Your search found 130 records
(Location: IWMI HQ Call no: PER Record No: H042963)
(0.32 MB)
Poor on-farm irrigation practices and rising groundwater table depths are the major reasons for low cotton yields in the Sardarya province of Uzbekistan. To ensure sustainability of cotton production in the area, precise calculations of irrigation requirements are needed to optimize crop yields and to keep groundwater table depth below the root zone to avoid soil salinization. To determine optimal groundwater table depth and irrigation amounts for the Sardarya province of Uzbekistan, the Soil–Water–Atmosphere–Plant (SWAP) model was used. SWAP was calibrated and validated using measured data from an experimental cotton field during the agricultural year of 2006 and 2007. The calibrated SWAP model was then used to simulate optimal groundwater table depth and irrigation amounts. The simulation results show that for the existing conditions in the study area, a groundwater table depth of approximately 200 cm together with an irrigation application of 2500m3 ha1 will be the most appropriate combination for optimal cotton yields ( 3.0 t ha1). However, to achieve maximum potential yields of cotton (5–6 t ha1), leaching of excessive salts from the root zone through freshwater application would be imperative. This would require rehabilitation of the existing drainage network in the area.
(Location: IWMI HQ Call no: e-copy only Record No: H043174)
(0.33 MB)
Until recently, aquifers located in hard rock formations (granite, gneiss, schist) were considered as a highly heterogeneous media, and no adequate methodology for groundwater management was available. Recent research studies have shown that when hard rocks are exposed to regional and deep-weathering processes and when the geology is relatively homogenous, a typical hard rock aquifer is made of two main superimposed hydrogeological layers each characterized by quite homogeneous specific hydrodynamic properties: namely the saprolite and the fissured layers. Therefore, for these cases, hard rock aquifers can be considered as a multi-layered system. Based on these works, an operational decision support tool (DST-GW ) designed for the management of groundwater resources in hard rock area under variable agro-climatic conditions has been developed. The tool focuses on the impact of changing cropping pattern, artificial recharge and rainfall conditions on groundwater levels at the scale of small watersheds (10 to about 100 km2 in case well-developed weathering profile). DST-GW is based on the groundwater balance and the ‘water table fluctuation method’, which are well-adapted methods in hard rock and semiarid contexts. Based on field data from an overexploited South Indian watershed (58 km2), the model allows calibrating, at watershed scale, the variation in specific yield of the aquifer with depth, as well as the rainfall-aquifer recharge relationship. Seasonal basin-scale piezometric levels are computed with an average deviation of š0Ð56 m compared to measurements from 2001 to 2005. The model shows that, if no measure is taken, the water table depletion will induce the drying-up of most of the exploited borewells by the year 2012. Scenarios of mitigation measures elaborated with the tool show that change in cropping patterns could rapidly reverse the tendency and lead to a sustainable management of the resource. This work presents the developed tool and particularly the hydraulic model involved in and its application to a case study. However, the purpose tool is applicable at watershed scale but not design for the groundwater management of a very small area or for a single borewell.
3 Ranjan, S. P. 2006. Numerical modeling of salinity intrusion: case study from southern coastal aquifer in Sri Lanka. Engineer, 39(4):19-25.
(Location: IWMI HQ Call no: PER Record No: H043248)
(0.68 MB)
4 Beven, K. J. 2006. Streamflow generation processes. Wallingford, UK: International Association of Hydrological Sciences (IAHS). 431p. (IAHS Benchmark Papers in Hydrology 1)
(Location: IWMI HQ Call no: 551.48 G000 BEV Record No: H043507)
(0.39 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H045846)
(0.23 MB)
Water demand for irrigated agriculture is increasing against limited availability of fresh water resources in the lower reaches of the Amu Darya River e.g., Khorezm region of Uzbekistan. Future scenarios predict that Khorezm region will receive fewer water supplies due to climate change, transboundary conflicts and hence farmers have to achieve their yield targets with less water. We conducted a study and used AquaCrop model to develop the optimum and deficit irrigation schedule under shallow groundwater conditions (1.0–1.2 m) in the study region. Cotton being a strategic crop in the region was used for simulations. Capillary rise substantially contributes to crop-water requirements and is the key characteristic of the regional soils. However, AquaCrop does not simulate capillary rise contribution, thereby HYDRUS-1D model was used in this study for the quantification of capillary rise contribution. Alongside optimal irrigation schedule for cotton, deficit strategies were also derived in two ways: proportional reduction from each irrigation event (scenario-A) throughout the growth period as well as reduced water supply at specific crop growth stages (scenario-B). For scenario-A, 20, 40, 50 and 60 % of optimal water was deducted from each irrigation quota whereas for scenario-B irrigation events were knocked out at different crop growth stages (stage 1(emergence), stage 2 (vegetative), stage 3 (flowering) and stage 4 (yield formation and ripening)). For scenario-A, 0, 14, 30 and 48 % of yield reduction was observed respectively. During stress at the late crop development stage, a reduced water supply of 12 % resulted in a yield increase of 8 %. Conversely, during stress at the earlier crop development stage, yield loss was 17–18 %. During water stress at the late ripening stage, no yield loss was observed. Results of this study provide guidelines for policy makers to adopt irrigation schedule depending upon availability of irrigation water.
6 Lennartz, B.; Janssen, M.; Tiemeyer, B. 2011. Effects of artificial drainage on water regime and solute transport at different spatial scales. In Shukla, M. K. (Ed.) Soil hydrology, land use and agriculture: measurement and modelling. Wallingford, UK: CABI. pp.266-290.
(Location: IWMI HQ Call no: e-copy SF Record No: H045784)
7 Mukherji, A.; Rawat, S.; Shah, Tushaar. 2013. Major insights from India’s minor irrigation censuses: 1986-87 to 2006-07. Economic and Political Weekly, 48(26-27, Supplement):115-124.
(Location: IWMI HQ Call no: e-copy only Record No: H045912)
(0.46 MB)
Based on data from the four minor irrigation censuses conducted by the Ministry of Water Resources between 1986-87 and 2006-07, this paper points out that India’s groundwater sector has slowed down since 2000-01, most markedly in eastern India. It examines the reasons for this and also looks into how farmers have been responding to lowered groundwater tables. Besides identifying some factors that have not changed since the mid-1980s, it emphasises that there are wide regional variations in the country’s groundwater economy and management strategies need to be crafted accordingly.
(Location: IWMI HQ Call no: PER Record No: H045915)
(0.78 MB)
Excessive irrigation and poor drainage conditions are the major factors contributing to rising groundwater tables and soil salinity in the irrigated areas of Central Iraq. Therefore calculations of precise irrigation requirements are necessary to optimize crop production and keep the groundwater table below the root zone to avoid soil salinization. In this study, the soil–water–atmosphere–plant (SWAP) model is used to determine optimal groundwater table depth and irrigation amounts for the study area. SWAP was calibrated using field data from the study area during the wheat and maize season of 2011–2012. The modelling results reveal that under current irrigation practices (600mm to wheat and 1000mm to maize), more than 30% water is lost as deep percolation. This causes a rise in the groundwater table and reduction in crop yields. The model simulations suggest that a groundwater table depth of 200 cm together with an irrigation application of 500mm to wheat and 600mm to maize will be the best combination to attain optimal yields. Therefore a drainage system in these areas should be installed to maintain groundwater table depth around 200 cm. Maintaining adeeper groundwater table will not be suitable as costs will increase and crop responses negligible. For long-term sustainability, rehabilitation of existing drainage systems to evacuate excessive salts from the root zone will be imperative.
(Location: IWMI HQ Call no: e-copy only Record No: H046205)
(2.33 MB)
This paper analyzes the effect of the shallow water table on water use of the winter wheat (Triticumaestivum L.) that has replaced alfalfa (Medicago sativa) on the irrigated lands of the Fergana Valley,upstream of the Syrdarya River, in Central Asia. The effect of the shallow water table is investigated using HYDRUS-1D. Numerical simulations show that the contribution of the groundwater to evapotranspiration increases with a rising water table and decreases with increasing irrigation applications. Under irrigation conditions, an increase in the groundwater evapotranspiration is associated mainly with an increase in evaporation loss, causing a buildup of salinity in the crop root zone. Evaporation losses from fields planted with winter wheat after the harvest amount up to 45–47% of total evaporation thus affecting soil salinity and ecosystem health. Promoting the use of groundwater for irrigation in order to lowerthe groundwater table is suggested to achieve water savings from the change in the cropping pattern.Unlocking the potential of groundwater for irrigation in the Fergana Valley can also contribute toward managing soil salinity and improving the health and resilience of water, land and ecosystems of water,land and ecosystems (WLE).
(Location: IWMI HQ Call no: e-copy only Record No: H046591)
(1.73 MB)
Developing reliable methods to estimate stream baseflow has been a subject of interest due to its importance in catchment response and sustainable watershed management. However, to date, in the absence of complex numerical models, baseflow is most commonly estimated using statistically derived empirical approaches that do not directly incorporate physically-meaningful information. On the other hand, Artificial Intelligence (AI) tools such as Genetic Programming (GP) offer unique capabilities to reduce the complexities of hydrological systems without losing relevant physical information. This study presents a simple-to-use empirical equation to estimate baseflow time series using GP so that minimal data is required and physical information is preserved. A groundwater numerical model was first adopted to simulate baseflow for a small semi-urban catchment (0.043 km2) located in Singapore. GP was then used to derive an empirical equation relating baseflow time series to time series of groundwater table fluctuations, which are relatively easily measured and are physically related to baseflow generation. The equation was then generalized for approximating baseflow in other catchments and validated for a larger vegetation-dominated basin located in the US (24 km2). Overall, this study used GP to propose a simple-to-use equation to predict baseflow time series based on only three parameters: minimum daily baseflow of the entire period, area of the catchment and groundwater table fluctuations. It serves as an alternative approach for baseflow estimation in un-gauged systems when only groundwater table and soil information is available, and is thus complementary to other methods that require discharge measurements.
11 Qureshi, Asad Sarwar. 2005. Climate change and water resources management in Pakistan. In Mirza, M. M. Q.; Ahmad, Q. K. (Eds.). Climate change and water resources in South Asia. Leiden, Netherlands: A. A. Balkema. pp.197-230.
(Location: IWMI HQ Call no: 577.22 G570 MIR Record No: H047180)
(4.62 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H047740)
(3.11 MB)
Management of canal system for agricultural production is challenging. The work presents GIS based integrated modelling, which integrates soil moisture accounting and irrigation water requirement module, rainfall–runoff module, system loss module and groundwater flow system module. Developed model is employed to evaluate different water management scenarios such as change in rainfall sequence (wet, normal and dry season), change in canal water supply, impact of canal lining and impact of land use changes including their socio–economic implications. The application of model is illustrated with real application in a part of Indo-Gangetic plain of Uttar Pradesh in India. It has been demonstrated that canal water use efficiency in diversion canal systems can be increased up to 58 percent.
(Location: IWMI HQ Call no: e-copy only Record No: H047751)
(1.69 MB)
Most studies on the environmental performance of irrigation have focused on the water–food–energy nexus, i.e. relationships between food production, water consumption and energy. However, water and energy are not the only relevant indicators of the environmental performance of irrigation systems. Life cycle assessment (LCA) is a holistic method that is well suited to comprehensive assessment. This paper aims at using LCA to assess the environmental impacts of contrasted groundwater pumping systems in semi-arid central Tunisia.
In line with previous studies, our results confirm that for groundwater pumping, energy has the highest environmental impacts on human health, the ecosystem and resource depletion. Our work also highlights that along with pump efficiency, the type of power source must be considered when ranking pumping systems based on environmental performance.
Indeed, diesel-powered pumping systems are more harmful than electric pumps when electricity is generated from natural gas and diesel-powered pump efficiency is low. However, the diesel pumping system becomes the best option when electricity is derived from coal and diesel-powered pump efficiency exceeds 12%.
Finally, water depletion has been shown of great importance in this study, and ongoing LCA improvements should facilitate a more comprehensive picture of these site-specific impacts.
14 Saha, D.; Zahid, A.; Shrestha, S. R.; Pavelic, Paul. 2016. Groundwater resources. In Bharati, Luna; Sharma, Bharat R.; Smakhtin, Vladimir (Eds.). The Ganges River Basin: status and challenges in water, environment and livelihoods. Oxon, UK: Routledge - Earthscan. pp.24-51. (Earthscan Series on Major River Basins of the World)
(Location: IWMI HQ Call no: IWMI Record No: H047811)
15 Bharati, Luna; Sharma, Bharat R.; Smakhtin, Vladimir. (Eds.) 2016. The Ganges River Basin: status and challenges in water, environment and livelihoods. Oxon, UK: Routledge - Earthscan. 327p. (Earthscan Series on Major River Basins of the World)
(Location: IWMI HQ Call no: IWMI Record No: H047808)
(0.41 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H047897)
(4.00 MB)
In this study, we tried to validate groundwater storage (GWS) anomaly obtained from a combination of GRACE and land-surface model based estimates, for the first time, with GWS anomaly obtained from a dense network of in-situ groundwater observation wells within 12 major river basins in India. We used seasonal data from >15,000 groundwater observation wells between 2005 and 2013, distributed all over the country. Two recently released GRACE products, RL05 spherical harmonics (SH) and RL05 mascon (MS) products are used for comparison with in-situ data. To our knowledge, this is the first study of comparing the performance of two independent GRACE products at a sub-continental scale. Also for the first time, we have created a high resolution (0.10 0.10 ) map of specific yield for the entire country that was used for calculating GWS. Observed GWS anomalies have been computed using water level anomalies and specific yield information for the locale of individual observation wells that are up-scaled to basin-scale in order to compare with GRACE-based estimates. In general GRACE-based estimates match well (on the basis of the statistical analyses performed in the study) with observed estimates in most of the river basins. On comparing with observed GWS anomaly, GRACE-SH estimates match well in terms of RMSE, while GRACE-MS estimates show better association in terms of correlation, while the output of skewness, kurtosis, coefficient of variation (CV) and scatter analyses remain inconclusive for inter-comparison between two GRACE estimates. We used a non-parametric trend estimation approach, the Hodrick-Prescott (HP) filter, to further assess the performance of the two GRACE estimates. GRACE-MS estimates clearly outperform GRACE-SH estimates for reproducing observed GWS anomaly trends with significantly (>95% confidence level) strong association in 10 out of 12 basins for GRACE-MS estimates, on the other hand, GRACE-SH estimates show significantly (>95% confidence level) strong association in 6 out of 12 basins. On the basis of the study output, we recommend using GRACE-MS estimates for groundwater studies over the region and other regions of the globe with similar climatic, hydrogeologic or groundwater withdrawal conditions.
(Location: IWMI HQ Call no: e-copy only Record No: H047899)
(1.32 MB)
Irrigation with groundwater consumes considerable energy as well as water resources across the world. Using a case study from Indian Punjab, this article emphasizes how a continued and massive use of groundwater for irrigation has reduced groundwater levels and increased carbon emissions. Estimates of C emissions from groundwater pumping for irrigation in Punjab indicate that over a period of 14 years (1998–2012), groundwater use has increased by 23%; groundwater levels have fallen by 5.47 m; energy requirements have increased by 67% resulting in increase in C emissions by 110%. Emissions rates have increased from 33 to 55 g m 3 of groundwater used, and 43.2 to 78 g-C kg 1 of grain. Thus, groundwater management is not only important to ensure sustainability of the finite resource but also is vital to control environmental consequences of groundwater use for irrigation.
(Location: IWMI HQ Call no: e-copy only Record No: H047907)
(2.47 MB)
Groundwater is a vital natural capital for the consistent and economic provision of potable water supply for both rural and urban environments. There is now a strong consensus that climate change poses a fundamental challenge to the well-being of all countries, with potential of being the harshest on countries already suffering from water scarcity. Dry zone of Killinochi basin in Northern Sri Lanka, which was devastated by civil war for last 25 years, is again being revitalized by human settlement and urbanization in last couple of years. However, the decreasing trend in the rainfall regime of the dry zones and the increase in population size (temporary inflow) and, hence, the demand for water for irrigation and other livelihood requirements, calls for a sustainable exploitation of the groundwater resources in the region. The development of a reasonable model for groundwater potential is need for the present time. This work strives to generate groundwater potential zonation map using integrated use of remote sensing and geographic information system (GIS) for Killinochi area, Northern Sri Lanka. Five different themes of information, such as geomorphology, geology, soil type (extracted from existing topo sheet); slope [generated from shuttle radar topography mission (SRTM) digital elevation model (DEM)]; and land use/land cover (extracted from digital processing of AVNIR satellite data) were integrated with weighted overlay in GIS to generate groundwater potential zonation map of the area. The final map of the area was demarcated by four different zones of groundwater prospects, viz., good (5.32 % of the area), moderate (61.90 % of the area) poor (26.61 % of the area), and very poor (6.17 % of area). The hydrogeomorphological units, such as alluvial plain, low slope area, and land occupied by forest, are prospective zones for groundwater occurrence in the study area.
(Location: IWMI HQ Call no: e-copy only Record No: H047956)
(4.60 MB)
Groundwater level measurements from 3907 monitoring wells, distributed within 22 major river basins of India, are assessed to characterize their spatial and temporal variability. Groundwater storage (GWS) anomalies (relative to the long-term mean) exhibit strong seasonality, with annual maxima observed during the monsoon season and minima during pre-monsoon season. Spatial variability of GWS anomalies increases with the extent of measurements, following the power law relationship, i.e., log-(spatial variability) is linearly dependent on log-(spatial extent). In addition, the impact of well spacing on spatial variability and the power law relationship is investigated. We found that the mean GWS anomaly sampled at a 0.25 degree grid scale closes to unweighted average over all wells. The absolute error corresponding to each basin grows with increasing scale, i.e., from 0.25 degree to 1 degree. It was observed that small changes in extent could create very large changes in spatial variability at large grid scales. Spatial variability of GWS anomaly has been found to vary with climatic conditions. To our knowledge, this is the first study of the effects of well spacing on groundwater spatial variability. The results may be useful for interpreting large scale groundwater variations from unevenly spaced or sparse groundwater well observations or for siting and prioritizing wells in a network for groundwater management. The output of this study could be used to maintain a cost effective groundwater monitoring network in the study region and the approach can also be used in other parts of the globe.
(Location: IWMI HQ Call no: e-copy only Record No: H047967)
(2.62 MB)
When estimating canal water supplies for large-scale irrigation schemes and especially in arid regions worldwide, the impact of all factors affecting the gross irrigation requirements (GIR) are not properly accounted for, which results in inefficient use of precious freshwater resources. This research shows that the concept of irrigation response units (IRU)—areas having unique combinations of factors effecting the GIR—allows for more precise estimates of GIR. An overlay analysis of soil texture and salinity, depth and salinity of groundwater, cropping patterns and irrigation methods was performed in a GIS environment, which yielded a total of 17 IRUs combinations of the Oktepa Zilol Chashmasi water consumers’ association in multi-country Fergana Valley, Central Asia. Groundwater contribution, leaching requirements, losses in the irrigation system through field application and conveyance and effective rainfall were included in GIR estimates. The GIR varied significantly among IRUs [average of 851 mm (±143 mm)] with a maximum (1051 mm) in IRU-12 and a minimum (629 mm) in IRUs-15, 16. Owing to varying groundwater levels in each IRU, the groundwater contribution played a key role in the estimation of the GIR. The maximum groundwater contribution occurred in IRUs dominated by cotton–fallow rotations as evidenced by an average value of 159 mm but a maximum of 254 mm and a minimum of 97 mm. Percolation losses depended on irrigation methods for different crops in their respective IRUs. The novel approach can guide water managers in this and similar regions to increase the accuracy of irrigation demands based on all the factor effecting the GIR.
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