in this well was found to be similar to the range of concentrations detected for Cl −  in pumping wells located over an area of about 1,000 km2 in the same aquifer. Similarly, vertical variations in NO3-{\rm{NO}}_{3}^{-} concentration in the single monitoring well represent more than 50% of the total variation in nitrate levels in pumping wells sampled across the entire aquifer. These results graphically illustrate that data from pumping wells, which extract unknown mixtures of groundwater from different depths, cannot provide adequate information about groundwater quality for management purposes.  相似文献   

19.
Ramteke  Gajanan  Singh  R.  Chatterjee  C. 《Water Resources Management》2020,34(13):4233-4252

Climate change triggers changes in temperature, precipitation, evapotranspiration, etc. and has a significant impact on water resources in many regions. Considering the increasing scarcity of water as a result of climate change, conservation of water and groundwater recharge have become crucial factors for water resources planning and management. In this paper, an attempt is made to study the detailed hydrological behaviour of a treated watershed using physically based distributed hydrological modelling system MIKE SHE to assess the impact of conservation measures on watershed hydrology considering future climate change. Three hypothetical management scenarios are simulated for the period 2010–2040. RegCM4 regional climate model is used in the study for RCP 4.5 and RCP 8.5 scenarios. Detailed hydrological water balance is extracted for individual years from 1979 to 2009 to compare relevant components. The evaluation for base period shows 10.06% reduction in surface runoff and 11.33% enhancement in groundwater recharge. Further simulation with RCP 4.5 and RCP 8.5 scenarios show notable reduction in surface runoff and increase in groundwater recharge. The structures in the micro-watershed influence the surface runoff and increase infiltration into the soil, resulting in higher groundwater recharge. MIKE SHE simulations for various structures management scenarios establish the role of conservation measures in reducing surface runoff and enhancing groundwater recharge under substantial effect of climate change. The results will assist in decision-making on watershed development plans in quantitative terms, including planning for water conservation measures in the face of climate change.

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20.
石川河富平地区地下水长期处于采补失衡状态,大范围含水层被疏干,形成区域性降落漏斗,针对拟建的石川河富平地下水库,设置5种开采回灌方案,建立地下水流数值模型模拟不同方案下地下水库水位和蓄水库容变化情况。结果表明:各回灌方案在消除降落漏斗的同时,均能较好地恢复地下水水位,且不超过地下水库的调蓄上限水位;回灌量相同、回灌方式不同时,逐日回灌方式的水位恢复效果优于灌期+非灌期回灌方式,较2018年地下水水位平均抬升13.55 m,蓄水库容增加2.99×108 m3;回灌量不同时,较大回灌量对地下水水位的影响大于回灌方式,即泾惠渠水源回灌时,水位抬升程度最大,为19.77 m,蓄水库容相应增加4.36×108 m3。模拟结果可为地下水库的调蓄与运行提供参考。  相似文献   

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