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1.
Groundwater is the only source of drinking water for the inhabitants of the Kalahari. Thus understanding spatial and temporal
variations in groundwater recharge is very important and a regional-scale water balance model has therefore been set up for
a 209,149 km2 catchment in north-eastern Namibia and north-western Botswana. The model has a spatial resolution of 1.5 × 1.5 km, daily
model time-steps, and climatic input parameters for 19 years are used. The distributed, GIS-based, process-oriented, physical
water balance model (MODBIL) used in this study considers the major water balance components: precipitation, evapotranspiration,
groundwater recharge, and surface runoff/interflow. Mean precipitation for the study area is 409 mm a−1, while mean actual evapotranspiration is 402 mm a−1 and mean groundwater recharge is 8 mm a−1 (2% of mean annual precipitation). The recharge pattern is mainly influenced by the distribution of soil and vegetation units.
Groundwater recharge shows a high inter- and intra-annual variability, but not only the sum of annual precipitation is important
for the development of groundwater recharge; a large amount of precipitation in a relatively short period is more important.
Published independent data from the Kalahari in Namibia, Botswana and the Southern African region under similar climatic conditions
are used to verify the modelling results. 相似文献
2.
Soil Erosion Assessment in a Hilly Catchment of North Eastern India Using USLE, GIS and Remote Sensing 总被引:9,自引:1,他引:8
In the present study, soil erosion assessment of Dikrong river basin of Arunachal Pradesh (India) was carried out. The river
basin was divided into 200 × 200 m grid cells. The Arc Info 7.2 GIS software and RS (ERDAS IMAGINE 8.4 image processing software)
provided spatial input data and the USLE was used to predict the spatial distribution of the average annual soil loss on grid
basis. The average rainfall erositivity factor (R) for Dikrong river basin was found to be 1,894.6 MJ mm ha−1 h−1 year−1. The soil erodibility factor (K) with a magnitude of 0.055 t ha h ha−1 MJ−1 mm−1 is the highest, with 0.039 t ha h ha−1 MJ−1 mm−1 is the least for the watershed. The highest and lowest value of slope length factor (LS) is 53.5 and 5.39 respectively for the watershed. The highest and lowest values of crop management factor (C) were found out to be 0.004 and 1.0 respectively for the watershed. The highest and lowest value of conservation factor (P) were found to be 1 and 0.28 respectively for the watershed. The average annual soil loss of the Dikrong river basin is 51 t
ha−1 year−1. About 25.61% of the watershed area is found out to be under slight erosion class. Areas covered by moderate, high, very
high, severe and very severe erosion potential zones are 26.51%, 17.87%, 13.74%, 2.39% and 13.88% respectively. Therefore,
these areas need immediate attention from soil conservation point of view. 相似文献
3.
In the present study the SHETRAN river basin modelling system was used in conjunction with Geographic Information System (GIS) to estimate potential erosion and deposition rates within the catchment and the concentrations of sediment in a flow at the catchment outlet on the example of the 114.31 km2 mountainous torrential Lukovska River catchment in Serbia. The streams in the Lukovska River catchment are short, steep and often produce hazardous torrential floods as a consequence of strong rainfall of short duration. The soil erosion and sediment discharge were analysed in view of the catchment response to physical characteristics of the catchment. Considering that the most of total annual sediment discharge in watersheds of torrential character is achieved during storm events, the SHETRAN modelling system was calibrated on the example of a storm event in 1986 and validated for three other storm events in 1974, 1976 and 1979. The simulated results of discharges and sediment concentrations at the catchment outlet for both calibration and validation events were compared with the observed data and found to be reasonable. The changes of erosion and deposition rates within the catchment and in the course of time were estimated for the calibration event in 1986. The simulated erosion rates were within the range of 1 to 10.5 t/ha and corresponded to the observed rates of erosion in Europe during extreme rain events. The presented methodology is useful in identifying the erosion vulnerable regions in a catchment where erosion control measures should be implemented. 相似文献
4.
Ivars Reinfelds 《Water Resources Management》2011,25(9):2319-2334
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
5.
River Perkerra catchment with an area of 1207 km2 is drained by River Perkerra, which is one of the rivers flowing into Lake Baringo whose drainage area is 6820 km2. The lake is in a semi-arid area of Kenya. Its depth has reduced from 8 m in 1972 to 2.5 m in 2003 due to siltation resulting from high erosion rates in the catchment. The entire catchment is characterised by very steep slopes on the hillsides and gentle slopes in the middle and lower reaches where the surface is bare with very little undergrowth. Interventions to control soil erosion in this fragile ecosystem have been limited partly because of lack of data on erosion and its spatial distribution. In the present study, Universal Soil Loss Equation (USLE) was used in conjunction with GIS Arc/Info and Integrated Land and Water Information Systems (ILWIS) to estimate potential soil loss from River Perkerra catchment. Various physical parameters of the equation were derived by analysing spatial data and processing Landsat TM satellite imagery of the catchment. The estimated potential soil erosion from the catchment was 1.73 million tonnes/year while the sediment yield at the catchment outlet was found to be 1.47 million tonnes/year. The sediment delivery ratio derived using an empirical equation was 0.83. This figure indicates that a higher proportion of sediments generated in the catchment is delivered at the outlet. The use of GIS enabled the results of erosion potential to be mapped back onto the catchment. This is useful in identifying priority areas that require urgent management interventions in controlling soil erosion. 相似文献
6.
Regional Scale Erosion Assessment of a Sub-tropical Highland Segment in the Western Ghats of Kerala,South India 总被引:3,自引:1,他引:2
Revised Universal Soil Loss Equation (RUSLE) has been used in combination with remote sensing and GIS techniques to assess
the spatial pattern and annual rate of soil erosion in the Munnar Forest Division in Western Ghats, Kerala, India. The RUSLE
takes into account several factors such as rainfall, soil erodibility, slope length and steepness, land cover and erosion
control practice for soil erosion prediction. Maximum soil loss of 109.31 t h−1y−1 and the areas with extreme erosion (erosion is higher than 50 t h−1y−1) are confined to 11.46% of the total area, while the area occupied by severe erosion (erosion rate between 25 and 50 t h−1y−1) is 27.53%. The high rate of annual soil erosion is associated with areas of high terrain alteration from the plantation
activities and highly elevated hills/plateau margins with steep side slopes. Such an output is highly useful in decision making
context to avoid land acquisition in erosion risk areas, or, alternatively, to recommend soil conservation measures to reduce
soil loss, if developmental activities are to be continued at high soil erosion risk areas. 相似文献
7.
E. Molina-Navarro S. Martínez-Pérez A. Sastre-Merlín R. Bienes-Allas 《Water Resources Management》2014,28(8):2129-2143
Accelerated soil erosion is a threat for the societies due to the loss of ecosystems services. Soil erosion and sediment delivery have been assessed in a small catchment of Central Spain with a new water body, the Pareja Limno-reservoir, located in its outlet. This limno-reservoir was created in 2006 with environmental and recreational purposes in the riverine zone of a large reservoir. Sedimentation risk is an issue of concern regarding limno-reservoirs environmental feasibility. Thus, the study of the soil erosion in the Pareja Limno-reservoir catchment and its sediment delivery seemed of the utmost importance. In this paper we establish an affordable and simple methodology to address it. A soil erosion and deposition monitoring network was installed in the Ompólveda River basin (≈88 km2), which flows into the Pareja Limno-reservoir. Results obtained were related with those from a sedimentation study previously carried out in the limno-reservoir. Gross hillslope erosion in the catchment was 6.0 Mg ha?1 year?1, which is in agreement with values reported for Mediterranean areas. After subtraction of the deposition measured, a soil loss of 1.2 Mg ha?1 year?1 was found in the catchment. Sediment delivery ratio (SDR) was estimated to be 3.8 %. SDR is low as a result of the low connectivity between the stream network and the limno-reservoir. Some local characteristics may also have a secondary influence in the low SDR value. Results obtained support the environmental feasibility of the Pareja Limno-reservoir from the sedimentation risk perspective. They also demonstrate that the methodology followed allows the assessment of soil loss and sediment delivery at a catchment scale, and the identification of areas where the erosion problems are most severe. 相似文献
8.
The generalised likelihood uncertainty estimation (GLUE) approach was applied to assess the performance of a distributed catchment
model and to estimate prediction limits after conditioning based on observed catchment-wide streamflow. Prediction limits
were derived not only for daily streamflow but also for piezometric levels and for extreme events. The latter analysis was
carried out considering independent partial duration time series (PDS) obtained from the observed daily streamflow hydrograph.
Important data uncertainties were identified. For streamflow the stage-discharge data analysis led to estimate an average
data uncertainty of about 3 m3 s − 1. For piezometric levels, data errors were estimated to be in the order of 5 m in average and 10 m at most. The GLUE analysis
showed that most of the inspected parameters are insensitive to model performance, except the horizontal and vertical components
of the hydraulic conductivity of one of the geological layers that have the most influence on the streamflow model performance
in the application catchment. The study revealed a considerable uncertainty attached to the simulation of both high flows
and low flows (i.e., in average terms 5 m3 s − 1 before the Bayesian updating of the prediction limits). Similarly, wide prediction intervals were obtained for the piezometric
levels in relevant wells, in the order of 3.3 and 1.5 m before and after the Bayesian updating of the prediction limits, respectively.
Consequently, the results suggest that, in average terms, the model of the catchment predicts overall outputs within the limitations
of the errors in the input variables. 相似文献
9.
Aliakbar Nazari Samani Hassan Ahmadi Aliasghar Mohammadi Jamal Ghoddousi Ali Salajegheh Guy Boggs Razieh Pishyar 《Water Resources Management》2010,24(8):1531-1549
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
10.
Fine sediment (<63 µm) storage in river channels frequently represents a significant term in catchment sediment budgets and plays an important role in diffuse pollution problems. A combination of a sediment remobilization technique and the fingerprinting approach was used to examine the storage and provenance of fine sediment on the channel bed of two contrasting lowland permeable catchments in the UK. In the upper Tern (∼231 km2) study catchment, estimates of mean fine sediment storage on the channel bed ranged between 860–5500 g m−2, with an overall average of 2391 g m−2, compared to 470–2290 g m−2 and 1065 g m−2 in the Pang (∼166 km2) and 770–1760 g m−2 and 1255 g m−2 in the Lambourn (∼234 km2) sub‐catchments. Mean total fine sediment storage on the bed of the main channel was equivalent to 37% (upper Tern), 38% (Pang) and 21% (Lambourn) of the mean annual suspended sediment loads measured at the catchment outlets. Over the study period, the total gain (1427 t) and loss (1877 t) to fine sediment storage on the channel bed in the upper Tern catchment were equivalent to 82% and 108% of the mean annual suspended sediment load, respectively, compared to 149% (740 t) and 136% (678 t) in the Pang sub‐catchment, and 39% (422 t) and 49% (528 t) in the Lambourn sub‐catchment. The source of the fine sediment stored on the channel bed within each study area varied. In the upper Tern catchment, the weighted mean relative contributions from individual source types were estimated to be 35 ± 5% (pasture), 51 ± 5% (cultivated) and 14 ± 3% (channel banks and subsurface sources). The corresponding estimates were 49 ± 8%, 33 ± 5% and 18 ± 5% for the Pang sub‐catchment, compared to 19 ± 6%, 64 ± 5% and 17 ± 5% for the Lambourn sub‐catchment. These sediment source estimates have important implications for the design and implementation of targeted sediment control policies within the study areas. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
11.
Nitrate in the Water-Supply Wells in the Mancha Oriental Hydrogeological System (SE Spain) 总被引:1,自引:0,他引:1
A. Moratalla J. J. Gómez-Alday J. De las Heras D. Sanz S. Castaño 《Water Resources Management》2009,23(8):1621-1640
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
12.
Lior Netzer Noam Weisbrod Daniel Kurtzman Ahmed Nasser Ellen R. Graber Daniel Ronen 《Water Resources Management》2011,25(5):1315-1324
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
13.
Lake-Level Change and Water Balance Analysis at Lake Qinghai,West China during Recent Decades 总被引:7,自引:0,他引:7
Xiao-Yan Li He-Ye Xu Yong-Liang Sun Deng-Shan Zhang Zhi-Peng Yang 《Water Resources Management》2007,21(9):1505-1516
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
14.
Christine Rivard Yves Michaud René Lefebvre Christine Deblonde Alfonso Rivera 《Water Resources Management》2008,22(11):1649-1675
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
15.
A Stream Water Availability Model of Upper Indus Basin Based on a Topologic Model and Global Climatic Datasets 总被引:1,自引:1,他引:0
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
16.
Alba María Guadalupe Orellana González Rodrigo Máximo Sánchez-Román Marcos Vinicius Folegatti Cornélio Alberto Zolin 《Water Resources Management》2011,25(13):3371-3386
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
17.
Assessing Crop Water Demand by Remote Sensing and GIS for the Pontina Plain, Central Italy 总被引:1,自引:1,他引:0
Raffaele Casa Matteo Rossi Giuseppe Sappa Antonio Trotta 《Water Resources Management》2009,23(9):1685-1712
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
18.
Daniel El Chami Maroun El Moujabber Alessandra Scardigno 《Water Resources Management》2009,23(11):2361-2378
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
19.
A Simple Conceptual Model of Sediment Yield 总被引:2,自引:0,他引:2
Pradeep Kumar Bhunya S. K. Jain P. K. Singh S. K. Mishra 《Water Resources Management》2010,24(8):1697-1716
The sediment graphs (time distribution of sediment yield) are very essential if the sediment transports the pollutants that
are toxic at high concentrations, requiring determination of peak, rather than average sediment flow rate. In this paper,
an effort has been made to develop a simple conceptual model of sediment yield based on Soil Conservation Service Curve Number
(SCS-CN) method, instantaneous unit sediment graph (IUSG) method, and Power law and the performance is tested using real field
data of Chaukhutia watershed of Ramganga river catchment (area = 452.25 km2). The proposed model is found to provide realistic estimates of temporal variation of sediment yield as well as total sediment
yield during a storm event. The model is found to be most sensitive to parameter β followed by k,
\upalpha\upalpha, A, and ns. A comparison is made with the existing IUSG based models of Kumar and Rastogi (J Hydrol 95:155–163, 1987) and Raghuwanshi et al. (J Hydraul Eng ASCE 120(4):495–503, 1994) for developing sediment graphs. 相似文献
20.
Estimations of Evapotranspiration and Water Balance with Uncertainty over the Yukon River Basin 总被引:2,自引:1,他引:1
Wenping Yuan Shuguang Liu Shunlin Liang Zhengxi Tan Heping Liu Claudia Young 《Water Resources Management》2012,26(8):2147-2157
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